New Method For Preparation Of Konjac-Based Cation Exchange Resin, Structure And Adsorption Characteristics

Early resins used in the field of Bio-Macro Molecular （such as protein） Separation were Polystyrene-based ione xchange resins. But these synthesized ion exchange resins were not suitable for separation of proteins, because of their small aperture, high charge density and hydrophobic interaction between resins and proteins. In order to overcome shortages of synthesized resins on bio-macromolecular separation, researchers developed polysaccharide-based ion exchange resins with big network aperture, hydrophilicity, low charge density, such as cellulose-based, glucan-based and agarose-based ion exchange resins. But production process of these type resins are complex and results in higher production costs, it drastically limits the scope of their use. The KGM which has granular morphology of its own,good hydrophilicity, large specific surface area and can be controlled network aperture by regulating medium polarity can be used as a highly industrialized application vector material.In this study, granular konjac powder was modified with the functional group -phosphate by the dry preparation for the first step, and then the KGM monoester phosphate was carried out crosslinking reaction in ethanol aqueous solution. To obtain the different size network aperture granular cation exchange resins, the ratio of the benign solvent （water） and the expansion inhibitor （ethanol） was controlled ingeniously. Relevant parameters of resins were determinated. The structure of resins were characterized by modern instruments. Adsorption of standard BSA on CL-KGMP were studied.The main conclusions of this paper were described as follows:1. The order of factors influencing the degree of substitution on konjac glucomannan phosphate ester was: phosphate dosage> reaction temperature> reaction time> mol ratio of NaH₂PO₄ and Na₂HPO₄> content of urea > pH value. The results showed that the optimum conditions for Konjac glucomannan phosphate ester preparation were: content of phosphate agent 3.5%, reaction temperature 170℃, reaction time 4h, the mol ratio of NaH₂PO₄ and Na₂HPO₄ 1:2, content of urea 3% and pH 4.0. In this condition the high degree of substitution sample（DS=0.17） could be obtained. 2. Low-cost way to subtly control the size of gel network aperture could be achieved by regulating the ratio of the benign solvent （water） and the expansion inhibitor （ethanol）, and the granular cation exchange resins with different size gel network aperture were obtained.3. FI-IR analysis showed phosphate group on the KGMP and CL-KGMP molecules; X-ray diffraction analysis showed the crystallinity decreasing when KGM was converted to KGMP and CL-KGMP; DSC analysis showed the thermal stability decreased from KGM to CL-KGMP, and the thermal decomposition temperature decreased about 50℃; SEM analysis indicated that when KGMP was cross-linked by sodium trimetaphosphate, the surface became uneven and brought out a little fold-like pore structure, specific surface area increased significantly.4. The type of buffer, buffer concentration, ionic strength, pH could affect adsorption capacity of BSA on CL-50. The adsorption equilibrium of BSA on CL-50 could describe by Langmuir model, this adsorption was monolayer adsorption. Thermodynamic parameters of adsorption:△S>0,△H>0,△G were -9.18（15℃）、-9.95（20℃）、-10.73（25℃）、11.52（30℃）KJ/mol; The kinetics of adsorption was plotted by pseudo second order model; Column chromatography analysis showed that the flow rate, sample concentration and the ratio of height to diameter had a great impct on penetration behavior of BSA on CL-50.