Comparison between Chemical Modification of Biochar for Different Environmental Applications

Biochar is a carbon-enriched product produced by thermochemical treatment of biomass under oxygen-deprived conditions. Its unique physicochemical properties have attracted considerable attention as a multifunctional material for various environmental applications. While biochar inherently possesses some pores and functional groups like carbonyl and hydroxyl groups, the amount is minimal compared to the bulk surface of biochar. The resultant physicochemical properties of biochar, including its surface morphology and functional groups, can be further improved through different chemical modification methods. This review aims to provide an overview of different chemical modification methods, including the activation using different acid and basic reagents, nanomaterial impregnation and magnetisation. Their effects on biochar's physicochemical properties, surface functionalities, and potential applications are explored. The enhanced properties of chemically modified biochar would have greater applicability in different applications, especially for pollutant removal, soil remediation and wastewater treatment. Future research should focus on improving the efficiency of modification processes and chemical recovery to prevent chemical wastage and produce biochar with desired characteristics for industrial-scale application. The integration of various chemical modification strategies with magnetization could produce biochar with enhanced surface functionalities and facilitate its recovery from aqueous environments.