Roles of ZnCl2 and FeCl3 in preparing high performance corn stover-based carbon materials for efficient removal of Cr (VI) from wastewater

Abstract

The roles of ZnCl2 and FeCl3 in preparing carbon materials from corn stover for efficient removal of Cr(VI) from wastewater were investigated in the present study. ZnCl2 activation created micropore and defective graphite structures to produce a high SBET of carbon materials (1409.7 m2/g) with abundant active adsorption sites. FeCl3 activation promoted the formation of Fe3O4 and Fe2ZnO4 on carbon materials, which exhibited potential magnetic separation properties. The Zn/Fe-activated carbon materials (CSM-Zn/Fe-2(2:1)) showed the maximum Cr(VI) removal of 185.8 mg/g. The process for the removal of Cr(VI) from wastewater fitted well with pseudo-second-order kinetics and Langmuir models. A reduction mechanism of Cr(VI) removal from wastewater by Zn/Fe-activated carbon was discovered in this study. Pore adsorption, electrostatic interaction and chemical interactions were found to play important roles in the adsorption of Cr(VI) onto the carbon materials. The C-C/C=O groups in the carbon materials originating from ZnCl2 activation promoted the reduction of Cr(VI) to Cr(III), followed by re-adsorption on carbon materials and release to the solution, which was found to significantly enhance Cr(VI) removal. These findings helped achieve the valorization of waste biomass to produce high performance carbon materials for treating Cr(VI)-containing wastewater in engineering applications.