Soil treatment with ammonium acetate buffer with a pH range of 4.5–5.5 was the most appropriate for the determination of mobile compounds of Cu and other metals in highly polluted peat soil. Triple soil treatment with water and ammonium acetate is necessary for the complete extraction of the water-soluble and exchangeable fractions, respectively. Additionally, we propose a procedure of full extraction of the exchangeable metal fraction from peat soils while using single treatment with 0.1 N HNO3. This scheme allows evaluating geochemical mobility of metals and current environmental harm of polluted soils with a high content of organic matter.An evaluation of fraction composition and transformation of metal compounds emitted by metal ore processing enterprises and accumulated in soils is crucial for assessing the environmental risks of pollution and ecosystem benefit of remediation. The aim of this study was to develop a suitable sequential fractional procedure for metal pollutants for the peat soils matrix in the impact zone of a Cu-Ni smelter. Three experiment series were performed: (a) the study of the effect of ammonium acetate buffer pH in the range of 3.7–7.8 on the soil metal extraction; (b) the study of the effect of additional volume and frequency of soil treatment with solutions on the content of water-soluble, ammonium acetate extractable, and 0.1 N HNO This study of the content and transformation of metal compounds in soils polluted due to the activities of enterprises engaged in processing metal ores is an important task that allows for us to assess the environmental risks of industrial pollution and predict the effect of soil pollution on other living and non-living components of ecosystems ,2. The cA study of only the gross metal content is not sufficient for the assessment of metal behavior in the soil ,4. The pThe most of sequential extraction procedures separate the following metal fractions: (a) water-soluble; (b) exchangeable; (c) reducible bound to Fe/Mn oxides/hydroxides; (d) oxidizable bound to organic matter (OM) and sulfides; and, (e) residual—compounds firmly bound in the crystal lattices of stable minerals ,8,9,10 .Water-soluble and exchangeable fractions are the most mobile and bioavailable forms of metal compounds in soils . Metal fIt is impossible to achieve 100% selectivity by sequential extraction due to a large number of metal compounds in soil, as their properties can both vary significantly or be similar to each other. Therefore, the choice of extraction method is a compromise between a stronger, but less selective, and less strong, but more selective reagents ,16,17.Ammonium acetate buffer (AAB) is an extracting reagent of complex action, demonstrating various types of interaction with the soil ,8,18. ThFor highly polluted soils, the extraction procedure might differ from the conventional one. Studies of the changes of the number of treatments with extractant, its volume and pH, and duration and speed of shaking with the solution were reported ,19,20.3, because this acid can extract more strongly bound metal compounds than AAB [3 allowed us to describe the sorption of both Cu and Ni by vermiculite and lizardite [Besides the exchangeable fraction, the water-soluble fraction of pollutants also should be analyzed as the most mobile metal fraction . For indthan AAB ,21. The izardite .The activity of the copper-nickel enterprises in the Murmansk region of Russia led to the hard pollution of ecosystems and the formation of industrial barrens . AnalysiThis research aimed to develop the optimal method of the analysis of mobile metal form in extremely polluted peat soil in the impact zone of the copper-nickel plant. The tasks were: (1) the determination of the pH of extractant for the analysis of the exchangeable fraction; (2) the modifying of the standard procedure (increase in the volume of extractant or the number of soil treatments by extractant) providing a high level of extraction of mobile metal compounds (water-soluble and exchangeable fractions); and, (3) the study of 0.1 N nitric acid as the alternative reagent for the full extraction of mobile metal compounds from the peat soil.2. The mixed soil sample was air-dried at a temperature of 20 ± 2 °C and sieved (mesh size of 1.25 mm); the magnetic fraction was removed from the soil.The study site was located at the industrial barren in 0.7 km from the Cu/Ni smelter of the Kola Mining and Metallurgical Company  in the Murmansk Region of Russia. Peat eutrophic soil (Eutric Histosol) was sampled from the depth 0–5 cm, as this layer is the most contaminated. The soil was collected from 10 equidistant points on the total area of 400 mPotentiometric measurements (with the water ratio of 1:25) determined the values of pH and Eh in soil samples .3 concentrated acids.The total content of chemical elements in peat soil was determined after autoclave microwave decomposition in the SW4 system in the DAK100 autoclaves  while using a mixture of HF and HNOThree experiment series were conducted in order to study the influence of the extraction conditions on the metal content in geochemical fractions.4CH3COO and 1 M CHCOOH at different ratios [In the first series, the effect of the pH values of AAB on the extraction of chemical elements was studied. In the first step, a water-soluble fraction was removed from the peat soil by treatment with distilled water (2 g soil per 50 mL of water) to eliminate the contribution of the most mobile fraction. Subsequently, the samples were treated with a 50 mL AAB solution. Nine AAB solutions with pH values of 3.7–7.8 were prepared by mixing 1 M NHt ratios . After 63) were investigated: (1) multiple sequential treatment by water and AAB ; (2) the two-fold increase of extractant volume ; and, (3) one-fold soil treatment by 0.1 N HNO3.In the second series, different treatments of soil by extractants  on the distribution of chemical elements in the potentially mobile form was studied. The soil sample was sequentially treated according to the technique that was proposed by Tessier (as described in ) to deteThe solutions were analyzed by a mass spectrometer with inductively coupled plasma . Multielement calibration solutions Inorganic Ventures   were used for the instrumental calibration. Standard reference materials were used for quality control: CRM-SOIL-A , GSO 7126-84 Bil-1, GSO 902-76 SP-2, GSO 903-76 SP-3, SDPS, SKR-1 .Each determination was performed in five replicates. The precision of detection was 0.1–3% for Ni, Cu, Pb, Cd, Si, Mn, and 6–15% for other elements.The pH of the peat soil was 3.7 ± 0.1, Eh-284 ± 15 mV, and the content of organic carbon was 33 ± 2%. We can determine the content of AAB-soluble metal fraction at different pH values by changing the composition (and pH) of AAB. It should be noted that the acetate ion content decreases in AAB solutions at high pH values, which leads to the predominance of the cation exchange process occurring in the solution. The acetate ion content becomes higher at low pH values, and complexation becomes the primary mechanism of cation retention in the extracting solution.For Cu extraction, we observed the high maximum value at pH ~4.5; the concentrations of Cu decrease at pH value higher or lower than 4.5. This result differs from the data that were reported for soils with low content of organic carbon  that can3 also increased with a decrease of extractant volume , whereas the content of a mobile form of such PTM as Cu, Ni, Co, and Cd was 62–88% . For the3 and AAB showed that the amount of metals extracted by 0.1 N HNO3 was almost the same as their total content after threefold sequential extraction by water and AAB  after the triple treatment led to the redistribution of elements in the potentially mobile form. The percentage of components that were associated with Fe, Mn-hydroxides naturally decreased in the series with the three-fold treatment by AAB, and this tendency was observed for all of the investigated elements . The shaIn the first part of the study, we investigated the effect of the pH values of the AAB solution on the content of the water-soluble and exchangeable metal fractions. AAB with a pH of 7.0 is used to determine the content of mobile metal forms in most of the international protocols ,30,31. AFirst of all, the soil that was studied in this research was characterized by a high content of mobile Cu. The content of elements extracting by AAB was found to be highly dependent of the pH value for Cu and Fe. The concentration of metals in the resulted solutions was maximum at the pH of AAB within a range of 4.5–5.5. Gumbara and Sumawinata  suggeste3, we demonstrated that the fraction extracted by this solution could be, to the same degree, extracted by three-fold treatment with AAB.In the second part of the study, we investigated the effect of repeated soil treatment with extractant on the concentration of metals in the resulting solution, as well as the effect of the increased volume of the extractant. The obtained results indicate the incomplete extraction of water-soluble and exchangeable fractions from highly polluted peat soil when carrying out analyses using the single treatment. This problem is known, especially for soils with a high content of OM . Our resIn the third part of the study, we examined the effect of the full extraction of chemical elements in actually mobile form of elements (water-soluble and exchangeable) while using triple soil treatment by AAB solution on their content in potentially mobile form. Full extraction led to a redistribution of the portion of chemical elements between exchangeable fraction and fractions bounded by Fe/Mn-(hydr)oxides and OM. More stringent extraction conditions lead to the extraction of sorbed forms, the bond strength of which with the carrier phases can be described as less strong. The removal of this fraction does not require the destruction of the carrier phases according to the Tessier method. Information regarding the amount of such forms can be useful in evaluating the changes in the geochemical mobility of metals at alkaline geochemical barriers during soil remediation while using vermiculite- and serpentine rich mining waste .3; (4) extraction of fraction associated with (hydr)oxides of Fe and Mn; and, (5) extraction of fraction bound by OM. Among these fractions, fractions 1–3 are referred to the actually mobile form, fractions 4–5 to the potentially mobile form.Thus, we propose the following modification for the Tessier’s scheme of the sequential extraction of different metal fractions to estimate the geochemical mobility of metals in highly polluted peat soil: (1) three-fold treatment with distilled water; (2) single extraction with AAB; (3) extraction with 0.1 N HNOThe method of the metal extraction with AAB solutions in wide pH range is a useful tool for studying the influence of various factors on the content of mobile components in polluted soil . The div


