Effect of water- and acid-pickling of aquaticplant biochar on the adsorption of Cd

Abstract To reveal the influencing factors and mechanism of adsorption of heavy metal Cd by biochar, different elution solvents (water and dilute acid solution) were used in this paper to elute the residual ash substances after pyrolysis of biochar, then the pH was regulated to investigate the adsorption effect of biochar on Cd in different treatment conditions. The precipitation experiments of Cd by biochar soaking and washing filtrate showed that the precipitation of root, stem and leaf of Acorus calamus L. contributed a great deal to the heavy metal removal system, which accounting for 81%, 77% and 98%, respectively, and the adsorption effect of biochar of roots, stems and leaves of Acorus calamus L. on Cd was slightly increased after washing. The adsorption experiment of biochar pickling on heavy metals showed that the adsorption effect of biochar on heavy metals Cd decreased greatly after pickling, which may be due to the removal of most of the minerals on the surface of biochar after pickling and the decrease of pH value of biochar. This work can provide insights into the use of biochar to control Cd.