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

STUDY ON ALCOHOLIC FERMENTATION IN A STATIONARY BASKET BIOREACTOR WITH IMMOBILIZED YEAST CELLS

The use of a stationary basket bioreactor with immobilized S. cerevisiae cells indicated the possibility to extend the number of alcoholic fermentation cycles that can be carried out with the same biocatalysts to over nine. Although the rates of glucose consumption and ethanol production were lower than those recorded for the mobile beds of immobilized yeast cells, the mechanical lysis of the biocatalysts is avoided in the case of basket bed. Due to the substrate and product accumulation inside the basket bed, the fermentation process can be improved by washing out the biocatalysts bed over two or four cycles

KINETIC STUDIES ON BIODEGRADATION OF LIPIDS FROM OLIVE OIL MILL WASTEWATERS WITH FREE AND IMMOBILIZED Bacillus sp. CELLS

The studies on the biodegradation of lipids from olive oil mill wastewater with free and immobilized Bacillus sp. cells indicated that the maximum specific rate of the process is reached at pH = 8. The use of immobilized cells allows to increasing the number of biodegradation process cycles, but reduces the rate of the process. In this case, the process rate depends on the biocatalysts size and cells concentration inside them. Thus, at bacterial cells concentration of 9 g d.w./100 mL biocatalyst, the apparent specific rate varied from 4.65 to 1.46×10-2 h-1 by increasing the biocatalyst particles diameter from 3 to 4.2 mm.The cumulated influences of the particles size and cells concentration have been included in a mathematical model for the apparent specific rate of lipids biodegradation. The model offers a good concordance with the experimental data, the average deviation being of +/- 7.38%

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: 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

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

Bioreactors with stirred bed of immobilized cells - 2. studies on distribution of mixing efficiency

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