Quartz sandstone (QS) is a mine waste; therefore, its use in construction allows for both reducing the cost of the concrete and contributing to the utilization of waste. The scientific originality of this study is the identification of models of the effect of QS aggregate on the physicomechanical, durability characteristics, and eco-safety of greener high-strength concrete. The study used an energy-efficient method of non-thermal effects of electromagnetic pulses on the destruction mechanisms of quartz-containing raw materials. The characteristics of quartzite sandstone aggregates, including the natural activity of radionuclides, were comprehensively studied. The features of concrete hardening, including the formation of an interfacial transition zone between the aggregate and the cement matrix, were studied, taking into account the chemical and morphological features of quartzite sandstone. In addition, the microstructural and morphological properties of concrete were determined after a 28 day curing. In this study, the behaviors of the concrete with QS aggregate were investigated, bearing in mind the provisions of geomimetics science on the affinity of structures. The results obtained showed that the QS aggregate had the activity of natural radionuclides 3–4 times lower compared to traditional aggregates. Efficient greener concrete with a 46.3 MPa compressive strength, water permeability grade W14, and freeze–thaw resistance of 300 cycles were also obtained, demonstrating that the performance of this greener concrete was comparable to that of traditional concrete with more expensive granite or gabbro diabase aggregates. The current stage of the development of civilization is characterized by a deteriorating environmental situation, a lack of energy resources as well as natural and technological disasters ,2,3. A pMany authors have worked on research to develop innovative sustainable concrete and/or mortar utilizing some aggregates. Longo et al.  obtainedOf great importance is the cost of aggregates while taking care of the environment. An effective step along this path is the use of simultaneously produced rocks.Granite, gravel, and limestone are the most popular and widespread sources of crushed stone, which are expensive, and their deposits are not available in all countries . The seaThe goal of the paper was to study the possibility of using quartz sandstone, which is simultaneously mined rock, as aggregate for greener high-strength concrete. To achieve this goal, the following tasks were solved, the determination of the activity of natural radionuclides of the QS aggregate, the development of greener high-strength concrete using quartz sandstone (screening as fine aggregate and crushed stone as coarse aggregate), and the study of the physicomechanical properties and durability characteristics of developed concrete.As a coarse aggregate, quartz sandstones of the Lebedinsky deposit (Russia) were used a, which Thus, according to the main indicators, crushed stone from quartz sandstone meets regulatory requirements. The value of intergranular voidness of crushed stone from QS indicates the potential of improving its particle size distribution. Low water absorption of crushed stone from quartz sandstone reduces the water demand of concrete mixes.Samples of crushed stone from quartz sandstone consisted of 95% quartz of the green shale degree of metamorphism. Its quality assessment is based on the internal energy potential, which is determined by the imperfection of the crystal lattice of minerals, inclusions of a mineral-forming medium, gas–air inclusions, surface morphology, degree of crystallinity of minerals, dimension, etc. Thus, based on the study of the mineralogical composition, chemical composition, and structure of the QS mining waste of the Lebedinsky deposit, it can be concluded that all samples met the requirements for raw materials for the production of crushed stone. All experiments were carried out using Portland cement CEM I 42.5N , satisfying the requirements of EN 197-1 ,28,29. T3  consumption of crushed stone of all types. The slump of concrete mixes was 16 cm with a mass ratio of sand to the total aggregates equal to 0.4. To obtain the specified strength characteristics (concrete of classes C 25 and C 30), as well as to identify the potential capabilities of coarse aggregate from quartz sandstone, the cement consumption when selecting the composition of concrete varied from 350 to 400 kg/m3 .To evaluate the granulometric composition of the materials, a MicroSizer 201 laser particle analyzer  was used, which made it possible to determine particles with a size from 0.2 to 600 μm. The specific surface area of raw materials and binders was determined by gas permeability using a PSH-11 device. An ARL X’TRA device  was used for X-ray diffraction (XRD) analysis. The microstructure was studied using a high-resolution scanning electron microscope TESCAN MIRA 3 LMU . The X-ray fluorescence (XRF) pattern was also investigated by scanning electron microscope.The specific effective activity of natural radionuclides of crushed stone was researched using a Gamma Plus universal spectrometric complex  according to Russian State Standard GOST 30108-94 .3 according to EN 12390-3:2009 [Determination of the compressive strength was carried out on specimen cubes with sizes 150 × 150 × 150 mm0-3:2009 . The spe3 in accordance with EN 12390-9:2006 [The freeze–thaw resistance of the specimens was researched by the method of alternate freezing and thawing on cubes of 70 × 70 × 70 mm0-9:2006 . The spe3 in size. For this, a setup having 6 sockets was used. Water was supplied to the lower end part. Visual observation of the resistance to water with increasing pressure was conducted. Furthermore, a flow chart of the studies is provided in The water resistance of concrete was estimated by the “wet spot” on the specimens—cylinders 100 × 100 × 150 mmTo maximize the disclosure of the stored energy of raw materials and their directed use while reducing the energy intensity of the technological process for producing building composites, the methods of chemical, thermal, and mechanical activation were used. The article used an energy-efficient, environmentally friendly method of non-thermal effects of electromagnetic pulses on the destruction mechanisms of quartz-containing raw materials. When current flows with extremely high power but moderately low energy through the matrix of mineral components, electrical breakdown channels as well as induced fracture zones are formed. This leads to the softening of mineral complexes with the formation of highly dispersed particles of increased activity and solves the problem of the destruction of raw materials. As a result, the number and nomenclature of hydration products increases and the density of the concrete increases; this leads to an increase in the mechanical properties of concrete.According to the provisions of geomimetics science on the affinity of structures proposed by Lesovik , for deseffA was determined. In order to obtain the value of effA, the specific activity of radium 226Ra—RaA, thorium 232Th—ThA, and potassium 40K—KA was measured and summarized according to the formula: effA = RaA + 1.31ThA + 0.085KA —is ensured.Granite consists of 30–35% quartz, approximately 60% feldspars, and the rest is mica. The cleavage of feldspars is perfect, but that of mica is very perfect. The adhesion to cement paste for feldspars and mica is very low, so granites cannot be used to produce high-strength concrete ,18. GabbIn the granite structure, quartz does not have as many crystal lattice defects as in quartz sandstone, which explains its lower reactivity. The ITZ is less dense; microcracks are present in it . This is3, the water resistance of concrete corresponded to the W6 grade, and with an increase in cement consumption to 400 kg/m3, it increased to W12–W14. The freeze–thaw resistance of the concrete complied with grades F200 and F300.For structural materials operating in environmental conditions, weather resistance is of great importance, which affects the durability characteristics. Thus, concrete with a crushed stone from quartz sandstones exceeds a similar type of concrete from granite or gabbro diabase crushed stone in strength. The value of compressive strength corresponded to classes C25 and C30. An increase in compressive strength by 14% in concrete with quartz sandstone indicates the possibility of reducing the consumption of cement in such concrete.3, the water resistance of the concrete corresponded to the W6 grade, and with an increase in cement consumption to 400 kg/m3, it increased to W12–W14. The freeze–thaw resistance of the concrete complied with grades F200 and F300. Thus, concrete with crushed stone from quartz sandstones exceeded similar types of concrete with granite or gabbro diabase crushed stone in strength. The value of compressive strength corresponded to classes C25 and C30. An increase in compressive strength by 14% in concrete with quartz sandstone indicates the possibility of reducing the consumption of cement in such concrete.It was established that the use of crushed stone from quartz sandstone provided greater freeze–thaw resistance and water resistance compared to the gabbro diabase or granite specimens. The test results indicated high durability of the obtained concrete. When cement consumption was 350 kg/mThe economic efficiency of the results of the work was to reduce the cost of aggregates through the use of mine waste. In addition to the fact that this waste had no value, it can also generate income for the one who is utilizing it. The environmental objective achieved along with this makes it possible to consider the developed material with the use of aggregates from mine waste as cost-effective and environmentally effective.−Quartz sandstone, which is a mine waste, can be used as aggregate for a high-strength, greenest concrete;−The activity of natural radionuclides of the tested aggregate from quartz sandstone is 3–4 times lower than that of traditional types of crushed stone: granite and gabbro diabase;−The use of a crushed stone from QS provides concrete with strength corresponding to grades C25 and C30. Mechanical properties of cement composite with coarse aggregate from quartz sandstone are 12–15% higher compared to concrete from traditional ones;−3 corresponded to grades F200 and W8, respectively, and with a cement consumption of 400 kg/m3 corresponded to grades F300 and W14, respectively.The freeze–thaw and water resistance of concrete on crushed stone from QS provides a sufficient level of durability. The indicators of freeze–thaw and water resistance of concrete with a cement consumption of 300 kg/mQuartz sandstone is a mine waste; therefore, its use in construction allows both for reducing the cost of the concrete and contributing to the utilization of waste. The novelty of this study is the identification of models of the effect of QS aggregate on the physicomechanical, durability characteristics, and eco-safety of concrete. In the investigation campaign, the properties of greener high-strength concrete made with QS aggregate was investigated, bearing in mind the provisions of geomimetics science on the affinity of microstructures. Results were obtained on the properties of aggregate made of quartz sandstones activated by non-thermal effects of electromagnetic pulses as well as the heavyweight concrete based on it. On the basis of the results obtained, the following conclusions are listed:Furthermore, the perspectives for further scientific research can be directed to the possibility of obtaining aggregates from incidentally mined rocks for the creation of various building products. This will contribute to the expansion of the range of local raw materials used to obtain concrete components and the expansion of the field of research in the direction of studying the features of the processes of structure formation of composites using various fine and coarse aggregates.


