High-efficiency removal of lead/cadmium from wastewater by MgO modified biochar derived from crofton weed

The adsorption performance and mechanisms of Pb²⁺ and Cd²⁺ in wastewater using MgO modified biochar derived from crofton weed (MBCW600) are investigated. The Pb²⁺ and Cd²⁺ adsorption capacities of MBCW600 by the Hill model reach 384.08 mg/g and 207.02 mg/g, respectively, which is larger than that of original biochar. Pb²⁺ could be more easily captured by MBCW600 compared to Cd²⁺ in the multimetal system. Mg²⁺ contributes to Pb²⁺ and Cd²⁺ adsorption among coexisting cations. The exhausted MBCW600 could be well regenerated by simple method after use. The adsorption mechanism study indicates that Pb²⁺ and Cd²⁺ removal are primary contributed to mineral precipitation and ion exchange. The effective treatment volumes of Pb²⁺ and Cd²⁺ wastewater achieve 3050 mL and 2150 mL in the fixed-bed column experiment, respectively. Therefore, MBCW600 presents remarkable adsorption capability, excellent recoverability and large throughput, which shows the potential application in future treatment of wastewater containing heavy metal.