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Journal Details
Format
Journal
eISSN
1899-4741
First Published
03 Jul 2007
Publication timeframe
4 times per year
Languages
English

Search

Volume 19 (2017): Issue 4 (December 2017)

Journal Details
Format
Journal
eISSN
1899-4741
First Published
03 Jul 2007
Publication timeframe
4 times per year
Languages
English

Search

20 Articles
Open Access

Change in dust collection efficiency of liquid collectors in conditions of dedusting liquid recirculation

Published Online: 29 Dec 2017
Page range: 1 - 7

Abstract

Abstract

The high efficiency of industrial wet scrubbers is the result of a simultaneous formation of dust particle collectors. Collectors can be understood as droplets of atomised liquid, bubbles formed in the conditions of intensive barbotage, liquid surface and wet surfaces. All collectors are formed during the operation of a circulating unit. The efficiency of dust collection process also depends on the ability of dust particles to be absorbed by collectors. The study provides an experimental analysis of the effect of the increasing concentration of a dust collection liquid in the conditions of full liquid recirculation on the efficiency of dust collection process in the examined types of collectors.

Keywords

  • dust collectors
  • dust removal efficiency
  • wet scrubbers
Open Access

Simulation of SOFCs based power generation system using Aspen

Published Online: 29 Dec 2017
Page range: 8 - 15

Abstract

Abstract

This study presents a thermodynamic Aspen simulation model for Solid Oxide Fuel Cells, SOFCs, based power generation system. In the first step, a steady-state SOFCs system model was developed. The model includes the electrochemistry and the diffusion phenomena. The electrochemical model gives good agreement with experimental data in a wide operating range. Then, a parametric study has been conducted to estimate effects of the oxygen to carbon ratio, O/C, on reformer temperature, fuel cell temperature, fuel utilization, overall fuel cell performance, and the results are discussed in this paper. In the second step, a dynamic analysis of SOFCs characteristic has been developed. The aim of dynamic modelling was to find the response of the system against the fuel utilization and the O/C ratio variations. From the simulations, it was concluded that both developed models in the steady and dynamic state were reasonably accurate and can be used for system level optimization studies of the SOFC based power generation system.

Keywords

  • Solid Oxide Fuel Cell system
  • modelling
  • methane
  • reforming
  • CPO
Open Access

Flow behavior in weakly permeable micro-tube with varying viscosity near the wall

Published Online: 29 Dec 2017
Page range: 16 - 21

Abstract

Abstract

Weakly permeable micro-tubes are employed in many applications involving heat and/or mass transfer. During these processes, either solute concentration builds up (mass transfer) or steep change in temperature (heat transfer) takes place near the permeable wall causing a change in the viscosity of the fluid. Results of the present work suggest that such change in viscosity leads to a considerable alteration in the flow behavior, and the commonly assumed parabolic velocity profile no longer exists. To solve the problem numerically, the equation of motion was simplified to represent permeation of incompressible, Newtonian fluid with changing viscosity through a micro-tube. Even after considerable simplification, the accuracy of the results was the same as that obtained by previously reported results for some specific cases using rigorous formulation. The algorithm developed in the present work is found to be numerically robust and simple so that it can be easily integrated with other simulations.

Keywords

  • hollow-fiber
  • micro-tube
  • permeation
  • algorithm
  • variable viscosity
  • velocity profile
  • equation of motion
  • navier-stokes equation
Open Access

Galvanic coupling effects for module-mounting elements of ground-mounted photovoltaic power station

Published Online: 29 Dec 2017
Page range: 22 - 27

Abstract

Abstract

This communication reports on the concerns associated with possible generation of galvanic coupling effects for construction materials that are used to manufacture mounting assemblies for ground-mounted photovoltaic (PV) power stations. For this purpose, six macro-corrosion galvanic cells were assembled, including: hot-dip Zn/Magnelis®-coated steel/Al and stainless steel (SS)/Al cells. Corrosion experiments involved continuous, ca. three-month exposure of these couplings in 3 wt.% NaCl solution, conducted at room temperature for a stable pH value of around 8. All corrosion cells were subjected to regular assessment of galvanic current-density and potential parameters, where special consideration was given to compare the corrosion behaviour of Zn-coated steel samples with that of Magnelis®-coated electrodes. Characterization of surface condition and elemental composition for examined materials was carried-out by means of SEM and EDX spectroscopy techniques.