The latter data were compared with existing experimental and theoretical data from the literature along with data calculated using the Miedema model.Solution calorimetry with liquid aluminum as the bath was conducted to measure the enthalpy of a solution of magnesium and palladium as well as the standard formation enthalpies of selected magnesium-palladium alloys. These alloys were synthesized from pure elements, which were melted in a resistance furnace that was placed in a glove box containing high-purity argon and a very low concentration of impurities, such as oxygen and water vapor. A Setaram MHTC 96 Line evo drop calorimeter was used to determine the energetic effects of the solution. The enthalpies of the Mg and Pd solutions in liquid aluminum were measured at 1033 K, and they equaled −8.6 ± 1.1 and −186.8 ± 1.1 kJ/mol, respectively. The values of the standard formation enthalpy of the investigated alloys with concentrations close to the Mg Energy is a very important commodity in life. Most energy still comes from natural sources, such as coal and oil, but scientists all over the world are constantly searching for an alternative, renewable, and efficient energy source to reduce the climate change caused by the combustion products of natural fuels, which have a negative impact on the climate . HydrogeResearch on solid-state hydrogen storage materials has been conducted for many years. Some of these materials are metals and their alloys and are capable of reversibly absorbing large amounts of hydrogen. Magnesium has been studied extensively for applications as a hydrogen storage material because magnesium hydride, which Mg creates as it reacts with hydrogen, has a high gravimetric and volumetric density of hydrogen storage  ,6,7. How6Pd, Mg4Pd, Mg5Pd2, MgPd, and Mg0.9Pd1.1).The phase diagram of the Mg-Pd system was estimated for the first time by Nayeb-Hashemi and Clark . It was Next, based on their own experimental data from differential thermal analysis (DTA) for Pd alloys for the composition range between 0 and 56 at.%, Makongo et al.  presente6Pd, Mg57Pd13, Mg3Pd, Mg5Pd2, and MgPd intermetallic phases were conducted and published by Fernandez et al. [6Pd and Mg5Pd2 intermetallic compounds were measured by Delsante et al. [The calculations of the formation energy for the Mgz et al. ,35. The e et al.  using die et al. . They wee et al. .This work is a continuation of research on the thermodynamic properties of the Mg-Pd system initiated by our group. This paper presents an extension of the results of the formation enthalpies of Mg-rich alloys which correspond to intermetallic phases. During the calorimetric measurements, different types of metallic baths were used. The choice of bath is determined by its ability to dissolve the test components forming the alloy during the test. In addition, the bath should have a low melting point, negligible evaporation pressure in the temperature range chosen for tests, and a lower density (as compared to the tested specimen) to prevent the sample from floating on the surface of the liquid bath. For many years, molten tin was used as the main solvent in the calorimetric measurements. However, liquid tin was not always is the best possible solvent for dissolving transition metals, as discussed by Colinet in . In the 2O < 0.5 ppm, O2 < 0.1 ppm, N2 was not monitored and was absorbed by Ti at 1100 K). Calculated and weighted (0.1 mg precision) amounts of metals (Pd and Mg) were melted in a resistance furnace in stainless steel crucibles . After melting and careful stirring, the liquid alloys were poured into a specially designed steel ingot mold. Finally, the obtained alloys were annealed at 663 K for 72 and 84 h  and SEM/EDS (FEI Quanta 3D SEM). A full description of these results was presented in our previous work , and botThe calorimetric studies were performed in a protective argon atmosphere with the use of a Setaram MHTC 96 line evo drop calorimeter using alumina crucibles. The conducted calorimetric studies were similar to our previous calorimetric measurements presented in ,41,42. BfH) values of the measured phases at 298 K were calculated from the difference in the heat effects, which corresponded to heating the samples from room temperature (298 K) to the measurement temperature (1033 K) and observing the dissolution of the studied phases and their components in the aluminum bath. The ΔfH values were computed using the following equation:fH is the enthalpy of the formation of the measured phase; xMg and xPd are the mole fractions of the components, respectively; and The enthalpy of the formation , and these calculated values fluctuate between 5 and 7 kJ/mol of atoms. One can suppose that several reasons influence the discrepancy between the results from the direct synthesis method and those obtained from the solution method. In the direct reaction method, the reason for this may be the partial reaction of the sample during the preparation of the powders, the oxidation of the powders, and the fact that the reaction in the calorimeter may not be complete during the measurement. Moreover, for the direct method, the XRD studies were performed after the sample had cooled down together with the calorimeter, which allowed the sample to have a longer reaction time. Taking these factors into consideration for the discrepancies obtained with the Mg5Pd2 phase, it seems that the dissolution method appears to be more accurate for measuring the remaining palladium-rich phases.As seen in n method , as welln method . A largen method ,46 and t3Ti phase were the results obtained from both calorimetric methods in good agreement, while for the remaining phases from the Al-Ti system the differences were about 5 kJ/mol of atoms for the AlTi phase and about 10 kJ/mol of atoms for the AlTi3 phase. Moreover, it was proven that, during the reaction of titanium and aluminum powders, the first obtained product was the Al3Ti phase, regardless of the applied proportion. For this reason, the data for the enthalpy of formation for the Al3Ti phase obtained from both methods are consistent. In the case of the AlTi and AlTi3 phases, the observed differences in the enthalpy of formation values indicate that the reaction of phase formation was not completed in the calorimeter, and this is the reason for the differences in the results obtained from the two methods.Similar observations have been reported by Rzyman et al. , who com6Pd, ε, Mg5Pd2, and Mg2Pd intermetallic phases that were measured by solution calorimetry a liquid aluminum bath. The obtained data for the limiting partial enthalpy of a solution of Pd and Mg in liquid aluminum can be used in future studies of phases and alloys containing these metals in their composition.This paper presents experimental data of the limiting partial enthalpy of a solution of magnesium and palladium in liquid aluminum at 1033 K, as well as the standard formation enthalpy values of four alloys with chemical compositions close to the Mg6Pd intermetallic phase agrees well with both the values obtained by the solution calorimetry in liquid Sn and direct reaction methods.The obtained value for the formation enthalpy of the alloy close to the Mg5Pd2 intermetallic phase, the ΔfH values determined by both solution calorimetry methods are similar and more exothermic than the data obtained by the direct reaction method.In the case of an alloy with a composition very close to the MgMoreover, data on the standard enthalpies of formation of the Mg-Pd solid phases measured by solution calorimetry showed a slightly better correlation with those obtained by the ab initio calculations than those calculated by the Miedema model.The calculated formation enthalpies of the Mg-Pd phases and alloys by the ab initio method were more exothermic in comparison to those calculated by the Miedema model, and the observed differences varied between 5 and 15 kJ/mol of atoms.


