Role of the biochar modified with ZnCl2 and FeCl3 on the electrochemical degradation of nitrobenzene

The Zn/Fe-modified biochar on nitrobenzene (NB) removal during the electrolysis was investigated in this study. Both the Fe and Zn-modified biochar enhanced the NB adsorption compared with the unmodified biochar due to their greater specific surface area and more abundant surface function groups, respectively. The electrolysis under 2-11 V with the assist of both Fe/Zn-modified biochar achieved effective NB removal (>93%). The removal rate under 2 V using Zn/Fe-modified biochar (similar to 94%) was higher than that of the un-modified biochar (similar to 80%), whereas the removal was similar for those under 5, 8 and 11 V. The NB removal under 2 and 5 V was attributed to both adsorption and electrochemical decomposition of NB molecules. Electrolysis under 5 V by Fe-modified biochar had a higher degree of NB mineralisation than that using un-modified and Zn-modified biochar. This was likely that the Fe-modified biochar exhibited higher electrocatalytic properties, facilitating the further NB mineralisation. The center dot OH played significant roles in the degradation of NB by Fe-modified and un-modified biochar but did not significantly participated for the test using Zn-modified biochar. This was possibly because the Zn-modified biochar could adsorb greater amounts of center dot OH into the inner pores of Znmodified biochar via its greater porosity and specific surface area, which may prevent the contact between center dot OH and NB molecules. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The Zn/Fe-modified biochar showed better performance in removing nitrobenzene (NB) due to their larger specific surface area and more abundant surface function groups. Electrolysis using Fe/Zn-modified biochar at 2-11 V achieved effective NB removal, with the highest removal rate observed at 2 V. Fe-modified biochar exhibited higher NB mineralization under 5 V, possibly due to its higher electrocatalytic properties, facilitating further NB mineralization.