Removal of p-arsanilic acid and phenylarsonic acid from water by Fenton-coagulation process: influence of substituted amino group

Abstract Phenylarsonic acid compounds, which were widely used in poultry and swine production, are emerging contaminants due to their considerable solubility in water and the highly toxic inorganic arsenic species forming potential during their biotic and abiotic degradation in the natural environment. Herein, we investigated the optimal conditions to treat typical organoarsenic contaminants ( p -arsanilic acid ( p -ASA) and phenylarsonic acid (PAA)) in aqueous solution based on Fenton-coagulation process for oxidizing them and capturing the released inorganic arsenic, and elucidated the influence mechanism of substituted amino group on removal. Results showed that the pH value and the dosage of H 2 O 2 and Fe 2+ significantly influenced the performance of the oxidation and coagulation processes. The optimal conditions for removing 20mg L -1 -As in this research were: 40mg L -1 Fe 2+ and 60mg L -1 H 2 O 2 (the mass ratio of Fe 2+ /H 2 O 2 = 1.5), initial solution pH of 3.0 and final solution pH of 5.0 adjusting after 30 min Fenton oxidation reaction. Meanwhile, the substituted amino group observably influence the oxidation and coagulation performance of phenylarsonic acid compounds. Amino group could make phenylarsonic acid compounds more easily be attacked by ·HO and supply more binding sites for forming complexes with Fe 3+ hydrolysates, resulting in higher oxidation rate and better coagulation performance.