Showing papers in "Periodica Polytechnica Chemical Engineering in 2019"

Mg and La Co-doped ZnO Nanoparticles Prepared by Sol–gel Method: Synthesis, Characterization and Photocatalytic Activity

Abstract: In this study, La and Mg doped, and co-doped ZnO nanoparticles were prepared using the sol-gel method. The prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and N2 physisorption techniques. The XRD results indicated that the prepared nanoparticles can be well adopted by the hexagonal wurtzite structure crystal and there are no second impurity peaks. Studies of the FESEM, EDX and TEM have shown that the samples have uniform spherical-like morphology with a homogenous distribution. The incorporation of La and Mg into the ZnO lattice had no effect on the morphology of the nanoparticles, but a reduction in the size of the grains (≈ 14 nm to ≈ 7 nm) was observed due to the insertion of these ions. The results of N2 physisorption indicated that there was an increase in BET surface area and pore volume for doped and co-doped samples. The results of DRS showed an increase in band gap energy and a blue shift at the absorption edge for doped and co-doped samples. The photocatalytic activity of the prepared catalysts was evaluated in the removal of RhB under UVA irradiation. The results showed that Mg5%-La5%/ZnO had the highest photoactivity (91.18 %) among all samples.

CFD Analysis of CO2 Sequestration Applying Different Absorbents Inside the Microporous PVDF Hollow Fiber Membrane Contactor

Abstract: The sequestration process of greenhouse contaminants such as CO2 via hollow fiber membrane contactor (HFMC) is regarded as a promising technology to manage the deleterious impressions of CO2 on environment such as global warming and air pollution. This investigational paper renders a wide-ranging 2D simulation in order to assess the removal performance of CO2 from CO2/CH4 gaseous stream (containing 80 % CH4 and 20 % CO2) in the HFMC. As the novelty, the evaluation of CO2 acid gas removal from gaseous mixture applying four novel absorbing agents (potassium threonate (PT), piperazine (PZ), pure water (H2O) and methyldiethanolamine (MDEA)) is implemented in the HFMC with the aim of introducing a more efficient liquid absorbent for CO2 sequestration. Model validation is done based on the comparison of mathematical model outcomes and experimental data in a wide range of H2O velocity and confirms a desirable agreement with an average relative deviation (ARD) of approximately 3 % for CO2 flux. It is perceived from the results that PZ is introduced as the most efficient liquid absorbent for CO2 sequestration and MDEA, PT and H2O are in the next category (100 % removal using PZ > 96 % removal using MDEA > 89 % removal using PT > 57 % removal using H2O). The results corroborate that increase in membrane tortuosity and gas velocity negatively affects the sequestration process while increment of module length and porosity improve the separation of CO2.

Intensified Thermal Conductivity and Convective Heat Transfer of Ultrasonically Prepared CuO-Polyaniline Nanocomposite Based Nanofluids in Helical Coil Heat Exchanger

Abstract: In this study, investigation of convective heat transfer enhancement with the use of CuO–Polyaniline (CuO–PANI) nanocomposite basednanofluid inside vertical helically coiled tube heat exchanger was carried out experimentally. In these experiments, the effects of different parameters such as Reynolds number and volume % of CuO–PANI nanocomposite in nanofluid on the heat transfer coefficient of base fluid have been studied. In order to study the effect of CuO–PANI nanocomposite based nanofluid on heat transfer, CuO nanoparticles loaded in PANI were synthesized in the presence of ultrasound assisted environment at different loading concentration of CuO nanoparticles (1, 3 and 5 wt.%). Then the nanofluids were prepared at different concentrations of CuO–PANI nanocomposite using water as a base fluid. The 1 wt.% CuO–PANI nanocomposite was selected for the heat transfer study for nanofluid concentration in the range of 0.05 to 0.3 volume % and Reynolds number range of was 1080 to 2160 (±5). Around 37 % enhancement in the heat transfer coefficient was observed for 0.2 volume % of 1 wt.% CuO–PANI nanocomposite in the base fluid. In addition, significant enhancement in the heat transfer coefficient was observed with an increase in the Reynolds number and percentage loading of CuO nanoparticle in Polyaniline (PANI).

