Marek Henczka

Effects of Mixing on Parallel Chemical Reactions in a Continuous-Flow Stirred-Tank Reactor

Effects of turbulent mixing on the course of two fast parallel chemical reactions (neutralization of sodium hydroxide and hydrolysis of ethyl chloroacetate) carried out in a continuous-flow stirred-tank reactor are experimentally investigated and theoretically interpreted. Mixing effects are modelled using mechanistic models (E-model) and a closure method based on CFD.

Closure problem for parallel chemical reactions

Abstract The effect of micromixing on parallel reactions was studied experimentally and interpreted theoretically using closure models. A solution of soduim hydroxide was contacted with a pre-mixture of hydrochloric acid and ethyl chloroacetate solutions in a tubular reactor equipped with an impingement mix-head. Two different impingement mix-heads were applied: the first was T. shaped with two feeding nozzles; the second was equipped with six feeding nozzles. The selectivity of the parallel reactions was then dependent upon the mix-head used, the Reynolds number, the concentretion of reactants and the volume ratio of reagent solutions. The effect of the volume ratio of the reagant solutions on the selectivity was used as the test effect for closure models. It is shown that simple closures based on moments are not able to describe properly the behaviour of parallel reactions. A closure method based on the probability density functions of the concentrations of chemically inert species and on the interpolation of the local concentrations of reactants between the asymptotes on infinitely slow and infinitely fast chemical reactions is verified experimentally.

Optimisation of a direct plating method for the detection and enumeration of Alicyclobacillus acidoterrestris spores

A direct plating method for the detection and enumeration of Alicyclobacillus acidoterrestris spores has been optimised. The results of the application of four types of growth media (BAT agar, YSG agar, K agar and SK agar) regarding the recovery and enumeration of A. acidoterrestris spores were compared. The influence of the type of applied growth medium, heat shock conditions, incubation temperature, incubation time, plating technique and the presence of apple juice in the sample on the accuracy of the detection and enumeration of A. acidoterrestris spores was investigated. Among the investigated media, YSG agar was the most sensitive medium, and its application resulted in the highest recovery of A. acidoterrestris spores, while K agar and BAT agar were the least suitable media. The effect of the heat shock time on the recovery of spores was negligible. When there was a low concentration of spores in a sample, the membrane filtration method was superior to the spread plating method. The obtained results show that heat shock carried out at 80°C for 10 min and plating samples in combination with membrane filtration on YSG agar, followed by incubation at 46°C for 3 days provided the optimal conditions for the detection and enumeration of A. acidoterrestris spores. Application of the presented method allows highly efficient, fast and sensitive identification and enumeration of A. acidoterrestris spores in food products. This methodology will be useful for the fruit juice industry for identifying products contaminated with A. acidoterrestris spores, and its practical application may prevent economic losses for manufacturers.

Particle Elaboration Using Supercritical Media for Drug Delivery Into the Human Lungs

Application of aerosol powders enables fast, controlled delivery of therapeutic agents into the human lungs, and then into the blood. Hence, the method is used to deliver inhaleable drugs to the deep lung for the treatment of systemic and respiratory diseases. However, it requires applying of drug particles with controlled particle size, particle size distribution (PSD) and particle morphology. To introduce drugs into the tracheobronchial and pulmonary regions one needs to use micronized pharmaceuticals with strictly defined particle size ranges between 0.1 Lim and 5 (urn. There are many traditional industrial techniques to produce powdered solids (grinding, jet milling), however, they do not guarantee the proper particle size. Particle design using supercritical fluids represents an interesting alternative to milling techniques. Design of particles is considered presently as a major development of supercritical fluids applications, which results in large number of publications and patents — see (Jung and Perrut, 2001) for recent literature and patent survey. These methods are based on crystallization of a solid phase from a solution with the use of supercritical fluids with the goal to obtain high purity materials and narrow particle size distribution.

Reactive extraction of succinic acid using supercritical carbon dioxide

ABSTRACT Reactive extraction using supercritical carbon dioxide (scCO2) and tri-n-octylamine (TOA) was evaluated as a separation method of succinic acid from an aqueous solution. The reactive extraction of succinic acid was performed at varying initial acid concentrations in aqueous solution (0.07–0.45 mol∙dm−3), temperature (35–65°C) and pressure (8–16 MPa). The succinic acid separation was conducted in both batch mode and semi-continuous mode. The highest reactive extraction efficiency of approx. 62% was obtained for the process conducted in semi-continuous mode at 35°C and 16 MPa for the initial acid concentrations in aqueous phase of 0.39 mol∙dm−3.

Supercritical Fluids in Green Technologies

Supercritical fluid technologies offer the possibility to obtain new products with special characteristics or to design new processes, which are environmentally friendly and sustainable. By using supercritical fluids as the processing media, one can also avoid the problem of solvent residues and restrictions on the use of conventional organic solvents in industrial technologies. In this overview some novel applications of supercritical fluids are presented and the future expected development in the field of high pressure green technologies is outlined.

Cleaning Porous Materials Using Supercritical Fluids

In this work, processes for cleaning porous materials using supercritical fluids as cleaning media are considered. In the first part of the work, a literature review is provided, showing examples of successful development of such processes. In the literature review, the processes are characterized and advantages resulting from application of supercritical fluids are explained. The advantages and disadvantages of using supercritical fluids as cleaning media are discussed. In the second part of the work, practical guidelines for development of novel processes for cleaning porous materials, in which supercritical fluids can be applied, are formulated. The guidelines include the review of references processes as a starting point for process design, the analysis of the physical properties of the investigated system, investigation of potential negative effect of treatment with SCFs on the porous material’s key properties, experimental investigation of the process, as well as process optimization and scale-up. The guidelines are illustrated with an exemplary process—cleaning microfiltration membranes using supercritical carbon dioxide instead of liquid organic solvents. Despite some technological challenges and limitations, supercritical fluids can be applied in many processes for cleaning porous materials, leading often to safer and more environmentally friendly processes, as well as to products of superior quality.

Influence of mixing on the course of reactive extraction of citric acid using supercritical CO2

Influence of mixing on the course of reactive extraction of citric acid using supercritical CO2