Study on Synthesis and Adsorption Properties of ReO₄ ^- Ion-Imprinted Polymer

In this work, an ion imprinted polymer (ReO₄ ^--IIP) of the perrhenate ion based on acrylamide (AM) and acrylic acid (AA) was prepared by solution polymerization using ReO₄ ^- as a template ion, N,N-methylenebisacrylamide (NMBA) as cross-linkers, hydrogen peroxide-vitamin C (H₂O₂-Vc) as an initiator, and a mixed solution of water (H₂O) and methanol (CH₃OH) with volume ratio v(H₂O)/v(CH₃OH) = 3:7 as a solvent. During the process of synthesis condition investigation and optimization, the adsorption capacity (Q) and the separation degree (R) in the equimolar concentration mixture solutions of NH₄ReO₄ and KMnO₄ were adopted as indexes, and the obtained optimal conditions were as follows: the molar ratios of NMBA, NH₄ReO₄, AA, H₂O₂, and Vc to AM were 5.73, 0.052, 1.29, 0.02, and 0.003, and the temperature and time of polymerization were 40 °C and 28 h, respectively. Under optimal conditions, the sample with indexes, Q and R of 0.064 mmol/g and 3.20, were harvested. What is more, a further reusability study found that good adsorption selectivity was maintained after repeating the experiment 9 times. Taking the non-IP prepared under the same conditions as a control, Fourier transform infrared spectroscopy, transmission electron microscopy, and Brunauer Emmett Teller were used to characterize the structure of the ReO₄ ^--IIP prepared under the optimal conditions. Finally, the kinetic study results showed that the zero-order kinetic model could better describe the adsorption process. The thermodynamic study results showed that the Langmuir model was more suitable for describing the isotherm adsorption process of the IIP.