The Latent Heat of Supercritical Fluids

Abstract: The article discusses the notion of a supercritical latent heat during 'pseudoboiling': Experimental, numerical, and theoretical evidence show that the supercritical state space is not homogeneous, but can be divided into liquid-like and gas-like domains, separated by an extension to the coexistence line -- the Widom line. The key concept are two limit states of ideal liquid and ideal gas, characterized by constant heat capacities, and analyze the transition between them. Then, analogous to subcritical vaporization, a supercritical state transition from liquid to gaseous overcomes intermolecular attractive forces, albeit over a finite temperature interval rather than at an equilibrium temperature. This distributed latent heat is in fact approximately invariant with respect to pressure for (0 < p < 3 p_(cr)) and is thus valid at subcritical and supercritical conditions. This view also changes the perspective on subcritical latent heat: while it is an accurate representation of the required energy at very low pressures, the contribution of the distributed latent heat dominates the equilibrium latent heat as the critical pressure is approached.

Fuel Properties of Butanol – Hydrogenated Vegetable Oil Blends as a Diesel Extender Option for Internal Combustion Engines

Abstract: European legislation and new engine technologies require better quality in fuels, and the diesel scandal pushes engine and fuel developers to investigate new solutions. The decrease of fossil energy sources and the new, stricter emission regulations necessitate the discovery of renewable sources. Biofuels are an obvious solution to replace fossil fuels in a more environmentally conscious way. This study presents a new approach with the analytical investigation of butanol, hydrogenated vegetable oil, and diesel oil blends.In the presented phase of the research, our focus was on the most application- critical chemical properties of the fuels, to analyze if the three component blends are suitable for compression ignition engines. A wide-ranging chemical-analytical test plan was prepared with nearly 20 parameters measured of the chemical and physical parameters of blends, especially regarding flash point, cetane number, viscosity and cold filter plugging point (CFPP).The findings prove that from an engine-critical characteristics point of view butanol – hydrogenated vegetable oil – diesel blends are a potential solution, as HVO and butanol counterbalance its critical parameters.

Cannabinoids Enriched Extracts from Industrial Hemp Residues

Abstract: Obtaining phytocannabinoids, associated with various medicinal and therapeutic properties with no reported side effects, is one of the hot topics. The phychotropic Δ9-tetrahydrocannabinol (THC) is less than 0.2 % in industrial cultivars therefore can be grown legally in many EU countries. Harvesting and processing of hemp for fiber or seeds generates large amount of wastes containing substantial amounts of bioactives such as cannabidiol (CBD) which are the primary cannabinoids along with cannabidiolic acid (CBDA), cannabinol (CBN), cannabigerol (CBG), and cannabichromene (CBC). The aim of this work was to optimize the extraction of cannabinoids from industrial hemp threshing residue using supercritical carbon dioxide extraction in pilot scales. The effects of extraction pressure and temperature on the extraction yield were evaluated. Three ground and pelleted samples of the same type but with different harvesting time were also compared. After derivatization of the samples the cannabinoids and the minor THCs were quantified by GC-MS. The extraction yields were between 0.2 – 6.59 g/100 g dry mass depending on the source of hemp residue and on the process parameters of the extraction process. By increasing the pressure of extraction (in the range of 25-45 MPa at 45 °C) the extraction yields increased, meanwhile the yields of cannabinoids showed no significant increase. The volatile compounds were successfully separated from the cannabinoids with fractionated separation. From hemp threshing residues essential oil free extracts with high content of cannabinoids were obtained at 35 MPa extraction pressure and 45 °C temperature setting the first separator at 8 MPa and 40 °C.

Chemical Composition and Amino Acid Content in Different Genotypes of Wheat Flour

Abstract: The purpose of this study was to evaluate the chemical parameters and amino acid content in 10 genotypes of soft Albanian wheat organically grown and collected during the summer seasons of 2014. The thin layer chromatography method was used for the identification the content of amino acids and spectrophotometry was used to determine the concentration of indentified amino acids. The results exhibited high protein content (13.73 % - 17.32 %) and relative high content of total amino acid content (6.3 % - 10.9 %). The most abundant of all amino acids was glutamic acid (in all genotypes) and cysteine (PZA 1, PZA 2, PZA 3, PZA 4, PZA 5, PZA 6, PZA 7, and PZA 10).

Rheology Based Design of Shear Thickening Fluid for Soft Body Armor Applications

Abstract: The ballistic resistance of high-strength fabrics improves upon impregnation with Shear Thickening Fluids (STFs). The performance of such STF treated fabrics depends on the rheological properties of the STF which in turn are governed by the physicochemical properties of the STF. The present study utilizes rheological characterization of shear thickening silica-polyethylene glycol dispersions (of different material configurations in terms of packing fraction, particle size and continuous phase viscosity) to assess their performance and obtain the best STF material configuration for ballistic body armor applications based on the design criteria proposed herein. The ballistic performance assessment results showed that the STFs with high packing fractions which thicken discontinuously, are highly effective compared to the continuously shear thickening fluids. Furthermore, the use of smaller particle size dispersed phase in the STF formulation was determined to be economical. Also, the use of lower molecular weight dispersion medium was suggested as it allows for a broader working temperature range of the STF. Additionally, the technological issues associated with the development and the practical application of STF-Armor were addressed.

