Preparation Of Cellulose Composite Membranes For Adsorption Of Ciprofloxacin Hydrochloride

As an important fluoroquinolones antibiotic,ciprofloxacin hydrochloride?HCIP?is widely existed in water and soil,which poses a great threat to ecological health.Therefore,it is very important to remove it from surroundings.In this paper,cellulose membranes and cellulose composite membranes were prepared for HCIP adsorption based on phase inversion technique.The structure and properties of membranes were tested by series methods including Fourier transform infrared spectroscopy?FT-IR?,X-ray diffractometer?XRD?,scanning electron microscope?SEM?,thermogravimetric analysis?TGA?and water contact angle techniques.Furthermore,adsorption experiments for HCIP were also carried out.Firstly,cellulose membranes were prepared with microcrystalline cellulose as solute,ionic liquid 1-butyl-3-methylimidazolium chloride?[BMIM]Cl?as solvent and dimethyl sulfoxide?DMSO?as cosolvent.The optimum solvent ratio R?1:1?and temperature?50°C?were determined by single factor experiments.It was indicated that after being treated with ionic liquid,the transformation of crystalline structure from I to II occurred.Cellulose membranes also appeared higher thermodynamic stability and good hydrophilicity.The surface of them was smooth and flat,while their internal structure was affected by solvent ratio.Under the condition of 25°C,the maximum adsorption capacity of cellulose membrane to HCIP was 25.00 mg/g.And the adsorption data could be well expressed in pseudo-second order kinetic model.Secondly,ultrasound-assisted Hummers method was applied to synthesize graphene oxide.Graphene oxide-cellulose composite membrane?GOCE?and magnetic graphene oxide-cellulose composite membrane?FGCE?were fabricated by blending and coating with cellulose as basic structure support.Layered structure was observed on GO surface via SEM micrographs.With rough internal structure,the composite membranes both possess large specific surface area.According to the results of FT-IR and XRD,a large number of hydrogen bonds formed between GO and cellulose molecules.Compared to GOCE,FGCE showed relatively excellent thermal stability and hydrophilic properties owing to addition of nano Fe₃O₄.Finally,the adsorption properties of composite membranes?FGCE?were explored.The maximum adsorption capacity of FGCE to HCIP could reach at236.39 mg/g at a pH of 6.0⁶.7,which was much higher than the value of GOCE?196.08 mg/g?.The presence of cations such as Na⁺,NH₄⁺and Ca²⁺or anions such as Cl^-,HSO₄^-and H₂PO₄^-all had negative effect on adsorption ability to varying degrees.FGCE has a good corrosion resistance in acidic solutions and can be recycled four times.Controlled by chemisorption,the adsorption process is spontaneous and exothermic.The experimental data of thermodynamic and kinetic for HCIP were well fitted to the Freundlich adsorption isotherm model and pseudo-second order kinetic model.