Keywords

  • PV mounting assembly
  • Zn-coated steel
  • Magnelis® coating
  • galvanic coupling
Open Access

Biological screening and assessment of certain substituted monoazo heterocycles containing sulphur and / or nitrogen and their seleno like moieties

Published Online: 29 Dec 2017
Page range: 28 - 35

Abstract

Abstract

The monoazo substituted five membered heterocycles, along with their seleno like moieties are still of interest in organic chemistry due to their medicinal and valuable applications. In continuation of our interest in the study of heterocyclic azo compounds containing sulphur and / or nitrogen heteroatoms, the synthesis of 5-aryl mono azo-thiazol-2-ylcarbamoyl-thiophene along with their seleno like derivatives of pyridine, pyridazine and quinolone, were accomplished. All the synthesized compounds were in vitro screening of their antioxidant activity, antitumor activity against Ehrlich ascites carcinoma cell EACC cell line and antimicrobial activity against various pathogenic microorganisms, such as Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) and fungi strains of Aspergillus flavus and Candida albicans. The structural–activity relationship was studied based on the obtained data.

Keywords

  • thiophene
  • antioxidant activities
  • antitumor agents
  • pathogenic microorganisms
  • selenium
Open Access

Preparation of Ag nanoparticles-reinforced polyamide 6 nanocomposites by in situ polymerization and investigation of its properties

Published Online: 29 Dec 2017
Page range: 36 - 40

Abstract

Abstract

Polyamide 6 (noted as PA6)/Ag nanocomposites were prepared by an in situ solution polymerization method. AgNO3 was used as filler and was directly reduced to silver nanoparticles resulting in uniformly dispersed nanoparticles in the PA6 matrix. The thermal stability, crystallization, melting performance, and dispersion properties of the PA6/Ag nanocomposites were studied using transmission electron microscopy (TEM), thermogravimetric analysis (TG), differential thermal scanning calorimetry (DSC), X-ray diffraction (XRD), and polarized light microscopy (POM). Furthermore, the mechanical and tribological behaviors of as-prepared nanocomposites were evaluated using universal tensile testing, impact testing, and friction testing machines. The results show that Ag-nanoparticles are evenly dispersed in PA6 and decrease in size with increasing Ag content. Whereas the crystallinity increased with increasing Ag content, the crystallization temperature of the nanocomposites did not change significantly. However, the mechanical and tribological properties of the nanocomposites increased compared with pure PA6.

Keywords

  • solution polymerization
  • Ag nanomaterials
  • nanocomposites
  • crystallization properties
  • mechanical properties
Open Access

Preparation and properties of cellulose membranes with graphene oxide addition

Published Online: 29 Dec 2017
Page range: 41 - 49

Abstract

Abstract

The paper presents results of research on the preparation of cellulose membranes with graphite oxide addition (GO/CEL). Initially, a cellulose (CEL) solution in 1-ethyl-3-methylimidazole acetate (EMIMAc) was obtained, to which graphene oxide (GO) dispersed in N,N-dimethylformamide (DMF) was added. From this solution, composite membranes were formed using phase inversion method. It was observed that the GO addition influences the physico-chemical properties of GO/CEL composite membranes, resulting in an increase in their mass per unit area, thickness and density, and a decrease in sorption properties. In addition, the study of transport properties has shown that GO/CEL membranes do not absorb BSA particles on their surface, which prevents the unfavorable phenomenon of fouling. An important feature of the obtained membranes is the specific permeate flux which reaches high values (~124 L/m2×h) at 3.8% of the GO addition to the cellulose matrix.