Photocatalytically Active Amorphous and Crystalline TiO2 Prepared by Atomic Layer Deposition

Abstract: In this work, the photocatalytic properties of amorphous and crystalline TiO2 deposited on oxide and polymer nanoparticles by atomic layer deposition (ALD) were studied. Beside TiO2, as reference, both ALD grown amorphous Al2O3 and crystalline ZnO layers were also examined. When choosing the carrier, the priority was that it had no effect on the photocatalytic activity of TiO2; therefore the oxide layers were deposited on SiO2 and poly(methyl-methacrylate) (PMMA) nanoparticles. The amorphous SiO2 particles were synthetized by the Stöber method, while the PMMA particles were prepared by emulsion polymerization. Both the bare and core/shell composite nanoparticles were investigated by SEM-EDX, TEM, FT-IR, and XRD. Finally, the photocatalytic activity of PMMA, SiO2 and the core/shell nanoparticles was measured by the decomposition of methylene orange, monitored by UV-Vis spectroscopy. Based on the results, the SiO2 was uniformly coated with the deposited oxide films, while in the case of the PMMA a contiguous web-like polymer/TiO2 matrix was formed. During the photocatalytic reactions, the amorphous Al2O3 was not active, while the crystalline ZnO and TiO2 showed good photocatalytic activity. The amorphous TiO2 deposited by ALD on the SiO2 and PMMA nanoparticles had smaller, but a clearly detectable photocatalytic effect on the photodegradation of methylene orange.

Processing Efficiency, Simulation and Enzyme Activities Analysis of an Air-Lift Multilevel Circulation Membrane Bioreactor (AMCMBR) on Marine Domestic Sewage Treatment

Abstract: The implementation of latest International Maritime Organization emission standard raised stringent requirements for marine domestic sewage discharge. In this study, an air-lift multilevel circulation membrane reactor (AMCMBR) was operated to analyze effects of various ecological factors on effluent of marine domestic sewage. Back-propagation (BP)-Artificial Neural Network (ANN) was used to simulate effect of each ecological factor on reactor performance. The activities of four enzymes were investigated to reveal microbial activities in reactor. Experimental results indicates that the Hydraulic Retention Time (HRT), Mixed Liquid Suspended Solids (MLSS) and pH value cannot be less than 4 h, 3000 mg/L and 6, respectively to meet the IMO emission standard for effluent COD. A small value of mean square error (0.00147) indicated that BP-ANN can well describe the relationship between operation parameters (influent COD, HRT, MLSS, and pH) and effluent COD. The order of relative importance was pH ≈ MLSS > HRT > influent COD. Polyphenol oxidase and urease can serve as indicating factors for reactor performance, whereas dehydrogenase and nitrate reductase showed less susceptible towards varied influent COD and MLSS.

The utilization of struvite produced from human urine in agriculture as a natural fertilizer : a review

Abstract: Most of the nutrients in municipal wastewater originate from urine. Nevertheless, chemical fertilizers are commonly used in the agriculture instead of urine. There are some problems related to the direct utilization of urine, such as micropollutants present in urine, odour and storage of large volume of urine. In wastewater, phosphorus may contribute significantly to the pollution of the aquatic systems. Therefore, wastewater treatment techniques are mainly focusing on removing phosphorus. Phosphorus is collected in the sludge either by a chemical or by a biological process. With the growing concern of micropollutants present, which are in the sludge, the use of sludge in agriculture has been gradually decreasing. It means that the phosphorus content in sludge is not recycled efficiently whereas the use of limited mineral phosphorus resources is growing. To overcome these issues, urine could be collected separately and struvite could be produced. This may recover about 90 % of phosphate in urine. In this paper, the use of human urine and struvite as a fertilizer in the agriculture and the production of struvite is discussed. Results showed that the struvite could be an effective natural fertilizer.

