Efficient transformation and elimination of roxarsone and its metabolites by a new α-FeOOH@GCA activating persulfate system under UV irradiation with subsequent As(V) recovery

Roxarsone (ROX) is extensively used as a feed additive which tends to leave toxic inorganic arsenic (As) in the natural environment. A composite of reduced graphene oxide and carbon nanotubes was impregnated with goethite designated as a-FeOOH@GCA and tested as an integrated catalyst and adsorbent for ROX decontamination. Nearly 100% of the ROX was transformed in a-FeOOH@GCA activating persulfate (PS) under UV36s irradiation system at relatively low dosage of the a-Fe0OH@GCA catalyst (250 mg L-1) in 120 min. The As(V) released in the ROX oxidation was simultaneously adsorbed onto the surface of the a-FeOOH@GCA. A possible ROX transformation pathway is proposed. The As(V) adsorbed on catalyst was recovered and used to form an efficient Ag3Asa4 photocatalyst. This work further extends the oxidation-adsorption technology in solving organoarsenical contamination without producing secondary pollution.