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.

Automated summary

The MgO modified biochar derived from crofton weed (MBCW600) showed high adsorption capacities for Pb2+ and Cd2+ in wastewater, with Pb2+ being more easily captured than Cd2+ in a multimetal system. The study also highlighted the importance of Mg2+ in the adsorption process. Additionally, the exhausted MBCW600 could be effectively regenerated and showed potential for future applications in wastewater treatment containing heavy metals.