Synthesis of imprinted amino-functionalized mesoporous silica and their selective adsorption performance of Pb 2+ , Cu 2+ , and Zn 2+

The synthesis of imprinted amino-functionalized mesoporous silica (IAFMS) are using lead, copper, and zinc ions as imprinting species, anhydrous ethanol as a solvent, PEG-2000 as a template agent, tetramethylammonium hydroxide (TMAOH) as an auxiliary template agent, and tetraethoxysilane (TEOS) as a source of silica. The amino group was provided via the most common agent (3-aminopropyl)triethoxysilane (APTES). Based on the uniform design and response surface analysis, the optimum molar ratios of synthetic species such as APTES:heavy metal ions:TMAOH:PEG-2000:TEOS:anhydrous ethanol were determined as 0.270:0.065:0.25:0.073:1:50. Subsequently, Pb-IAFMS, Cu-IAFMS, and Zn-IAFMS were prepared with the same ratios as the above. Then, isothermal adsorption and selective adsorption of Pb(II), Cu(II), and Zn(II) were carried out. The results showed that the adsorption of heavy metal ions was mainly a chemical adsorption, the adsorbent surface was not a completely uniform adsorption, and a higher temperature was beneficial to the adsorption of heavy metal ions. Compared with q m values in the Langmuir model, the adsorption capacities of target ions onto imprinted materials can be 32.6–71.2% higher than those on the non-imprinted material. Values of relatively selective coefficients of IAFMS ranged from 4.35 to 18.45, which reveals the remarkable affinities of imprinted samples to the corresponding ions.