Development of Polypropylene-based Thermoplastic Elastomers with Crumb Rubber by Dynamic Vulcanization: A Potential Route for Rubber Recycling

Abstract: In our current paper the preparation and properties of thermoplastic elastomer produced by dynamic vulcanization is presented and discussed. We dynamically vulcanized natural and styrene butadiene rubber (NR/SBR) phase by continuous extrusion. Dispersion and in-situ vulcanization of the rubber phase occurred simultaneously in a co-rotating twin screw extruder. We used a random polypropylene copolymer (rPP) as the thermoplastic matrix and untreated crumb rubber (CR) to partially substitute the neat fresh rubber in order to check whether this is a potential recycling route for waste rubber products. We studied the effect of various rubber formulations, various processing conditions (screw speed and configuration) and various CR particle size distributions by characterizing the mechanical performance of the thermoplastic dynamic vulcanizates (TDVs) with tensile and hardness tests and their morphology by evaluating SEM micrographs taken from the fracture surfaces of the tensile specimens. The results showed that increasing screw speed and more high-shear elements in the screw setup led to a finer dispersion of the rubber phase, resulting in improved mechanical properties. The ultimate tensile properties of the best TDVs reached 20.5 MPa in tensile strength and 550 % in strain at break. However, partial replacement of the fresh rubber with untreated CR caused a significant deterioration in mechanical properties, due to poor adhesion between the CR particles and the matrix and rubber. This suggests that some kind of pre-treatment (e.g. by microwave or other devulcanization techniques) is necessary to enhance the surface activity of the CR particles.

Changes in total polyphenol content and antioxidant capacity of stinging nettle (Urtica dioica L.) from spring to autumn

Abstract: Total polyphenol content and antioxidant/reducing capacity of stinging nettle (Urtica dioica L.) leaves and roots collected from wild-grown plants were investigated during the vegetation period. From both fresh and dried samples of leaves and roots, water extracts were prepared by brewing at 60, 80 and 100 °C for 3 hours, and ethanolic extracts of 20 % (v/v) and 70 % (v/v) by extracting at room temperature for 72 hours. The total polyphenol content was determined spectrophotometrically with Folin-Cioceltau reagent and the antioxidant capacity was measured by ferric reducing ability of plasma (FRAP) assay. Our results showed that the optimal harvest time is in the spring (April). Water extracts had the highest total polyphenol content and antioxidant capacity in this period. The amount of valuable compounds released increased by higher extraction temperature in both plant parts. In water extracts of nettle leaves, two times higher polyphenol content was obtained than in that of roots. Both kind of ethanolic extractions resulted in a higher polyphenol content in the leaves harvested in the spring period. For the roots, it was higher for samples collected in the autumn, which is also reflected in the values of antioxidant capacity. Water extracts of fresh leaves harvested in April had more than twice higher total polyphenol content than in October. For dried samples, raising the temperature did not cause a significant change in the total polyphenol content, however, it has resulted in increased antioxidant capacity both for the dried leaf and root samples.

Anomalous Properties of Some Fluids − with High Relevance in Energy Engineering − in Their Pseudo-critical (Widom) Region

Abstract: Recent results are shown about the peculiarities of the pseudo-critical region, with special emphasis on properties important for energy production and conversion. The property-map of some materials, which are relevant as model fluids or as working / cooling fluids in energy engineering (argon, methane, water and carbon dioxide) and their relative positions to various adiabats – influencing their stability through the anomalous properties – are presented. Some potential technological problems related to the existence of these anomalies are discussed.

Process Intensification by Using a Helical Capillary Microreactor for a Continuous Flow Synthesis of Peroxypropionic Acid and Its Kinetic Study

Abstract: Peroxypropionic acid (PPA) is an important organic chemical compound. Due to its versatile oxidizing properties, it is used in the oil, chemical and other industries. In this article, an attempt was made for the production of PPA in a Teflon helical capillary microreactor without and with homogeneous catalyst. The article reports the perhydrolysis of PPA with the effect of various parameters such as concentration of hydrogen peroxide, molar ratio of reactants, radius of curvature of the microreactor, concentration of catalyst and temperature. The reaction is slow, as the PPA equilibrium was found to be reached within 10 min at a temperature of 50 °C and at 10 mol % catalyst loading based on propionic acid. The reaction was carried out in 13.25 and 23.25 mm radius of curvature of the microreactor in which 4.0375 and 3.488 mol/L concentrations of PPA respectively were obtained at 50 ºC and 10 mol % catalyst. It indicates that as radius of curvature decreases, better mixing was provided among the reactants for the reaction to give enhanced yield and selectivity. From the experimental data and the kinetic expressions, the expressions of activation energies and reaction rate constants were determined. For PPA synthesis and hydrolysis, the activation energies were 43.897 and 20.658 kJ/mol respectively without catalyst, while the activation energies for both the cases were 42.314 and 17.514 kJ/mol respectively with catalyst of 10 mol% based on propionic acid. The dean number, curve tube friction factor and pressure drop also determined for the helical capillary microreactor.

