A critical review of mechanisms involved in the adsorption of organic and inorganic contaminants through biochar

Successful application of low-cost adsorbent like biochar has introduced multidisciplinary areas of science, particularly with respect to remediation of both organic and inorganic contaminants in soil and water. This review briefly consolidates the currently available literature to comprehend the overall adsorption mechanisms of organic and inorganic contaminants through biochar. Generally, biochar produced at low pyrolysis temperature is suitable for the adsorption of inorganic contaminants by following the adsorption mechanisms of electrostatic interaction, precipitation, and ion exchange. However, relatively high pyrolysis temperature favors the adsorption of organic contaminants by increasing the surface area and micropores of biochar along with pore filling and hydrophobic and electrostatic interaction as predominant adsorption mechanisms. This review also summarizes the critical factors (pyrolysis temperature, solution pH, dosage of biochar, contact time, co-existed ions, modification/activation, aging process, etc) affecting the overall adsorption efficiency of the biochar. Overall, further field studies and experimentation are required for the reduction of cost in biochar production and its reuse.