Extraction Of Butyric Acid Research Articles

Butyric acid production by Clostridium butyricum with integrated extraction and pertraction

The properties of an organic phase (Hostarex (20% w/w) in oleylalcohol) for extractive and pertractive fermentative production of butyric acid by Clostridium butyricum were investigated and the ability of this organic phase to be used in the fermentation process was established. The distribution coefficient of butyric acid between water and the organic phase could be increased up to 13 in diluted solutions but decreased to 3.0 with an increase of pH up to 5.2 (pH of the fermentation process). The kinetics of direct extraction of butyric acid during both extraction and pertraction were two and three times, respectively higher than the reverse processes. Reverse stripping was faster, but remained slower than direct stripping. These results demonstrated that both extraction and pertraction could be successfully joined with fermentation. An increase of total butyric acid concentration, from 7.3 g l −1 in the control to 10.0 g l −1 in extractive fermentation and to 20.0 g l −1 in pertractive fermentation and concurrent increases of yield of butyric acid from 0.24 g g −1 in the control up to 0.30 g g −1 in pertractive fermentation, showed the great possibility of successful integration of these separation processes with fermentative production of butyric acid by C. butyricum.

Evaluation of solvent and pH for extractive fermentation of butyric acid

The effects of nine organic extractive reagents on growth and acid production by Clostridium butyricum S21 were examined to evaluate their possible use in extractive fermentation of butyric acid. Oleylalcohol alone and in a mixture with Hostarex A327 ( n-octyl( n-decyl)amine) and pure tri-hexylphosphate (THP) did not appear to be toxic. The presence of THP decreased the selectivity of butyrate production. High toxicity was shown by n-octanol and isodecanol alone and in mixtures with the extractant Hostarex A327 and diluent n-aleanes. An acceptable decrease of butyric acid concentration, productivity and production selectivity (7·26, 0·33 and 0·54 respectively) compared with optimal pH of 6·5 (11·75, 0·60 and 0·73, respectively) was obtained at pH 5·2. At this pH the distribution coefficient of butyric acid between water and Hostarex A327 (20% w/w) in oleylalcohol was about 3·0. It was four times lower than for the diluted solution (13·2) and two times lower than for the concentrated (6·5) solution of butyric acid at pH 4·0, but about three times higher than in the case of pure oleylalcohol (1·01) at pH 5·2. Hostarex A327 (20% w/w) in oleylalcohol as an extractive reagent at a pH of 5·2, can be used for the production and in situ extraction of butyric acid.

Extraction Equilibria of Butyric Acid with Organic Solvents

Abstract Fourteen solvents (five with a tertiary amine and different diluents, four C8-C18 alcohols, dibutylether, two hydrocarbons, and two vegetable oils) have been tested for the extraction of butyric acid. The highest distribution coefficient for butyric acid is shown by solvents with tertiary amines. A ternary solvent with amine extractant, n-alkanes as diluent, and higher alcohol as modifier can be advantageous in this procedure. Amines enable the extraction of acid at a pH above the pK a value up to about pH 5.6. With an increase of the molecular weight of alcohol, the value of the distribution coefficient decreases. Its value for pure alcohols is independent of the concentration of acid in the aqueous phase. Equilibrium data suggest that the stoichiometry of the acid-alcohol complex is 2:1, and only undissociated acid is extracted.

Recovery of butyric acid, valeric acid, and caproic acid (BVC acids) from an aqueous waste stream using tributylphosphate (TBP) as an extractant

The distribution coefficients, K D, were measured for the extraction of butyric acid, valeric acid, and caproic acid with tributylphosphate from an aqueous waste stream. The measurements were also carried out in the presence of salts such as sodium sulphate and sodium chloride. The results presented are expected to aid process environmental engineers.

On-line extraction of volatile fatty acids in acidogenic chemostat culture using a supported liquid membrane

An on-line extraction of volatile fatty acids (acetic and butyric acids) from acidogenic fermentation in chemostat cultures using a supported liquid membrane (SLM) was investigated in order to overcome end-product inhibition. By using SLM, the high-cell-density retaining dilution rate of the chemostat could be increased, thus enhancing the microbial acidogenesis. To further understand this phenomenon, the growth and extraction kinetics were studied. The effect of substrate concentration was found to obey the Haldane equation. Regarding the inhibition by volatile fatty acids, it turned out that undissociated butyric acid rather than acetic acid severely inhibited the growth, corresponding to non-competitive kinetics. The extraction rates of the acids were proportional to their undissociated concentration as well as to the SLM area/broth volume, and butyric acid extraction was easier than that of acetic acid.