Biochar application for soil amendment and water remediation: A critical review

Biochar, a carbon-rich material derived from biomass through thermochemical processes like pyrolysis and hydrothermal carbonization, has gained significant attention for its dual role in soil amendment and water remediation. This review examines recent advancements in biochar production, emphasizing the influence of feedstock types and process parameters on its physicochemical properties. Pyrolysis and hydrothermal carbonization yield biochars with distinct characteristics, ranging from high fixed carbon content for long-term carbon sequestration to enhanced nutrient retention capabilities. For soil applications, biochar improves fertility, water retention, and microbial activity, while reducing nutrient leaching and mitigating heavy metal toxicity. For water remediation, biochar's high porosity and functional groups make it effective in adsorbing heavy metals, pharmaceuticals, and dyes. Moreover, pretreatments like chemical activation can enhance its adsorption capacity, making biochar a versatile material for environmental remediation. This critical review correlates biochar properties with its environmental applications, highlighting optimization strategies for targeted uses.