Aqueous Mercury Sorption by Biochar from Malt Spent Rootlets

Biochar produced from malt spent rootlets was employed for the removal of Hg(II) from pure aqueous solutions. Batch experiments were conducted at 25 degrees C. The optimum pH value for Hg(II) sorption onto biochar was 5. Biomass dose and contact time were examined to determine sorption kinetics and equilibrium capacity constants. The increase of biochar dose resulted in higher sorption efficiency. After a 24-h contact time at biochar concentrations of 0.3 and 1 g/L, the Hg(II) removal was 71 and 100 %, respectively. Based on the sorption kinetic data, the biochar sorption capacity for mercury reached its maximum after 2 h; 33 % of Hg(II) was removed within the first 5 min. Based on the isotherm data, the maximum biochar sorption capacity for Hg(II) was 103 mg/g. Finally, HCl, EDTA, NaCl, HNO3, H2SO4, and distilled water leaching solutions were tested for Hg(II) desorption with HCl being the most effective.