Research Of Seperating L-Arginine With Method Of Ion Exchange From Lystine Motherliquid

During the process of extracting L-Arginine from Lystine motherliquid by ion-exchange method, the desalting of Lystine motherliquid, adsorption of L-Arginine by ion exchanger and eluent's fine purification were studied.First, the solvent extraction associating with precipitation method was suggested to desalt the Lystine motherliquid. The effects of concentrations of sodium chloride and sodium sulfate, the initial concentrations of hydrochloric acid and sulfuric acid on depickling were investigated. The results showed the separating coefficient between hydrochloric acid and sulfuric acid was increasing while increasing the concentrations of sodium chloride and sulfuric acid, the separating coefficient decreased under the existence of sodium sulfate, raising the concentration of hydrochloric acid caused that the separating coefficient was increasing before decreasing. After seven-stage cross current extraction, concentration of chloride ion of Lystine motherliquid varied from 3.2mol/L to 0. 1mol/L or less, the last desalting rate>98%.Second, adsorption kinetic curve and isotherm at 25 C of L-arginine on resin A, resin B and carboxylic ion exchange fiber were measured, the results showed that the equilibrium time of these three ion exchangers were 2 hours, 40 minutes and 30 minutes, respectively; and the maximal equilibrium adsorbances were 115.94, 136.49 and 91.76 mg/g, respectively; The influences of pH value, temperature, time, concentrations of sodium chloride and ammonia chloride on L-Arginine's adsorption by these three ion exchangers were investigated, the results indicated that the proper pH value was between 7 and 8 during adsorbing, the adsorption rates of L-Arginine of these three ion exchangers were all decreasing rapidly under the existences of sodium chloride and ammonia chloride, temperature had little effect on adsorption of L-Arginine by these three ion exchangers, process could be operated at room temperature. Considering both of the maximal equilibrium adsorbance and equilibrium time, macropore cation exchange resin B was chose as the ion exchanger of the technology of separating L-Arginine from Lystine motherliquid by ion exchange method, its curves of adsorption and elution were studied, the result showed elution rate reached 99%.Third, the phenyl aldehyde precipitation method and ion-exchange method were utilized to refine the eluent. The effects of solution's pH value, mol ratio between phenyl aldehyde and L-Arginine, concentrations of sodium chloride, ammonia chloride andL-Lystine, initial concentration of L-Arginine on precipitation rate of a -tolylene arginine were investigated, the results indicated that phenyl aldehyde precipitation method's appropriate pH value was higher than 11, suitable mol ratio between phenyl aldehyde and L-Arginine was 1.25, initial concentration of L-Arginine was must higher than 15g/L, sodium chloride had little effect on precipitation rate, on the contrary, ammonia chloride and L-Lystine had great effect on it, both of them must be eliminated; At the same time, adsorption isotherm at 25 C of L-Lystine on anion exchange resin A was measured, the result showed that the maximal equilibrium adsorbance was 30mg/g, the influences of solution's pH value, temperature, concentration of chloride ion on adsorption of L-Lystine by anion exchange resin A were also studied, the results indicated that appropriate operational pH value was 0.5 0.2, the effect of temperature on adsorption ratio was little, process could be operated at room temperature, the concentration of chloride ion must be eliminated.Finally, the Lystine motherliquid was desalted by the solvent extraction associating with precipitation method, then separated the L-Arginine roughly by adsorption on the ion exchange B column, the eluent was refined through the phenyl aldehyde precipitation method. The result showed that percentage extraction of L-Arginine reached 80%.