SEPARATION OF p-AMINOBENZOIC ACID BY REACTIVE EXTRACTION. 1. MECHANISM AND INFLUENCING FACTORS

The comparative study on the reactive extraction of p-aminobenzoic acid with Amberlite LA-2 and D2EHPA in two solvents with different polarity (n-heptane and dichloromethane) indicated that the extractant type and solvent polarity control the extraction mechanism. Thus, the reactive extraction with Amberlite LA-2 occurs by means of the interfacial formation of an aminic adduct with three extractant molecules in low-polar solvent, or of an salt with one extractant molecule in higher polar solvent. Similarly, the extraction with D2EHPA is based on the formation of an acidic adduct with two extractant molecules in n-heptane, or of a salt with one extractant molecule in dichloromethane. The most efficient extraction has been reached for the combination Amberlite LA-2-dichloromethane

SEPARATION OF p-AMINOBENZOIC ACID BY REACTIVE EXTRACTION 1. MECHANISM AND INFLUENCING FACTORS

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New extraction techniques on bioseparations: 2. Pertraction, direct extraction

The second part of this review presents our original results on the separation of some biosynthetic products (antibiotics, carboxylic acids, alcohols) by pertraction and direct extraction from broths without biomass filtration. For the analyzed systems, the experimental conditions required for reaching maximum separation efficiency and the mathematical models describing the process have been established. For all the studied cases, these extraction techniques simplify the technologies and reduce the overall cost of the product

Rutin estraction from hardhay flowers - Hyperici herba and underbrush fruits - Hippophaes fructus

The study of rutin extraction from autochthonous hardhay flowers (Hyperici herba) and underbrush fruits (Hippophaes fructus) with methanol, ethanol and 1-propanol at different concentrations, temperatures and duration indicated that the most efficient solvent was 1-propanol, the optimum concentration being determined by the amount and type of natural compounds from the two plants.Using statistical analysis and a factorial second order experiment two mathematical correlations between the degree of rutin extraction and the main parameters influencing the process (1-propanol concentration temperature, duration) were established. For both extraction systems, the considered variables control the extraction process to an extent of 99.2 99.5%, the solvent concentration exhibiting the most important influence especially for rutin extraction from underbrush fruits (Hippophaes fructus)

New extraction techniques on bioseparations: 1. Reactive extraction

The complexity of downstream processes for biosynthetic products constitutes a particularity of industrial biotechnologies, especially because of the biosynthetic product high dilution in fermentation broth, their chemical and thermal liability and the presence of secondary products. For these reasons, new separation techniques have been developed and applied to bioseparations. Among them, reactive extraction, pertraction (extraction and transport through liquid membranes) and direct extraction from broths have considerable potential and are required for the further development of many biotechnologies. This review is structured on two parts and presents our original results of the studies on the separation of some biosynthetic products (antibiotics, carboxylic acids, amino acids, alcohols) by reactive extraction in the first part, and by pertraction and direct extraction from broths without biomass filtration in the second. For all the analyzed cases, these extraction techniques simplify the technologies by reducing material and energy consumption, by avoiding product inhibition, by increasing the separation selectivity, therefore decreasing the overall cost of the product

Optimization of mixing in stirred bioreactors - 1. Comparative analysis of mixing efficiency with different radial impellers for simulated broths

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Optimization of mixing in stirred bioreactors - 2. Selection of optimum impellers combinations for non-aerated simulated broths

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Studies on oxygen mass transfer in stirred bioreactors 2: Suspensions of bacteria, yeasts and fungis

The aim of these experiments is to study the oxygen mass transfer rate by means of the mass transfer coefficient, for a stirred bioreactor and different fermentation broths, using a large domain of operating variables. For quantifying the effects of the considered factors (concentration and morphology of the biomass, specific power input, superficial air velocity surface aeration) on ka, the experiments were carried out for non-respirating biomass suspensions of Propionibacterium shermanii Saccharomyces cerevisiae and Penicillium chrysogenum, mycelial aggregates (pellets) and free mycelia morphological structures

Fractionation of the mixture obtained by the enzymatic hydrolysis of penicillin G

Using the experimental data on the individual physical and reactive extraction of 6APA with 1,2-dichlororethane, D2EHPA and Amberlite LA-2 together with data on the influence of the pH value of the aqueous phase and the Amberlite LA-2 concentration on the selective separation of 6APA, PG and PAA from a mixture, a process flow sheet for the fractionation of the solution obtained by the enzymatic hydrolysis of PG has been elaborated and applied. Thus, at pH=10, 6APA was selectively separated by four extraction stages, the overall extraction degree being 98.8%. PG was selectively extracted from the raffinate at pH=6 by three extraction stages, adjusting the molar concentration of Amberlite LA-2 to the value of the PG molar concentration for each extraction stage. The antibiotic extraction degree was 99.6%