Andrzej Noworyta

Catalytic membrane preparation for enzymatic hydrolysis reactions carried out in the membrane phase contactor

Abstract Two concepts of the localisation of hydrolytic enzymes with the use of a membrane phase contactor are presented in the paper. Because of the participation of water molecules in the process, the enzyme should be immobilized so that it could be in contact with the aqueous phase. Thus, enzyme immobilisation on the hydrophobic membrane surface and in the hydrophilic membrane pores was considered. The lipase from Candida antarctica and from pancreatic porcine were selected for experiments. Both enzymes were adsorbed on the polypropylene membrane surface, packed in the pores of nitrocellulose and cellulose membranes and bound within the pores of the polyamide membrane after its activation with glutaraldehyde. On the basis of the amount of immobilized protein, enzyme activity and stability, the most appropriate preparation of each immobilized lipase was chosen having on mind its further application in the biphase organic solvent—water system.

Immobilization of penicillin acylase on acrylic carriers

Penicillin acylase obtained from E. Coli (E. C. 3.5.1.11) was covalently bound via glutaric aldehyde to acrylic carriers crosslinked with divinylbenzene or ethylene glycol dimethacrylate. The best enzymatic preparation was obtained by using ethyl acrylate/ ethylene glycol dimethacrylate copolymer. 1 cm3 of the carrier bound 6.4 mg of protein, having 72% activity in relation to the native enzyme. The preparation lost only 10% of its initial activity after 100 d of storage at 4°C. A negligible effect of immobilization on the enzyme activity at different temperatures or pH as well as significant increase of the stability of the immobilized enzyme at elevated temperatures were observed.

On the removal of silica from aluminate solutions: Mechanism and kinetics of the process

Abstract During the extraction of alumina from siliceous (non-bauxite) minerals by alkaline leaching some of the silica enters the solution as silicate ions. In order to obtain high-grade aluminium hydroxide, it is necessary to remove this from the aluminate solutions. The process reported in this paper employs Ca(OH) 2 suspensions and enables the silicate concentration to be reduced to a few ppm. It is suggested that the product, hydrogarnet, exerts a catalytic effect on the reaction rate which was found to be temperature-dependent.

A system for cleaning condensates containing ammonium nitrate by the reverse osmosis method

Abstract A process in which membrane techniques are used to obtain clean technology of ammonium nitrate production is described. The possibility of integration of this traditional chemical industry technology with membrane separations is revealed. Original technology has been patented and implemented. The aim of the system is to obtain a concentrate with ammonium nitrate concentration ranging from 40 to 80 g/dm 3 . The system consists of three elements-centers: preparation of raw material and preliminary filtration, three stages of reverse osmosis, and final degassing of the permeate. Very good results obtained during the 3-year operation of the system initiated further projects in this industry.

Modeling of enzymatic conversion in the catalytic gel layer located on a membrane surface

Equations describing a multi-phase bioreactor with a catalytic membrane located on the boundary of phases, of which one is a substrate reservoir, were formulated. A model analysis of the process was carried out and the effect of main operating parameters of such a reactor, i.e., the catalytic layer thickness and the coefficients of diffusion mass transport in both phases, was determined. Two periods with different methods of supplying the catalytic layer can be distinguished in the process. There is also a characteristic thickness of the catalyst layer: when it is exceeded, the process duration is no longer shortened although full substrate conversion from the supply stream not always has a place. It is recommended to apply thin layers because then the catalyst activity is fully used. The analyses of the influence of mass transfer showed that substrate mass transfer in the water phase to the catalyst layer has a slight effect on the process rate when the intensification of its transfer in the organic phase might have a significant influence on the process rate.

Mathematical model of the desiliconization of aluminate solutions

Abstract A mathematical model was developed for the process of complete desiliconization of aluminate solutions produced in the recovery of alumina from ores. In this model a hypothesis is put forward that the desiliconization process is of an autocatalytic nature, thus enabling the induction period (which is typical of the process) to be taken into account. The coefficients of the model were determined and a formula thus derived, which can be widely used for design purposes. The model is discussed in relation to other concepts.

Membrane reactor with soluble forms of penicillin acylase

The present paper summarizes studies on designing an enzyme membrane reactor for the continuous hydrolysis of penicillin G. For the reactor containing native penicillin acylase, a thermally treated polysulfone membrane of 10,000 Da nominal cut-off was selected, whereas in the case of the reactor containing stabilized enzyme, an untreated polysulfone membrane with the same cut-off parameter is preferable. The hydrolysis processes were carried out in the appropriate membrane reactors for three days continuously. Both enzyme preparations were stable during that period. The expected conversion of penicillin G was estimated on the basis of a kinetic equation. Good agreement between the calculated and the measured data was obtained; however, comparison of the enzyme stability at 37°C shows that penicillin acylase mixed with poly(ethyleneimine) is several times more stable than the native enzyme. The membrane reactor with penicillin acylase stabilized by poly(ethyleneimine) seems to be very promising as far as industry applications are concerned.

Efficient utilisation of hydrogel preparations with encapsulated enzymes – a case study on catalase and hydrogen peroxide degradation☆

Graphical abstract

Mass transfer in the membrane phase contactor with an enzyme gel layer immobilized on a membrane

In the membrane phase contactor, the rate of reagent mass transfer from organic phase (a reservoir) to water phase (a reaction phase) depends on the three different resistances: the organic phase resistance, the resistance generated by the membrane and the water phase resistance. In the case when the enzyme is immobilized on the membrane surface and forms a gel layer, an additional mass transfer resistance is generated that could have an important influence on total mass transfer rate. Its value is directly proportional to the layer thickness and assumes particularly high values in the system where the distribution coefficient is much higher than unity. Since the gel layer thickness affects simultaneously the process yield, the decision concerning the amount of protein immobilized on the surface should be considered in detail.

Kinetic behavior of penicillin acylase immobilized on acrylic carrier

The usefulness of Lillys kinetic equation to describe penicillin G hydrolysis performed by immobilized penicillin acylase onto the acrylic carrier has been shown. Based on the experimental results characteristic kinetic constants have been estimated. The effect of noncompetitive inhibition of 6-amino penicillanic acid has not been found. Five components of reaction resistance have been defined. These components were also estimated for the reaction of the native enzyme as well as the Boehringer preparation.