Progress and future prospects in biochar composites: Application and reflection in the soil environment

In recent years, environmental pollution is a major global concern and adversely affecting human health and the economy. The environmental properties of soil are exceptionally complex, which makes the remediation and treatment more challenging and expensive. In this aspect, sustainable materials (biomaterials, biochar, and composites) present an effective and efficient remediation solution. Exactly, biochar and its relative composites can achieve novel properties with addition of metal oxides, surface agents, and nano-material. The present review study provides quantitative analysis and addresses the advantages of using biochar composites relative with pure biochar. The synthesis of Nano-metal assisted biochar, properties and utilization in improving soil properties as well as heavy metal removal are reviewed. Specific attention has been paid to the impacts of biochar and its composite on soil fundamental properties such as pH, cation exchange efficiency, bulk density, porosity, water retention capability, soil organic matter (SOM) and redox reactions. Significant emphasis is focused on soil remediation, in particular, the elimination of heavy metals utilizing biochar-based composites. Further research is urged to verify the proposed mechanisms involved biochar composites-microbial interactions and heavy metal remediation considering short term and long term efficiency for improvement.