Removal of Arsenic from water by photocatalysis

What is it about?

A typical approach for removing As from drinking water includes a pre-oxidation step to transform the more toxic As(III) to As(V) and a subsequent separation process for As(V) removal. Unfortunately, typical oxidants result in the formation of toxic oxidation by-products, so alternative options, such as TiO2 photocatalysis, have been investigated. But As(V) produced by oxidation of As (III) remains adsorbed on the catalyst surface, thus limiting process efficiency. In this work a new catalyst based on molybdenum oxide supported on titania (MoOx/TiO2) was succesfully investigated (complete photocatalytic oxidation of As(III) (5 mg L−1) to As(V) took place after 120 min exposure to UV-A light) to overcome this drawback. Moreover, UV LED irradiation was found to be more effective (96% As(III) converted) than the UV-A light system (75% As(III) converted).

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Why is it important?

High oxidation efficiency of As(III) (more toxic) to As(V). Moreover, the new photocatalytst (MoOx/TiO2) did not adsorb As(V) which was completely released into the solution, thus preserving its surface activity and, consequently, drastically reducing operating costs related to catalyst reactivation

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