The Screening of Molecularly Imprinted Pre-assembly System for Benzimidazole Fungicides and Its Adsorption Properties
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Abstract:
Molecularly imprinted polymers (MIPs) of benzimidazole fungicides were synthesized by the precipitation polymerization method. The common maternal nucleus, 2-aminobenzimidazole (AMB), was selected as template molecule, Gaussian 09W molecular modelling software and H-NMR were involved to determine types and proportions of functional monomers and types of solvents in preassembled system. The optimum preparation conditions of MIPs were optimized through orthogonal experiment design. Under optimal conditions, structural characterization and adsorption properties of MIPs were studied by scanning electron microscopy (SEM), brunauer-emmett-teller (BET), fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analyser (TGA) and adsorption experiment. According to computer molecular simulation and nuclear magnetic spectral analysis, itaconic acid (IA) and acetonitrile were selected as function monomer and solvent, respectively. The molar ratio of AMB and IA was determined as 1:2. Based on the above results, the optimum imprinting conditions were established through orthogonal experiments. MIPs were prepared under the above mentioned preparation conditions, indicating a good thermal stability. The results of dynamic adsorption experiments showed that the adsorption process of MIPs to carbendazim (CBZ) conformed to the pseudo-second-order kinetic model, and the adsorption equilibrium time was 120 min. The equilibrium adsorption capacity (Q) of CBZ was 8.87 mg/g, and the imprinting factor (IF) was 2.89. The Scatchard analysis showed that MIPs had two classes of adsorption sites. MIPs showed good adsorbability not only to CBZ, but also to other benzimidazole fungicides such as thiamidazim, albendazole and benzimidazim. The MIPs synthesized by this method were used as solid-phase extraction fillers to remove the benzimidazole fungicides in Dendrobium polysaccharide extract. The removal rates of four benzimidazole fungicides were higher than 92% and the loss rate of total sugar was 14.94%.