Phenol Removal by Novel Choline Chloride Blended Cellulose Acetate-Fly Ash Composite Membrane

Abstract: A novel composite membrane (CM) was prepared by coating choline chloride (ChCl) blended cellulose acetate (CA) on fly-ash based ceramic substrate for phenol removal. Different amount (0-1 g) of ChCl was blended with CA to synthesize various CMs. Amount of ChCl in CA increases the contact angle, average pore radius, permeability of CM from 55.15° to 71.55°, 1.6 to 6.83 nm and 0.0057 to 0.0152 L·m−2·h−1·kPa−1, respectively. Phenol rejection increased from 56 to 93 % while increasing ChCl amount in CA. Phenol removal decreased from 94.26-64.23 % and 91.09-78.62 % with increase in applied pressure (69-483 kPa) and feed concentration (50-200 mg·L−1). However, removal rate increased from 80.46-92.47 % with increase in pH 2-12. Among all CMs, CC5 is identified as best CM with maximum phenol removal efficiency (92.7 %) and flux (1.86 L·m−2·h−1) at 207 kPa applied pressure and 100 mg·L−1 of feed phenol concentration. The obtained results reveal that blending of 0.9 % ChCl with CA can significantly enhances the phenol removal efficiency and this could be used as potential CM for treatment of phenol bearing wastewater.

A New Correlation Method for Estimating Thermal Conductivity of Carbon Dioxide in Liquid, Vapor and Supercritical Phases

Abstract: In this study, a new correlation for estimating thermal conductivity (TC) of carbon dioxide was developed based on 2319 data points. The data points were at the temperature ranging from 250 to 1100 K, pressure ranging from 1 to 3000 bar and density ranging from 0.3 to 1400 Kg.m-3 in different phases of liquid, vapor and supercritical. The statistical parameters including average absolute deviation (AAD%), average percent relative error (ARE%), sum of absolute residual (SAR) and the coefficient of determination (R2) have been calculated to evaluate the accuracy of present correlation. The obtained values of AAD%, ARE%, SAR and R2 were 1.98, −0.64, 3510.1 and 0.995, respectively. The predictions of proposed correlation were also compared with three widely used correlations. The results showed that the proposed correlation is able to accurately calculate thermal conductivity of carbon dioxide. In addition, the proposed model is superior to all the existing empirical models considered.

The influence of osmotic dehydration in polyols solutions on sugar profiles and color changes of apple tissue

Abstract: The following study aims to evaluate the changes in profile of selected sugars and content of polyols in the apple tissue after osmotic dehydration. What makes this research innovative is the use, in the osmotic pre-treatment, of solutions which have hitherto not been commonly used in fruit processing by researchers worldwide. Selected substances from the polyols group (erythritol, xylitol, and maltitol) were used as osmotic agents in 30 % concentrated solutions. The ideal osmotic pressure, as well as efficiency of the process, was calculated, and these parameters were the highest in the case of erythritol. It was confirmed that type of osmotic solution and time of the process have significant influence on discussed parameters. Osmotic dehydration in polyols solutions resulted in increasing the content of these compounds during the process and minor changes in sugars profile of apple tissue. Color changes caused by pre-treatment were small, but still they could be noticed by an inexperienced observer.

Bio-oil and Fuel Gas Production from Agricultural Waste via Pyrolysis: A Comparative Study of Oil Palm Empty Fruit Bunches (OPEFB) and Rice Husk

Abstract: Biomass-based energy from agricultural wastes is a promising alternative energy source since its abundant supply and renewable. Biomass is converted into gas and liquid fuel through biochemical or thermochemical treatments. In this work, oil palm empty fruit bunches (OPEFB) and rice husk are pyrolyzed to produce gas and liquid fuel. The reactor temperature and feed mass are varied to obtain the best operating condition in a semi-batch pyrolysis reactor. The experimental results showed that the best operating temperature in pyrolysis process to produce bio-oils from OPEFB and rice husk was at 500 °C with 4.3 % (w/w) and 2.6 % (w/w) of bio-oil yields, respectively. The pyrolysis product distribution and their chemical composition are strongly affected by operating condition and the types of biomass. The GC-MS analysis results showed that the primary pyrolysis products components consist of hydrocarbons and oxygenated compounds such as carboxylic acids, phenols, ketones and aldehydes. Thermodynamic properties such as thermal conductivity of the biomass also influenced the product distribution of the biomass pyrolysis.

