Kinetics and isotherm analysis of 2,4-dichlorophenoxyl acetic acid adsorption onto soil components under oxic and anoxic conditions.
2,4-dichlorophenoxyl acetic acid (2,4-D, pKa = 2.8) is used extensively as a herbicide in agricultural practices. Its sorption behavior on both untreated and soils treated to significantly remove specific components (organic and iron and manganese [Fe-Mn] oxides and hydroxides phases) was investigated under oxic and anoxic conditions. The chemical and structural heterogeneity of the soil components were characterized by elemental analysis and X-ray diffraction (XRD). The coexistence of the various components seems to either mask sorption sites on the untreated soil surfaces or inhibit interlayer diffusion of 2,4-D. All sorption data conform to the Freundlich description and a pseudo-second-order kinetic model. There was a strong positive correlation between sorption capacity K(d), and surface area (r(2) ≤ 0.704), but a negative correlation was uncovered with both pH and organic carbon (r(2) ≤ -0.860). The results indicate that 2,4-D is preferably sorbed under oxic rather than anoxic conditions and it is greater on soils containing a high Fe content. There was incomplete 2,4-D sorption reversibility, with desorption occurring more rapidly under anoxic conditions. The study suggests that stimulation of Fe III reduction could be used for the bioremediation of a 2,4-D-contaminated site.
['Ololade|Isaac A|IA|', 'Alomaja|Folasade|F|', 'Oladoja|Nurudeen A|NA|', 'Ololade|Oluwaranti O|OO|', 'Oloye|Femi F|FF|']
D015084:2,4-Dichlorophenoxyacetic Acid D000327:Adsorption D005290:Ferric Compounds D006540:Herbicides D006863:Hydrogen-Ion Concentration D007700:Kinetics D017895:Manganese Compounds D010087:Oxides D012987:Soil D012989:Soil Pollutants D014961:X-Ray Diffraction
soil components herbicide sorption desorption 2 4-dichlorophenoxyl acetic acid organic matter