The Preparation Of Chitosan-Based Fibrous Materials And Research Of Adsorption Performance For Metal Ions

With the development of social economy,environmental pollution has attracted worldwide attention.Especially the heavy metal pollution,it can cause great harmness to ecological environment and human health.At present,it is urgent to develop the comprehensive prevention and treatment of heavy metal pollution.It is of great significance to explore the novel control measures of heavy metal pollution for the sustainable development of human society.This paper had developed and synthesized three kinds of novel chitosan-based materials including CCP,PET-AA-CS and CSTEC fibers.The novel adsorption materials were characterized by scanning electron microscopy?SEM?,atomic force microscope?AFM?,contact angle,fourier infrared spectrum?FTIR?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?technology and so on.Adsorption experiments were carried out to investigate the adsorption performance of adsorption materials for heavy metal ions.Effects of different influence factors?such as the solution pH,metal ion concentration and exposure time,etc.?for the adsorption materials were investigated in the removal of heavy metal ions in queous solution.Adsorption isotherm,kinetics and thermodynamic models were used for the fitting of experimental data in the static experiments to understand the adsorption performance of adsorption material,adsorptionrate,thermodynamicbehaviorsandadsorptionmechanism.Adsorption-desorption experiments were carried out to investigate the adsorption stability of adsorption materials.Adsorption mechanism of heavy metals on the new adsorption materials was discussed by infrared spectroscopy and X-ray photoelectron spectroscopy.It is investigated the adsorption performance of copper ions on the CSTEC fibers in the dynamic adsorption bed.The content of this research can summarized as follows:?1?A novel chitosan modified polyethylene terephthalate?PET?composite adsorbent?CCP?was specifically fabricated using dip-padding method for the removal of toxic metal ions from aqueous solutions.The adsorption experiments demonstrated that the adsorption process of metal ions on the surface of CCP was well fitted with the Langmuir isotherm model and the pseudo-second-order kinetic model.Maximum adsorption values(q_max)of18.7,23.7,and 31.2 mg g^-11 were obtained from Langmuir isotherm model for the Zn?II?,Cu?II?,and Pb?II?,respectively.?2?Functional PET fiber?PET–AA–CS?was prepared by oxygen–plasma pretreatment and grafting of acrylic acid?AA?and low molecular weight chitosan?LMCS?on the Polyethylene glycol terephthalate?PET?as substrate.The chemical propertie of sanples were characterized by FTIR,XRD and XPS.Results showed that acrylic acid and LMCS were successfully grafted on the PET fiber.In addition,carboxyl group and amine groups were the main adsorption sites.The adsorption of copper ions on the PET–AA–CS was pH–dependent with the maximum capacity of 68.9 mg g^–1.Adsorption process was well fitted to the Langmuir isotherm model and pseudo–second–order model.Results showed that the adsorption process was mainly the chemisorption.?3?Composite modified adsorbent?CSTEC?was synthesized as novel fibrous materials for the adsorption of Cu?II?and Pb?II?ions from water in this study.The kinetics study revealed that adsorption processes of Cu?II?and Pb?II?ions on the CSTEC followed the second-order kinetics model.CSTEC showed better performance(Cu²⁺,95.2 mg g^-1;Pb²⁺,144 mg g^-1)than most of other adsorbents.The adsorption processes of metal ions on the CSTEC fibers were well fitted to the Langmuir isotherm model and pseudo–second–order model.Results showed that the chemical adsorption and monolayer adsorption reaction played an important part in the adsorption process.CSTEC fiber has better adsorption-desorption stability.?4?CSTEC fiber as the adsorption material,which was fixed in the adsorption bed in the form of a string of adsorbents.Copper ions as the adsobate,the dynamic adsorption experiment was carried out for the analysis the adsorption behaviors.One-dimensional water quality model was used to study and predict the transition and transform rule of metal ions in river for the sudden accident,providing the theoretical basis for he actual emergency application of novel materials.