Preparation of magnetic molecularly imprinted polymer nanoparticles by surface imprinting by a sol–gel process for the selective and rapid removal of di-(2-ethylhexyl) phthalate from aqueous solution

Magnetic molecularly imprinted polymer nanoparticles for di-(2-ethylhexyl) phthalate were synthesized by surface imprinting technology with a sol-gel process and used for the selective and rapid adsorption and removal of di-(2-ethylhexyl) phthalate from aqueous solution. The prepared magnetic molecularly imprinted polymer nanoparticles were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and vibrating sample magnetometry. The adsorption of di-(2-ethylhexyl) phthalate onto the magnetic molecularly imprinted polymer was spontaneous and endothermic. The adsorption equilibrium was achieved within 1 h, the maximum adsorption capacity was 30.7 mg/g, and the adsorption process could be well described by Langmuir isotherm model and pseudo-second-order kinetic model. The magnetic molecularly imprinted polymer displayed a good adsorption selectivity for di-(2-ethylhexyl) phthalate with respect to dibutyl phthalate and di-n-octyl phthalate. The reusability of magnetic molecularly imprinted polymer was demonstrated for at least eight repeated cycles without significant loss in adsorption capacity. The adsorption efficiencies of the magnetic molecularly imprinted polymer toward di-(2-ethylhexyl) phthalate in real water samples were in the range of 98-100%. These results indicated that the prepared adsorbent could be used as an efficient and cost-effective material for the removal of di-(2-ethylhexyl) phthalate from environmental water samples.