(396a) Thermally Enhanced Advanced Oxidation-Driven Regeneration on Iron-Activated Biochar for Removal of Microcystin-LR in Water and Wastewater

In this study, a cyclic process of adsorption and persulfate (PS) oxidation-driven regeneration using FeCl₃-activated biochar (FA-BC) was suggested as a cost effective process for removal of microcystin-LR (MC-LR) in lake water. For enhancing overall treatment efficiency, the effects of temperature on adsorption and PS regeneration were investigated. While the increase in temperature resulted in a drastic increase in the MC-LR adsorption rate on FA-BC, the MC-LR oxidation and PS reaction rates were remarkably improved by factors of 3.4 and 3.5 with increasing temperature from 20 °C to 50 °C. In addition, the lower pH and higher PS concentration led to the higher regeneration efficiency of MC-LR-spent FA-BC by PS oxidation. Both diffusion and desorption of MC-LR from FA-BC were thought to control the MC-LR oxidation rate during the PS oxidation-driven regeneration of MC-LR-spent FA-BC. The sulfate radical was proven to be the main oxidant participating in the PS oxidation process, however, the crystal structures of α-Fe₂O₃, Fe₃O₄, and Fe⁰ in FA-BC were stable during PS oxidation. Under the conditions of 200 mg/L PS, pH 6, and 50 °C, 83 - 99% regeneration efficiencies were achieved during four cycles of adsorption-PS regeneration in DI water and lake water. Therefore, this study indicates high regeneration of MC-LR-spent FA-BC by PS oxidation, which would allow cost-effective treatment of MC-LR in water.