Studies On The Adsorption Of Heavy Metal Ions Onto Chitosan-Hydroxyapatite

With the development of modern industry, the emissions of waste water containing heavymetals is more and more bigger and is also more complex, which environmental protectionworkers get more attention about the treatment of waste water containing heavy metals.In thestudy of treatment of this kind of waste water, we reached a consensus: characteristics ofeffective treatment should be highly efficient, convenient, not secondary pollutional. Theways to removal of heavy metal ions in industrial water which have chemical precipitation,electrolysis-coagulation, adsorption and so on, especially adsorption is more interesting.Chitosan is a crude macromolecular compound, the active functional groups（-NH2,-OH） inChitosan’s molecular formula can chelated heavy metal ions, so, Chitosan can used as amacromolecular sorbent to remove heavy ions. Furthermore, Chitosan is avirulent and itwould not bring secondary contamination, moreover, Chitosan can disassemble by biologiccatabolism. However, Chitosan dissolve into water causing the loss of adsorbent because of–NH2becoming into–NH3+when chitosan adsorbed metal ions in the acidic environment;secondly, the presence of hydrogen bonds by Chitosan molecular chain and molecular chainbetween the internals will affect the adsorption capacity; again, mechanical strength, thermalstability and chemical stability of chitosan also need to be improved. To improve theperformance of chitosan, the means of modifiation are often crosslinking, derivatization,blending with other polymers or inorganic. However, these methods are or only one aspectof the performance of local improvement, or the existence of mixed uneven, or the existenceof defects of strict operation and costly price, which affect their practical application.Hydroxyapatite formula for Ca10（PO4）6（OH）2, it is the main inorganic mineral compositionof human and animal bones, with special crystal chemical structure,to many kinds of metalions have widely you’re likelier and adsorption fixed effect. It can be used in metal ion in thewaste water treatment, but the hydroxyapatite brittleness is big, toughness shortcomings alsolimits the lower its application.Organic polymer/inorganic composite material has advantages of both polymers and inorganic substances. In this paper we use improved method for the in situ compositehydroxyapatite chitosan composite materials. It was found that it was good at adsorption ofthe metal ions. This paper studied the adsorption of Ni²⁺, Co²⁺, Zn²⁺in aqueous solution ontoHydroxyapatite chitosan composite material and the influence of physical and chemicalparameters such as pH value, reaction time and temperature and initial concentration on theadsorption process. It determined the optimal adsorption conditions. Kinetics andthermodynamics of the adsorption of Ni²⁺, Co²⁺, Zn²⁺onto Chitosan-Hydroxyapatitecomposite material was studied, and we got the kinetics and thermodynamics equation, Eaand the thermodynamics constant.