Study On The Preparation And Adsorption Performance Of Magnetic Chitosan Nanocomposite

Magnetic Chitosan is a kind of adsorbent which has high adsorption performance,suitable for large-scale adsorption, and easy to modification and reuse. In this research, theadsorption and separation of different heavy metal ions using magnetic chitosan and modifiedmagnetic chitosan have been discussed in detail. The Fe3O4are obtained by chemicalco-precipitation method.The solution pH and surfactant dosage and other factors on theconduct of Fe3O4nanoparticle nucleation are investigated. It demonstrated that the obtainedFe3O4has a super paramagenetic property and easy to monodisperse.The adsorption properties of heavy metal ions using magnetic chitosan and their modifiedproducts are investigated from different perspectives, such as magnetic generation, multipleion adsorption, experimental conditions, approximating and separation of the thermodynamicdata and so on. The chitosan microsphere can be generated using the glutaraldehyde betweenFe3O4and magnetic chitosan. The single factor experiments such as stirring rate, the amountof glutaraldehyde, Span-80amount, reaction time, reaction temperature and NaOHconcentration and other aspects are investigated to optimize the preparation conditions, theaverage particle diameter of prepared magnetic chitosan is220μm and average pore diameteris14.15nm. By optimizing the reaction temperature, pH, initial concentration and adsorbentdosage and other conditions, among the10mg/L~600mg/L ion concentrations ranges, theeffect of initial concentration on the adsorption capacity is investigated. It can be found that asthe initial concentration increased the adsorption capacity increases, but the adsorption amountchanged little. The adsorption capacities of magnetic chitosan to the copper, cadmium, nickelat50mg/L can reach to55.39mg/g、43.64mg/g、31.02mg/g。The modified magnetic chitosan is synthesized by using diethylenetriamine and citricacid to modify the magnetic chitosan. The particle size and diameter of the product are almostas the same as the magnetic chitosan, and it has a stable magnetic property. The chemicaladsorption capacity of modified products has been improved, the adsorption capacities to Cu2+,Cd2+and Ni2+at50mg/L are all higher than50mg/g, and they remained above92%after15times analysis and generations.By investigating the adsorption properties of the magnetic chitosan to the heavy metal ion, it can be observed that the Freundlich model has the highest correlation through theanalysis of experimental data using the thermodynamic model. The adsorption process can bedescribed as follows: Firstly, it produced a very unstable monolayer adsorption in a short time;after that, it occurred a multi-layer adsorption and a column packing; then extending theadsorption time, the chemical bonding between sorbent functional groups and metal ionsbecomes firmly, and the adsorption capacity also increased steadily. The adsorptionequilibrium has been achieved finally.