The methodology for determining the models used for predicting the sorption and catalytic parameters in the process was presented. The analysis of the influence of the sorption and catalytic parameters of activated carbons as well as the oxidizer dose on the removal dynamics of organic dyes-phenol red and crystal violet-was carried out based on the designated empirical models. The obtained results confirm the influence of specific surface area (S) of the activated carbon and oxidizer dose on the values of the reaction rate constants related to the removal of pollutants from the solution in a simultaneous process. It was observed that the lower the specific surface area of carbon (S), the greater the influence of the oxidizer on the removal of pollutants from the solution. The proposed model, used for optimization of parameters in a simultaneous process, enables to analyze the effect of selected sorbents as well as the type and dose of the applied oxidizer on the pollutant removal efficiency. The practical application of models will enable to optimize the selection of a sorbent and oxidizer used simultaneously for a given group of pollutants and thus reduce the process costs.The paper presents the results of studies on the modeling and optimization of organic pollutant removal from an aqueous solution in the course of simultaneous adsorption onto activated carbons with varied physical characteristics and oxidation using H The increasing population, environmental pollution and climate change effects, such as severe droughts, place a heavy burden on water resources. Industry is the sector which exerts the strongest environmental pressure on water quality. Along with its intensive development, increasing amounts of new and complex chemical compounds occur, which together with wastewater, as well as municipal and industrial wastes, infiltrate into the natural environment, usually in the first stage during migration to surface waters ,2. SinceThe literature data ,29,30,31Despite numerous studies, the course of this process is not explained in a clear way. According to Toledo , the orgThe results of previous research indicate that the removal of organic compounds from aqueous solution using activated carbons and oxidizing agents belonging to AOPs is a more efficient process than in the case where the oxidation and sorption processes are realized separately. However, there is no universal treatment technology using simultaneous processes. In each case, the technology is adjusted to the specific properties of wastewater to be treated. The opinions on the mechanics of this process are mixed. There is no information on the properties that should characterize the activated carbons used in these reactions and what is the influence of the oxidizing agent on the physicochemical properties of activated carbons. As indicated in previous studies , the effThe application of simultaneous methods for their optimization enables to analyze the influence of the properties of selected sorbents as well as the type and dose of the applied oxidizer on the efficiency of pollutant removal.The application of mathematical models for predicting the course of the adsorption process with set operational sorption parameters was investigated in numerous papers ,41,42,43However, in a majority of cases, the models presented describe the sorption of single pollutants on selected carbon adsorbents. Moreover, greater attention was drawn to the sorption process conditions, rather than to the physicochemical properties of the employed activated carbon. As a result, the practical application of such models is limited, because they cannot be used for predicting sorption of another group of adsorbents. No information on the modeling of sorption in simultaneous processes in the presence of oxidizers was found in the literature. Therefore, devising the models for predicting sorption on activated carbons, which account for the diversity of the physicochemical parameters of a sorbent, different adsorbates and the presence of an oxidizing medium, seems to be reasonable.ehl), methylene number (MBN), iodine number (IN), S, soluble substance content (Cont.s.sol)) and oxidizer dose (H2O2) on the dynamics of the sorption process (Freundlich and Langmuir isotherms) and removal of pollutants from aqueous solutions (reaction rate constants in pseudo-first- and pseudo-second-order equations). The obtained results were used to designate mathematical models (by means of the multiple regression method) for calculating the parameters describing the dynamics of sorption and pollutant removal based on the activated carbon characteristics and oxidizer dose. The calculations were performed using the results of laboratory studies as well as identification of sorption and pollutant removal dynamics in aqueous solutions [The paper presented the methodology of creating the mathematical models for optimization of a simultaneous sorption process of activated carbon adsorption with chemical oxidation of pollutants from aqueous solutions via hydrogen peroxide, on the example of crystal violet and phenol red. The article showed the methodology of conducting statistical analyses aimed at determining the influence of selected carbon characteristics  and phenol red (C19H14O5S), commonly used for dyeing fabrics, paper products and printing ink, thus found in the textile and dye industry wastewater. They are also used as analytic reagents. These substances are characterized by low efficiency of removal from aqueous solutions and wastewater using physical and biological methods.The object of research involved the two dyes: crystal violet , used in the treatment of water and wastewater, removal of organic compounds, including pesticides, as well as dechlorination of water and improvement of its taste;F-200S–spent F-300 carbon following several years of use in a water treatment station in Goczałkowice, to be disposed of;F-200R–F-200S activated carbon following several years of use in a water treatment station in Goczałowice, subsequently regenerated with the Fenton’s agent.In order to determine the correlations between the activated carbon properties and the removal efficiency of the analyzed organic substances, the following organic carbons were selected see :WDex andThe methodology for the designation of models predicting the kinetic parameters in the models describing the sorption isotherms and removal of pollutants in aqueous solutions using activated carbons, was proposed .p, dechlorination half-length-Dehl, iodine number-IN, detergent number-DetN., methylene number-MBN, ash content-Cont.ash, soluble substance content-Cont.s.sol., pH of the aqueous extract-pH) with hydrogen perodixe (H2O2) as the oxidizer.The analyses in the assumed methodology are based on the results of laboratory tests related to sorption and pollutant removal performed on the activated carbons with diversified physical characteristics  as well as regeneration of spent activated carbon. The subsequent measurement steps and their methodology are discussed in detail in The measurement experiments can be divided into several stages which involve analytic determination of the activated carbon characteristics, removing crystal violet and phenol from a solution through: sorption, oxidation via HOn the basis of the conducted experiments , the empirical models were fitted to the theoretical data. For the sorption models, the process kinetics parameters were determined based on the Langmuir and Freundlich isotherms. While removing pollutants from the solution (activated carbon as the oxidizer), the process kinetics was identified based on the pseudo-first- and second-order equations. Thus, the values of reaction rate constants were determined.The influence of carbon characteristics and the oxidizer dose on their dynamics was analyzed on the basis of the process kinetics calculations . For this purpose, the correlation matrices were calculated. This enabled to determine which parameters of activated carbons and oxidizers affect the sorption and pollutant removal processes. Moreover, the correlation between the analyzed characteristics of activated carbons, having a significant influence on the selection of optimal independent variables for the kinetic models, was determined. This served as the basis for designating the models for predicting the values of process kinetics parameters. The characteristics of activated carbons were optimized in order to achieve high pollutant removal efficiency in shortest time possible. The proposed solution, in contrast to those presented in other papers ,58,59 isFreundlich:Langmuir:e—amount of adsorbate adsorbed per unit mass of activated carbon (mg/g), ce—equilibrium concentration of the adsorbate (mg/L), KF—coefficient in the Freundlich isotherm model (mg/g), n—coefficient in the Freundlich isotherm model, KL—coefficient in the Langmuir isotherm model (L/mg), am—sorption capacity value in the Langmuir isotherm model (mg/g).The analysis of sorption onto activated carbons was performed assuming the following equations:Pseudo-first-order:Pseudo-second-order:0—initial substrate concentration (mg/L), ct—substrate concentrations after a given time (t) (mg/L), t—reaction time (s), k1—first order reaction rate constant (s−1), k2—second order reaction rate constant (M−1·s−1)On the basis of the studies on the changes in the concentration of crystal violet and phenol red in the solution in the presence of activated carbon and oxidizer  the foll2). On the basis of the obtained value of this parameters, the identified sorption mechanisms (process physics) were discussed for the analyzed variants of the experiments  in terms of the designated R2 values and differences between them. For instance, when the calculated R2 value for the data interpolated using a pseudo-second order equation was greater than the data modeled with a pseudo-first ordered equation, it was assumed that the kinetics of pollutant removal was in line with Equation (4). In turn, when the R2 value obtained for the data interpolated with the Freundlich isotherm equation was greater than the results of calculations using the Langmuir isotherm, it was assumed that the sorption mechanism was in accordance with relation Equation (1).In the case of sorption and pollutant removal from the solution, the correlation between the results and calculations was measured using the coefficient of determination (RMultiple linear regression (MLR) constitutes one of the simplest and most commonly employed methods for creating linear models. In this method, the forecast relationship has the following form :(5)y=∑i=L, am, KF, and n) as well as removal of pollutants from the solution (k) were determined.In order to optimally assign the independent variables to the empirical models, the correlation coefficients were calculated between the characteristics of carbons as well as the kinetics parameters in the sorption models (Freundlich and Langmuir isotherms) and pollutant removal . These calculations enabled to eliminate the dependent variables from the models. By applying the multiple regression method, the empirical models for calculating the coefficients pertaining to sorption , the value c0 = 20 mg/L was assumed in the calculations for phenol red and crystal violet; ct—substrate concentrations after a given time (t) (mg/L).During the process design, the costs of reagents, its dynamics and degree of pollutant reduction in wastewater are of great importance. In order to design a process optimally, the costs of reagent consumption have to be decreased while simultaneously achieving the highest reduction of pollutants in shortest time possible. On the basis of Equations (3) and (4), the subsequent conditions for process optimization were described using the following relationships:In the presented analyses, the main criterion for the optimization of pollutant removal from wastewater was time t, which enabled to achieve high reduction of dye concentration in the aqueous solution. Therefore, the combination of carbon characteristic and oxidizer dose, for which time t enabling high reduction of pollutants (η = 90%) in the solution was the shortest, was sought.On the basis of Equations (6) and (7), the influence of activated carbons characteristics and oxidizer doses on shortening the time of pollutant removal from the solution  was analyzed assuming the required reduction.2O2 dose and the kinetic parameters of dye removal. The MS method [hl), using different doses of the oxidizer , which were associated with obtaining different kinetic constants k1 and k2 with respect to the removal of both analyzed dyes from the water solution .The multidimensional scaling (MS) method was used in order to visualize the similarity level for the component of matrix containing the data connected with the properties of employed activated carbons along with the HS method ,62 made S method . Its aim2, similarly as for crystal violet, is higher for the Langmuir model, whereas for WG-12, the R2 coefficients are at a similar level. In turn, for the spent activated carbons (F-200R and F-200S) it can be stated that in the case of the regenerated spent carbon F-200S, the sorption dynamics is clearly in accordance with the Freundlich isotherm for both considered dyes. However, the match is not as obvious for spent carbon F-200R, the coefficients of determination R2 are at a similar level in relation to both models; however, for phenol red, R2 is greater for the Langmuir model. Due to slight differences between the coefficients of determination R2, in majority of cases it was difficult to unequivocally determine the sorption mechanism, which was discussed in detail in the paper by Dąbek et al. [On the basis