Keywords

  • cellulose
  • ionic liquid
  • graphene oxide
  • membranes
  • transport properties
Open Access

Montmorillonite as the catalyst in oxidation of limonene with hydrogen peroxide and in isomerization of limonene

Published Online: 29 Dec 2017
Page range: 50 - 58

Abstract

Abstract

In our studies montmorillonite (MMT) was used as the heterogeneous, natural catalyst. This material was previously prepared by bentonite purification with help of the sedimentation method. The obtained catalyst was characterized by: XRD, SEM, BET and EDX. Catalytic tests with montmorillonite as the catalyst were performed with the natural terpene – R-(+)-limonene. This compound was oxidized with hydrogen peroxide and, moreover, in the separate process it was also isomerized. As the main products of limonene oxidation were detected: (1,2-8,9)-diepoxide, perillyl alcohol, carvone, carveol, 1,2-epoxylimonene and 1,2-epoxylimonene diol. In the isomerization of R-(+)-limonene were formed: terpinenes, terpinolene and p-cymene. Conversions of limonene in these processes reached 70–80%. The application of montmorillonite (the natural of origin) in the studied processes (oxidation and isomerization) is environmentally friendly, it allows to reduce the cost of the studied processes. The resulting products of the processes of oxidation and isomerization of R-(+)-limonene have many applications.

Keywords

  • montmorillonite
  • R-(+)-limonene
  • oxidation
  • isomerization
  • hydrogen peroxide
  • heterogeneous catalysis
Open Access

Adsorption of propan-1-ol vapour on Sorbonorit 4 activated carbon – equilibrium and dynamic studies

Published Online: 29 Dec 2017
Page range: 59 - 64

Abstract

Abstract

The study examined the adsorption of propan-1-ol (1PN) vapour on Sorbonorit 4 (S4) activated carbon in cyclic Electrothermal Temperature Swing Adsorption (ETSA) process. Dynamic adsorption capacity and breakthrough time were determined based on column studies. Thomas model was used to describe experimental breakthrough curves. Adsorption isotherms for 1PN vapour on S4 activated carbon were tested at 293 to 413 K. The experimental data were examined by using three multi-temperature isotherm models: Toth, Sips and hybrid Langmuir-Sips. Results indicate that S4 activated carbon is a heterogeneous adsorbent and the hybrid Langmuir-Sips model provides the best-fit experimental data. The energy requirement for 1PN electrothermal desorption from S4 bed (ca. 170–200 kJ/mol) was about 3 to 3.5 times larger than the isosteric heat of adsorption (56.8 kJ/mol), which was calculated using Toth adsorption isotherm.

Keywords

  • activated carbon
  • propan-1-ol
  • multi-temperature isotherms
  • electrothermal desorption
  • breakthrough curve
Open Access

Removal of Rhodamine B from aqueous solution by ZnFe2O4 nanocomposite with magnetic separation performance

Published Online: 29 Dec 2017
Page range: 65 - 74

Abstract

Abstract

Magnetic ZnFe2O4 nanocomposite (ZnFe-NC) was used as an adsorbent for the removal of Rhodamine B (RB) from aqueous solution. The synthesized nanocomposite was characterized by XRD, SEM, HRTEM, BET and FTIR. The effects of various parameters such as initial RB concentration (5–25 mg L−1), pH (3.4–11.1) and temperature (20–60°C) were investigated. The adsorption capacity at equilibrium increased from 5.02 to 9.83 mg g−1, with the increase in the initial concentration of RB from 5 to 25 mg L−1 at pH 7.0 and at 20°C. The experimental results indicated that the maximum RB removal could be attained at a solution pH of 4.4 and the adsorption capacity obtained was 6.02 mg g−1. Kinetic adsorption data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order model and the intraparticle diffusion model. The adsorption kinetics well fitted using a pseudo-second-order kinetic model. The experimental isotherm data were analyzed using two isotherm models, namely, Langmuir and Freundlich. The results revealed that the adsorption behavior of the RB onto ZnFe-NC fitted well with the Langmuir isotherm model. In addition, various thermodynamic parameters, such as standard Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) have been calculated.

