Thesis (M.Eng.)--Chulalongkorn University, 1999

The extraction equilibrium of synthetic L-lysine and L-lysine from mother liquor were studied at various carriers, D2EHPA, concentration. Each experiment was carried out at room temperature for 48 hours with a stirred speed of 420 rpm. It was found that the distribution coefficient of synthetic L-lysine was greater than that of L-lysine from mother liquor and both values vary with the carrier concentration. The extraction equilibrium constant (Kex) are 5.26x10-4 and 4.72x10-5 dm3/mol for L-lysine in synthetic solution and in mother liquor respectively. It was also found that 1 mole of lys+ reacted with 1.2 and 2 moles of monomeric form of D2EHPA to form complex for L-lysine in synthetic solution and mother liquor, respectively. L-lysine extraction from mother liquor was carried out in batch type facilitated ELM stirred extractor. W/O membrane extraction phase was D2EHPA as carrier, span 80 as surfactant in n-dodecane and HCl solution as stripping phase. The effects of various conditions were investigated. The experimental results showed the optimum conditions for this process to be at pH5, 2n HCl, 1%span 80(v/v), 10%D2EHPA (v/v), volume ratio 1:2, and 360 rpm. And by these optimum conditions, 20% initial extraction of L-lysine from mother liquor was obtained in the first minute. The influence of carrier concentration on the permeation rate can be predicted by the model presented in this study