Highly-efficient amphiphilic magnetic nanocomposites based on a simple sol-gel modification for adsorption of phthalate esters.

In this work, a novel amphiphilic magnetic nanocomposite (Fe3O4@A-O) used for the adsorption of phthalate esters was synthesized by a simple sol-gel surface modification method, during which hydrophilic amino groups of 3-aminopropyltriethoxylsilane and hydrophobic alkyl chains of N-octyltrimethoxysilane were modified onto Fe3O4 nanoparticles. Morphologies and surface structures of as-prepared magnetic nanomaterials were characterized in detail. The preparation, adsorption, and desorption conditions of Fe3O4@A-O were investigated systematically and the adsorption mechanism was discussed. The Fe3O4@A-O exhibits quite fast adsorption for six phthalate esters, which only takes two minutes and is 10 ∼ 720 times shorter than other reported adsorbents. Theoretical adsorption capacities of Fe3O4@A-O for dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, and didecyl phthalate are >1000 mg/g according to the Freundlich fitting. With ethanol as desorption solvent, it only takes one minute to reach desorption equilibrium. In addition, Fe3O4@A-O can be collected from aqueous solution with an applied magnet in just three seconds, and it shows satisfactory stability and reusability after recycling 10 times. The developed amphiphilic adsorbent exhibits great promises in the removal of phthalate esters because of its easy preparation, excellent adsorption and desorption performances, rapid magnetic separation, and good reusability.