Boric acid-modified activated carbon for glycerol removal from high-salt wastewater

Abstract

Epoxy resin production wastewater contains glycerol and NaCl, which cause high energy consumption and environmental pollution during wastewater treatment. Therefore, the adsorption of glycerol on boric acid in low-temperature modified activated carbon was investigated for the first time. Under the optimum conditions of a modification temperature of 80℃, a mass ratio of boric acid to activated carbon of 1:1, and a modification time of 6 h, the modification of activated carbon was realized. It was found that the removal of glycerol by activated carbon before and after modification was found to be 0.10 % and 99.67 % (10 °C), indicating that boric acid endows activated carbon with a stronger ability to adsorb glycerol; The higher the pH of the wastewater, the higher the removal rate of glycerol, while the salt content of the wastewater has little effect. This study used batch adsorption to show that modified activated carbon could adsorb up to 1100 mg g−1 of glycerol, which was in line with the proposed pseudo-second-order kinetic model. After 8 cycles of adsorption and desorption, the modified activated carbon lost only 12.46 % of the adsorption capacity. Combined with the results, the existence of boron hydroxyl groups on activated carbon is the key to glycerol adsorption.