Comparative Studies of Free and Facilitated Pertraction of Erythromycin from Streptomyces erythreus Broths

The paper presents the results obtained by analyzing the free and facilitated pertraction of Erythromycin from S. erythreus broths with cells concentration between 5 and 20 g L–1 DM. using dichloromethane as liquid membrane and D2EHPA as carrier. The pertraction has been carried out in pseudosteady-state regime, using the U-shaped pertraction cell that allows obtaining and easily maintaining the free liquid membrane. The increase of the biomass concentration in the feed phase led to the significant reduction of the initial and final mass flows of antibiotic, the addition of carrier in the liquid membrane attenuating this effect. Compared with the pertraction from simulated broths having the same apparent viscosity, but without solid phase, the mass flows are reduced up to 5 times for free pertraction, respectively up to 3 times for facilitated pertraction. Only the membrane permeability was favorably influenced by the biomass presence and accumulation, but this effect did not lead to the real increase of process efficiency

Separation of p-Aminobenzoic Acid by Reactive Extraction in the Presence of 1-Octanol as Phase Modifier

The paper presents the studies on reactive extraction of p-aminobenzoic acid with two extractants (Amberlite LA-2 and D2EHPA) dissolved in two solvents with different dielectric constants (n-heptane, dichloromethane), at various 1-octanol concentrations in the solvent. The addition of 1-octanol induced the increase of the extraction efficiency, the most important influence being recorded for the solvent with lower polarity (n-heptane). Moreover, the volumetric fraction of alcohol controls the number of extractant molecules participating in the interfacial product formation. This effect was more important for the extraction in low-polar solvent and was concretized in the reduction of number of Amberlite LA-2 molecules included in the interfacial compound from 3, in the absence of alcohol, to 1, for φ = 20 % alcohol. Indifferent to alcohol fraction in organic phase, for the reactive extraction with D2EHPA in n-heptane, the number of extractant molecules decreased from 2, in the absence of 1-octanol, to 1 in the presence of 1-octanol. The limitation of solute solvation by extractant due to the increase of solvent polarity led to the reduction of the extraction constant and to the amplification of the differences between the extraction constants obtained for the same extractant and the two solvents

Comparative Study on Pantothenic Acid Separation by Reactive Extraction with Tri-n-octylamine and Di-(2-ethylhexyl) Phosphoric Acid

The mechanism of reactive extraction of pantothenic acid with tri-n-octylamine and di-(2-ethylhexyl) phosphoric acid was analysed for three solvents in the presence or absence of 1-octanol. In the absence of 1-octanol, the stoichiometric ratio between the solute and tri-n-octylamine was 1:1 for dichloromethane, 1:2 for butyl acetate, and 1:4 for n-heptane. In the presence of 1-octanol, the formation of aminic adducts was restricted, the stoichiometries for the interfacial reaction between the acid and tri-n-octylamine becoming 1:1 for dichloromethane and butyl acetate, 1:2 for n-heptane. A similar effect has been observed for extraction with di-(2-ethylhexyl) phosphoric acid, the structure of the interfacial compound being changed for n-heptane and butyl acetate from HAE2 in the absence of 1-octanol to HAE by addition of this alcohol. The highest extraction constants were obtained when extractant associates were formed. However, when the extraction mechanism was the same, the increase in organic phase polarity influenced positively the value of extraction constant

Scale-up of Aerobic Stirred Bioreactors Using the Mixing Time Criteria 1. Simulated Broths

The paper is dedicated to the analysis of the scale-up of an aerobic stirred bioreactor from 4 L working volume to 40 L using the mixing time criterion, taking into account its required conditions and effects. Therefore, if the selected operating parameters allow obtaining similar values of mixing time in the larger bioreactor as in the reference one, it is possible to maintain also the specific power consumption by scaling-up. However, the shear forces in the larger bioreactor are amplified with 23 – 35 %, the most important increase being recorded for high viscous broths

Eco-friendly Production of Chemicals 1. Improvement of Enzymatic Production of Acetophenone by Direct Extraction

Acetophenone can be enzymatically produced by conversion of methylbenzylamine using transaminase. The enzymatic process is strongly affected by the product inhibition, thus requiring the acetophenone removal from the media during its synthesis. In this purpose, the individual and selective extraction of acetophenone and methylbenzylamine with the biocompatible solvent nheptane containing 1-octanol, D2EHPA or TOA has been analyzed at three values of pH (5, 7, and 9). Regardless of the solvent used and pH-value, the highest efficiency has been reached for extraction of acetophenone, the difference between the extraction yields of acetophenone and methylbenzylamine being amplified during the separation of these compounds from their mixture. On the basis of the experimental selectivity factors and taking into consideration both the possible loss of substrate from the media and the pH required for enzymatic reaction, pH = 7, it has been concluded that the optimum solvent combination is the mixture between n-heptane and 1-octanol. This solvent mixture allowed reaching high selectivity factor of 315, corresponding to the extraction yield of acetophenone of 94.5 % and of methylbenzylamine of only 0.3 %

Separation of Amino Acids from Their Mixture by Facilitated Pertraction with D2EHPA

The study on facilitated pertraction of some amino acids with D2EHPA as carrier underlined the significant influence of the pH gradient between the aqueous phases, carrier concentration and mixing intensity. The amino acids can be separated selectively by varying the pH value of feed phase, due to the formation of the corresponding ionic species. The increase of the carrier concentration inside the liquid membrane leads to the intensification of the initial and final mass flows. The amplitude of this effect depends on the molecular size of the pertracted amino acid. The permeability factors are positively influenced by the increase of the pH value of feed phase and rotation speed of the stirrers in the aqueous phases, but are negatively affected by the increase of the stripping phase pH. For all studied amino acids, the pertraction system reaches its maximum capacity of solute transfer at γ = 60 g L–1 carrier concentration

SYNERGIC EXTRACTION OF PANTOTHENIC ACID WITH TWO DIFFERENT EXTRACTANTS

Abstract -The influences of extractants concentrations and solvent polarity on the efficiency of pantothenic acid separation by synergic extraction with tri-n-octylamine (TOA) and di(2-ethylhexyl) phosphoric acid (D2EHPA) mixture have been analyzed. The results indicated the formation of an interfacial compound which includes one molecule of pantothenic acid and one of D2EHPA, its hydrophobicity being increased by solvation with additional TOA molecules. For solvents with lower dielectric constants, n-heptane and n-butyl acetate, the number of amine molecules participating in the interfacial complex formation was controlled by solvent polarity and D2EHPA concentration, decreasing with the increase of these two parameters. For dichloromethane, the chemical structure of the extracted compound remained the same regardless of D2EHPA concentration. The most important synergic effect corresponded to the extractant mixture dissolved in nheptane, at low D2EHPA concentration in the organic phase (5 g/l)