The decay of silver nanoparticles in preoxidation process

Highlights: • Exposure to NaClO, H₂O₂, and KMnO₄ promoted the decay of Ag-NPs. • The release of metal ions from NPs should be considered in water oxidation treatment. • Higher dosage of oxidants and calcium ions promoted the decay of Ag-NPs. • The presence of humic acid and sulfide ions inhibited the decay of Ag-NPs. • The decay of Ag-NPs under exposure to oxidants was significantly affected by the pH. To investigate the fate of metal-based nanoparticles in water oxidation treatment processes, the decay of Ag-NPs in the presence of three kinds of water treatment preoxidants, sodium hypochlorite (NaClO), hydrogen peroxide (H₂O₂) and potassium permanganate (KMnO₄), was investigated in this work. Dissolution of Ag-NPs into silver ions (Ag⁺) was found to occur under exposure to NaClO, H₂O₂ and KMnO₄. The morphology of Ag-NPs changed after reacting with NaClO, H₂O₂ and KMnO₄. Factors affecting the decay of Ag-NPs, i.e., the dosage of oxidants, pH, the presence of humic acid, typical ions in water, and the size of the nanoparticles, were investigated. A higher dosage of oxidants, the presence of calcium ions, and lower size of Ag-NPs promoted the decay of Ag-NPs. The presence of humic acid and sulfide ions inhibited the decay of Ag-NPs. The decay of Ag-NPs under exposure to oxidants was significantly affected by the pH. The mechanism of the Ag-NPs in the presence of oxidants under different environmental conditions is also discussed.