Preparation Of Hybrid Crosslinked Microsphere Materials Based On Chitosan And Montmorillonite And Its Adsorption Properties Study

In this paper, chitosan was intercalated into the crystal layers ofmontmorillonite by ion exchange firstly, then CTS/MMT hybrid crosslinkedmicrosphere material, whose properties was good, was prepared and theadsorption property with Cu²⁺ was studied.With CTS and MMT as the raw material, CTS/MMT intercalated compound wasprepared in solution. The effect of reaction conditions such as reactiontime, reaction temperature, the proportion of CTS and MMT and the molecularweight of CTS on the intercalation result was studied through methods ofXRD, FTIR, TEM and TGA. The intercalation mechanism of CTS in MMT wasdiscussed. The results revealed that the molecular weight of CTS affectedintercalation largely. The interlayer distance of MMT can be expanded toabout 1.5nm from 1.25nm when used the larger molecular weight CTS, andcan be expanded to 1.5～1.9nm when used the smaller ones. There may beexist two kinds of intercalation mechanism. One is fast intercalationaroused by the force of MMT layer surface wiht weak electric field, andthe other is intercalation due to the chitosan diffusion.With CTS and MMT as the raw material, CTS/MMT hybrid crosslinkedmicrosphere was prepared through inverse suspension Crosslinking byformaldehyde and epichlorophydrin. The effect of operating conditions onthe properties of the microsphere was investigated. The structure of themicrosphere was characterized by FTIR, XRD, SAM and TGA. The resultsindicated that MMT was dispersed in the microphere in intercalated type,whose interlayer distance was about 1.5～1.7nm. A good-ball-shape, high-capacity, large-porosity microphere was obtained under the optimumreaction conditions. The crystalline grade of crosslinked chitosanreduced and the thermal stability decreased.The properties of hybrid crosslinked microsphere adsorbed Cu²⁺ wasresearched. The results showed that microsphere adsorbed Cu²⁺ mainly bycomplexation, the experimental data fit well into the Langmuir andFreundlich adsorption isotherm at the same time, and the process obeyedthe formation of monolayer adsorption. The adsorption isotherm could bedescribed in these two kinds of adsorption model under experiment scope.The adsorption kinetics research indicated that the adsorption of Cu²⁺ onmicrosphere was the second kinetics model. The adsorption capability wasbecoming when adding more NaCl or MgCl₂ to the system, and the effect orderwas MgCl₂＞NaCl. The adsorption capability could be the biggest when thepH of the solution at about 3.4.