Separation kinetics of l-phenylalanine by ion-exchange process

Enzyme-ion exchanger interactions in serine alkaline protease separation: theory, equilibria and kinetics

The term biotechnology first appeared in the programs of the Scientific and Technological Research Council of Turkey (TUBITAK) in 1982. The State Planning Organization (SPO) in 1988 defined biotechnology and the scientific fields. Moreover, it put forward an institutional framework and suggested priority areas for research and development. Turkey has been researching and investing in biotechnology for almost four decades. This review covers the development of science and technology policy with its history, consensus and consequences, bio-industries in Turkey, and research activities in biotechnology at Turkish Universities. Details are provided by the research groups in response to a common request for information on their activities and major publications in the field. The information provided has been grouped under thematic topics within the broad theme of biotechnology, and summarized within these topics. Although many aspects of biotechnological research are being pursued in Turkey, it appears that the most common research activities of the field are in fermentation processes, environmental biotechnology, and biomedical engineering.

Biotechnology in Turkey: an overview.

The adsorption amount and selectivity of L-tryptophan (l-Trp) on the hydrophobic interaction and ion exchange mixed-mode chromatography medium HD-1 were studied as well as the salt resistance of the resin via adsorption equilibrium experiments. The adsorption mechanisms of l-Trp were illuminated by combining adsorption equilibria and a kinetics analysis. The separation effect was studied by dynamic separation experiments in a fixed-bed. The results indicate that an increase of the concentration proportion of l-Trp zwitterion benefits the adsorption of l-Trp. The resin shows a high adsorption selectivity for l-Trp at different pH values. The adsorption amount of l-Trp is not affected significantly by NaCl. Various groups play a role in the adsorption of l-Trp. An adsorption energy lower than 8 kJ/mol indicates that the adsorption of l-Trp is mainly based on non-electrostatic interactions, with an electrostatic interaction as a supplement. The adsorption equilibrium model considering the dissociation equilibrium of the resin and l-Trp proposed in this work can simulate the adsorption equilibrium data of l-Trp at different pH values as well. The mass transfer rate of l-Trp is controlled by intraparticle and liquid film diffusion simultaneously. The fixed-bed packed with resin HD-1 can separate l-Trp with the purity of l-Trp higher than 99%, recovery rate higher than 95%, and concentration of 4.69 × 10–3 mol/L.

Adsorption Equilibria, Kinetics, and Column Dynamics of L-Tryptophan on Mixed-Mode Resin HD-1

Turkey is a country not usually associated with industrial biotechnology. However, when current research potential in universities and other R & D centers and particularly contributions made to the international literature since the mid- 1980s are taken into account, high-quality international-level work is now commonplace, especially in areas such as industrial microbiology, enzyme technology, biomaterials and biological wastewater treatment. Work in plant biotechnology is at a relatively early stage, but is expected to become a rapidly developing force in the near future. The present article documents current potential in Turkey, based on significant publications produced during the last 8 years.

B i o tec h no1 og i cal Develop men ts i n Tu r key

Kinetics of the separation of L-glutamic acid (GLU) by ion exchange has been studied with strongly acidic H+-type cation exchange resin Amberlite IR-122. Since glutamic acid is a trivalent ampholyte and dissociates according to three equilibrium reactions, separation of G+ ions by a cation exchange process is accompanied by the dominant reversible reaction, i.e. G++H+ ⇄ G0. Accompanying reversible reaction has an effect on the ion exchange rate, and decreases the performance of the process comparing with the ideal case that the exchanging ions retain their identity. The analysis was performed first with the ion exchange column, DIC (L/D=0.52); and then with the ion exchange column, IC (L/D=10.9). The data were collected with model glutamic acid solutions for both DIC and IC columns/reactors. IC experimental results were then compared with that of DIC and the effect of scale up on ion exchange process was investigated. The experimental results have provided an adequate basis for the design calculations, and the design parameters were determined. Rate coefficients for the liquid phase mass transfer controlled cation exchange process were calculated and interrelated with a plot of jMfactor versus Reynolds number.

S. Takaç

Papers

Kinetics of ion exchange process for separation of glutamic acid