Acetone-butanol production, extractive

Acetone-butanol production, extractive fermentation in aqueous two-phase systems, 80... 

Vitamin B12 has been extracted from activated sludge or as a by-product of the acetone-butanol process. The vitamin is also synthesized by microorganisms in intestinal habitats. For commercial purposes, Bacillus, Propionibacterium or Pseudomonas species and more recently methanogenic bacteria are utilized. Yields of up to 50 mg l-1 can be achieved. The reaction mixture is evaporated and used as a feed supplement for various domestic animals or further purified and crystallized for medical use 59). 

Processes for production of ethanol and acetone-butanol-ethanol mixture from fermentation products in membrane contactor devices were presented in Refs. [88,89]. Recovery of butanol from fermentation was reported in Ref. [90]. Use of composite membrane in a membrane reactor to separate and recover valuable biotechnology products was discussed in Refs. [91,92]. A case study on using membrane contactor modules to extract small molecular weight compounds of interest to pharmaceutical industry was shown in Ref. [93]. Extraction of protein and separation of racemic protein mixtures were discussed in Refs. [94,95]. Extractions of ethanol and lactic acid by membrane solvent extraction are reported in Refs. [96,97]. A membrane-based solvent extraction and stripping process was discussed in Ref. [98] for recovery of Phenylalanine. Extraction of aroma compounds from aqueous feed solutions into sunflower oil was investigated in Ref. [99]. 

Production of bulk chemicals. The production of solvents is normally characterized by a general inhibition phenomenon which has been mainly attributed to the changes in membrane permeability, or to the toxic effects on the metabolic pathway. Aqueous two-phase systems have been shown to be effective as media for the extractive fermentation of a number of solvents which include ethanol, acetone-butanol and acetic acid (3). Improved productivity has been achieved in most of the cases as compared to the conventional fermentations, which is significantly due to the elimination of product inhibition. However, there is an indication that changes in the microenvironment of the microbial cells due to the presence of non-metabolizable polymers could also contribute, in the initial phases, to the increased production. The addition of PEG and dextran to a growth medium, for instance, was shown to give increased initial ethanol yields, as a result of decrease in the chemical potential of water (8). 

Grobben, N. G., Eggink, B., Cuperus, F. P., Huizing, H. J. (1993). Production of acetone, butanol and ethanol (ABE) from potato wastes fermentation with integrated membrane extraction. Applied Microbiology and Biotechnology, 39, 494—498. 

The interest in w-butanol as a biofuel has increased in recent years owing to its superior fuel qualities compared to ethanol. These include a higher octane number, lower heat of vaporization, higher energy density (energy/volume), and lower vapor pressure. However, in the traditional ABE (acetone-butanol-ethanol) fermentation process, the concentration of n-butanol coming from the fermenter is lower than that achieved in ethanol fermentation. In addition, acetone and ethanol are also produced. Recent studies to improve yield and increase w-butanol concentration have explored fed-batch systems with stripping, adsorption, liquid-liquid extraction, distillation, and/or pervaporation to recover products. 

Nondispeisive phase contact Extraction of products in fermentation process producing ethanol and acetone-butanol-etha-nol (ABE) (microporous/porous hydrophobic membranes)... 

Yen, H.W., Wang, Y.C., 2013. The enhancement of butanol production by in situ butanol removal using biodiesel extraction in the fermentation of ABE (acetone-butanol-ethanol). Bioresource Technology 145,224-228. 

In continuing the pilot plant reaction, once the temperature had subsided to 25°C, the solution was stirred for 2 hr to ensure that the reduction was complete (HPLC). The excess sodium borohydride was consumed by the addition of acetone (20 liters) over approximately 90 min. The exothermic reaction was readily controlled in the temperature range 30-35°C. To recover the product, salts were filtered and the acetone distilled out. The desired product was extracted with -butanol and the extract was washed with water. The -butanol layer was stripped and the residue was dissolved in toluene. Further salts were filtered, the toluene was stripped out, and the (S)-2-amino-2-phenylethanol product was distilled under vacuum the yield was 81%. 

