Šaržna kristalizacije aktivne farmaceutske tvari: modeliranje kinetike i ravnoteže

Development of a mathematical model for batch crystallization of fesoterodine fumarate, an active pharmaceutical ingredient, in 2-butanone is presented. The model is based on population, mass and energy balances, and takes into account nucleation, crystal growth and agglomeration. Equilibrium solubility was determined experimentally by ATR-FTIR spectroscopy. Kinetic parameters were determined by fitting of experimental and simulated concentration curves and particle size distributions for six crystallization experiments, performed under different operating conditions. The model was validated and the results show good agreement with experimental data. This work is licensed under a Creative Commons Attribution 4.0 International License.U radu je prikazan razvoj matematičkog modela šaržne kristalizacije fezoterodin fumarata, aktivne farmaceutske tvari, u 2-butanonu. Model se temelji na populacijskoj bilanci te bilanci tvari i energije, a uzima u obzir nukleaciju, rast kristala i aglomeraciju. Ravnotežna topljivost određena je eksperimentalno pomoću spektroskopije ATR-FTIR. Kinetički parametri su određeni primjenom eksperimentalnih i simuliranih krivulja koncentracije i raspodjele veličine čestica za šest kristalizacijskih eksperimenata provedenih pod različitim uvjetima. Model je validiran i rezultati su u skladu s eksperimentalnim podatcima. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Biosorpcija olova u laboratorijskoj koloni s nasutim slojem imobilizirane biomase gljive Rhizopus nigricans u obliku peleta: matematički model i pokusi

The biosorption of lead ions from aqueous solution on a self-immobilized Rhizopus nigricans biomass has been studied. Experiments were performed in a laboratory scale packed bed column at different liquid flow rates and biosorbent bed heights. Recorded experimental breakthrough curves were compared to those predicted by a mathematical model, which was developed to simulate a packed bed biosorption process by a soft, self-immobilized fungal biosorbent. In the range of examined experimental conditions, the biomass characteristics such as pellet porosity and biosorption capacity substantially affected the predicted response curve. General correlations for the estimation of the intra-pellet effective diffusivity, the external mass transfer coefficient, as well as axial dispersion were successfully applied in this biological system with specific mechanical properties. Under the experimental conditions, mass transfer is controlled by the external film resistance, while the intra-pellet mass transfer resistance, as well as the effect of axial dispersion, can be neglected. A new parameter α, the fraction of active biomass, with an average value of α=0.7, was introduced to take into account the specific biomass characteristics, and consequently the observed non-ideal liquid flow through the bed of fungal pellets.Ispitivana je biosorpcija iona olova iz vodene otopine na imobiliziranu biomasu gljive Rhizopus nigricans. Pokusi su provedeni u laboratorijskoj koloni s nasutim slojem, pri različitom protoku vodene otopine i visini sloja biosorbenta. Krivulje su proboja uspoređene s krivuljama izračunatim pomoću matematičkoga modela, razvijenog za simulaciju adsorpcije na pelete meke biomase gljive. Na izračunatu su krivulju znatno utjecali poroznost i adsorpcijski kapacitet biomase. U tom su biološkom sustavu specifičnih mehaničkih svojstava uspješno primijenjene općenite korelacije radi procjene stvarne difuzivnosti i koeficijenta prijenosa tvari unutar peleta, te koeficijenta aksijalne disperzije. Pri eksperimentalnim je uvjetima prijenos tvari kontroliran otporom unutar ovojnice peleta, dok se otpor unutar samoga peleta i aksijalna disperzija mogu lako zanemariti. U model je uveden novi parameter α, koji je dio aktivne biomase, a iznosi 0,7. Tako su uzete u obzir specifične značajke biomase te neidealan protok vodene otopine kroz sloj peleta gljiva

Natural plant extracts as active components in chitosan-based films: A comparative study

Chitosan-based films with separately incorporated plant extracts obtained from oak (Quercus robur), hop (Humulus lupulus), and brown algae (Laminaria hyperborea) were evaluated and mutually compared regarding structural, physicochemical, and antibacterial properties. Processing of chitosan and extracted raw substances led to the development of blended films with diverse physical appearances and physicochemical properties. Starting from the oak extract-containing film and ending with the algal extract-containing film, blended films shown ascending trends in moisture content (21.5% – 28.3%), total soluble matter (23.8% – 28.9%), and elongation at break (14.0% – 31.0%) as well as descending trends in tensile strength (12.7 MPa – 5.5 MPa), Young’s modulus (230.8 MPa – 19.4 MPa), and total phenolic content (9.1 mgGAE gfilm⁻¹ – 1.0 mgGAE gfilm⁻¹). The films loaded with oak and hop extracts had improved optical properties reflected in the ability to completely block the light transmittance at the wavelengths below ∼330 nm. Moreover, the same films exhibited the appearance of inhibition zones implying the antibacterial activity against Bacillus subtilis

