Simultaneous removal of cadmium, lead, chromate by biochar modified with layered double hydroxide with sulfide intercalation

In this study, a novel KOH-activated biochar modified with Mg2Al-LDH with S2-intercalation (KBC-LDH-S) was proposed for simultaneous adsorption of anions and cations. The adsorption capacity, thermodynamic and ki-netic studies, effects of initial temperature and solution pH were investigated. Furthermore, the adsorption characteristics in both single and ternary Pb-Cd-Cr systems were investigated. Comparing with bare biochar, the adsorption capacity of KBC-LDH-S was increased by 387.8 % for Cd2+ (190.4 mg/g), 358.1 % for Pb2+ (392.2 mg/g), 1106.0 % for total Cr (170.7 mg/g) and 4602 % for Cr6+ (833.8 mg/g). The S2-intercalation effectively increased the adsorption capacity of CrO42-by 3370 % and promoted simultaneous adsorption. The interlayer anion exchange and redox reaction occurred between CrO42-and S2-to generate Cr3+, and then promoted the adsorption of CrO42-. Besides, the adsorption amount and total removal efficiency first increased and then decreased with the increasing concentration in the Pb-Cd-Cr ternary system.

Automated summary

A novel KOH-activated biochar modified with Mg2Al-LDH with S2-intercalation (KBC-LDH-S) was proposed for simultaneous adsorption of anions and cations. The adsorption capacity, thermodynamic and ki-netic studies, effects of initial temperature and solution pH were investigated. Furthermore, the adsorption characteristics in both single and ternary Pb-Cd-Cr systems were investigated.