Selective adsorption and photodegradation of residual norfloxacin in water using a mTiO2 based inorganic molecularly imprinted magnetic photocatalyst

Abstract

In this study, a mesoporous TiO₂ (mTiO₂) based inorganic molecularly imprinted magnetic photocatalyst was prepared for the selective adsorption and photodegradation of residual antibiotics in water. Direct molecularly imprinted TiO₂ shells were coated on nano-Fe₃O₄ (Fe₃O₄@TiO₂) through a sol–gel imprinting technique using norfloxacin (NOR) as a template, then the amorphous imprinted TiO₂ shells were transformed into mesoporous crystalline anatase (Fe₃O₄@mTiO₂) by a microwave-assisted hydrothermal method, and Ag NPs were simultaneously in situ reduced on the surface (Fe₃O₄@mTiO₂@Ag) to enhance the photodegradation performance. The as-prepared inorganic molecularly imprinted Fe₃O₄@mTiO₂@Ag (MIFTA) nanocomposites showed excellent specificity for the target molecule NOR, and the adsorption capacity was as high as 135.7 μg mg⁻¹, which was 1.4 to 2.3 times higher than that of other fluoroquinolone antibiotics. The photodegradation rate of MIFTA for NOR was 0.0129 min⁻¹, which was about 3.1 times faster than that of non-imprinted Fe₃O₄@mTiO₂@Ag (NIFTA). In addition, the used MIFTA nanocomposites can be easily recycled by magnetic separation and subsequent water elution. These results indicate that prepared MIFTA nanocomposites were expected to provide an efficient, environment friendly, and low-cost approach for the selective removal of residual antibiotics in water.