Crop-residues derived biochar: Synthesis, properties, characterization and application for the removal of trace elements in soils

Crop-residues derived biochar has emerged as a viable and environment-friendly material to remediate contaminated soils. In this article, we discuss the synthesis methods, properties, characterization techniques, and applications of crop-residues derived biochar to remediate soils contaminated with trace elements (TEs). To our knowledge, this is the first review on this topic. First part of this review describes the global soil pollution status of TEs with an emphasis on their sources. The efficiency of biochar is strongly dictated by the production technologies that subsequently tune their physicochemical characteristics which are critically discussed. The performance of the crop residues biochar for the remediation of TEs in contaminated soils is also discussed with a particular focus on the underlying mechanisms. The challenges and the future research directions associated with crop residues derived biochar have been identified to promote research into this sustainable source of biochar.