Enhancing Gasoline Range Hydrocarbons by Catalytic Co-pyrolysis of Rice Husk with Low Density Polyethylene (LDPE) Using Zeolite Socony Mobil#5(ZSM-5)

Abstract: In the present work, catalytic co-pyrolysis of rice husk with low density polyethylene (LDPE) was investigated to enhance the amount of gasoline range hydrocarbons in the bio-oil. Zeolite Socony Mobil#5(ZSM-5) was used as catalyst. The specific surface area, pore volume and the average pore size of ZSM-5 were evaluated to be 418.041 m2/g, 0.227 cc/g and 1.628 nm respectively. Optimum temperature for obtaining highest bio-oil yield for non-catalytic co-pyrolysis was 600 °C, resulting in yield of 51.26 %. For catalytic co-pyrolysis, the optimum temperature was 500 °C with a bio-oil yield of 38.87 %. H/C ratio of gasoline range hydrocarbon oil obtained by catalytic co-pyrolysis was 1.21, while the oxygen content was 2.51 %.The results of GC HRMS revealed that, the gasoline range hydrocarbon oil obtained by catalytic co-pyrolysis contained 17.65 % Cycloalkanes, 6.131 % alcohols, 31.75 % esters and 32.68 % alkenes.

Kinetic Model of Crude Palm Oil Hydrocracking Over Ni/Mo ZrO2–Pillared Bentonite Catalyst

Abstract: Crude Palm Oil hydrocrcaking has been carried out over Ni/Mo ZrO2–pillared bentonite catalyst in a fixed bed reactor. Crude Palm Oil hydrocracking over Ni/Mo ZrO2–pillared bentonite catalyst formed 3 products i.e. gas, oil and coke. The oil product from Crude Palm Oil hydrocracking was analyzed by using gas chromatography to determine its composition. Three types of fraction were classified i.e. gasoline, kerosene and diesel oil. In this research, the focused of the study is of hydrocracking kinetics by using lump kinetic models. The kinetic model was solved by using the software MATLAB R2018b involves the effect of catalyst activity on the reaction rate. The results of the kinetic study show that the 4-lump (Crude Palm Oil, gas coke and oil) and 6-lump reaction models (Crude Palm Oil, gas, coke, gasoline, kerosene and diesel) can be used to explain the Crude Palm Oil hydrocracking over Ni/Mo ZrO2–pillared bentonite catalyst. The 4-lump kinetic model has 5 rate constants and the 6-lump kinetic model has 14 rate constants.

Biodegradation of 2,4,6-Trinitrotoluene (TNT) with Bacteria Isolated from TNT-polluted Waste Pink Water

Abstract: In this study, bacterial strains that can use TNT as a nitrogen source isolated from TNT contaminated pink water. We isolated 5 bacterial strains and the isolated bacteria were cultured in medium containing TNT and TNT degradation capacities of isolates were determined by spectrophotometric analysis. According to the results of the analysis that have done, 3 bacterial isolates that have high TNT degradation capacity were selected and the isolates were identified with firstly Gram-staining then with 16S rRNA sequence analysis method. According to the sequence of 16S rRNA, water isolates were identified as Stenotrophomonas maltophilia (SU K2), Klebsiella pneumoniae (SU K3), Raoultella planticola (SU K4). During the TNT degradation studies, at the end of 24 h incubation time, in the medium containing 100 mg/L TNT, TNT degradation rate for SU K2, SU K3 and SU K4 were determined 70 %, 96 % and 93 % respectively. 4-aminodinitrotoluene and 2-aminodinitrotoluene accumulations were detected in the culture medium of all isolates as intermediate products formed during the degradation of TNT by HPLC analysis. Additionally, nitrite accumulation was detected in the culture medium of all isolates and the influence of temperature and pH on the degradation of TNT was also investigated. It was determined that SU K2 isolates have the highest TNT degradation capacity at 35 °C, the others have at 30 °C and all isolates degraded TNT fastest at pH 7. The results of the study show that the new isolates can be useful for the removal of TNT in a wastewater treatment system.

Mathematical Modeling of Nutrient Release from Capsulated Fertilizers

Abstract: The article is devoted to the study of reducing the technogenic load from high-dose nitrogen pollution of the soil layer by encapsulating granules of nitrogen fertilizers in slowly soluble phosphate-containing membranes. The process of dissolving and washing out of the primordial soil layer of the nutrients from urea, encapsulated by superphosphate shells in soil columns, was studied according to agrochemical techniques. The purpose of the work is to determine the parameters of the investigated process, based on which the previously developed physical model of soil washing of moving nitrogen forms, based on experimental data. The process of changing the loss of nitrogen from the soil when using different types of fertilizers depending on the amount of washing was studied by simulation. Mathematically, the process is described in general terms as a linear differential equation of the first order in partial derivatives. The solution of the equation under the initial and boundary conditions allowed to calculate the parameters of the model describing the nature of changes in the losses of nitrogen from the soil column. Comparison of calculated and experimental data showed a coincidence of values with a correlation coefficient above 0.96 for investigated nitrogen fertilizers with different composition of the phosphate-containing coating.

