Effective solid phase extraction for the enrichment of p-nitrophenol in water using microwave-assisted synthesized fly ash@ p-nitrophenol surface molecular imprinted polymer

摘要

In this study, microwave-assisted fly ash@p-nitrophenol surface molecular imprinted polymer (FA@PNP-SMIP) was prepared for the recognition of p-nitrophenol (PNP). FA@PNP-SMIP was synthesized with gamma-ureidopropyltrimethoxysilane, azodiisobutyronitrile (AIBN) and ethylene glycol dimethacrylate (EGDMA). Fly ash (FA) was developed as a carrier due to its unique hollow structure and high thermal stability. Characterization of the FA@PNP-SMIP was conducted via scanning electron microscope (SEM), Fourier transform infrared reflection (FTIR), Brunauer-Emmett-Teller (BET) and thermogravimetry (TG). The surface of FA@PNP-SMIP is rougher than that of fly ash@p-nitrophenol surface non-imprinted polymer (FA@PNP-SNIP). Under optimum conditions, the maximum adsorption capacity reached 102.5 mg g(-1). The optimum conditions used were pH 7 and 303 K. As the concentration of PNP increased, the adsorption capacity increased quickly at first, then started slowing. The pseudo-second-order kinetic model could well describe the adsorption process, indicating the adsorption reaction was controlled by chemical adsorption. Adsorption isotherm data were well fitted by Freundlich model, suggesting that the adsorption reaction was a multilayer adsorption. The thermodynamic analysis proved that the adsorption process for PNP was spontaneous and endothermic. The relative selectivity coefficients of PNP/2, 4-dinitrophenol, PNP/catechol and PNP/phenol all exceeded 2. The combination of FA@PNP-SMIP and solid phase extraction achieved the best enrichment effect of PNP (98.8). The developed method provided a good linear relationship ranging between 1 and 10 mu g mL(-1). The limit of detection (LOD) and limit of quantification (LOQ) were 0.011 and 0.036 mu g mL(-1), respectively. This study offers a facile and general method for the enrichment of PNP in water.