Preparation and characterization of carboxymethyl cellulose/chitosan/alginic acid hydrogels with adjustable pore structure for adsorption of heavy metal ions

• Adjusting the pore structure of hydrogels affects the adsorption performance. • PSCA is a physical hole-forming method. • PSCA does not affect hydrogel active site. • The content of PSCA and adsorption capacity are in an inverted U shape. • The hydrogel can handle Cr(VI), Cu(II), and Ni(II) simultaneously. In this study, a Pore Structure Control Agent (PSCA) was proposed to adjust the pore structure of hydrogels and quickly solve the problem of heavy metal pollution. PSCA is a mixed solution consisting of Glycerol (GL), Ethyl Orthosilicate (TEOS), Isopropanol (IPA), H 2 O, and Hydrochloric Acid (HCl). As the addition amount increases, the pore size decreases, and the adsorption capacity first increases and then weakens. PSCS 2 wt% was added, and the adsorption was completed in 20 min. Using borax as a cross-linked agent and coagulant, the heavy metal adsorption hydrogel was prepared by a one-step polymerization method combined with the sol–gel method. The three hydrogels prepared with Carboxymethyl Cellulose (CMC), Chitosan (CS), and Alginic Acid (AA) as raw materials adsorbed Cr(VI), Cu(II), and Ni(II) in a sum greater than 750 mg/g. The kinetic fitting results of Cr(VI) show that the hydrogel belongs to physical adsorption, and Cu(II) and Ni(II) belong to chemical adsorption. The Freundlich adsorption isotherm model indicated that the hydrogel belongs to multilayer adsorption. The proposal of PSCA controls the structure of the hydrogel and has a certain promotion effect on the treatment of heavy metal pollution.