Modification Strategies of Biochar and Their Research Progress in Cr(VI) Pollution Remediation

Hexavalent chromium Cr(VI) is one of the most toxic heavy metals accumulated in the natural environment systems, which poses a serious threat to living organisms worldwide. Biochar is a type of carbon -rich solid substance produced via hypoxic pyrolysis of biomass and regarded as an efficient adsorbent for Cr(VI) pollution remediation due to its large specific surface area, well -developed porous structure and abundant functional groups. To further enhance the adsorption performance of biochar and make it easier to separate and recycle, researchers have carried out extensive researches on the modification of biochar, and physical, chemical, and biological modification strategies have been explored to strengthen the adsorption ability of biochar towards Cr(VI). Based on the researches of biochar modification in recent years, this review systematically sorted out different modification strategies of biochar, compared the remediation efficiencies of Cr(VI) pollution by different kinds of modified-biochar, discussed the potential mechanism of modified-biochar towards Cr(VI) removal, and put forward prospects for the future research direction of biochar.