Enhanced H2O2 activation and sulfamethoxazole degradation by Fe-impregnated biochar

Some uses of biochar/H2O2 in the removal of organic pollutants from sewage have made the advanced oxidation of pharmaceuticals and personal care products by modified biochar possible. However, little is known about the performance of modified biochar and the mechanism of this process. Herein, the activation of H2O2 by Fe-impregnated biochar (FBC, produced from maize straw, wheat straw and peanut shell) was studied, and the removal of sulfamethoxazole (SMX) was specifically investigated. The results show that Fe-impregnated biochar had the ability to activate H2O2 and degrade SMX and its performance was better than that of the original biochar. With the increase of pyrolysis temperature from 350 °C to 700 °C, Fe-impregnated maize straw (1 g/L) enhanced the decomposition of H2O2 (3 mM) from 66% to 99% within 2 h. The degradation of SMX (10 μM) by FM700/H2O2 within 2 h reached 100%, which was approximately 3 times of that of the original biochar. The mechanism of activation-degradation was elucidated by electron paramagnetic resonance (EPR). The results show that the interaction of H2O2 with C-OH promoted the generation of HO and that HO and non-radical sites jointly attacked SMX to degrade it. Impregnation with Fe not only increased the specific surface area of the biochar but also provided more active sites to activate H2O2 and degrade SMX.