APPLICATION OF MODIFIED BIOCHAR FOR HEXAVALENT CHROMIUM SORPTION FROM WATER

Abstract

In this study, we prepared novel mosambi peel biochar (M–BC) and KOH-based engineered mosambi peel biochar (KOH–M–BC) and used for the removal of hexavalent chromium (Cr(VI)) from water. Successful modification with KOH showed the highest Cr(VI) sorption at pH 4 (118.7 mg/g (98.5%)) on KOH–M–BC compared to M–BC (108.6 mg/g (90%)). The experiments related to effect of other major sorption parameters suggested that the maximum sorption was observed at 120 mg/L initial Cr(VI) concentration, 0.9 g/L sorbent dose and 4 hour contact time. The Langmuir (R2=0.98) isotherm model provided the best fitted data for both sorbents, notably for KOH–M–BC indicating the monolayer sorption. The pseudo-second-order model (R2=0.99) well-described the kinetics of Cr(VI) sorption on both sorbents. The FTIR results shows that the surface functional groups such as OH, C=O and COO– contributed to Cr(VI) sequestration by the both biochars. The SEM images showed the porous surface of KOH–M–BC which provided numerous sites for Cr(VI) attachment on biochar. The presence of Cr(VI) onto biochar after adsorption was also confirmed by XPS analysis. This findings of this research highlighted the importance of surface modification with alkali (KOH) and a potentially viable, green and cost-effective sorbent for Cr(VI removal from water.