Study on the remediation of heavy metal contaminated soils by citric acid and polyepoxysuccinic acid complex leaching

ABSTRACT

Soil leaching remediation has attracted extensive attention because of its good removal effect, short operation period and stable removal effect of heavy metals. The key to reduce the harm of heavy metal contaminated soil to the environment and human health is to use appropriate leachate to repair heavy metal contaminated soil. In this study, citric acid (CA), iron nitrate (Fe(NO₃)₃) and polyepoxysuccinic acid (PESA) with different concentrations were used as research reagents to explore the best combination of leaching effects of heavy metals (Cu, Zn, Pb, Cd) in contaminated soil. The effects of concentration of eluent, liquid to solid ratio and leaching time on leaching efficiency of heavy metals and the changes of soil physical and chemical properties before and after leaching were studied. The results showed that 0.5 mol/L CA and 0.05 mol/L PESA were combined according to the volume ratio of 7:3, and the leaching effect was the best when the liquid–solid ratio was 15 and the leaching time was 240 min. Under the optimal leaching condition, the four heavy metals in the soil had significant removal effects, and the removal rates were, respectively, 86.06% Cu, Zn 74.55%, Pb 67.88% and Cd 91.63%. The X-ray spectrum and Fourier infrared spectrum analysis of soil before and after leaching showed that CA-PESA combined leaching had little effect on soil structure change. This study provided theoretical support for the development and application of suitable leaching agents for the remediation of heavy metal-contaminated soil.

GRAPHICAL ABSTRACT

KEYWORDS:

• Heavy metal
• soil repair
• compound with leaching
• polyepoxysuccinic acid
• soil leaching

Acknowledgements

The authors are sincerely grateful to the reviewers and the editor for their useful comments that have helped us to improve the quality of our study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Date availability statement

Due to the nature of this research, participants of this study did not agree for their data to be shared publicly, so supporting data is not available.

Additional information

Funding

This work was supported by the Outstanding Young and Middleaged Scientific and Technological Innovation Team Plan in Hubei Province [grant numberT2020002] and Hubei’s Key Laboratory for Efficient Utilization and Agglomeration of Metallurgical Mineral Resources [grant number 2019zy006].