Prospective of Waste Lignocellulosic Biomass as Precursors for the Production of Biochar: Application, Performance, and Mechanism—A Review

This article demonstrates the significance and potential of biochar derived from waste materials via thermochemical technique for environmental remediation. Utilization of biochar has made substantial breakthroughs in increasing agricultural productivity, reducing greenhouse gas emissions and global warming, sequester atmospheric carbon into the soil, reducing bioavailability of environmental contaminants, and subsequently becoming a value-added product sustaining bioeconomy. It possesses several unique physicochemical properties (surface area, microporosity, and pH) which provide an avenue to maximize its efficacy to targeted applications and making it highly efficient, cost-effective, and environmentally friendly material for the removal of diverse contaminants. High-temperature pyrolysis produces biochar with high surface area, microporosity, and hydrophobicity which is suitable for the sorption of organic contaminants while low-temperature pyrolysis produces biochar suitable for inorganic/polar organic contaminants. Further, biochar modification significantly alters the surface charges and functionality and ash content and enhances cation exchange capacity. In addition, biochar serves as a promising alternative to the existing conventional wastewater treatment methods and offers the advantage of energy-intensive conditions, incomplete treatment of pollution, risk of secondary pollution of residual chemicals, and high investment requirements. This review discusses the utilization of various waste biomass materials as precursors for the production of biochar under different operating conditions. Production of biochar via pyrolysis was critically examined, especially influencing parameters and pyrolysis mechanism. Recent research on improving biochar adsorption property through physical and chemical modification has been explored. A connection between the structure and the application of biochar is also revealed. To increase the economic benefits of its implementation, future efforts should also be directed towards improving its adsorption capacity.