2.3. Cd2+ Adsorption Experiments

0.1 g of CMS was added into a conical flask, and then 100 mL of simulated wastewater containing 25, 50, 75, 100, 150, 200, and 250 μg/L of Cd²⁺ were added. The mixtures were stirred under constant temperature of 25 °C at 130 rpm for varying amounts of time. The supernatant was removed and the Cd²⁺ concentration was determined by a flame atomic adsorption spectrometry (FAAS) (WFX-210, Beifen-Ruili Analytical Instrument Co., Beijing, China). The amount of Cd²⁺ removed was calculated by the difference between the initial and equilibrium Cd²⁺ concentrations divided by the solid mass and multiplied by the liquid volume. The Cd²⁺ removal was calculated by the difference between the initial and equilibrium Cd²⁺ concentrations multiplied by 100. All experiments were done in triplicate, and the average and standard deviations are plotted in the figures.