Study On The Adsorption Characteristics Of Sisomicin On Macroporous Weakly-Acid

The domestic current sisomicin extraction technology is static adsorption and dynamic eluation based on 732 strong acid cation-exchange resin. In the light of this process's some shortcomings such as low exchange capacity ,tailing elution profile and low elution rate, a new extraction progress of sisomicin with macroporous weakly-acid exchange resins had been investigated.The methods for quantitative analysis of sisomicin by HPLC and by Polarimetry were established, which was available for the research of adsorption experiences and adsorption dynamics of sisomicin . According to the determined data in our potentiometric titration experiments, the polybasic ionization constants of sisomicin were estimated (pKb1＝5.008,pKb2＝5.397 ,pKb3＝5.916 ,pKb4＝6.48 , pKb5＝7.057)by means of stepwise linear regression and simultaneous equations. The distribution of different charged-ion of sisomicin in different pH conditions was simulated.After comparison test of ten cation-exchange resins with sisomicin solution, cation resin D113 was sorted out to extract sisomicin, which was characterized of higher exchange capacity and being easilier eluted with more concentrate curve peak and less tailing elution profile.Through static batch adsorption experiences, it was given that the optimum pH for adsorption of sisomicin was around 7.5~8.0. The effects of solution's concentration and stirring rate on resin D113's exchange capacity were studied. The isotherm equation was according Langmiur type. The correlation coefficient was 0.9805.In the dynamic exchange experiences of extraction of sisomicin, the dynamic exchange capacity of resin D113 was 23.37×104μg·ml-1, which was 9×104μg·ml-1 higher than that of resin 732, 11.7% higher than its static exchange capacity. What's more, the effect of the concentration, flow rate, the height and the diameter of the ion-exchange colomn and the diameter of the resin particles on the exchange capacity and the breakthrough curves were researched.By dynamic elution, the elution rate of resin D113 was 98.6%, which was 9% higher than that of resin 732. In addition, the effects of eluent's concentration,flow rate on the elution rate and the elution curves were studied.The surface diffusion model were established to simulate the adsorption process of sisomicin on the exchange resin D113. The model was solved by orthogonal collocation method. Then the intrapartical surface diffusion coefficient and the liquid diffusion coefficient were obtained by regression of the experiment data of adsorption rate curves combining with genetic algorithms. The mean square errors were not more than 0.023. The results showed that the numerical solutions were agree with the experiment data of adsorption rate curves. The adsorption progress could be described with the surface diffusion model very well. The intraparticle surface diffusion coefficient and the liquid diffusion coefficient were determined to be 2.80×10-8~5.20×10-8 and 9.00×10-5~3.00×10-4 when pH=7.8. Both the internal mass transfer resistance and external mass transfer resistance were rate-controlling step.