Purification, Characterization and De-Staining Potentials of a Thermotolerant Protease Produced by Fusarium oxysporum

Abstract: Proteases are important industrial enzymes and fungi prove to be good sources of such enzymes. Purification techniques are however necessary for increased specificity in activity and better industrial value. Based on this, a protease produced by a Fusarium oxysporum was purified to homogeneity by Sephadex G-200 column and α–casein agarose chromatography. The enzyme had a molecular weight of 70 kDa in SDS-PAGE. Purified Fusarium oxysporum protease had a specific activity of 93.88 U/mg protein. The purification magnitude was 7.7 and the total yield was 20 %. Purified protease had an optimum pH of 5.0 while the optimum temperature was 40 °C. The enzyme was also thermotolerant (approximately 100 % at 40 °C for 2 h). The enzyme activity was stimulated by surfactants and metal ions like, Tween-20 and Mg2+. Enzyme activity was inhibited in presence of PMSF and EDTA. Casein was found to be the best substrate for protease activity of Fusarium oxysporum FWT1. Protease were tested upon blood stain for de-clotting of blood and was found to exhibit good de-clotting and de-staining activity after 15 minutes treatment time.

Effect of Convective Drying Method of Chokeberry (Aronia melanocarpa L.) on Drying Kinetics, Bioactive Components and Sensory Characteristics of Bread with Chokeberry Powder

Abstract: The effects of three dehydration temperatures at 50, 60 and 70 °C of convective drying method on fresh fruits of black chokeberries (Aronia melanocarpa L.) were evaluated. The drying temperatures were found to have significantly different effects on the characteristics of dried fruits and powders, made by the dried fruits. The maximum drying rate at a temperature of 50 °C was 59 g/h, at 60 °C 102 g/h, and at 70 °C 115 g/h, and thus the drying time was 37 hours, 27 hours and 23 hours respectively. The drying temperature at 50 °C caused the least damage to the cell structure of the fresh chokeberries, bioactive components (anthocyanins, flavonoids, phenols) and total antioxidativity. The dehydrated chokeberries at the temperature of 50 °C had the highest ratio of total anthocyanins (376.89 ± 5.73 mg cyn-3-glu / 100 g dm), total flavonoids (1037.19 ± 3.83 mg CE / 100 g dm), phenols (1918.79 ± 3.26 mg GAE / 100 g dm) and antioxidant activity (37.11 ± 0.28 mg TE / 100 g dm). The drying process at a temperature of 50 °C required longer drying period, higher energy need and produced the chokeberry powder, which gave the bread with the best sensory characteristics, compared to a drying process at a temperature of 60 °C and 70 °C.

Predicting the Temperature and Composition – Dependent Density and Viscosity of Diesel Fuel – Ethanol Blends

Abstract: Density and viscosity are very important fuel properties which have a major influence not only on the fuel production, transportation and distribution processes but also on the processes that take place in an internal combustion engine. Developing robust and high precision density and viscosity models for stabilized diesel fuel – ethanol blends helps the production of fuel to adhere to the quality requirements regarding density and viscosity and the modeling and simulation of injection and combustion processes. For modeling the density and the viscosity of diesel fuel – ethanol blends, five mixtures were prepared with ethanol content up to 15 % (v/v) and were stabilized by adding tetrahydrofuran as a surfactant at room temperature. The temperature-dependent density and viscosity of the blends were measured at four different temperatures (0, 15, 40 and 50 °C) using an SVM 3000 type apparatus. Based on experimental data, several mixing rules were fitted to them and three new models were developed, of which two need only one experimental value. These models yield very good accuracies, presenting average relative deviations of 0.0604 % in the case of density and 3.8931 % in the case of viscosity.