of the conducted research , the thek et al. . While ak et al. ,65,66,67The obtained sorption results indicate that in the case of the fresh activated carbons, this process can be employed as a method for the removal of the analyzed dyes; however, this process requires longer time and is difficult to implement in an industrial installation, due to the presence of other adsorbing substances and suspensions.2O2), were determined. The calculation results were presented in As indicated by the abovementioned results, the sorption process efficiency can be improved by introducing an oxidizing agent into the system. The literature review showed that although the authors unequivocally indicate the purposefulness of integrating sorption and AOPs in order to improve to efficiency of pollutant removal, the mechanism of the simultaneous process is not fully explained; therefore, in order to ensure the optimal conditions, it is necessary to correlate the parameters related to the sorbent parameters as well as the type and dose of the oxidizer. On the basis of Equations (3) and (4), the reaction rate constants in the dye decomposition processes  in the presence of an oxidizer  using empirical models was considered. This aspect is very important from the point of generalizing the calculation results and creating universal models. Taking into account the correlation of selected characteristics of activated carbons (F = f(xi) and n = f(xi) as well as am = f(xi) and KL = f(xi).In order to complete the analyses, the possibility of determining the values of the model parameters  and n. The obtained relations between the parameters in the Freudlich and Langmuir models confirm in most cases that it is possible to develop universal models in which the kinetics of the sorption process is estimated based on the characteristics of the carbons.The results presented in p = 0.05 indicated a strong correlation between the mean dye concentration and the dechloration number, iodine number, as well as specific surface area. In av).Correlation matrices were created first as part of the conducted analyses, in order to evaluate the influence of selected activated carbon characteristics  on the concentration of selected pollutants. The results of analyses were presented in The correlation matrix also indicates that the greater the dechloration number , the greater the mean dye concentration in the solution following the process.Due to the high costs of the studies and the time of conducting the supplementary determinations, an attempt was made to designate the empirical models for predicting the reaction rate constants (k) in the pseudo-first (or second) order equations. For this purpose, the correlation matrices reflecting the relations between the determined kinetic parameters and the characteristics of carbons and the oxidizer dose, were designated. Then, depending on the obtained values of correlation coefficients, the empirical models were determined. The multiple regression method was employed for this purpose.The identification of independent variables for the model was performed using the Fischer-Snedecor distribution model. Statistically significant variables, in the confidence interval of 0.05 were assumed for analyses. Due to the limited amount of measurement data, the multiple cross validation method was used for the numerical experiment. The values of correlation coefficients for crystal violet and phenol red were given in hl) and oxidizer dose (H2O2).There is a correlation (r > 0.5) between the pseudo-first (second) order kinetic parameters and specific surface area (S), methylene number (MBN), dechlorination half-length (Dehl).There is almost complete correlation (r > 0.9) between the pseudo-first (second) order kinetic parameters and specific surface area (S), methylene number (MBN) and dechlorination half-length  of pseudo-first(second) order.An increase in S, DeThe conducted analyses  indicate1 and k2 values were determined with the Fischer-Snedecor distribution method. This served as a basis for creating the empirical models using the MLR method, having the following form:crystal violet (pseudo-first order):On the basis of the above-mentioned analyses, independent variables for the models used to calculate the kcrystal violet (pseudo-second order):phenol red (pseudo-first order):phenol red (pseudo-second order):0—minimal surface of activated carbon assumed for calculations; here, it amounts to S0 = 750 m2, ∆S—calculation step assumed in the analysis pertaining to the impact of changes in the specific surface of activated carbon on the reduction of pollutants; in this work, it was assumed as ∆S = 25 m2, H2O2-oxidizer dose, assumed as 0–3500 mg; β—degree of pollutant reduction in the solution, assumed as 90%.The influence of the activated carbon characteristics as well as the activated carbon characteristics and the oxidizer dose on the dynamics of pollutant removal from the aqueous solution was investigated. In the case of the analyzed dyes, higher coefficients of correlation were obtained using the pseudo-second order reactions see . Therefot·c0−1—is achieved. On the basis of Equation (14) it is possible to determine the effect of changes in the Dehl value on the time of pollutant removal from the solution at the assumed S values and H2O2 dose.Equation (12) enables one to analyze the influence of increasing specific surface of activated carbon for different assumed oxidizer doses on the changes in the pollutant removal time for the required reduction degree. In turn, Equation (13) allows analyzing the influence of increasing the oxidizer dose for the assumed surfaces of activated carbons on shortening the removal time of pollutants from the aqueous solution until the assumed reduction degree—β = ct(1), ηt(2) and ηt(3) curves describing the influence of activated carbon characteristics and oxidizer dose on the removal of the investigated pollutants from the solution   = f were determined for crystal violet –(14) were used to designate the ηsolution . The obtduction) a. Increal violet a. For ext(2) curves, it was observed that introducing an oxidizer into the system leads to an increase in the reaction rate constants. For Dehl = 4.5 and S = 850 m2 the reaction rate constant amounts to k2 = 0.0105 (phenol red)-2 = 0.011 —2O2 = 1600 mg increases their values to k2 = 0.012 and k2 = 0.023, respectively.On the basis of the obtained η2O2 in the reaction system (S = 850 m2 and Dehl = 4.5) shortens the pollutant removal time (phenol red) by 7% in comparison to the system without an oxidizer  by 33.5% compared to the non-modified process. This is in line with the results obtained by Santos et al. [2O2, which enhances the solution decolorization.This translates into a shortening of the pollutant removal time required to achieve the assumed reduction degree. For instance, inclusion of 800 mg Hoxidizer c. Assumis et al. , who indt(2) curves, it was observed that the lower the specific surface of activated carbon (S), the greater the influence of oxidizer on the pollutant removal process. For example, in the case of S = 800 m2 and H2O2 = 1600 mg, 90% crystal violet removal can be achieved 57.0% faster than in the system without this compound. In turn, for S = 900 m2, the same pollutant removal effect can be achieved 44.53% quicker. While analyzing the removal of phenol red from the solution, it was observed that for S = 800 m2 and H2O2 = 1600 mg, the 90% removal can be obtained 15.24% faster than in the system without an oxidizer. In turn, for S = 900 m2 and H2O2 = 1600 mg, 90% phenol red removal is 11.60% quicker than without the oxidizing compound.While analyzing the obtained ηt(3) = f curve was prepared for crystal violet  method was presented in The visualization of similarity levels for the matrix containing the data connected with the properties of the applied activated carbons with H2O2 oxidizer, it can be seen that the points in the graph for particular carbons move closer to each other as the dose increases, and the increasing similarity of the spent carbon to the general characteristics describing the fresh carbon is much more evident in the case of F-200R. Another similarity presented graphically using Multidimensional Scaling, is that the highest applied oxidizer dose (7500 mg H2O2/L) causes that the similarities between the analyzed results of dye removal by all employed carbons  are much greater (the points are spread apart) than in the case of the similarity between the employed carbons with a high oxidizer dose and without oxidizer. This is most evident on the example of relatively close proximity of the points corresponding to WDex 7500 and F 200S 7500 compared to the long distance between WDex 7500 and WDex 0. The distance between F-200R 7500 and F-200R 0 is even greater, whereas the point marked as F-200R 7500 lies closer to the points reflecting the process realized using fresh carbons with the greatest oxidizer dose.There is a visible similarity between the fresh activated carbons WG-12 and WDex and between the spent carbons F-200S and F-200R. Taking into account the amount of added H2O2/L, similarly as in the case of WDex.This is in line with the results of the conducted analytic studies , which s2O2) as well as the characteristics of the carbons: specific surface area (S), methylene number (MBN), dechlorination half-length (Dehl). The conducted laboratory studies showed the key influence of the surface area (S) of active carbon and the dose of oxidizer (H2O2) on the course of the pollutant removal process in the aqueous environment. For example, an increase in the S value from 750 m2 to 850 m2 (phenol red) assuming a dose of H2O2 = 800 mg leads to a decrease in the removal time  by 29.10%. Increasing the oxidizer dose to the value of H2O2 = 3200 mg indicates that an increase in S in the range of 750–800 m2 leads to a decrease of the minimum time required to removal the dye by 24.01% . The addition of an oxidizer into the system leads to an increase in the value of the constants rate. For Dehl = 4.5 and S = 850 m2, the constant rate is k2 = 0.0105 (phenol red) k2 = 0.011 . The addition of the oxidizer in the amount of H2O2 = 1600 mg leads to an increase in their values to k2 = 0.012 and k2 = 0.023. This leads to a required degree of removal of pollutants within a shortened time. It was also found that the smaller the surface of the carbon (S), the greater the influence of the oxidizer on the dynamics of the process of dye removal from the aqueous solution. For example, in the case of S = 800 m2 and H2O2 = 1600 mg, 90% dye removal  can be achieved with time shortened by 57% (compared to the system without oxidizer). In turn, for S = 900 m2, the same effect of dye removal can be obtained in time shortened by 44.53%. Dechlorination half-length (Dehl) also has a significant impact on the dynamics of the process. The increase in the Dehl value leads to a decrease in the rate of pollution removal. For example, for S = 850 m2, the increase in Dehl from 4.5 to 4.7 leads to an extension of the removal time of crystal violet from aqueous solution by 17.58% . For S = 850 m2, the increase in Dehl from 4.5 to 4.7 results in an extension of the removal time of phenol red from solution by 7.96% . The aforementioned correlations give the assumption for further modelling and process optimization.The obtained relations between the parameters in the Freudlich and Langmuir models confirm in most cases that it is possible to develop universal models in which the kinetics of the sorption process is estimated based on the characteristics of the carbons. The conducted analyses show that there is a strong correlation between the pseudo-first and second-order kinetic parameters, and the dose of the oxidizer  are much greater than in the case of the similarity between the same applied carbons with a high dose oxidizer and no oxidizer.The visualization of the similarity levels for the matrix containing the data related to the properties of the applied activated carbons together with oxidizer as well as the kinetic parameters of dye removal based on the multidimensional scaling method (MDS), indicates that the similarity of the spend carbons to the general characteristics describing fresh carbons increases with the oxidizer dose. The highest dose of the oxidizer used (7500 mg Hhl value on the time of pollutants removal for the assumed S values and the oxidizer dose.The developed models allow for analyzing the influence of the specific surface of activated carbon and applied different doses of the oxidizer on the change of the time of pollutants removal from aqueous solution at the required degree. The above-mentioned models also allow for analyzing the influence of the oxidizer dose increase for given surfaces of activated carbons on the decrease of the time of pollutants removal from the aqueous solution until the assumed degree achieved. The models can be also applied for determination of the impact of the change in the DeThe models developed on the basis of the analysis of the correlation between the kinetic parameters of the pollutant removal from the aqueous solution and the characteristics of the carbons together with the doses of the oxidizer used, are universal in nature. They allow for the prediction of simultaneous sorption and oxidation processes, taking into account the diversity of physicochemical properties of the sorbent, various adsorbates as well as the type and dose of the oxidizer. Thus, it will enable to optimize the selection of a sorbent and oxidizer used simultaneously for a given group of pollutants which allows to avoid the costly and time-consuming laboratory tests in order to adapt the process to the changing technological parameters.


