Study On The Adsorption Of Chitosan In Heavy Metal Ions Wastewater Treatment

With the development of industry, the removal of toxic and polluting heavy metal ions from wastewater has received much attention in recent years. And the search for an effective and economic method of removing toxic heavy metal ions required the consideration of unconventional materials and processes.Chitosan is a crude macromolecular compound,the active functional groups(—NH₂,—OH) in Chitosan's molecular formula can chelated heavy metal ions, so, Chitosan can used as a macromolecular sorbent to remove heavy metal ions. Furthermore, Chitosan is avirulent and it would not bring secondary contamination, moreover, Chitosan can disassemble by biologic catabolism. In this paper, the static adsorption properties of Chitosan for the heavy-metal-ions as copper ions, plumbum ions and zinc ions are observed. A systematic study was carried out to investigate influence of different conditions on the adsorption, such as pH value, initial concentration, temperature , dosage of Chitosan, the degree of deacetylation of Chitosan, particle size of Chitosan etc. It determined the optimal adsorption conditions. It is founded that the adsorption efficiency of Chitosan was affected intensively by pH mainly due to its affects on thecarried electric conditions of the Chitosan surfaces and heavy metal ions.The kinetics of adsorption of heavy-metal-ions by Chitosan was also studied. The adsorption rate was determined by diffusion rate of solute to Chitosan surface. The adsorption rate is fast at the beginning, then the rate decreases, especially when adsorptive concentration is high. The adsorption capability of Chitosan becomes weak with increasing time, finally attained the equilibrium.A fixed bed was designed and manufactured, the effect of its main parameters as concentrations, the bed length, flow rate etc on its various properties are discussed. And the breakthrough curves are determined for fixed bed with Chitosan. On the basis of discussion, we tried to use chemical deposition method and then adsorption by Chitosan in the treatment of actual wastewater contained heavy metal ions.A mathematical model is set up under the following hypothesis as (1) isothermal adsorption process, (2) homogeneous fixed bed, and (3) piston fluid. The numerical analysis for the model is carried on with Matlap6.0. It is shown that all these analysis result have a good agreement with experimental breakthrough curves. It is provided that the foundation for design of adsorption column about adsorption for wastewater contained heavy metal ions.