Simultaneous oxidation of 4-aminophenylarsonic acid and adsorption of the produced inorganic arsenic by a combination of Co3O4-La2CO5@RSBC with peroxymonosulfate

4-aminophenylarsonic acid ( p -ASA) is usually employed as feed antibiotics which can kill bacteria, protozoa and spirochetes. When p -ASA is released into the environment by biological metabolism, it could be broken down to produce hypertoxic inorganic arsenic, including arsenite (AsO 3 3- ) and arsenate (AsO 4 3- ). In this study, cobalt and lanthanum composites loaded on rice straw biochar labelled as Co 3 O 4 -La 2 CO 5 @RSBC was obtained. The material was used as an efficient catalyst for peroxymonosulfate (PMS) activation and adsorbent to achieve the simultaneous degradation of p -ASA and adsorption of arsenic. 100% decomposition of p -ASA (50 μmol L -1 ) could be realized within 30 min, coupled with nearly complete removal of inorganic arsenic during 80 min at initial pH = 7. Co 3 O 4 -La 2 CO 5 @RSBC also possessed superior reusability and stability. Even in the third cycle, more than 95% of p -ASA was decomposed and meanwhile 92.5% of inorganic arsenic was removed. No cobalt ions were detected, and the concentration of lanthanum ions in the three cycles ranged from 8.05 to 9.90 mg L -1 , which was much lower than those reported in previous studies. A series of the material characterizations, electron paramagnetic resonance technology and scavenger tests were utilized to unveil the possible catalytic mechanism and the transformation pathways of p -ASA and arsenic. It was confirmed that 1 O 2 , O 2 ∙ - ${\mathrm{O}}_2^{\bullet -}$ , OH ∙ ${}^{\bullet }\text{OH}$ , and SO 4 ∙ - ${\mathrm{SO}}_4^{\bullet -}$ generated from the PMS activation were responsible for the degradation of p -ASA and the oxidation of As(III) to As(V). Meanwhile, As(V) was rapidly adsorbed by Co 3 O 4 -La 2 CO 5 @RSBC. This study provides us with a novel and efficient approach to control p -ASA pollution in aqueous solution.