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.

Advanced Thermochemical Conversion Approaches for Green Hydrogen Production from Crop Residues

“…The slow pyrolysis process occurs in a drum reactor or rotary kiln maintained at moderate temperatures of between 300°C and 700°C. The heat is applied slowly at less than 1°C/s for a residence time of more than 300 s. The products of the slow pyrolysis process are usually biochar (35%-45%), bio-oil (25%-35%), and syngas (20%-30%) [35]. Feedstocks such as woody biomass, microalgae, and agricultural waste must be cut or chopped to between 2-50 mm size before inserting them into the reactor [36].…”

Distribution of Heavy Metals in Water and Bottom Sediments in the Basin of Lake Gusinoe (Russia): Ecological Risk Assessment

“…There are various methods to remediate contaminated and degraded soil near ash dumps and industrial areas, which include phytoremediation, as well as the use of mulch, lime, biosolids, and fly ash as soil conditioners. Other technologies, such as adsorption, biodegradation, and in situ chemical oxidation, are available for soil remediation and pollutant removal [28][29][30].…”

“…The ecological state of the lake is also monitored by the Buryat Center for Hydrometeorology and Environmental Monitoring, and their results also indicate an escalation of anthropogenic impacts [27]. Additionally, the integration of various environmental parameters and pollutant data through ecological risk indexes can offer a comprehensive evaluation of the lake's susceptibility to anthropogenic pressures, assisting in developing specific mitigation strategies [28][29][30][31][32][33].…”

Iron-modified biochar improves plant physiology, soil nutritional status and mitigates Pb and Cd-hazard in wheat (Triticum aestivum L.)

“…Various modification methods like loading mineral/metal salts on the BC surfaces can enhance BC’s HM adsorption capacity ( Wang et al., 2020 ; Ali et al., 2022 ; Zhu et al., 2022 ). Modified biochar can efficiently limit the solubility and bioavailability of HMs in soil by affecting metals speciation, absorption, precipitation, and complexation mechanisms ( Wang et al., 2020 ; Chandra et al., 2023 ). In accordance with the concept of sustainable development, it is crucial to prepare modified biochar as an efficient, stable, economical, and environment-friendly amendment for the reclamation of HMs polluted soils.…”