Optimizing the generated waste proportion to improve the characteristics of biochar for CO2 sequestration and other applications

Biochar is a carbon-rich material with many active functional groups that can absorb harmful compounds. It can effectively remove dissolved organic matter, heavy metals, and toxic metals from the soil. A significant advantage of biochar is its ability to absorb CO2, facilitating its efficient removal. Producing biochar from diverse waste sources, including plants, animals, municipal/industrial waste, and micro/macroalgae, not only helps reduce CO2 emissions in the atmosphere but also produces eco-friendly biochar, which can absorb CO2. Thus, waste materials can be efficiently employed in the production of biochar. The construction of roads and sidewalks for pedestrians with biochar supports the removal of CO2 emitted from vehicles. It plays a significant role in the high release of harmful gases that increase the global temperature and thus are eliminated without reaching the atmosphere. This creates a better utilization of biochar, and the different wastes utilized in making biochar at an optimum ratio on a large scale can be efficiently utilized, thus creating a new field of application. Research is required before implementation to ensure its practical use. Various applications have been accomplished using this biochar production approach. These applications include biofuel and biogas generation, wastewater and heavy metal removal, microplastic elimination, biofertilizer and biopesticide production, supercapacitor and electrode creation, and dye adsorption or degradation. This approach effectively removes harmful and waste contaminants while generating products with zero energy emissions. This review emphasizes the substantial progress in producing biochar from waste materials and its contribution to CO2 sequestration, thereby mitigating the environmental impact.