The crystallization characteristics of composites were analyzed, the curves of the conductance current with the change of field intensity were analyzed, and the space charge distribution of each material were investigated. The results of crystallization show that the crystalline properties and crystallinity of the composites are higher than the matrix LDPE, the addition of SiO2 particles increases the composites’ crystallinity significantly, and the intercellular spacing of micro-nano composites is the smallest among all materials. The curve of conductance current versus electric field intensity shows that the tightness of the crystal structure can effectively hinder the movement of the molecular chain, inhibit carrier migration, while shortening the free travel of electrons, thereby reducing the electric conduction current of the material. The experimental results of the space charge accumulation curve further show that the compact crystal structure of the material is beneficial to the dissipation of space charge in the dielectric.Low-density polyethylene (LDPE) is one of the most comprehensive products used as insulation materials in power equipment. How to improve its dielectric properties by doping inorganic particles in LDPE has always been the focus of many researchers. In this paper, silica (SiO High-voltage DC cable provides the possibility of accurate and real-time control of power transmission in a power system. At the same time, it can make the asynchronous interconnection of power grid safe and stable in different frequencies and incompatible states. It is still widely regarded at home and abroad as a cutting-edge technology. Low density polyethylene (LDPE) is widely used in the production of high voltage DC cable because of its excellent electrical insulation performance and processing characteristics ,2. Howev2 and studied the effect of functional group chain length on polyethylene/silica nanocomposites. They found that the chain length of the functional group will affect the motion mechanics process of charge transport, and at the same time, the removal of hydroxyl on the surface of SiO2 will make it hydrophobic, thus changing the charge transport behavior [2 particles and nano-Al2O3 particles in matrix LDPE by the melting-blending method and found that the concentration and type of nanoparticles have a significant impact on the mechanical and electrical properties of materials. They found that when the content of nanofiller was low , the dispersion of nanopowder was better, the interfacial adhesion was enhanced, and the mechanical properties were the best. Among all of the composites, PE/2% nano-Al2O3 had better mechanical and dielectric properties [In recent years, it has been found that the addition of inorganic particles in composite materials can effectively improve the breakdown field strength ,9,10, subehavior . Panaiteoperties . Tjong eoperties .Nanoparticles are easy to agglomerate, and it is difficult to achieve excellent dispersion in the composite system; this varies the conclusions drawn by different researchers. In order to improve the dispersion of nanoparticles in a polymer, people try to add micro- and nanoparticles into the matrix polymer at the same time, hoping to obtain composite materials with excellent performance through the interaction of micro- and nanoparticles. At present, existing studies have shown that adding micron particles together with nanoparticles into the matrix can not only avoid the agglomeration of nanoparticles, but also increase the performance of the matrix ,27,28. M2 and layered micro-MMT were doped into polyethylene matrix, both of which SiO2 and MMT doping mass fraction were 1 wt%. The MMT/LDPE, SiO2/LDPE, SiO2-MMT/LDPE and MMT-SiO2/LDPE micro-nano composites were prepared by melt blending, of which the order of adding micro- and nanoparticles is changed in SiO2-MMT/LDPE and MMT-SiO2/LDPE micro-nano composites. From the polarizing microscopic test and microcosmic test, the microcrystalline structure of each material could be explored. The composite conductivity current and space charge characteristics under different electric field intensity and order of adding micro-nano particles were discussed in this article, which could explore the impact mechanism of micro- and nanoparticles on internal electrical charges transport and space charge suppression property of composite In this article, a bridge between the microstructure and the macroscopic electrical properties is established, which provides a theoretical reference for understanding the influence of the microstructure on the macroscopic properties. Experimental results show that the compactness of material crystal structure has a significant impact on electrical properties.The nano-SiO2 selected in the experiment was from Beijing Deke Daojin Science and Technology  with a size of 30 nm. The MMT was purchased from Qinghe Chemical Plant in Zhangjiakou, China. The particle size of the original montmorillonite is about 40–70 μm, and the cation exchange capacity is 0.9–1.2 mol/kg. Silane coupling agent (KH570) was purchased from Beijing Deke Daojin Science and Technology. Low density polyethylene (LDPE) was purchased from Jinshan Petrochemical Company , with a density of 0.924 g/cm3 and a melting index of 2 ± 0.3 g/ (10 min 2.16 kg).Our research group previously set the particle addition content at 3% and found that the composite material has not been effectively improved in terms of crystallization behavior and conduction current performance . Relevan2 treated with KH570 coupling agent and MMT modified by organic intercalation of KH570 and Octadecyl Trimethyl Ammonium Chloride were melted and blended with LDPE matrix by torque rheometer. Five kinds of composite materials were prepared, both the content of SiO2 and MMT are 1 wt%, and the order of adding SiO2 and MMT particles was changed. The specific operations are as follows:Hydrophobic SiO2 or MMT particles) was added for melting blending. LDPE, MMT /LDPE, SiO2/LDPE, SiO2-MMT/LDPE, and MMT-SiO2/LDPE composite materials were prepared successively according to the above operation. During the preparation of SiO2-MMT /LDPE and MMT-SiO2/LDPE composite materials, the addition order of SiO2 and MMT particles was changed. SiO2-MMT/LDPE composite materials were first added with SiO2 particles and then MMT particles, while MMT-SiO2/LDPE composite materials were first added with MMT particles and then SiO2 particles. After materials were made, each material was cut into relatively small particles with scissors and placed in a dry environment for 24 h pretreatment. Then, plate vulcanization machine for the tabletting operation was used. The temperature of the plate vulcanization machine was set at 140 °C. The material was treated with step-up pressure method; that is, 0 MPa pressure for 5 min, 10 MPa pressure for 5 min, and finally under full pressure (15 MPa) for 5 min. Then, the samples were obtained by cooling under full pressure.The temperature was set at 140 °C and the speed was 50 r/min by a computer connected to the internal mixer. Before the formal experiment, it is necessary to clean the internal mixer with pure LDPE, and then prepare the samples required for the experiment. Firstly, the low-density polyethylene material was added to the internal mixer for about 20 min. After it was completely melted, the filler (SiO4 and concentrated H2SO4 (etching solution) with a mass fraction of 5% for 5 h, and the solution was stirred every half an hour, so that the crystal morphology of various materials could be better observed under a polarizing microscope. After etching, the samples were taken out with tweezers and washed with plenty of deionized water. The washed samples were placed in an ultrasonic cleaner and cleaned again for about a quarter of an hour. After the moisture on the surface of the sample evaporates, each sample was placed under a polarizing microscope for observation and photographing.The crystal morphology of samples was observed with polarizing microscope . Firstly, the samples were immersed in a pre-configured mixture of KMnOThe crystallization and melting process of the samples were measured by the method of differential scanning calorimetry (DSC), and DSC-1 equipment of Mettler Toledo was used. The temperature rises and falls rates were both selected to be 10 °C/min and carried out under a nitrogen atmosphere. The weighing amount of each sample is 10–15 mg. The samples were first raised from room temperature (25 °C) to 140 °C and then cooled to room temperature (25 °C). This is to eliminate the thermal history of various materials and make the polymer melt into a uniform molten state distribution. The ordered structure in the polymer melt has been eliminated, and it has become a completely disordered melt . After that, the temperature was slowly raised to 140 °C again. During the heating process, the DSC curve was plotted.This experiment is based on the Chinese standard GB/T 1410-2006. The measurement system consists of a high voltage DC generator, a protective resistance, a picoammeter and a three-electrode measuring unit, as shown in In this experiment, pulsed electro-acoustic (PEA) method is adopted. The system consists of high voltage DC power supply, pulse generator, upper and lower electrodes, preamplifier, oscilloscope and computer, etc., as shown in 2 and MMT separately and changing the order between them and blended with LDPE. 2, the unit cell size was further reduced, but the unit cell spacing was slightly larger. It can be seen from 2-MMT/LDPE composite prepared by adding SiO2 particles first and MMT particles later are further reduced. In 2/LDPE with MMT particles added first and then SiO2 particles are slightly reduced compared with SiO2-MMT/LDPE with SiO2 particles added first and then MMT particles, and the internal crystal structure of the material is more compact. This is because the large-sized particles are added first, and the large-sized particles occupy a certain space in the matrix, and then the small-sized particles are added to further fill the gaps. The large-size particles added later in the SiO2-MMT/LDPE composite material squeezed and destroyed the structure formed by the small-size particles, so the structure is not as tight as the MMT-SiO2/LDPE.The composite materials prepared by compounding SiODSC-1 differential scanning calorimeter was used to test the crystallinity and melting temperature of composite materials. The measurement condition was nitrogen atmosphere, the rising and cooling rate was 10 °C/min, and the temperature range was 25 °C to 150 °C. The test results were shown in B is the rate of temperature rise/fall, and the calculation results are listed in The melting enthalpy tion (1) .