C. Pei-lin
2010
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Journal
Journal of Chemical Engineering of Chinese Universities
Abstract
5-Aminolevulinic acid (ALA) has wide applications in many fields,such as in medicine,agriculture,etc...In order to separate 5-aminolevulinic acid hydrochloride (ALA·HCl) from fermentation broth,a novel separation procedure combining membrane permeation,reactive extraction and crystallization was proposed.The large molecular weight impurities in fermentation broth were removed by ultra filtration,then the filtrate was concentrated by reverse osmosis and the ALA recovery ratio is 86.4%.The di(2-ethylhexyl)phosphoric acid (D2EHPA) and n-hexanol were chosen respectively as the optimum extractant and diluter,and the mixture of D2EHPA and n-hexanol (1:1,v/v),the initial aqueous pH value of 6.5,the phase ratio (R org/aq) of 0.5 and 20℃ were found to be the optimum extraction conditions.After two-stage extraction,the organic phases were mixed together to conduct the one-stage back extraction.The back extraction of organic phase was carried out with 1 mol·L-1 HCl solution at 30℃,and the phase ratio (raq/org) used is 0.5.The recovery ratio of ALA in extraction process reaches 79.8%.The aqueous phase after back extraction is then treated respectively by decolourization,vacuum concentration and crystallization,and the overall yield of the separation process and the product purity of ALA·HCL reach 55.2% and 99.5%,respectively.