Effect of nZVI/biochar nanocomposites on Cd transport in clay mineral-coated quartz sand: Facilitation and rerelease

Shi Zhou; Xue Ni; Houlang Zhou; Xiangmin Meng; Huimin Sun; Jun Wang; Xianqiang Yin

doi:10.1016/j.ecoenv.2021.112971

Effect of nZVI/biochar nanocomposites on Cd transport in clay mineral-coated quartz sand: Facilitation and rerelease

Ecotoxicol Environ Saf. 2021 Nov 11:228:112971. doi: 10.1016/j.ecoenv.2021.112971. Online ahead of print.

Authors

Shi Zhou¹, Xue Ni¹, Houlang Zhou¹, Xiangmin Meng², Huimin Sun³, Jun Wang⁴, Xianqiang Yin⁵

Affiliations

¹ College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
² Political and Law Commission of Chengwu County Party committee, Heze, Shandong 274200, PR China.
³ College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, PR China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling, Shaanxi 712100, PR China.
⁴ College of Resources and Environment, Key Laboratory of Agricultural Environment in Universities of Shandong, Shandong Agricultural University, Tai'an, Shandong 271000, PR China.
⁵ College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, PR China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling, Shaanxi 712100, PR China. Electronic address: xqyin@nwsuaf.edu.cn.

PMID: 34775343
DOI: 10.1016/j.ecoenv.2021.112971

Abstract

The development and application of nano-biochar synthesized by ball milling technology is still challenging in the field of environmental remediation because of its higher activity with pollutants. The purpose of this study was to investigate the transport behavior of two kinds of biochar nanoparticles (nanobiochar (NBC) and nZVI-modified nanobiochar (nZVI-NBC)) and Cd²⁺ in clay mineral (kaolinite, illite, and montmorillonite)-coated quartz sand columns. The interaction between biochar nanoparticles and Cd²⁺ in saturated porous media was studied in cotransport experiments. Then, the effect of biochar nanoparticles on the release of Cd²⁺ in contaminated media was explored by elution experiments. The cotransport experiments showed that the mobility of Cd²⁺ was enhanced by two kinds of biochar nanoparticles, while the transport of biochar was limited due to the presence of Cd²⁺. The elution experiments showed that the transport of biochar nanoparticles can be inhibited by Cd²⁺ previously immobilized in the sand column, and Cd²⁺ can be rereleased by biochar nanoparticles. The rerelease ability of nZVI-NBC to Cd²⁺ is weaker than that of NBC because nZVI is more easily retained in the sand column after oxidation, thus strengthening the immobilization of Cd²⁺. In general, the recoveries of NBC, nZVI-NBC and Cd²⁺ in saturated porous media were reduced by the presence of clay minerals. The experimental results describing the stability of biochar nanoparticles in sand columns are consistent with those predicted by the Derjaguin-Landau-Verwey-Overbeek theory. The transport behavior of Cd²⁺ and biochar nanoparticles in sand columns can be well simulated by advection-dispersion-reaction. These findings reveal the interaction between biochar nanoparticles and heavy metals in the soil environment and provide new insights into the transport and fate of environmental remediation materials and pollutants in the underground environment.

Keywords: Biochar nanoparticles; Cd(2+); Coated sand; Transport; nZVI.