Adsorption/desorption performance of Pb2+ and Cd2+ with super adsorption capacity of PASP/CMS hydrogel

Super-absorbent polyaspartic acid/carboxymethyl salix psammophila powder (PASP/CMS) hydrogel was prepared by aqueous solution polymerization. PASP/CMS hydrogel was characterized by FT-IR, XRD, SEM and XPS. The results show that PASP/CMS hydrogel is prepared by graft copolymerization of the -COOH of polyaspartic acid (PASP) and the -CH2OH of carboxymethyl salix psammophila powder (CMS). The surface of that hydrogel becomes dense from loose porosity, and Pb2+ and Cd2+ are adsorbed onto the surface of hydrogel. The crystallinity of CMS is destroyed by the addition of PASP. The initial concentration of Pb2+ and Cd2+, pH, adsorption time and adsorption temperature on the adsorption effect were studied through experiments. And results showed that hydrogel has a good removal effect on Pb(II) and Cd(II) ions. Pseudo-second-order kinetic and Langmuir isotherm models are represented in the process, which are spontaneous, exothermic and decrease of randomness, and it's a single layer chemical adsorption. At the same time, the effect of desorption experimental parameters (HNO3 initial concentration, desorption time, and desorption temperature) on the experiment was studied and optimized.