Tine Koloini

Dynamic capacity studies of CIM (Convective Interaction Media)® monolithic columns

The characterization of CIM® DEAE monolithic columns in terms of dynamic binding capacity is presented in this paper. Breakthrough experiments were performed for capacity determination. Bovine serum albumin (BSA) was used as a model protein. It is shown that CIM® monolithic columns have good batch-to-batch reproducibility as well as long-term stability. The experiments performed under different linear velocities demonstrated that the dynamic capacity is unaffected at least up to a linear velocity of 2450 cm/h. Furthermore, the breakthrough curve slope is constant, indicating that the capacity would remain constant at even higher linear velocities. The adsorption isotherm of BSA dissolved in 20 mM Tris-HCl buffer shows a constant capacity of around 30 mg/mL of support down to a concentration of 20 μg/mL. The capacity is substantially influenced by the ionic strength; however, 20% of the maximal capacity is still preserved at 0.3 M NaCl.

Esterification of Benzoic Acid in Microwave Tubular Flow Reactor

Abstract Acid-catalyzed esterification of benzoic acid with ethanol was investigated in a continuous tubular flow reactor heated by microwaves. The microwave reactor operated at medium pressure and high temperature conditions. Esterification was catalyzed with sulfuric acid and with ion exchange resins. Kinetic parameters of esterification were determined in a stirred glass vessel using conventional heating. A mathematical model was proposed to describe temperature profiles and to predict the conversion of the reaction in the tubular flow microwave reactor. The calculated conversions of benzoic acid based on predicted temperature profiles agree with experimental data. The operating conditions in the microwave reactor allowed us to achieve high conversions at relatively low residence times.

Temperature influence on the dynamic binding capacity of a monolithic ion-exchange column

This work investigates the influence of temperature on the binding capacity of bovine serum albumin (BSA), soybean trypsin inhibitor and L-glutamic acid to a CIM (DEAE) weak anion-exchange disk monolithic column. The binding capacity was determined experimentally under dynamic conditions using frontal analysis. The effect on the dynamic binding capacity of dimers present in the BSA solution has been evaluated and a closed-loop frontal analysis was used to determine the equilibrium binding capacities. The binding capacity for both BSA and soybean trypsin inhibitor increased with increasing temperature. In the case of L-glutamic acid, an increase in the binding capacity was observed with temperature up to 20 degrees C. A further increase in temperature caused a decrease of the dynamic binding capacity.

Hydrolysis of sucrose by conventional and microwave heating in stirred tank reactor

Abstract The reaction kinetics of the hydrolysis of sucrose to fructose and glucose under catalysis by the strongly acidic cation-exchange resin Amberlite 200C in R-H form was investigated in thermal and microwave fields using a standard laboratory stirred tank reactor. The Teflon stirrer was used to eliminate the mass transport resistance and to assure homogeneous reaction temperature which was accurately measured by a specially designed Ni—Cr—Ni thermocouple. A Teflon water cooling coil was used for maintaining constant temperature in the reactor during microwave irradiation. The rate constants for the reaction at various temperatures were measured in experiments conducted in a water bath and the Arrhenius parameters were calculated. No rate enhancements or reductions of reaction time were observed when reactions were carried out under microwave irradiation at the same reaction temperature. It was shown again that the reaction kinetics in thermal and microwave fields did not differ.

Kinetics of catalytic transfer hydrogenation of soybean oil

The catalytic transfer hydrogenation of soybean oil was studied by using various concentrations of sodium formate solutions, an emulsifier and paladium on a carbon catalyst. Sodium formate concentration and addition of the emuldifier significantly affect the reaction rate because of their influence on the liquid/liquid interface. Under conditions in which diffusion effects are eliminated, all reactions carried out in diluted sodium formate solution obey first-order kinetics with respect to fatty acids. This allows control over the hydrogenation process of soybean oil, needed to obtain partially hydrogenated oil containing about 1% linolenic acid and a relatively high level of linoleic acid with no increase in the stearic acid concentration.

On-line measurement and analysis of yeast flocculation

The ability of yeast to flocculate is important in different separation processes, especially in the beer industry. Because of the regulation purposes, there is a need for online monitoring. With the presented measuring set-up, consisting of a peristaltic pump, a photometer, and a computer, it is possible to determine the onset of flocculation as well as to follow flocculation intensity and the concentration of nonflocculated cells. It was found that for the yeast strain Saccharomyces cerevisiae ZIM 198 the decrease of nonflocculated cells (after flocculation has occurred) during the exponential growth can be described by an exponential equation for the first-order process, whereas the increase of free cells due to dispersion of the flocs during the stationary phase follows the form of the growth curve. It was also demonstrated that the absorbency profiles of yeast sedimentation can be described by the second-order equation suggested by Stradford and Keenan for the decrease of cell concentration during sedimentation. (c) 1997 John Wiley & Sons, Inc.

Parametric Sensitivity of a Dynamic Model for a Pilot Single-Stage Wastewater Treatment Plant

The application of models in most treatment plants is limited due to a lack of advanced input parameter values required by the models. Although the numbers of parameters are presented in the literature, the range of some parameters is too wide considering the parametric sensitivity of the dynamic model. On the other hand, some parameters depend on the nature of a specific wastewater treatment plant. The present paper is concerned with a dynamic model of the activated sludge process in a single stage wastewater treatment plant with parametric sensitivity and evaluation. Model calibration was successfully experimentally confirmed for the steady-state operational conditions.

Nonflocculent versus total biomass ratio as a criterion for starting the biomass separation process

We introduce the ratio of nonflocculent versus total biomass as a criterion for starting cell separation from the medium. This criterion can be applied for the automation of the process regardless of the process dynamics. Its minimum indicates the optimum period of time for the start of the separation process with regard not only to nonflocculent cell concentration, but also medium attributes. In contrast to the concentration of nonflocculent cells, which has two minima, first at the beginning of the process and another broader one in the period during which maximum flocculation is present, the ratio has a single minimum and can therefore be implemented as a criterion for cell separation. To calculate the ratio value, in addition to an on-line method for nonflocculent biomass measurement described elsewhere, an on-line method for the total biomass of flocculent yeast is proposed. It is based on the absorbency measurement of the cell biomass, previously deflocculated by EDTA. Therefore, it can be applied in bioprocesses with transparent media and yeast that can be deflocculated by EDTA. Copyright 1998 John Wiley & Sons, Inc.