Simultaneously-efficient electro-sorption of Pb(Ⅱ), Cu(Ⅱ) and Cd(Ⅱ) by Cu2+ modified superactive carbons

Capacitive deionization (CDI) is promising for deeply removing heavy metal ions from polluted water. The performance of CDI is largely determined by electrode material. Activated carbon (AC) as electrode material has many advantages, but no reported ACs display high adsorption performance for multiple heavy-metal ions simultaneously. In this study, a novel Cu2+-modified AC was prepared and used to remove ions from single or multiple heavy-metal-ion solutions. In single heavy-metal-ion solution, the ion removal percentage was 95.2 %, 93.9 %, and 92.1 % in 70 mg/L of PbCl2, CuCl2, and CdCl2 solutions, respectively, exceeding the corresponding values reported for carbon electrode materials. This is mainly attributed to its developed pore structure (SBET = 3287 m2/g, Vtot = 2.38 cm3/g, and Vmic = 1.05 cm3/g) and abundant O-containing functional groups. The saturated adsorption capacities for Pb2+, Cu2+, and Cd2+ were 412 mg/g, 368 mg/g, and 345 mg/g, respectively. The carbon also displayed excellent cycling stability, with nearly 100 % adsorption capacity retention after 20 cycles. In multiple heavy-metal-ion solution, the adsorption capacity and adsorption selectivity followed the order of Pb2+ (59.92 mg/g) > Cu2+ (32.94 mg/g) > Cd2+ (25.12 mg/g). This study provides a carbon with unique properties for simultaneously-efficient removing Pb2+, Cu2+, and Cd2+.