Recent advancements in biochar preparation, feedstocks, modification, characterization and future applications

Biochar is a stable carbon-rich product synthesized from biological materials through different heating techniques. The main aim of this review is to evaluate various biochar production methods, parameters affecting the production of biochar, facilities to investigate the composition and structure of biochar, mechanism associated with production of biochar as well as various modification procedures to suit biochar for different applications. Various methods used to synthesize biochar include pyrolysis, torrefaction, gasification, hydrothermal and flash carbonization. Several factors such as feedstock composition and type, pyrolysis conditions such as temperature and time strongly influences the property of synthesized biochar. The physico-chemical properties of biochar strongly influence the role of biochar in several applications such as fuel cells, biosorption, agriculture, supercapacitors, catalyst/support and environmental remediation. It was identified through research efforts that the properties of biochar can be altered using various chemical or physical agents to suit various applications. Thus, the present review consolidates recent advancements in biochar research with special attention towards contaminant remediation and agricultural applications.