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

Abstract

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.

Hydrogels derived from galactoglucomannan hemicellulose with inorganic contaminant removal properties

“…8a shows that the increase in the initial concentration led to an increase in the amount adsorbed per gram of bioadsorbent. This behaviour may be due to the fact that this greater quantity of Pb( ii ) ions can provide a higher driving force for effective collision between ions and active sites of the hydrogel, thereby promoting the transfer of ions between the two phases (diffusion from the solution phase to hydrogel phase) and more collisions between ions and active sites of the hydrogel (Chen et al 2020; 50 Wang et al 2021 51 ). This behaviour can be attributed to an increase in driving force, given by the concentration gradient, which exceeds the resistance of the mass transfer between the bioadsorbent and the adsorption medium due to the increase in the diffusion rate of the metal ions.…”

Efficient Removal of Heavy Metals from Aqueous Solution Using Licorice Residue-Based Hydrogel Adsorbent

“…Commonly used crosslinking agents include citric acid, epichlorohydrin, and glutaraldehyde [43,44]. In a previous study, the crosslinking of cellulose using epichlorohydrin (EPI) had shown improvements in adsorption capacity, chemical stability, pore size distribution, and mechanical properties [45]. In comparison, glutaraldehyde raised concerns regarding the potential presence of toxic residues after the reaction [46].…”