Despite the expanding presence of microscale technology in chemical synthesis and energy production as well as in biomedical devices and analytical and diagnostic tools, its potential in biocatalytic processes for pharmaceutical and fine chemicals, as well as related industries, has not yet been fully exploited. The aim of this review is to shed light on the strategic advantages of this promising technology for the development and realization of biocatalytic processes and subsequent product recovery steps, demonstrated with examples from the literature. Constraints, opportunities, and the future outlook for the implementation of these keygreen engineering methods and the role of supporting tools such as mathematical models to establish sustainable production processes are discussed.
COBISS.SI-ID: 1536258243
Natural organic matter in drinking water is causing concern especially due to the formation of disinfection by-products (DBPs) by chlorine, as these are proven to have adverse health effects on consumers. In this research, humic acid was used as a source of dissolved organic carbon (DOC) in drinking water. Overall, the potential benefits of hidrodynamic cavitation for DOC removal were emphasized for low ratio between applied oxidants to DOC and high UV absorbance of the sample. Investigated DBPs formation potentials require special attention for H2O2/UV AOPs and combinations with HC.
COBISS.SI-ID: 1537341379
The kinetics of enzymatic aldol reaction catalyzed by DERA (2-deoxyribose-5-phosphate aldolase) was studied. The reaction between acetyloxyacetaldehyde/acetaldehyde and chloroacetaldehyde/acetaldehyde in the presence of DERA produces chiral lactol intermediates, which are useful in the synthesis of optically pure super-statins. The experimental approach was designed studying batch and fed-batch reaction conditions adding different amounts of applied reactants. A three-step kinetic model was proposed including the formation of the intermediate product, synthesis of the main desired product and the synthesis of the side product by parallel non-desired secondary reaction. The kinetics of enzyme inactivation caused by reactants was also included in kinetic model design. The establishment of the kinetic model based on the two-substrates binding assuming random mechanism. After the development of the kinetic model, kinetic parameters were determined by non-linear least squares approximation search method, until the minimal differences between experimental and calculated data were achieved. The highest concentrations of the desired main product were produced in the case of fed-batch experiments applying such feeding regime that minimal surplus of reactants in the reaction mixture was attained, which consequently led to lower losses in the enzyme activity. Obtained kinetic parameters showed similar value of inactivation constant for acetyloxyacetaldehyde and acetaldehyde, whereas in the case of chloroacetaldehyde the number was significantly higher. To our knowledge, this is the first developed kinetic model describing the DERA catalyzed reaction of 2-substituted acetaldehydes to corresponding lactols. Obtained kinetic model can be used in further reactor design in the manner of optimizing the process by lowering the loss of enzyme activity in order to achieve higher amounts of the desired main product.
COBISS.SI-ID: 1752623
A mathematical model comprising transport phenomena and enzyme-catalyzed reaction performed on the inner walls of the continuously operated microreactor with surface-immobilized-transaminase was developed. Oriented enzyme immobilization enabling unhindered accessibility of enzyme active sites was obtained by using fusion protein N-SBM-ATA-wt consisting of selected x-transaminase ATA-wt and the positively charged Zbasic2 tag, which established ionic interactions with silicon/glass microchannel surface. Enzyme-catalyzed transamination of methylbenzylamine and pyruvate to acetophenone and L-alanine was described by surface kinetics based on a ping-pong bi-bi mechanism. Reaction kinetic parameters were preliminarily defined in a batch system using various initial substrates concentrations and further applied in the surface reaction description.
COBISS.SI-ID: 1537316803
Droplet-based liquid–liquid extraction in a microchannel was studied, both theoretically and experimentally. A full 3D mathematical model, incorporating convection and diffusion in all spatial directions along with the velocity profile, was developed to depict the governing transport characteristics of droplet-based microfluidics. The finite elements method, as the most common macroscale simulation technique, was used to solve the set of differential equations regarding conservation of moment, mass and solute concentration in a two-domain system coupled by interfacial surface of droplet-based flow pattern. The model was numerically verified and validated online by following the concentrations of a solute in two phases within the microchannel. The relative azobenzene concentration profiles in a methanol/n-octane two-phase system at different positions along the channel length were retrieved by means of a thermal lens microscopic (TLM) technique coupled to a microfluidic system, which gave results of high spatial and temporal resolution. Very good agreement between model calculations and online experimental data was achieved without applying any fitting procedure to the model parameters.
COBISS.SI-ID: 1536245187