Modification of activated carbon using sodium citrate and its effect on the adsorption of copper ions

Activated carbon (AC) was modified with sodium citrate at a concentration of 5–15% by impregnation to develop a new type of adsorbent, named Nx–AC where x is the concentration. Their pore structures and surface chemical properties were characterized by N2 adsorption, Boehm titration and FT-IR. The adsorption of copper ions by the Nx–AC and the regenerated ones were investigated through a static adsorption method. Results showed that the carboxyl content had a great influence in the adsorption properties of Nx–AC for copper with the adsorption capacity of N15–AC being 1.76 times higher than the parent AC, which was higher than those of the N5–AC and the N10–AC. The adsorption capacity of the regenerated N15–ACs for copper can reach 98.2% and 95.9% of the original N15–AC for the first and second regenerations, respectively.