Sodium alginate/ diatom-based blotting hydrogel material for Pb(II) removal: Effect of crosslinker optimization on its composition, selectivity, and desorption rate

In this study, we report a novel adsorption material (SAD-IIP), which is used for the directional adsorption of Pb (II), the polymerization time, the amount of crosslinking agent and the crosslinking time were optimized by response surface design, and the effect of the amount of crosslinking agent on the adsorption of lead on SAD-IIP was analyzed. The numerical control of cross-linking agent directly determines the number of effective imprinting sites, which affects the orientation selectivity of target ions and the desorption rate of the adsorbent. The results showed that the best adsorption performance was obtained when the polymerization temperature was 59.14 degrees C, the amount of glutaraldehyde was 1.20 ml, and the crosslinking time was 92.55 min. The adsorption amount and imprinting factor were 244.09 mg/G and 9.90, respectively, the self-polymerization and self-crosslinking of the adsorbent in the imprinting process are effectively avoided. The adsorption mechanism of SAD-IIP is ion exchange with Ca2+ and chelation coordination of sulfhydryl, hydroxy, carboxyl with lead ion. After 10 cycles, the removal rate of Pb (II) and desorption rate of SAD-IIP were 92.75% and 70.43%, respectively. These results indicate that the rational control of the introduction conditions of cross -linking agent is of theoretical and practical value for the preparation of new hydrogel imprinting materials for selective adsorption of target ions and efficient recovery of Pb (II).