The Role of Modified Biochar for the Remediation of Coal Mining-Impacted Contaminated Soil: A Review

Abstract

Land degradation and the release of contaminants such as heavy metals into the environment due to mining activities is a concerning issue worldwide. The bioaccumulation of heavy metals in the environmental matrix can severely damage flora and fauna and negatively impact human health. The poor physicochemical properties of mine spoil generated through mining operations make restoration of such contaminated and degraded lands challenging. In recent years, an exponential growth in the development and applications of biochar and its composites for the remediation of heavy metal-polluted environmental matrices such as soil and water has been observed. The literature review found that 95 review papers were published in the last five years reviewing the utility of biochar for heavy metals removal from the aqueous environment. However, no paper was published focusing on the application of biochar and its composites for the remediation of heavy metal-contaminated coal mine soil. The objective of the present review is to critically review the impact of mining activities on the environment and the role of biochar and its composites in the remediation of heavy metal-contaminated mine soil. This review presented a detailed discussion and sufficient data on the impact of mining practices in India on the environment. In addition, it critically discussed the methods of the production of biochar from various wastes and methods of modifying the pristine biochar to develop functionalized biochar composites. The detailed mechanism through which biochar and its composites remove and immobilize the heavy metals in the soil was discussed. The efficacy of biochar for the remediation of contaminated mine soil was also critically evaluated using various case studies and data from previously published articles. Thus, the major conclusion drawn from the review is that the application of various functionalized biochar composites could effectively manage and remediate heavy metal-contaminated mine soil.