(1)Hm=6−1 . The melting temperature, crystallinity and melting heat of the five samples are shown in The crystallinity of the five samples can be calculated according to Equation (2), and the calculation results are shown in 2/LDPE material increased significantly, which may be due to the small size of SiO2 particles and the positive effect of heterogeneous nucleation. SiO2 particles were added first, and then MMT; however, the size of MMT particles is too large—the addition of MMT particles into the matrix will change the original crystal structure. At the same time, the large-size particles added later, as a nucleation center, will form new unit cells, which will inevitably squeeze the unit cell formed by the matrix and the small-size particles added first, and the original crystal structure will be extruded and destroyed, so that the crystallinity of the composite material is not as good as that added SiO2 particles alone. MMT particles were added first and SiO2 particles were added later, the size of MMT particles was large and the size of SiO2 particles was small, small-size particles was not as easy to squeeze into the material as that of the large-size particles, and unit cells formation is limited. As a result, the extrusion effect was weak and the nucleation interval could not be expanded as that of the large-size particles, so the crystallinity was slightly smaller than that of SiO2-MMT/LDPE. At the same time, adding particles will build many new heat conduction channels in the material, so that the melting temperature of the composite is improved.According to 2-MMT/LDPE slightly higher than that of MMT-SiO2/LDPE.From the experimental results, the smaller the particles, the more obvious this effect. When two kinds of particles are added, the latter will introduce into the heat conduction channel and extrude the original, and the extrusion effect is slightly greater than the introduction effect, so the melting temperature is reduced. In this process, large-size particles will be easier to squeeze in, easier to form gaps, and more heat conduction channels will be formed, which makes the melting temperature of SiOrrelated . Combine2-MMT/LDPE composite material, small-sized particles are added first and then large-sized particles; the squeezing of large particles expands the space for the electron movement, and a new conductive channel may even be constructed. Thus, the conductance current will increase.According to Equation (3), it is known that the threshold of field intensity will be reduced at this time, which is consistent with the experimental results in In order to better analyze the data, MATLAB software was used in this paper to fit the data in When there are traps in the medium, the traps will capture the charge, so the current rises slowly. If energy is applied to the medium all the time and the trap is filled, the current will rise sharply at this time, and the transition voltage meets the following equation:We can deduce the values of trap density and carrier mobility by Equations (4) and (5) , and theAccording to the results in 2-MMT/LDPE with MMT-SiO2/LDPE, the former will change the local state structure during the crowding process due to the large size of the MMT particles added later, which will lead to the increase of traps, thus resulting in the result that the trap density is higher than MMT-SiO2 /LDPE. From the carrier mobility of the composites, it can be seen that the addition of particles will hinder the movement of molecular chain and the migration of carriers, while the addition of large-size MMT particles weakens the blocking effect and increases the carrier mobility of SiO2-MMT/LDPE.Combined with the PLM experimental figure analysis, it can be seen that the closer the structure, the smaller the trap density inside the composite material, which further proves the previous inference. Comparing SiOAfter adding MMT particles, the space charge in the sample dissipates obviously. It can be seen from the PLM figure that the addition of MMT particles makes LDPE crystal perfect and structure more tightly regular, eliminating some LDPE structural defects, making some traps become shallow or disappear, which makes it difficult to capture charge and reduces the accumulation of space charge near the electrode. The results in 2 particles can also improve the structure of the composite, resulting in the reduction of space charge accumulation of SiO2/LDPE composite, but also lead to the introduction of deep traps [2/LDPE, while the space charge accumulation of the material is significantly lower than that of the latter, which indicates that most of the traps in MMT/LDPE are shallow traps, while those in the latter are deep traps. According to reference [2/LDPE.PLM results show that the introduction of SiOep traps . As showep traps . In thiseference , shallow2 particles and then MMT particles to create the positive and negative charges inside the material interlace. This occurs because of the addition of larger particles creates gaps in tightly packed structures. It can be seen from The first step is to add SiO2 particles makes the material structure compact and reduces the number of traps. Due to the introduction of MMT and SiO2 particles, the effect of deep traps and interfaces in the medium is enhanced, and the anti-electric field and interface scattering factors are more intense. Therefore, the space charge suppression effect of the MMT-SiO2/LDPE composite material is significantly improved. The experimental results are shown in However, adding MMT particles first and then the SiO2 particles into the matrix LDPE will make the internal crystal structure of the material more compact. The structure of the first large and then small addition mode (adding MMT particles first and then SiO2 particles) is more compact than that of the small first and then large addition mode (adding SiO2 particles first and then MMT particles). The latter will have a slight increase in structure gap and larger nucleation space due to the crowding of large particles. From the DSC experimental results, the simultaneous addition of micron MMT particles and nano-SiO2 particles will destroy the original crystal structure. In addition, the crystallinity of SiO2-MMT/LDPE and MMT-SiO2/LDPE is slightly lower than that of a single particle.From the PLM experimental results, it can be confirmed that the introduction of micron MMT particles and nano-SiO2/LDPE composite prepared by adding large-size MMT particles and then adding small-size SiO2 particles has an obvious blocking effect on carrier migration.From the curve of conductance current changing with field intensity and with the addition of particles, the structure of the material becomes compact. Some traps become shallow or disappear, and the threshold value of field strength is advanced. Meanwhile, the compact structure can effectively limit the movement of the molecular chain and reduce the conductance current. The MMT-SiO2-MMT/LDPE composite material was made by adding small-sized SiO2 particles first and then large-sized MMT particles. Due to the later squeezing of large particles (MMT), there are gaps in the structure, which reduces the effect of suppressing carrier migration. At the same time, new localized states appear in the material, which results in new traps and obvious space charge accumulation. The structure of MMT-SiO2/LDPE composite material made by adding large-size MMT particles first and then small-size SiO2 particles is more compact. While fully hindering the migration of carriers, it also aggravates the effects of scattering and anti-electric field and has a significant suppression effect on space charges.From the results of the space charge accumulation distribution curve, the compact and complete structure will make part of the localized state in the material become less than matrix, and cause the traps inside the material to be shallower or even disappear. After particles are added, the multiple effects of scattering and the counter electric field will increase the inhibition effect of the composite material on the space charge. The SiO


The smoother surface could be attributable to the reduced mean free path of silver due to the cage effect by the aluminum dopant.Ultra-thin and continuous metallic silver films are attracting growing interest due to the applications in flexible transparent conducting electrodes. The surface morphology and structure of silver film are very important for its electrical resistivity and optical loss. Therefore, roughness control is essential for the production of ultra-thin metallic electrode film. We have investigated the effect of aluminum doping on the improvement of surface morphology of ultra-thin silver films using molecular dynamics simulations. Al-doped silver films showed smaller surface roughness than pure silver films at various substrate temperatures. When the temperature of the substrate was 600 K, the roughness of Al-doped silver film first decreased, and then increased with the increase of the incident velocity of silver atoms. Silver atoms were more likely to agglomerate on the surface of the substrate after adding aluminum atoms, as aluminum dopants promoted the immobilization of silver atoms on SiO Ultra-thin metal films are wildly applicated in metamaterials, plasmonic devices, nanophotonic, and light-emitting diodes ,2. Recen2 substrate. Different deposition parameters, including the substrate temperature and incident velocities, were considered. Comparative analysis and a discussion of surface morphology and the initial formation between the pure silver film and the Al-doped silver film were carried out. This paper is expected to provide a theoretical reference for the preparation of high-quality ultra-thin silver film. For example, the kinetic energy of the incident atom is usually achieved by increasing the sputtering current power, whereas the power adjustment affects the concentration of