Roxarsone (ROX) is an organoarsenic compound that extensively served as feed additives in poultry industry. ROX tends to transform into more toxic inorganic arsenic in the natural environment. Post-treatments are necessary to completely eliminate arsenic contamination and relative environmental risks. In this study, a novelα-FeOOH@GCAnanocompositewas used as a bifunctional reagent for ROX decontamination. Activation of persulfate (PS) by α-FeOOH@GCA under UV irradiation (α-FeOOH@GCA/PS/UV) was first time employed for in-situ degradation of ROX and simultaneous adsorption of released arsenate (As(V)). Nearly 100 % of ROX was transformed in this system at relatively low dosage of α-FeOOH@GCA catalyst (250 mg L-1) and K₂S₂O₈ (3 mM) after 120 min irradiation and the released As(V) from ROX oxidation could be simultaneously adsorbed onto the surface of α-FeOOH@GCA.The possible transformation pathway of ROX is proposed starting from the cleavage of As-C bond of ROX by the attacking from the dominant surface sulfate radicals produced in α-FeOOH@GCA/PS/UV system. The adsorbed As(V) on the surface of α-FeOOH@GCA derived from ROX oxidation was recovered as an efficient photocatalyst Ag₃AsO₄. This study provides an novel integrated design to simultaneously combine oxidation of ROX, immobilization of As(V) formed and reclamation of As(V) in regenerant as a photocatalyst. 

Keywords: roxarsone, AOPs, persulfate activation, in-situ degradation-adsorption, As(V) recovery