A novel surface molecularly imprinted polymer (SMIP) selective for di(2-ethylhexyl) phthalate (DEHP) was prepared on the surface of silica gel, which was modified by aminopropyltriethoxysilane and acryloyl chloride in a two-step method, with DEHP as template, methyl acrylic acid (MAA) as functional monomer, ethyleneglycol dimethacrylate (EGDMA) as cross-linker and azobisisobutyronitrile (AIBN) as initiator. The prepared SMIP was characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and nitrogen adsorption-desorption analysis. The adsorption properties of the SMIP for DEHP were investigated. The results showed that the SMIP was porous and rough. Its specific surface area and pore volume were 292.05 m2/g and 0.299 cm3/g, respectively, which increased to 15 and 10 times that of silica gel, respectively. The adsorption performance is optimal under the conditions of pH value in the range 6~7. The adsorption equilibrium time was about 150 min. The isothermal adsorption process and adsorption kinetics could be well described by Langmuir and the pseudo-second-order kinetic model respectively. The saturated adsorption capacity is 16.08 mg/g. The SMIP exhibited excellent adsorption selectivity for DEHP. The SMIP prepared is a desirable solid-phase extraction agent for separation and enrichment of DEHP in complicated environmental samples.

Zhan Yang, Fangyan Chen, Yubin Tang and Shaoli Li