CuS enabled efficient Fenton-like oxidation of phenylarsonic acid and inorganic arsenic immobilization

Herein, copper sulfide (CuS) was introduced to the Fenton-like (Fe(III)/H2O2) system for the efficient removal of phenylarsonic acid (PAA). Results of reactive oxygen and Fe/Cu species showed that CuS preferentially reacted with Fe(III) and H2O2 to generate Cu(I) and superoxide anion (•O2-). These reductive species could efficiently promote the Fe(III)/Fe(II) and Cu(II)/Cu(I) cycles, and are beneficial to the sequential Fenton reaction to generate •OH. The organoic/inorganic arsenic species detected in the CuS/Fe(III)/H2O2 system confirmed that PAA was oxidized by •OH to hydroxylated organoarsenic and phenolic intermediates, which were further mineralized to oxalate and formic acid. Meanwhile, the inorganic As(III)/As(V) released during PAA degradation were efficiently immobilized by CuS. The PAA removal efficiency remained as high as 92.9 % after 5 cycles of the CuS-mediated Fenton-like process. These results demonstrate an innovative method for the treatment of organoarsenic-contaminated water, and provide new insights into the enhanced Fenton-like process utilizing sulfide minerals. [Display omitted] •CuS served as a co-catalyst in the Fenton-like system, promoted the reactive species generation and PAA degradation.•The production of Cu(I) and •O2- in the CuS/Fe(III)/H2O2 system facilitated the cycles of Fe(III)/Fe(II) and Cu(II)/Cu(I).•The simultaneous of PAA mineralization and inorganic arsenic immobilization were conducted in the CuS/Fe(III)/H2O2 system.