Microwave-assisted synthesis of magnetic surface molecular imprinted polymer for adsorption and solid phase extraction of 4-nitrophenol in wastewater

A novel sorbent based on surface molecularly imprinted polymers (MIPs) was prepared for efficient adsorption and extraction of 4-nitrophenol (4-NP) from water. Microwave-assisted surface imprinting technology was employed to synthesize the surface molecularly imprinted polymer of Fe3O4@SiO2@PNP-SMIP with the gamma-ureidopropyltrimethoxysilane as functional monomer, 4-NP as template molecule and Fe3O4@SiO2 as support material. It was characterized by Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and Brunner-Emmet-Teller (BET). The results indicated that Fe3O4@SiO2@PNP-SMIP can effectively adsorb and extract PNP. The adsorption capacity of this polymer for 4 NP can reach 134.23 mg.g(-1), in comparison with 64.07 mg.g(-1) of the corresponding non-imprinted polymer. The adsorption process could be well described with pseudo second order kinetic model (R-2 = 0.9900-0.9936) and the Langmuir model. The solid phase extraction efficiency of the Fe3O4@SiO2@PNP-SMIP to 4-NP could reach 99% under the condition of the initial 4-NP concentration of 6.5 mu g.mL(-1), pH of 7 and the eluent of 2 mL mixed solvent of methanol/acetic acid (5:1, v/v). And the selective SPE efficiency attained 99.2% in the presence of multiple structural analogues of 4-NP. These results demonstrate that Fe3O4@SiO2@PNP-SMIP could be employed for separation and detection of 4-NP from water samples.