the incident atom. Therefore, a separate discussion of the effects of concentration and incident kinetic energy in atomistic insights would be helpful for further investigation.In this paper, molecular dynamics (MD) simulations have been employed to investigate the aluminum doping effect on the deposition and growth process of silver films on amorphous SiOx-axis) × 85.53 Å (y-axis) × 120.00 Å (z-axis) as a super unit cell, which comprised the substrate region and the deposited film region, as shown in Molecular dynamics simulation is a well-established approach that is widely used for computational sub-micron scale investigations ,24. The 2 substrate was modeled as a tetrahedra-like structure and consisted of 3420 silicon atoms and 6912 oxygen atoms, which was defined as three blocks: the fixed block, the thermostat block, and the free block. The fixed block was defined from the bottom to 5 Å to prevent the substrate from slipping during the deposition along the Z direction, in which the atoms were fixed and could not move out through the bottom boundary. The thickness of the fixed block was proven to be sufficient in deposition simulations by a previous report [2 were considered.The amorphous SiOs report . The thes report . The temLJ is defined below:The parameters of potential functions and corresponding interactions between atoms are very important for the accurate prediction of the dynamics and material properties. The parameter set for the Tersoff potential ,30 had bij is the distance between atom i and atom j; ɛ is the height of Lennard–Jones potential energy. When Lennard–Jones potential energy is used for mixed materials, the two elements  should be using the Lorentz–Berthelot combination rules [LJ parameters are listed in In the formula above, γon rules . The LJ s, which was computed as follows [i is the Z coordinate of the topmost atoms in each region, Zmean is the mean height of the Z coordinate of the topmost atoms in each region, and n is the total number of regions divided. In this quantitative evaluation, the deposition surface was divided into 55 × 42 regions along the X-Y plane.The open visualization tool (OVITO) was used for the visualization of the calculation results, displaying the deposition process and the reactions to surface morphology . The sur follows :(2)Rs=∑i2 substrate are shown in The deposition process of pure silver film and Al-doped silver film on SiOFour snapshots of different times are presented to describe the deposition process. 2 substrates, with the aluminum proportion ranging from 0% to 30% in the deposited atoms. It is obvious that adding aluminum atoms greatly reduced the roughness of the film surface compared to pure silver film . Moreover, the surface morphology of Al-doped silver films gradually became rough when the proportion of aluminum atoms was above 10%. That is, the best doping concentration ratio for Al-doped silver film was 10% at a temperature of 600 K, while the value of RMS was around 4.65 Å.To further quantify the effects of aluminum composition on Al-doped silver film, different doping ratios of aluminum in silver films were considered. The temperature of the substrate is also a key parameter for the deposition. In this section, the effects of the deposition temperature of the substrate on the surface morphology of ultra-thin silver film were simulated and discussed. For pure silver deposition cases, 22,000 silver atoms were deposited in each calculation, while 20,000 silver atoms and 2000 aluminum atoms were simultaneously deposited in each calculation of Al-doped deposition. The temperatures of the substrate were increased from 450 K to 900 K.2 substrate are shown in z-axis. As shown in The snapshots of the deposited process of pure silver film and Al-doped silver film on SiOIn order to further quantify the effects of substrate temperatures on the surface morphology, the RMS of silver films were calculated by a statistical atom coordinate. The calculation results are presented in z-axis was set to 0 degrees, while the incident velocity of the silver atoms was maintained at 2 Å/ps. In each calculation, 20,000 silver atoms and 2000 aluminum atoms were deposited. The temperature of the substrate was set to 600 K in each simulation case. The surface morphologies of the Al-doped silver films grown on SiO2 substrate at different incident velocities of aluminum atoms are shown in z-axis. The surface morphology of the Al-doped silver film became smoother as the incident velocity of the aluminum atoms increased.The source power of sputtering or e-beam is also a key parameter for the fabrication of ultra-thin silver film electrodes, which determines the initial kinetic energy of deposition atoms. Therefore, the parameter of the incident velocity of silver and aluminum atoms was introduced into the study of Al-doped silver film deposition. In order to analyze the influence of aluminum atomic velocity independently, the incident velocity of aluminum atoms changed from 1 Å/ps to 60 Å/ps, and the incident angle from the To further quantify the effects of the initial incident velocity of aluminum atoms on the surface roughness of Al-doped silver film with different incident velocities of silver atoms, two more cases were calculated, in which the incident velocities of silver atoms were set at 5 Å/ps and 10 Å/ps, respectively. The RMS results of the Al-doped silver film versus the initial incident velocity of the aluminum atoms are presented in The surface roughness of Al-doped silver films significantly decreased as the velocity of the aluminum atoms increased from 1 Å/ps to 10 Å/ps. In the case of the velocities of the silver atoms being 5 Å/ps and 10 Å/ps, as the value of velocity continued to increase, the surface roughness of the Al-doped silver films decreased slightly. On the contrary, in the case of the velocity of the silver atoms being 2 Å/ps, the surface roughness of the Al-doped silver films increased slightly as the value of velocity continued to increase. These results indicate that a higher initial kinetic energy of aluminum atoms is beneficial to the formation of better surface morphology. Similar experimental research on sputtered silver films revealed that silver film prepared at plasma power 25 W contained more discontinuous pores than the film prepared at plasma power 50 W, and the surfaces are smoother when the plasma power increased to 75 W and 100 W . Another2 substrates at different incident velocities of silver atoms. The incident velocity of aluminum atoms was 2 Å/ps. The atoms are colored by the height of their coordinate along the z-axis. It is obvious that the surface morphology of Al-doped silver films was rough at 600 K, while it became smooth as the incident velocity of the silver atoms increased. This is because the high kinetic energy of aluminum atoms can overcome the random thermal motion of the substrate atoms and form a chemical bond with oxygen.The incident velocity of silver atoms should be discussed further to explore the effect of the incident velocity of deposition atoms on the surface morphology of Al-doped silver films. The following quantity calculations present the deposition process of Al-doped silver films that the incident velocity of silver atoms varies from 1 Å/ps to 60 Å/ps are shown in 2 substrate are shown in 2 substrate.Taking the above results into consideration, the morphological evolutions of ultra-thin Al-doped silver film revealed that a few aluminum atoms may strongly influence the migration and subsequent growth of silver films. Further research is presented to discuss the effects of aluminum atom doping on the initial deposition stage. The migration characteristics of silver atoms and aluminum atoms on SiOIn the deposition of the aluminum doping case, several silver atoms with a single aluminum atom were deposited on the substrate, and the snapshot results are shown in 2 substrate is larger than that of aluminum atoms, and aluminum atoms are more easily attached to SiO2 substrate than silver atoms due to their stronger bond with the oxidized surface. Then, the immobilization of the aluminum atoms promotes the immobilization of the silver atoms on the SiO2 substrate. It can be explained by the anchoring effect [Furthermore, reports show that the bond strength of Ag-O bonds is much weaker than that of Al-O bonds . This isg effect ,43, in wλ is a function of the concentration c of impurity, as A and B are constants. Increases in the concentration of aluminum results in the reduction of the mean free path of silver, and thus, the agglomerations. As a consequence, the roughness decreases.The reduced roughness due to the additive aluminum atoms in the subsequent growth process could be further explained by the sluggish migration, according to the cage effect , in whic2 substrate and formed a smoother silver film. Further studies indicated that Al-doped silver films show better surface roughness than pure silver films at various substrate temperatures. Moreover, when the temperature of the substrate is set to 600 K, the RMS of the Al-doped silver film first decreased, and then increased with the increasing of the incident velocity of deposited silver atoms. The optimum injection velocity was 30 Å/ps for the silver atoms and 10 Å/ps for the aluminum atoms. The atomic migration mechanism is that silver atoms are more likely to agglomerate on the surface of the substrate after adding aluminum atoms, as aluminum dopants promote the immobilization of silver atoms on SiO2 substrate, due to the anchoring effect. The smoother surface could be attributable to the reduced mean free path of silver, due to the cage effect by the aluminum dopant. The simulation results of this paper could be beneficial in guiding and regulating the deposition process and analyzing the film characteristics of transparent metallic conducting electrode films.We have systematically studied the effects of aluminum doping on the initial growth of ultra-thin silver films using molecular dynamics simulations. The critical conditions of Al-doped silver films under different aluminum compositions, substrate temperatures, and initial incident velocities were calculated, and the surface morphology and RMS surface roughness of deposited film were discussed. The results show that aluminum dopant promoted the immobilization of silver atoms on SiO