| The vast production and extensive use of antibiotics had caused serious harm to the environment and had threatened human health.Therefore,it is quite essential to develop high performance adsorbents to remove antibiotic contaminants from wastewater.In this paper,Fe-doped ZIF-8（Fe-ZIF-8）was obtained by doping Fe ion into ZIF-8 through the metal doping strategy.The adsorption performance of Fe-ZIF-8for ciprofloxacin（CIP）was systematically studied to evaluate the feasibility of Fe-ZIF-8 for the removal of antibiotic pollutants from wastewater.It was found that the adsorption performance of CIP removal on Fe-ZIF-8 was significantly improved comparing with the original ZIF-8,while the selective adsorption experiments showed that the selectivity of Fe-ZIF-8 was not very good for tetracycline pollutant.Therefore,the"thermal activation method"was used to improve the TC adsorption performance of Fe-ZIF-8 and the new adsorbent was called Fe-ZIF-8-500.It should be noted that after activation,the equilibrium adsorption capacities of Fe-ZIF-8-500 are remarkably higher than Fe-ZIF-8.Fe-ZIF-8 was synthesized by simple precipitation method with zinc nitrate hexahydrate,ferrous sulfate heptahydrate and dimethyl imidazole as reactants,and methanol as organic solvent.Through the analysis of BET,XRD,SEM,TEM,TGA,XPS and FT-IR,it can be seen that Fe was successfully doped into ZIF-8.After Fe-doping,the Fe-ZIF-8 maintains the original rhomboid dodecahedron structure,while the specific surface area and pore size decrease.The adsorption experiments showed that the adsorption rate of Fe-ZIF-8 on CIP was very fast,and the maximum adsorption capacity reached 1484 mg g-1.The adsorption kinetics and isotherm for the CIP adsorbed onto Fe-ZIF-8 matched well with the pseudo-second-order kinetics and Freundlich isotherm model,respectively,revealing the multilayer adsorption and chemisorption nature.The outstanding adsorption capacity of CIP can be attributed to the comprehensive interactions including electrostatic attraction,hydrogen bonding,surface complexation andπ-πinteraction.The novel adsorbent Fe-ZIF-8-500 was obtained at 500℃in N2 atmosphere by thermal activation method.A series of adsorption experiments showed that the TC adsorption capacity of Fe-ZIF-8-500 was significantly increased from 367 mg g-1 to867 mg g-1 after thermal activation,which can be ascribed the removal of the coordinated water molecules in Fe-ZIF-8 by thermal activation and exposed more active sites.These excellent properties not only provide a new idea for the treatment of antibiotics in wastewater,but also broaden the application of MOFs in wastewater treatment. |
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