Studies On Removal Of Norfloxacin By Imprinted CoFe₂O₄@TiO₂ Materials

Fluoroquinolones are synthetic antibiotics that are widely used and have drawn much attention in recent years for their frequent detection in water environment.Fluoroquinolones have specific biological effects and pose potential health risks to humans and the environment even at low concentrations.Therefore,it is important for the safe pollutant control technologies.In this paper,a new kind of magnetic molecular imprinting Composite(CoFe2O4@TiO2-MMIP),which could be regenerated in situ,was prepared based on the surface molecular imprinting technology,magnetic separation technology and photocatalytic technology with CoFe2O4 as magnetic core and norfloxacin as the target contaminant.The physical and chemical characterization indicated that the pore volume was significantly increased,which was helpful to increase the adsorption efficiency.The existence of anatase crystal indicated that magnetic molecular imprinting Composite could be regenerated by photocatalytic degradation.Fitting the experimental of batch adsorption,it was found that the process of norfloxacin adsorpted onto magnetic molecular imprinting Composite accorded with the second-order kinetic and the Langmuir isotherm model.The adsorption rate,maximum adsorption capacity and Langmuir constaint were 0.21g · mg-1 · min-1,14.260mg · g-1 and 5.187 L · mg-1,respectively.CoFe2O4@TiO2-MMIP had selective adsorption ability towards fluoroquinolones.The adsorption efficiency was closely related to the molecular structure,polarity and functional groups of the target contaminant.The adsorption capacity of CoFe2O4@TiO2-MMIP towarsdd norfloxacin was 26.8 times than carbamazepine.In multi-system,adsorption properties would be subject to similar structural competition substances.In this paper,the photocatalytic in-situ regeneration performance of CoFe2O4@TiO2-MMIP was also investigated.The adsorption efficiency towards norfloxacin could still reach 82.8%after nine regeneration cycles.The photocatalytic degradation process followed pseudo-first-order kinetic.The mineralization efficiency could reach 84.2%after 150min.Environmental factors affected both adsorption and photocatalytic process.Adsorption removal efficiencies towards norfloxacin by were only 4.5%and 23.6%when pH was 3 and 13,respectively.The existence of 0.1mM Cu2+ and Fe3+decreased removal efficiency from 94.5%to 53.0%and 10.2%,respectively.When the concentration of humic acid increased from 0.154mg · L-1 to 4.427mg · L-1,the adsorption efficiency of norfloxacin first increased and then decreased,while the photocatalytic degradation rate decreased.The effects of Fe3+,Na+,NO3-and SO42-on the photocatalytic degradation of magnetic molecular imprinting Composite were investigated.The effect of Fe3+ was the most significant.The adsorption removal efficiency and photodegradation rate were both decreased in drinking water and surface water compared to ultrapure water.Since the the anion and humic acid in drinking water and surface water competed with norfloxacin for adsorption sites and hydroxyl radicals,reducing the removal efficiency towards norfloxacin.In addition,turbidity could also affect the transmittance of ultraviolet light and reduce the UV intensity of CoFe2O4@TiO2-MMIP surface.