Enhanced Cr(VI) reduction and As(III) oxidation in ice phase: Important role of dissolved organic matter from biochar

Biochar-derived dissolved organic matter (DOM) effectively reduced Cr(VI) and oxidized As(III). Cr(VI) and As(III) could serve as a redox couple. Cr(VI) and As(III) redox conversion was more effective in the ice phase than aqueous phase. FTIR and ESR showed that biochar DOM served as both electron donor and acceptor.