Competitive adsorption and immobilization of Cd, Ni, and Cu by biochar in unsaturated soils under single-, binary-, and ternary-metal systems

Zhuowen Meng; Shuang Huang; Jingwei Wu; Zhongbing Lin

doi:10.1016/j.jhazmat.2023.131106

Competitive adsorption and immobilization of Cd, Ni, and Cu by biochar in unsaturated soils under single-, binary-, and ternary-metal systems

J Hazard Mater. 2023 Jun 5:451:131106. doi: 10.1016/j.jhazmat.2023.131106. Epub 2023 Feb 28.

Authors

Zhuowen Meng¹, Shuang Huang², Jingwei Wu³, Zhongbing Lin³

Affiliations

¹ State Key Laboratory of Water Resources and Hydropower Engineering Sciences, Wuhan University, Wuhan 430072, China. Electronic address: 2018202060124@whu.edu.cn.
² State Key Laboratory of Water Resources and Hydropower Engineering Sciences, Wuhan University, Wuhan 430072, China. Electronic address: hsh5527@whu.edu.cn.
³ State Key Laboratory of Water Resources and Hydropower Engineering Sciences, Wuhan University, Wuhan 430072, China.

PMID: 36907057
DOI: 10.1016/j.jhazmat.2023.131106

Abstract

This study investigated the competitive adsorption and immobilization of cadmium (Cd), nickel (Ni), and copper (Cu) by biochar in unsaturated soils under single-, binary-, and ternary-metal systems. The results showed that the immobilization effects by the soil itself were in the order of Cu > Ni > Cd, and the adsorption capacities of freshly contaminated heavy metals by biochar were in the order of Cd > Ni > Cu in unsaturated soils. The adsorption and immobilization of Cd by biochars in soils was weakened by competition more in the ternary-metal system than that in the binary-metal system; the competition with Cu caused a more significant weakening effect than that with Ni. For Cd and Ni, nonmineral mechanisms preferentially adsorbed and immobilized Cd and Ni compared to mineral mechanisms, but the contributions of the mineral mechanisms to the adsorption gradually increased and became dominant with increasing concentrations (at average percentages of 62.59%-83.30% and 41.38%-74.29%, respectively). However, for Cu, the contributions of the nonmineral mechanisms to Cu adsorption were always dominant (average percentages of 60.92%-74.87%) and gradually increased with increasing concentrations. This study highlighted that the types of heavy metals and coexistence should be focused when remediating heavy metal contamination in soils.

Keywords: Adsorption; Biochar; Competitive; Heavy metals; Quantitative mechanisms; Unsaturated soils.