Single and competitive adsorption of Cd(II) and Pb(II) from aqueous solution by activated carbon prepared with Salix matsudana Kiodz.

In this study, Salix matsudana activated carbon (SAC) was prepared by phosphoric acid activation, and the adsorption characteristics of Cd(II) and Pb(II) on SAC in single- and double-component solutions were investigated. In both systems, the adsorption capacities of both ions on SAC increased with the increasing initial pH value and temperature in the solutions, and the adsorption equilibrium was approached at 10 min. The adsorption process was spontaneous, endothermic, and depicted well by the pseudo-second-order adsorption model, and the equilibrium adsorption fitted reasonably well with the Langmuir isotherm. The maximum adsorption capacity (Qm) of Cd(II) and Pb(II) was 58.48 and 59.01 mg/g, respectively, in the single-element systems. However, it reduced to 25.32 and 31.09 mg/g, respectively, in the double-element system. The physicochemical property analysis showed that the specific surface area, total pore volume, and average pore diameter of SAC was 435.65 m2/g, 35.68 mL/g, and 3.86 nm, respectively. The SAC contained groups of -OH, C = O, and P = O. Results suggest that SAC had a good performance for the adsorption of Cd(II) and Pb(II) from solution, and the adsorption selectivity sequence was Pb(II) > Cd(II).