Bisepoxide-activated Hollow Silica Microspheres for Covalent Immobilization of Lipase from Burkholderia cepacia

Abstract: An efficient and easy-to-perform method was developed for covalent immobilization of lipase from Burkholderia cepacia (Lipase PS) on hollow silica microspheres (M540) by bisepoxide activation. For immobilization, various bisepoxides of different length, rigidity and hydrophobicity in their linkers were applied to activate the amino groups on the M540 support. Effect of the individual bisepoxides on the catalytic performance of the immobilized Lipase PS was studied by using lipase-catalyzed kinetic resolution (KR) of racemic 1-phenylethanol (rac-1) with vinyl acetate in batch mode. Catalytic activity, enantiomer selectivity, recyclability and thermal stability of the new immobilized Lipase PS biocatalysts were investigated. The optimal enzyme / support ratio with the support activated by the most efficient bisepoxide, i.e. poly(ethylene glycol) diglycidyl ether (PDE), was 1:5. The most efficient Lipase PS on PDE activated M540 showed an almost five fold higher biocatalytic activity value (rbatch = 42.8 U/g) with enhanced selectivity (ee(R)-2 = 99.1 %) to the free form of Lipase PS (rbatch = 9.0 U/g; ee(R)-2 = 98.9 %). The Lipase PS on PDE-M540 was compared to a commercially available immobilized Lipase PS biocatalyst (Lipobond Lipase PS) and also applied in a packed-bed enzyme reactor operated in continuous-flow mode, where the optimal temperature of M540-PDE-PS reached the 70 °C, while the optimum for Lipobond Lipase PS was 50 °C.

Immobilizing Ni (II)-Exchanged Heteropolyacids on Silica as Catalysts for Acid-Catalyzed Esterification Reactions

Abstract: Biodiesel was synthesized from oleic acid using Ni (II)-exchanged heteropolyacids immobilized on silica ( Ni0.5H3SiW / SiO2 ) as a solid acid catalyst. Based on detailed analyses of FT-IR, XRD, TG and SEM, the structural, surface and thermal stability of Ni0.5H3SiW / SiO2 were investigated. Obtained results demonstrated that the Keggin structure was well in the immobilization process and possess a high thermal stability. Various esterification reaction conditions and reusability of catalyst were studied. High oleic acid conversion of 81.4 % was observed at a 1:22 mole ratio (oleic acid: methanol), 3 wt. % catalyst at 70 °C for 4 h. The Ni0.5H3SiW / SiO2 catalyst was reused for several times and presented relatively stable. More interestingly, the kinetic studies revealed the esterification process was compatible with the first order model, and a lower activation energy was obtained in this catalytic system.

Study of Different Printing Design Type Polymer Samples Prepared by Additive Manufacturing

Abstract: 3D printing is one of the most progressive additive technologies today. It finds its application also in industry. In terms of mechanical properties, the printing design of the product is an important parameter. The presented study investigates the effects of the printing design of a thin-walled 3D polymer model on the mechanical properties of the model. The material used for printing was acrylonitrile-butadiene-styrene (ABS) and the 3D print method was Fused Deposition Modeling (FDM). ABS was tested at various die temperatures and with various printing designs at a constant 3D print speed and identical print bed temperature. We examined the effect of printing temperature and product printing design on the resulting mechanical properties. We compared theoretical and experimental results by CAE–FEM Advanced Simulation modules. Results tensile deformations at maximum load by experiment and simulations are comparable. The best results of testing the mechanical properties were found in the pattern printed at a 45° angle at temperature 285 °C.

Fabrication and Characterization of Nano Hybrid Cellulose Acetate-nanoTiO2/crosslinked Polyvinyl Alcohol Coated Membrane for Crude Clove Oil Purification

Abstract: The application of membranes for clove oil purification has the potential to improve the efficiency and effectiveness of processing. The main problem that occurs is the polymer-based membranes tend to change in properties such as weakening, dissolving, and swelling when contact with clove oil. In this study, cellulose acetate membrane was developed with TiO2 nano-particles to reduce swelling effect and coating with polyvinyl alcohol (PVA) to modify membrane surface. The membranes were prepared using dry-wet phase inversion method from dope solution with polymer concentration of 14–20 wt% and nano-particles of TiO2 with a concentration of 0–1.5 wt% in total solid. The formed membrane was coated with PVA with a concentration of 2–5 wt% crosslinked using glutaraldehyde. The SEM results show that prepared membrane are asymmetric membranes and show the coated layer of PVA on the surface. The FTIR spectra confirm that the PVA is successfully crosslinked and the addition of nano-particles TiO2 decreases the membrane swelling degree, significantly. In the addition of 0.5 wt% of nano-TiO2 can increase the flux from 0.54 to 0.66 L × m−2 × h−1 × bar−1. The coated membrane surface using PVA increases the selectivity of the membrane to produce clove oil permeates with eugenol content of 82.5 % from 68 %.