Stability and ecological risk assessment of nickel (Ni) in phytoremediation-derived biochar

Lei Wang; Xunjie Liu; Yangyang Wang; Xiaoshu Wang; Jin Liu; Tongtong Li; Xiaomeng Guo; Chao Shi; Ying Wang; Shaofeng Li

doi:10.1016/j.scitotenv.2023.166498

Stability and ecological risk assessment of nickel (Ni) in phytoremediation-derived biochar

Sci Total Environ. 2023 Dec 10:903:166498. doi: 10.1016/j.scitotenv.2023.166498. Epub 2023 Aug 24.

Authors

Lei Wang¹, Xunjie Liu², Yangyang Wang³, Xiaoshu Wang⁴, Jin Liu⁵, Tongtong Li⁶, Xiaomeng Guo⁵, Chao Shi⁴, Ying Wang⁷, Shaofeng Li⁸

Affiliations

¹ School of Materials and Environmental Engineering, Institute of Urban Ecology and Environment Technology, Shenzhen Polytechnic, Shenzhen 518055, PR China; Eco-Environmental Science Center (Guangdong, Hong-Kong, Macau), Guangzhou 510555, PR China.
² Eco-Environmental Science Center (Guangdong, Hong-Kong, Macau), Guangzhou 510555, PR China; Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, PR China.
³ School of Materials and Environmental Engineering, Institute of Urban Ecology and Environment Technology, Shenzhen Polytechnic, Shenzhen 518055, PR China; School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, PR China.
⁴ School of Materials and Environmental Engineering, Institute of Urban Ecology and Environment Technology, Shenzhen Polytechnic, Shenzhen 518055, PR China.
⁵ Eco-Environmental Science Center (Guangdong, Hong-Kong, Macau), Guangzhou 510555, PR China.
⁶ Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, PR China.
⁷ Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China. Electronic address: wangypaper@126.com.
⁸ School of Materials and Environmental Engineering, Institute of Urban Ecology and Environment Technology, Shenzhen Polytechnic, Shenzhen 518055, PR China. Electronic address: lshaofeng@szpt.edu.cn.

PMID: 37633368
DOI: 10.1016/j.scitotenv.2023.166498

Abstract

Improper treatment of heavy metal-enriched biomass generated after phytoremediation might cause secondary pollution in soil and water. At present, the pyrolysis process is an effective method for the treatment of phytoremediation residue. In this study, Ni-enriched biomass was prepared using hydroponics method and further pyrolyzed at different temperatures (300-700 °C). At low pyrolysis temperatures (below 500 °C), carbonate precipitation was the main reason of Ni stabilization in biochar. Nevertheless, the formed phosphate and aluminosilicate were important factors for immobilizing Ni in biochar at high pyrolysis temperatures (above 500 °C). Moreover, the oxidizable (F3) and residual (F4) components of Ni in biochar increased with increasing pyrolysis temperature, which indicated that higher pyrolysis temperature could effectively reduce the bioavailability of Ni in biochar. The results of deionized water, acidification, oxidation, and toxic characteristic leaching procedure (TCLP) experiments showed that pyrolysis temperature was the dominant factor for Ni stabilization in biochar. The ecological risk assessments further proved that pyrolyzed Ni-enriched biochar could reduce the environmental toxicity and potential ecological risks of Ni. In the soil simulated experiment, the soil microenvironment gradually promoted the transformation of Ni in BC_Ni^X from bioavailable fraction to stable fraction. Overall, this study would expose more reasonable reference for the long-term storage of phytoremediation residues.

Keywords: Ecological risk; Nickel (Ni); Phytoremediation residue; Pyrolysis; Stabilization.