Designing of manufacturing process of reformer integrated in system with HTPEM fuel cell stack

In this paper is shown designing of manufacturing process of reformer in polymeric electrolyte membrane (PEM) fuel cell. The process is based on reformer modelling, analyzing of reforming initial geometry and change of geometry. In addition to the numerical calculation, change of geometry is based on tool path simulation analysis in order to obtain more efficient reformer production. Before machining, tool path simulation was performed and generated by PTC Creo/Parametric software. The recommendations for geometry changing are given in order to decrease of machining costs, and are made so that did not affect the initial reformer performances. The reformer machining is carried out on a CNC milling machine and Wire EDM machine.Editors: Dr Nenad Mitrovic, Assistant Professor, Dr Milos Milosevic, Senior Scientific Researsher, Dr Goran Mladenovic, Assistant Professo

Designing of manufacturing process of reformer integrated in system with HTPEM fuel cell stack

In this paper is shown designing of manufacturing process of reformer in polymeric electrolyte membrane (PEM) fuel cell. The process is based on reformer modelling, analyzing of reforming initial geometry and change of geometry. In addition to the numerical calculation, change of geometry is based on tool path simulation analysis in order to obtain more efficient reformer production. Before machining, tool path simulation was performed and generated by PTC Creo/Parametric software. The recommendations for geometry changing are given in order to decrease of machining costs, and are made so that did not affect the initial reformer performances. The reformer machining is carried out on a CNC milling machine and Wire EDM machine.Editors: Dr Nenad Mitrovic, Assistant Professor, Dr Milos Milosevic, Senior Scientific Researsher, Dr Goran Mladenovic, Assistant Professo

Effect of Textural Properties and Presence of Co-Cation on NH3-SCR Activity of Cu-Exchanged ZSM-5

Comparative studies over micro-/mesoporous Cu-containing zeolites ZSM-5 prepared by top-down treatment involving NaOH, TPAOH or mixture of NaOH/TPAOH (tetrapropylammonium hydroxide) were conducted. The results of the catalytic data revealed the highest activity of the Cu-ZSM-5 catalyst both in the absence and presence of water vapor. The physico-chemical characterization (diffuse reflectance UV-Vis (DR UV-Vis), Fourier transform infrared (FT-IR) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, temperature-programmed desorption of NOx (TPD-NOx), and microkinetic modeling) results indicated that the microporous structure of ZSM-5 effectively stabilized isolated Cu ion monomers. Besides the attempts targeted to the modification of the textural properties of the parent ZSM-5, in the next approach, we studied the effect of the co-presence of sodium and copper cations in the microporous H-ZSM-5. The presence of co-cation promoted the evolution of [Cu–O–Cu]2+ dimers that bind NOx strongly with the desorption energy barrier of least 80 kJ mol−1. Water presence in the gas phase significantly decreases the rate of ammonia oxidation, while the reaction rates and activation energies of NH3-SCR remain unaffected

Deep eutectic solvents mediated extraction of pectin from apple pomace: Optimization and characterization studies

Fruits are the most utilized commodities among all horticultural crops. They are consumed raw, minimally processed, due to their nutrients and health-promoting compounds. With the growing population and changing diet habits, the production and processing of fruits, have increased very significantly to fulfil the increasing demands. Significant losses and waste in the fresh and processing industries are becoming a serious nutritional, economical, and environmental problem. The fruit waste is composed mainly of seed, skin, rind, and pomace, containing good sources of potentially valuable bioactive compounds. The apple pomace is rich in pectic substances and represents important raw material for pectin production all around the world. For example, the portion of residual apple pomace makes about 13 % of the total waste material and on the basis of dry mass, it contains 10–15% pectin. Currently, it is either used for animal feeding or is disposed of as an industrial waste. The extraction of pectin is usually performed using mineral acids, yielding a reasonable quantity of product while also saving time in the process. Even though pectin has various applications in the food manufacturing industry, consumers have a negative perception upon learning that strong acids are used in pectin extraction. Furthermore, high acidity speeds up corrosion and rust formation of the apparatus, leading to water pollution which contributes to environmental concerns. The present study reports the lab-scale procedure for extraction of pectin from the waste industrial apple pomace using deep eutectic solvents (DESs) as extraction medium. DESs turned to be an excellent choice for extraction because they are non-volatile at room temperature and non-toxic, while the majority of DESs are water-miscible depending on their components. The process consisted of the processing of apples, employing milling, enzymatic digestion and pressing. The further analysis included temperature and ultrasound assisted extraction and purification of pectin as well as the detailed physicochemical analysis of the obtained product. The applied procedure has resulted in satisfactory yields under mild extraction conditions, optimal extraction time and industrially preferred properties of the isolated pectin