Preparation And Properties Of Nickel Ion Imprinted Chitosan

Ion imprinting is a new way to separate selectively and specific purify heavy metal ions.In this paper,it was successfully prepared ion imprinted material sodium hydroxide coagulation bath by ion imprinting techniquel,with nickel ion as template ion,chitosan as functional monomer,sodium hydroxide as coagulation,bathhollow glass microbead as inorganic carrier,water as dispersion medium,and used dropping and ball forming method.The adsorption capacity and selective were studied by static adsorption method in binary systems of Ni???and Fe???and aqueous solutions of multicomponent systems.The space configuration and functional groups of imprined and adsorpted were studied by Fourier transform-infrared spectroscopy?FT-IR?.The micromorphology and element composition of ion imprinted material were studied coupled with energy dispersive spectrometer?EDS?and scanning electron microscopy?SEM?.The phase compositions of imprinted materals were investigated by X-ray diffraction?XRD?.The optical behavior of metal ions in aqueous solution was studied by UV-Vis before and after adsorpted.Based on these results,the following conclusions were drawn:The optimal preparation scheme of nickel ion imprinted material is:the initial concentration of nickel chloride is 2g/L,the desiccant temperature is 50?.The time is a hour,the coagulant was w=5%NaOH solution,the eluent was w=2%sulfuric acid,and the cross-linking agent was 5.0 ml/L glutaraldehyde.The optimum adsorption conditions for nickel ion imprinted materials during adsorption are:35?,pH=6;the adsorption rate could reach 98%,the saturated adsorption amount reach 8.608 mg/g,and the number of repeated using is 6 times.Selective adsorption capacity of imprinted material in binary solution:in Ni²⁺/Fe²⁺system,selectivity coefficient K of nickel ion reached 4434.65:in Ni²⁺/Co²⁺system,selectivity coefficient K of nickel ion reached 22274.90:in Ni²⁺/Cu²⁺system the selectivity coefficient of nickel ion reached 6210.99.In multi-component solutions(Ni²⁺,Cu²⁺,Co²⁺,Fe²⁺),the imprinted material has a good selective adsorption performance with 100%efficiency.In the chemical nickel waste liquid,electroplating nickel waste liquid and simulated industrial wastewater,nickel ions are adsorbed into the imprinted material well.The imprinted material is a three-dimensional spherical structure with a molecular formula of[C₇H₅O₅N₂]_n·SiO₂,had a weak crystallization ability with the crystallite size0.5506nm.During the adsorption process,imprinting holes for specific recognition is formeda tetragonal configuration of a complex with a coordination number of 4,with reacted by Ni²⁺and single electrons provided by N from-NH₂ on the surface.The decomposition reaction is an endothermic reaction,and the thermal stability is good at room temperature,which is conformed the Pseudo-second-order model.It belongs to chemical adsorption and contained to the Langmuir isothermal adsorption model.From the preparation process and characterization of the ion-imprinted polymer,it can be seen that the template ions and the functional monomers are pre-organized to form a complex in the solution,which is a dynamic equilibrium process,controlled by the change of Gibbs free energy,and also subjected to the effect of the stereoscopic spatial structure,At the same time,the functional group involved in the chelation reaction also maintains the corresponding hybrid mode,which still does not disappear after Ni²⁺is eluted,and is fixed during the crosslinking process.The main reason for the formation of holes.