Michiaki Matsumoto

Toxicity of ionic liquids and organic solvents to lactic acid-producing bacteria

In situ extractive fermentation of lactic acid using organic solvents has already been extensively investigated. Now ionic liquids are emerging as alternative solvents for volatile organic compounds traditionally used in liquid-liquid extraction. In this study, we examine whether lactic acid producing-bacteria can grow in the presence of a second phase of imidazolium-based ionic liquids or organic solvents. The lactic acid producing-bacteria used in this study are sensitive to organic solvents having 1 < log P < 4. We found that Lactobacillus delbruekii subsp. lactis NRIC 1683 could grow in the presence of a second phase of imidazolium-based ionic liquids as well as in the absence of the ionic liquids.

Synergistic extraction of organic acids with tri-n-octylamine and tri-n-butylphosphate

In order to develop new synergistic extraction system of organic acids, the extraction equilibria of organic acids (acetic, glycolic, propionic, lactic, succinic, fumaric, l-malic and itaconic, HnA) with tri-n-octylamine (TOA) and/or tri-n-butylphosphate (TBP) were measured. The solvation numbers of the acids were the same as the numbers of the carboxyl groups on each acid molecule in the extraction with TOA or TBP alone. The extraction equilibrium constants were roughly correlated with the hydrophobicity of the acid, except l-malic acid. In the case of using the mixed extractant of TBP and TOA, the synergism was observed in the extraction of all the acids investigated. Specially, the extractions of glycolic, lactic, succinic and fumaric acids gave a remarkable synergism. The extracted species were estimated to be HnA · 2TBP · TOA, in addition to HnA · (TOA)n and HnA · (TBP)n. The calculated results of the distribution ratio of organic acids based on the formation of three complexes explained well the experimental ones.

Recovery of boric acid from wastewater by solvent extraction

An extraction system for the recovery of boric acid using 2-butyl-2-ethyl-1,3-propanediol (BEPD) as an extractant was studied. Loss of the extractant to the aqueous solution was lowered by using 2-ethylhexanol as a diluent. The extraction equilibrium of boric acid with BEPD was clarified, and the equilibrium constants for various diluents were determined. Furthermore, continuous operation for the recovery of boric acid using mixer-settlers for extraction and stripping was successfully conducted during 100 hours.

Role of surfactants in the behavior of emulsion liquid membranes. Development of new surfactants

Abstract Surfactants play an important role in the emulsion liquid membrane (henceforth ELM) process. However, only two commercial surfactants have been used so far, Span 80 and polyamine. Relatively little attention has been spent in searching for other suitable surfactants. In order to develop new surfactants for the ELM process, in this study a series of derivatives of glutamic acid dialkyl esters and dialkyl-type quaternary ammonium salts were synthesized. Copper extraction by ELM was carried out in a stirred cell using these surfactants. It was found that glutamic acid dioleyl ester was a more suitable surfactant for the ELM process than Span 80 and polyamine as regards break-up, swelling and demulsification of the W/O emulsion, and enrichment of copper.

Extraction of lactic acid from fermented broth with microporous hollow fiber membranes

Non-dispersive solvent extraction of lactic acid based on anion-exchange reaction with tri-n-octylmethylammonium chloride dissolved in oleyl alcohol, the optimum extraction reagents selected for extractive fermentation of lactic acid with Lactobacillus rhamnosus, was attempted in a microporous hollow fiber membrane device. A satisfactory recovery of lactic acid from both aqueous solution and actual fermented broth was accomplished, signifying the great potential of integrating the membrane extraction with fermentation process. A theoretical model which took into account the mass transfer resistances across organic and aqueous films and membrane was developed to analyze and predict the extraction behavior. The model prediction was found to be in good agreement with the experimentally observed results.

Synergistic extraction of lactic acid with alkylamine and tri-n-butylphosphate: effects of amines, diluents and temperature

We performed the synergistic extraction of lactic acid with tri-n-butylphosphate (TBP) and alkylamines to find an optimum synergistic extraction system. We examined 12 alkylamines as co-extractants and found that extractability with alkylamines increases in order from tertiary>secondary>primary. Extractability increased with increasing alkyl chain length in trialkylamine; tri-n-octylamine (TOA) enabled the best extractability, however, further increases in chain length resulted in a decrease in extractability. The diluent effect was small due to a high concentration of TBP. We found that the synergistic extractions of lactic and succinic acids with TOA and TBP are exothermic processes.

Effects of Polyols and Organic Solvents on Thermostability of Lipase

The effects of polyols and organic solvents on the thermostability of lipase were studied. The thermodeactivation process of lipase obeyed a series deactivation model and four kinetic parameters were determined. The rate constant of the first deactivation process was found to be a key one. All the polyols used had a positive effect for stabilization of lipase and the extent of effect increased with polyol concentration and carbon number of polyol. The effect of organic solvents on the thermostability of lipase was investigated by incubating the lipase in the organic solvents before measuring their activities. The behavior of the thermodeactivation depended upon the organic solvents used; increased activity was observed in some solvents.

Biological nitrogen removal in a bubble column with a draught tube

Abstract A bubble column with a draught tube was applied as a small scale treatment unit of anaerobic-aerobic activated sludge processes in which nitrogen and phosphorus compounds were removed together with BOD sources. The inside of a draught tube was used as an aerobic zone and the annulus as an anaerobic zone. The circulation flow rate of the mixed liquor between these two zones was varied by changing the air flow rate into the draught tube. There existed the optimum values for volume ratio of aerobic/anaerobic zones, air flow rate and liquid circulation flow rate between two zones depending on the activities of nitrification and denitrification . The performance of the treatment unit was simulated by using the model of the liquid flow in the reactor and the kinetics of simultaneous nitrification and denitrification in the activated sludge floc. It became clear that the consumption of BOD source inside the floc should be considered to explain the drop of nitrogen removal at high aeration rate and long residence time.

Separation of lactic acid using polymeric membrane containing a mobile carrier

A cellulose triacetate (CTA) membrane containing trioctylmethyl ammonium chloride (TOMAC) as a carrier and o-nitrophenyloctyl ether (NPOE) as a plasticizer was developed for the in situ separation of fermented lactic acid. The separation characteristics of the CTA-TOMAC-NPOE membrane were investigated. The permeation rate of lactate through the CTA-TOMAC-NPOE membrane was comparable to that through a supported liquid membrane. TOMAC played the role of a mobile carrier in lactate transport. It was found that the CTA-NPOE membrane containing TOMAC has the advantages of allowing a high flux of lactate and having a low solubility of TOMAC in aqueous solution.

Selective adsorption of glucose on novel chitosan gel modified by phenylboronate

Abstract Novel gels from phenylboronate derivatives of chitosan were prepared for the adsorption of saccharides. Two chitosan gels were used: one modified by phenylboronate via Schiffs base formation (A) and one in which phenylboronate was introduced by amide formation (B). The adsorption characteristics of d -glucose and 1-methyl-α- d -glucoside on these gels were examined and compared with a commercial gel. Though both chitosan gels were inferior to the commercial gel in their adsorption capacity, the chitosan gel (A) showed a much higher selectivity of d -glucose to 1-methyl-α- d -glucoside in comparison to the commercial gel.