In-situ production and activation of HO for enhanced degradation of roxarsone by FeS decorated resorcinol-formaldehyde resins.

Fenton technology performs well in high-risk roxarsone (ROX) removal, but it is limited by the high HO transportation and storage risks. Herein, FeS decorated resorcinol-formaldehyde resins (FeS-RFR) were successfully prepared to in-situ produce and utilize HO for efficient removal of ROX. Under solar light illumination, resorcinol-formaldehyde resins (RFR) efficiently generated a high concentration of HO, with a yield of 500 μmol g h. FeS can in-situ decompose HO to generate ·OH, participating in the oxidation of ROX. As a result, the FeS-RFR catalyst degraded more than 97% of ROX within 2 h and ROX was selectively degraded into low-toxic As(V), which can be simply removed by traditional adsorption or precipitation processes. During the degradation of ROX, ·OH played a dominant role. Moreover, the cations (Na, K, and Ca), anions (SO, Cl), and humic acid had no noticeable inhibition effect on ROX removal. Furthermore, FeS-RFR can still remove 70% of ROX even after three cycles, proving that this in-situ photo-Fenton system exhibited stability. This study innovatively proposed a double-active site FeS-RFR photocatalyst for in-situ production and activation of HO and showed a sustainable and eco-friendly way for organoarsenic compounds degradation.