Preparation Of Xanthan Acidification Crosslinked Chitosan And Study On Its Adsorption On Heavy Metal Ions

Chitosan is the natural polymer containing amido and hydroxyl groups, which can coordinate with metal ions well. Its adsorbing capacity can be enhanced by changing chemical characteristic of the molecule, and its treatment of metal ions containing waste water is paid attention in recent year.Firstly, the schiff's bases between the benzaldehyde and the chitosan at the normal temperature was studied in this paper, then chitosan was cross-linked with epichlorohydrin and ethylenediamine; protection group drawn off by using hydrochloric acid after cross-linking, finally, chitosan was xanthan acidificated by carbon bisulfide, and the final production was gained at the same time. A best reaction condition was gained through orthogonal experiment: materiel ratio is 1:2, reaction temperature is 40℃, and -OH medium's chroma is 0.2mol/L,reaction time is 4 hours. And many analyzing measures such as FTIR, XRD and element analysis was adopted for characterizing the CTSN-CS2 and its middle production, the results showed that the product was correspond with the results supposed before.The adsorbent activity for Cu²⁺,Ni²⁺,Pb²⁺ of CTSN-CS2 was studied from five aspect namely, adsorption capacity,medium acidity,adsorption kinetics,adsorption isotherm and regeneration. Tests showed that the adsorption of CTSN-CS2 on Cu²⁺,Ni²⁺,Pb²⁺ were 2.645mmol/g,1.943mmol/g,1.856mmol/g in initial concentration 3.0mmol/L of heavy metal ions solution. The adsorption performance was influenced dramatically by medium acidity. When the pH was low, the absorbent's adsorption capacity was quite low to three kind of metal ion's. Along with the pH 's elevation, the metal ion's adsorptive capacity increased. The best pH was 5-6.CTSN-CS2 had the quick dynamics speed to three kind of ion's adsorptions, was quickest to the Cu²⁺ adsorption, approximately 4h achieves balanced, and the adsorption rate order is KCu> KNi > KPb. The tests of Adsorption kinetics showed:the uptake of CTSN-CS2 Cu²⁺,Ni²⁺,Pb²⁺increase with the increasing of initial concentrations until reache plateau. The uptake datas were analysed by the Langmuir isotherm and the Freundlich isotherm, and show the adsorption isotherms could be well fitted by the Langmuir equation. In the Cu²⁺,Ni²⁺,Pb²⁺ ternary system, the adsorption capacity for Cu²⁺,Ni²⁺,Pb²⁺ of CTSN-CS2 declined. It had the high adsorption capacity and the adsorption selectivity to Cu²⁺, lower to Ni²⁺and the Pb²⁺ adsorption capacity and the adsorption selectivity.