Photooxidation of p-Arsanilic Acid in Aqueous Solution by UV/Persulfate Process

Used as a kind of feed additive,p-arsanilic acid can pose a potential risk to organisms when abandoned in the environment. The photodegradation ofp-ASA was investigated under UV-C irradiation in the presence of persulfate (PS) in this work. The addition of PS facilitated the decomposition ofp-ASA and notably, the presence of 50 mmol PS brought about a nearly complete mineralization after 3 h, while an insignificant total organic carbon (TOC) removal was observed under UV irradiation (λ = 254 nm) only. Experimental results proved that sulfate radical (SO4•−) was responsible for the promotion effect. The cleavage of As-C bond released inorganic arsenic and caused the occurrence of various organic products, for example, hydroxybenzaldehyde, nitrobenzene, benzenediol sulfate, and biphenylarsinic acid. The application of PS with UV-C light may throw a light on thorough treatment forp-ASA containing wastewater.Keywords:p-arsanilic acid;photodegradation;UV/persulfate system;sulfate radical