Optimization of diatom-based blotting materials and their efficient selective adsorption of Pb(II)

In this study, diatom-based Pb(II) imprinted materials (DE/Pb(II)IIP) were synthesized using the surface ion imprinting method with diatomaceous earth as the substrate, 3-mercaptopropyltriethoxysilane (MPTES) as the functional monomer, Pb(II) as the template ion, and glutaric dialdehyde (GA) as the cross-linking agent to solve the pollution problem of Pb(II) ions in water in a targeted and selective manner. The response surface methodology-Box Behnken design was also utilized to analyze the effects of functional monomers, crosslinkers, and polymerization temperature alone, as well as their interaction relationship on the adsorption capacity of the adsorbents and to determine the optimal conditions for adsorbent synthesis. The systematic characterization of the DE/Pb(II)IIP adsorbent materials prior to and after adsorption revealed that MPTES was successfully grafted onto the diatom surface and cross-linked with GA to form uniformly distributed imprinted active sites while avoiding the fundamental problems of self-polymerization and self-cross-linking of functional monomers and crosslinkers. In addition, the combined action of S-Pb coordination and electrostatic adsorption is advantageous for Pb (II) adsorption. The adsorption process followed quasi-second-order kinetics and the Langmuir isothermal adsorption model, as kinetics, isotherm, and thermodynamics demonstrated. The adsorption procedure was governed primarily by homogeneous single-layer chemisorption and was exothermic. DE/Pb(II)IIP exhibited greater selectivity for Pb(II) adsorption than the chemically similar non-imprinted polymer. Excellent selectivity and regeneration properties indicate that DE/Pb(II)IIP is a type of Pb(II) selective recognition adsorption material with a stable structure that can be widely used to recover and utilize heavy metals from actual wastewater.