Study of lactic acid extraction with higher molecular weight aliphatic amines
TL;DR: In this article, the effects of organic phase extractant concentration and aqueous phase pH on the extraction process were examined with two extractants, trioctyl amine (TOA) and Aliquat 336, in three diluents (methylisobutyl ketone, octanol and paraffin liquid).
Abstract: Lactic acid extraction was studied with two extractants, trioctyl amine (TOA) and Aliquat 336, in three diluents (methylisobutyl ketone (MIBK), octanol and paraffin liquid). The effects of organic phase extractant concentration and aqueous phase pH on the extraction process were examined. Among the extractants, TOA was found to be a better extractant than Aliquat 336 in all the diluents. In experiments with 50% (v/v) TOA in methylisobutyl ketone, 79% lactic acid could be extracted (initial lactic acid concentration 86·96 g dm−3). MIBK had a profound effect on the extraction behaviour of TOA in comparison with octanol and paraffin liquid while none of the diluents affected the extraction with Aliquat 336. The extraction of lactic acid was favoured at low pH. The toxicities of TOA and the diluents to Lactobacillus rhamnosus NRRL B445 were also studied. While TOA was found to be highly toxic at the molecular and the phase level, the paraffin liquid was totally non-toxic. The extraction of glucose and yeast extract by TOA and the diluents used was found to be low, which thus enables the selective extraction of lactic acid. © 1998 SCI
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Abstract: The possibility of manufacturing a biodegradable polymer from lactic acid has led to extensive research in recovery of lactic acid produced by fermentation, by different downstream processing routes. This paper assesses the suitability of different downstream processing options such as reactive extraction, adsorption, electrodialysis, esterification and reactive distillation. It compares the costs of different process routes. The assessment indicates that the conventional precipitation of calcium lactate, followed by acidification, esterification and hydrolysis will be the most economical route although it generates large quantity of gypsum sludge.
224 citations
TL;DR: In this article, the lactic acid extraction by tri-n-octylamine dissolved in decanol and docecane has been studied and a mathematical model of extraction, taking into account formation of acid/amine complexes, has been composed and solved.
Abstract: The paper deals with the lactic acid extraction by tri-n-octylamine dissolved in decanol and docecane. The extraction efficiency depends on the initial lactic acid concentration and the initial pH value of the solution. In case of lactic acid extraction from simulated fermentation broth, the partially loading of extractant with HCl leads to increasing of the distribution coefficient. The extraction equilibrium constants have been determined. The strong influence of diluents on the values of the graphically determined extraction constant and the number of extractant molecules in the acid–amine complex has been shown. A mathematical model of extraction, taking into account formation of (1:1) (2:1) and (1:2) acid/amine complexes, has been composed and solved. The model fits very well the experimental results.
126 citations
TL;DR: In this paper, the authors applied the response surface methodology to optimize the separation of dl -tryptophan from aqueous solution, and obtained the maximum Y (100%) was obtained by employing the following predicted optimum extraction conditions: a pH of 12.46, a carrier concentration of 22.22%, and an initial amino acid concentration of 4.97 mM.
Abstract: Response surface methodology was applied to optimize the separation of dl -tryptophan from aqueous solution. dl -tryptophan was extracted into an emulsion liquid membrane containing Aliquat-336 in oleyl alcohol. The carrier concentration (10–30%, by volume), pH (10–14) and initial amino acid concentrations (1–7 mM) were the critical components of the separation optimized. Experiments were performed at 150 rpm stirring rate, for 30 min extraction time with equal volumes of organic and aqueous phases. The response surface equation to predict the extraction yield in the above range of critical components is Y=100.72+31.83x 1 +0.15x 2 +3.38x 3 −21.41x 1 2 −5.39x 2 2 −7.11x 3 2 +1.19x 1 x 2 −3.26x 1 x 3 −2.30x 2 x 3 where Y is the response, (extraction yield). Maximum Y (100%) was obtained by employing the following predicted optimum extraction conditions: a pH of 12.46, a carrier concentration of 22.22%, and an initial amino acid concentration of 4.97 mM.
114 citations
TL;DR: In this paper, a screening study using functionalized silica compounds showed functional groups containing multiple nitrogen-based functionalities and at least one double bond between nitrogen and carbon displayed higher acid affinity than the single tertiary amine functional group as present in trioctylamine.
Abstract: Reactive liquid–liquid extraction is a promising technology for the removal of lactic acid directly from fermentation media. For over five decades, tertiary amines (e.g. trioctyl amine) have been the state-of-the-art extractants for carboxylic acid extraction. However, to make fermentative carboxylic acid production with in situ recovery through extraction economically attractive, higher distribution ratios of the acids are required. The aim of this study was to develop extractants with a higher affinity for carboxylic acids than trioctylamine, and in particular for lactic acid. Key properties to achieve this goal are hydrophobicity and acid affinity. A screening study using functionalized silica compounds showed functional groups containing multiple nitrogen-based functionalities and at least one double bond between nitrogen and carbon displayed higher acid affinity than the single tertiary amine functional group as present in trioctylamine. After incorporating these functional groups in extractants the highest distribution coefficients of lactic acid were observed for N,N-didodecylpyridin-4-amine (27, vs 11 for trioctylamine at 25 °C). Back-extraction was demonstrated to be feasible, and is promoted by increasing the temperature and by addition of an anti-solvent such as heptane achieving single stage recoveries up to 80%.
99 citations
TL;DR: Capillary microreactors operated under the slug flow regime were investigated for the separation of lactic acid from the aqueous phase using liquid-liquid reactive extraction in this paper, where the experiments were performed at a 1:1 flow ratio of the organic phases in a setup consisting of an inlet Y-type mixer connected with a poly(tetrafluoroethylene) capillary microreactor and subsequently an outlet Y-shape phase splitter.
Abstract: Capillary microreactors operated under the slug flow regime were investigated for the separation of lactic acid from the aqueous phase using liquid–liquid reactive extraction. The experiments were performed at a 1:1 flow ratio of the aqueous to organic phases in a setup consisting of an inlet Y-type mixer connected with a poly(tetrafluoroethylene) capillary microreactor and subsequently an outlet Y-shape phase splitter. The extraction of lactic acid (intake: 0.11 and 0.055 M in water) using 15% (v/v) tri-n-octylamine in n-octanol under ambient conditions approached equilibrium after about 90 s in microreactors without noticeable emulsion formation. The measured reactive extraction performance in microreactors can be well described by a physical mass transfer model according to the penetration theory (developed from a model experimental study for the extraction of acetanilide from water to n-octanol) combined with an instantaneous irreversible reaction assumption.
75 citations