A rapid antimicrobial photodynamic water treatment strategy utilizing a xanthene dye with subsequent removal by Goethite Nanoparticles.
Although widely accepted as a water sterilisation technique, chlorination results in the production of potentially harmful by-products, mainly Trihalomethanes. Furthermore, the chlorination process requires specialised infrastructure, management and high costs. In this research paper a potential alternative sterilisation technique was investigated. This rapid three-step process utilized Goethite Nanoparticles and the photosensitising capabilities of a xanthene dye. Rose Bengal (RB) a compound primarily used as a stain to diagnose damaged tissue in the eye was utilized under visible light excitation to sterilise water containing gram-positive Staphylococcus aureus and Bacillus cereus. Bacterial reductions (cfu/ml) of up to 6log10 are reported at RB concentrations of 0.5 mg/L and 10 mg/L for S. aureus and B. cereus, respectively. Goethite Nanoparticles (GNP's), an iron oxyhydroxide, were synthesised by co-precipitation of iron salts and used to adsorb RB post-sterilisation. Poly-vinyl Alcohol (PVA) functionalised GNP's were synthesised to highlight the adsorbent capabilities of the GNP surface. The adsorption capacity for uncoated GNPs was 476.19 mg/g, this reduced to 170.4 mg/g for PVA-GNP's, highlighting the highly porous nature of the synthesised GNP surface. Adsorption was optimal in slightly acidic conditions (pH5-6). The adsorption parameters best followed Lagergens Pseudo-second order kinetics with correlation coefficients close to unity. At the highest envisaged RB concentration (10 mg/L) approximately 20 mg/L GNP's was required to remove the dye from solution post-treatment. Flame Atomic Absorption analysis of the water post-removal revealed Iron concentrations of 0.058 mg/L. This correlates to removal efficacy of 99.71% with residual iron levels below the EU recommended limit of 0.2 mg/L.
['Doyle|Sean|S|', 'Meade|Elaine|E|', 'Gao|Jinhui|J|', "O'Hagan|Barry|B|", 'Callan|John F|JF|', 'Garvey|Mary|M|', 'Fowley|Colin|C|']
D000327:Adsorption D000900:Anti-Bacterial Agents D006863:Hydrogen-Ion Concentration D058085:Iron Compounds D007700:Kinetics D008903:Minerals D053758:Nanoparticles D013211:Staphylococcus aureus D014874:Water Pollutants, Chemical D018508:Water Purification D014966:Xanthenes
Photodynamic water treatment Goethite nanoparticle Magnetic nanoparticle water treatment Nanoparticle accumulative toxicity Nanoparticle residuals Nanoparticle water treatment