Studies On Riboflavin Crystallization, Separation And Purification

First, the solubilities of riboflavin in pure water and in different concentration hydrochloride aqueous solution (w =0.14,0.16,0.17,0.20,0.24,'w'meant the HCl fraction in mixture aqueous solution) under different temperatures, viz. 283K, 288K, 293K, 298K, 303K, etc., were measured by steady method, respectively. The data of solubility was obtained through regression of solubility model——the equation ofλh, which relevancy effect was stable and convergent in hydrochloride aqueous solution. The empirical formulae betweenλ, h and w were obtained. The solubility and supersolubility of riboflavin in hydrochloride aqueous solution under 283K,288K, 293K, etc. were mensurated and analyzed. The width of crystallization metastable zone was determined. These studies about crystallization thermodynamics made the base for the industrial manufacture of riboflavin. Based on single factor experiments, such as the prime solvent, diluent and temperature, etc., the significance factors were gotten from the variance analysis of the Two-Lever Experiment Design. By use of the Response-Surface Test, with the Statistic Analysis Software( SAS ), the dilution crystallization process and the controlling parameters were optimized.Next, the effects of physical field on riboflavin crystallization were studied to obtain stable sphericity crystal. From the electron paramagnetic resonance spectrum of riboflavin, there was an un-partnership electron in riboflavin, that meant riboflavin was paramagnetism. The nucleation rate and growth rate, which were of importance for the design and performance of the industrial crystallizer, were accelerated in ultrasound field, and the crystalization inducement period was shortened. Moreover, the regular sphericity crystal grain was gotten in appropriate ultrasonic field, and riboflavin yield and purity were not affected.The third, according to the peculiarity of Bacillus subtilis 24/pMX45 fermentation broth, serveral ways of riboflavin separation and purification were analyzed. As a result, there was high impurity in sample from the straight-separation method. The yield and purity of riboflavin product from the alkali-dissolved method were 55%, 92.5%, respectively. The crystal shape was needle. However, followed crystallization-control way, applied ultrasonic dilution crystallization processing, globe riboflavin crystal yield was 73% and purity 98.3%. Furthermore, the main quality indexes accorded with GB14752-93 and the codex of P.R.C., and the flow-scatteredness was increased.In the end, the adsorbility of macroporous adsorptive resins for riboflavin were studied. The results showed that the saturated static adsorption of AB-8 resin was 12.1mg/g resin. And the effects of concentration,pH,temperature on the adsorbilities of AB-8 resin were measured. Meanwhile, under the conditions of pH=6 and normal temperature, the dynamic adsorption curve of AB-8 resin for riboflavin was determined. Additionally, through the elution curves, the optimal eluant was the mixture of alcohol and 0.1M NaOH (1:1, v/v). Applying AB-8 resin, about 44% remnant riboflavin in crystallization mother liquor and cleaning solution were reclaimed.