Effects of Coal Gasification Slag on the Migration of Cd²⁺ and Pb²⁺ in Soil

Abstract

In recent years, coal gasification slag has been widely used as an adsorbent in many countries worldwide. To better understand remediation of soil heavy metal pollution by coal gasification slag, it is necessary to examine and analyze the influence mechanism of the adsorption characteristics of coal gasification slag on the migration of heavy metal ions in the soil. In this study, we used a soil water movement model and convection-dispersion equation and constructed a model of heavy metal migration after soil improvement by coal gasification slag; then, we evaluated and predicted the influence of heavy metal infiltration with liquid on groundwater after soil improvement. Combined with the soil column experiment, HYDRUS-1D software was used to predict the migration behavior of heavy metals in the soil. The results showed that the dispersion of the sample with coal gasification slag was smaller than that of the original soil sample, and the permeability coefficient of the soil was reduced by 59.34%; after adding coal gasification slag, the adsorption rates of Cd²⁺ and Pb²⁺ on the soil samples were higher than 95% and 99% respectively. The constructed heavy metal migration model was fitted well and predicted the migration behavior of heavy metals in the soil satisfactorily. The addition of coal gasification slag can effectively prevent the infiltration of Cd²⁺ and Pb²⁺ in the soil and can mitigate groundwater pollution. Therefore, using the adsorption characteristics of coal gasification slag to study the migration behavior of Cd²⁺ and Pb²⁺ in soil has important practical significance for soil adsorption and provides a new idea for the comprehensive utilization of coal gasification slag.

Keywords:

• Heavy metals
• soil column experiment
• adsorption capacity
• dispersion
• leaching rate

Acknowledgements

We give our deep thanks to the reviewers and editors for their valuable comments to improve our paper.

Disclosure statement

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

Additional information

Funding

In this study, the finance supports are given by National Key R&D Program of China (2018YFE0103800); the Fundamental Research Funds for the Central Universities, CHD (300102299302, 300102299102, 300102299104), One Hundred Talent Plan of Shaanxi Province, International Collaborative Research of Disaster Prevention Research Institute of Kyoto University(2019W-02) and Excellent projects for science and technology activities of overseas staff in Shaanxi Province (2018038).