The Preparation Of Chitosan-metal Complex Nonwoven And Its Application On The Adsorption Of Dye And Tetracycline Pollutants From Aqueous Soultion

With the rapid development of industrialization and urbanization,more and more pollutants come into the environment water through industrial waste water,sewage and other ways.It not only poses a new threat for people’s water security,but also proposes new challenges to the existing water pollution control technology.On the basis of sustainable development,the exploitation of a variety of high capacity adsorbent which is easy to be recycled and replaced,suitable for joint treatment,economical and environment-friendly,is an important problem that environmental workers need to solve at present.Thus,in this paper,chitosan nonwoven fabric was used as the active carrier to be constructed an adsorption device that is suitable for nonwoven adsorption reaction.Subsequently,the chitosan nonwoven was modified chemically to prepare many adsorption materials.Then,the adsorption of dye and trace tetracycline in waste water was studied.The major research contents are listed as follows:（1）In this study,in order to overcome the solid/liquid separation inconvenience of chitosan powder adsorbents,a novel adsorption device with the sleeve cylinder was designed to match the chitosan nonwoven for the sake of easy separation.The inner cylinder is porous and wrapped by chitosan nonwoven.Moreover,the performance of the adsorption device was studied.Then,the effect of the dosage of chitosan nonwoven,reaction time,the initial concentration of dye and p H were discussed.The results showed that,the dye removal rate can reach above 90% when the dosage of chitosan nonwoven is 4 8 g with 90 120 min reaction time.In this system,the sorption of C.I.Acid Red 73 to chitosan nonwoven could maintain high efficiency in a wide p H range from 3 to 7 with a maximum adsorption capacity of 88.43 mg/g.Besides,through SEM,XRD and XPS,it reveals the electrostatic adsorption of AR73 onto the-NH3+ sites,which is similar to common chitosan-based adsorbent.（2）Al-doping chitosan nonwoven was prepared to enhance the adsorption ability of chitosan nonwoven through the chelation interaction between dyes and metal centers of the Al-doping chitosan nonwoven.In this system,the sorption of C.I.Acid Red 73 to Al-doping chitosan nonwoven could maintain high efficiency in a wide p H range from 3 to 10 with high maximum adsorption capacity of 260.03 mg/g.Additionally,the studies of reusability,p H sensitivity,the effect of the coexisting ions and the adsorption of other organic dyes indicated that the Al-doping chitosan nonwoven fixed in sleeve cylinder reactor was technically feasible,highly efficient,and implies a potential of practical application for dyeing effluent treatment.（3）The Zn-doping chitosan nonwoven adsorbent was prepared and the adsorption of trace tetracycline in waste water was studied.The results showed that the optimal concentration and time of zinc ion modified chitosan nonwoven was 0.005 mol/L and 12 h,respectively.The adsorption kinetics of tetracycline on Zn-doping chitosan nonwoven conformed to the pseudo-second-order kinetics model.Tetracycline on Zn-doping chitosan nonwoven accorded with Langmuir-Freundlich isotherm equation with high adsorption capacity of 7.785 mg/g when the initial concentration of tetracycline was between 0 and 5 ′ 10-4 mol/L.While the adsorption capacity is linear with the equilibrium concentration when Ce ranges from 4 ′ 10-4 mol/L to 1 ′10-5 mol/L,which is in accordance with Henry’s law.It can be deduced that the adsorption of trace tetracycline on Zndoping chitosan nonwoven is controlled by the combination of Zn²⁺ and lone electron pair（O and N）of tetracycline molecules.（4）The fluorescence spectra of aluminum ions with chlortetracycline and zinc ions with tetracycline were studied.On the basis of the above results,chitosan were chosen as carriers to load metal ions for the adsorption of tetracycline.The chitosan powder and nonwoven were respectively used as carriers to be observed the yellow fluorescence intensity.Therefore,with the advantage of easy replacement and recovery of chitosan nonwoven,the adsorption saturation can be judged by the luminescent degree of adsorbent under the irradiation of UV lamp.