Development of Optimal Conditions for Synthesis of Molecularly Imprinted Polymers for Effective Terbium Sorption

Molecularly imprinted polymers (MIPs) as well as non-imprinted polymers (NIPs) were synthesized for selective sorption of lead and terbium. The ratio of raw monomers for the terbium-MIPs' synthesis was optimized based on the results of the synthesis of lead-MIP. It was found that the molar ratio of template/monomer/monomer/cross-linker = 1:5:5:8 was the most accurate for successful synthesis of the target MIP. As a result, the yields of the MIP and NIP on terbium were 59.3% and 61.2%, respectively. The structure of the imprinted samples was determined by FTIR spectroscopy. SEM analysis of the imprinted structures showed that the Tb-MIP contained a large number of pores compared to the NIP. The size of these pores ranged from 0.779 μm to 1.874 μm. The results of sorption experiments showed that the adsorption efficiency of Tb-MIP was seven times higher than that of NIP: the sorption degree was 70.80% for MIP and 9.95% for NIP. The imprinting factor was calculated and was equal to 7.06. The sorption process was described by the Radushkevich and pseudo-second-order kinetic models. It was shown that sorption by NIP occurred with a fast saturation of a lower Tb concentration, and the MIP's sorption passed slower and more efficiently. The desorption degrees of Tb-MIP and NIP were 90.15% and 52.67%, respectively.