Adsorptive removal of ciprofloxacin from water by carboxymethyl cellulose/κ-carrageenan/MIL-53 composite aerogel
Ciprofloxacin(CIP),a kind of popular fluoroquinolone antibiotics,has been widely used in the treatment and prevention of anti-infective diseases in humans and animals,but most of CIP is excreted to aqueous environment in the form of original drugs or metabolites.It is of great significance to investigate the efficient removal of CIP in water for the protection of ecological environment and human health.In the work,carboxymethyl cellulose(CMC)/MIL-53 and CMC/κ-carrageenan(κ-CG)/MIL-53 composite aerogels were prepared by using CMC and CMC/κ-CG aerogels as carriers and in situ loading of MIL-53,a popular metal-organic framework material.The performance and mechanisms of these composite aerogels on adsorptive removal of CIP were studied.CMC/MIL-53 and CMC/κ-CG/MIL-53 composite aerogels represented high adsorption capacity for CIP at pH ranging from 4.0 to 9.0 and high salt concentration,showing good both salt and alkali resistance.The adsorption of CIP on CMC/MIL-53 and CMC/κ-CG/MIL-53 composite aerogels are monolayer chemisorption process with theoretical maximum adsorption capacities of 1.105 mmol·g-1 and 1.464 mmol·g-1,respectively,at neutral condition.Combined with the results of apparent adsorption performance and the analysis of FTIR and XPS spectra before and after CIP adsorption,it can be concluded that the multi-adsorption mechanisms were involved in adsorption of CIP by these composite aerogels,including hydrogen bonding,electrostatic adsorption,π—π electron donor-acceptor interaction and complexation.Under neutral and alkaline conditions,the leaching amount of Fe3+ions is lower than the concentration threshold specified by the World Health Organization.It effectively solves the problems of easy loss and difficult recovery of the original powdered MIL-53 in water.In comparison to CMC/MIL-53,CMC/κ-CG/MIL-53 composite aerogel has higher performance in CIP removal and better application potential in actual water.
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