To develop more economical and efficient heavy metal adsorbents, natural bentonite was employed as a raw material, and triethoxyvinylsilane served as a grafting agent to achieve the grafting bonding of sodium polyacrylate and bentonite. Structural alterations in the modified bentonite were analyzed through thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The adsorption and desorption characteristics of SAPAS-Bentonite and raw bentonite were compared and tested under various conditions, including time, temperature, pH, and lead ion concentration. The adsorption and desorption properties of sodium polyacrylate-grafted bentonite (SAPAS-Bentonite) were compared under various conditions (time, temperature, pH, and lead ion concentration). The results revealed that the modified method successfully achieved nano-scale coating of bentonite particles with sodium polyacrylate, leading to an increase in the maximum adsorption capacity of lead ions by 47.5%, reaching 165.73 mg g. A greater adsorption affinity for lead ions was exhibited by the outer sodium polycarboxylate portion of SAPAS-Bentonite compared with the inner bentonite. The adsorption of internal bentonite was limited by blocking when the adsorption of sodium polyacrylate did not reach the upper limit. The adsorption isotherm shifted from the Langmuir monolayer characteristic of the original bentonite to the S-shaped isotherm, reflecting the sodium polycarboxylate properties of SAPAS-Bentonite. Both bentonites demonstrated strong retention capacity for lead, with SAPAS-Bentonite surpassing raw bentonite in performance. This study provides valuable insights into the potential of SAPAS-Bentonite in the treatment of heavy metal pollution.

Organic diacid (oxalic and succinic) adsorption onto montmorillonite is feasible, but weak (~1 mg/g). The comparison of chemical and radiochemical determinations reveals that 80% of the acid in contact with the smectite is used to attack the clay lattice. The pH is the main parameter involved in adsorption, and fixation passes through a minimum for pH 6 to 7. Polyacrylate adsorption is also weak (~1.5 mg/g). It changes with the nature of the exchangeable cation of smectite. Its pH-dependence displays a pronounced maximum for a value corresponding to the pKa of the acidic functions (pH ~6.8), and a minimum at about pH 8. On the assumption that a polyacrylate macromolecule is 100% hydrolyzed, it follows that the-COOH groups carried by 20% hydrolyzed Polyacrylamide molecules (such as those used in the tertiary recovery of petroleum) contribute at the very most to 10% of the total adsorption onto clay. Fixation, therefore, involves predominantly protonation of the amide functions at the edge surfaces of the clay. The acidic functions play a minor role in the adsorption phenomenon in that they affect the length of the macromolecule. The extent of this contribution, however, is virtually impossible to estimate.