UVC-enhanced oxidation of As(III) at neutral pH using zerovalent iron nanoparticles Deisy C. Pabón [1] , Marta I. Litter* [1]

https://www.academia.edu/3065-9736/2/4/10.20935/AcadNano7928 The presence of arsenic in water for human consumption is a dramatic problem that causes serious health problems. Inorganic As species (As(III) or As(V)) are the most common and toxic forms, of which As(III) is the most harmful, mobile and difficult to remove; therefore, preoxidation into As(V) is generally performed in removal procedures. Irradiation using UV-Vis light is a way to enhance the oxidation of As(III) when using zerovalent iron nanoparticles (nZVI). In this study, As(III)-containing solutions of high concentrations (1–10 mg l−1) at a circumneutral pH were treated with commercial nZVI (with an average 50 nm particle size) using different molar ratios (MRs) of As(III) to total iron under UVC irradiation (with a 254 nm germicidal lamp). The optimal conditions for the treatment were an initial As(III) concentration of 1 mg l−1, an MR = 1:30, and a pH of around 6. The oxidation was enhanced compared with that in experiments in the dark and heightened with an increase in the amount of nZVIs. A mechanism was proposed. The most important features of this 254 nm system are that the As(III) oxidation by the nanoparticles is enhanced by UVC irradiation, compared with that in the same experiments under UVA-Vis light (centered at 365 nm), because a higher amount of H2O2 is formed and adding external H2O2 is not needed. The As(V) formed remains partially adsorbed onto the final iron products and partially dissolved in the suspension, from which it can later be removed using conventional technologies. The process is efficient, low-cost, and easily scalable.