The primary source of isoprene today is as a by-product in the production of ethylene via naphtha cracking. A solvent extraction process is employed. Much less isoprene is produced in the crackers than butadiene, so the availability of isoprene is much more limited. Isoprene also may be produced by the catalytic dehydrogenation of amylenes, which are available in C-5 refinery streams. It also can be produced from propylene by a dimerization process, followed by isomerization and steam cracking. A third route involves the use of acetone and acetylene, produced from coal via calcium carbide. The resulting 3-methyl-butyne-3-ol is hydrogenated to methyl butanol and subsequently dehydrogenated to give isoprene. The plants that were built on these last two processes have been shut down, evidently because of the relatively low cost of the extraction route. 

Therefore the condensed product is treated by adsorption on charcoal followed by desorption with acetone. The acetone solution is distilled, and the chiral units are finally obtained. In some cases, such as C4 chirals, extraction with a solvent such as ethylacetate, butylacetate or butanol can be used. The method chosen depends on the solubility of the chiral compound in water or the solvent. 

The technique for the isolation of nicotinic acid depends on the starting material. In most cases, a preliminary hydrolysis is required either with acids or alkalies. The extractions are more complete if the material is rendered free of lipids, a necessary step when working with animal products. The free acid is extracted from the hydrolysate with organic solvents such as hot alcohol. It may then be separated as such from the organic solvent extract or in the form of an ester or as the copper salt the free acid can be recovered from the copper salt by H2S treatment. Purification is carried out by crystallization from concentrated water or alcohol solutions. Nyc et al. extracted nicotinic acid from the mycelium of Neurospora with acetone. Subsequent purification steps included the formation of the barium salt, acidification with H2SO4 and adsorption of the free nicotinic acid on charcoal. Elution was accomplished with 4% aqueous aniline and the final purification step involves recrystallization from a i 4 mixture of acetic acid and benzene. Leifer et al. have applied paper chromatography with M-butanol saturated with ammonia to separate nicotinic acid from contaminating materials. 

The demise of solvent fermentation in North America and East Asia between the late 1950s and the early 1960s resulted from both the competitive uses for molasses, which drove up the cost of raw materials, and the rise of the petrochemical industry, which drove down the price of the chemically synthesized huta-nol and acetone. However, this industrial fermentation did not totally disappear after the 1960s. The continued operation of the fermentation in South Africa between 1936 and 1982 illustrates the importance of the local conditions in determining the cost effectiveness and the necessity of the fermentation. The use of butanol as an extractant by the food and pharmaceutical industries may also create a demand for the fermentation product as it does not contain the carcinogens that may be present in butanol produced from petrochemicals. The continued use of the fermentation process to produce butanol in China may partly be due to this consideration. 

The same technique applies to the preparation of vitamin B from horse liver, which is even richer than hog liver in this vitamin (459). The preparation of vitamin B, from yeast is carried out by the same technique, after a treatment of the yeast extract with conjugase. The crystallized product obtained from yeast is identical with that prepared from liver. Stokstad et al. (557) isolated the liver L. casei factor from the precipitate obtained by treating the aqueous liver extract with 85% ethanol. The active substance is separated by successive adsorption on norit A and Superfiltrol, the last eluate being precipitated by baryta and ethanol. The L. casei factor is esterified, and the esterified product is extracted by butanol. After removal of butanol, the substance is dissolved in methanol and chromatographed on a column of Superfiltrol. It is then eluted with 70 % aqueous acetone. The active esterified product thus eluted is pure, and on hydrolysis yields the free acid which crystallizes. The latter is identical to the vitamin Bo of Pfiffner et al. (459). 

Acetone and butanol, two important organic chemicals, are nowadays exclusively made by chemical synthesis. During the Second World War, however, a fermentation process was used in many countries for the production of a mixture of both. Some members of the Clostridium genus are able to transfer commeal and molasses into the desired mixture of these chemicals, the ratio of which is determined by the kind of raw material and the bacteria species used. The maximum overall concentration obtainable is 2%. The process was abandoned after the war in most countries but returned into discussion when oil prices increased in the 1970 s. It is not very likely that this process will be used again unless the technology is improved (immobilized biocatalysts, extractive fermentation) and raw material prices are favorable. 

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