Removal of phthalate ester compound from PVC plastic samples using magnetic molecularly imprinted polymer on the surface of superparamagnetic Fe3O4 (Fe3O4@MIPs)

Abstract

In this study, novel magnetic molecularly imprinted polymers (MMIPs) were successfully synthesized for selective separation of di(2-ethylhexyl)phthalate (DEHP) in PVC sample solutions. Polymerization was carried out using Fe3O4 modified by oleic acid, ethylene glycol dimethacrylate (EGDMA), methacrylic acid (MAA), and benzoyl peroxide (BPO) in the presence of DEHP as template molecule to produce MMIPs named Fe3O4@MIPs. Magnetic non-molecularly imprinted polymers (MNIPs) were also prepared for comparison purposes. The structure and physical properties of MMIPs and MNIPs were characterized using FT-IR, SEM, TEM, VSM and zeta potential analysis. The FT-IR spectra showed that MMIPs were successfully synthesized, indicated by the presence of a Fe-O peak at 586 cm−1, a benzene derivative peaks at 709, 1072, and 1155 cm−1, a carbonyl peak of MAA at 1728 cm−1 and a C–H peak of oleic acid at 2954 cm−1. SEM and TEM measurements showed that MMIPs were porous polymers with a smaller particle size than MNIPs. VSM measurement showed that MMIPs were superparamagnetic with a saturation magnetism value of 39.92 emu/g. MMIPs have a better adsorption capacity than MNIPs with an imprinting factor (IF) value of 3.37 and a maximum adsorption capacity value of 17.21 mg/g. The sorption studies showed that the adsorption process followed the Langmuir isotherm model and fitted well to a pseudo-second-order kinetic model with ΔHo of −82.17 kJ mol−1. Moreover, MMIPs were more selective to DEHP than dibutyl phthalate (DBP), with a selectivity coefficient value of 4.57. The desorption test showed that MMIPs showed good regeneration with a desorption percentage of 98.42% and decreasing in adsorption capacity of 11.2% after three times regenerations. DEHP removal from PVC samples using MMIP showed that polymer could reduce the matrixes effect with a recovery percentage of around 91.03–99.68%.