Keywords

  • adsorption
  • Rhodamine B
  • ZnFeO
  • kinetics
  • thermodynamics
Open Access

Ionic [Ru] complex with recyclability by electro-adsorption for efficient catalytic transfer hydrogenation of aryl ketones

Published Online: 29 Dec 2017
Page range: 75 - 79

Abstract

Abstract

The efficient reuse of homogeneous catalyst is important. Cation complex of [Ru(η6-p-cymene)(PPh3)(CH3CN) Cl]PF6 with different ligands was synthesized and characterized by infrared spectroscopy (IR), 1H-, 13C- and 31P-nuclear magnetic resonance spectroscopy (1H-, 13C- and 31P-NMR), element analysis (EA), and high resolution mass spectrometry (HR-MS). The complex was used as a catalyst for the hydrogen transfer reduction of carbonyl for the first time, presenting an excellent catalytic performance of 89%–98% conversion of acetophenone and its derivatives. The catalyst may be efficiently reused by the electro-adsorption of 10 times to one catalyst recovery. The cation [Ru] complex presented advantages of both homogeneous and heterogeneous catalysts.

Keywords

  • ionic Ru complex
  • transfer hydrogenation
  • electron-adsorption
  • catalyst recovery
Open Access

The research of anti corrosive properties of various compositions on samples of standard metals

Published Online: 29 Dec 2017
Page range: 80 - 86

Abstract

Abstract

In this proceeding. the compositions of the T-30 turbine oil with liquid rubber. Co. Ni. Zn. Mg and Ba salts of the natural petroleum acids (NPA) boiling in the range 220–340°C and nitro compounds which are produced on the basis of C14H28 α-olefins have been investigated in different ratio and contents as metalworking fluids (MWF). The physical and chemical properties of the produced compositions have been studied. and the morphology of inhibited carbon steel surface was analyzed and characterized by using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) techniques. The effect of the temperature on the inhibition efficiency and thermodynamic parameters have also been reported. The thermal analyzer was used for the thermogravimetric analysis (TG/DTA) of the prepared MWF. The experiments have been operated with different concentrations of the inhibitor on the steel plates in condensation and environment phases in the experiment chamber.

Keywords

  • metalworking fluids and lubricants
  • corrosion
  • liquid rubber
  • natural petroleum acids
Open Access

Effect of textural and chemical characteristics of activated carbons on phenol adsorption in aqueous solutions

Published Online: 29 Dec 2017
Page range: 87 - 93

Abstract

Abstract

The effect of textural and chemical properties such as: surface area, pore volume and chemical groups content of the granular activated carbon and monoliths on phenol adsorption in aqueous solutions was studied. Granular activated carbon and monolith samples were produced by chemical activation. They were characterized by using N2 adsorption at 77 K, CO2 adsorption at 273 K, Boehm Titrations and immersion calorimetry in phenol solutions. Microporous materials with different pore size distribution, surface area between 516 and 1685 m2 g−1 and pore volumes between 0.24 and 0.58 cm3 g−1 were obtained. Phenol adsorption capacity of the activated carbon materials increased with increasing BET surface area and pore volume, and is favored by their surface functional groups that act as electron donors. Phenol adsorption capacities are in ranged between 73.5 and 389.4 mg · g−1.

Keywords

  • activated carbon monoliths
  • phenol adsorption
  • textural and chemical characteristics
  • immersion calorimetry
Open Access

Purification of the gas after pyrolysis in coupled plasma-catalytic system

Published Online: 29 Dec 2017
Page range: 94 - 98

Abstract

Abstract

Gliding discharge and coupled plasma-catalytic system were used for toluene conversion in a gas composition such as the one obtained during pyrolysis of biomass. The chosen catalyst was G-0117, which is an industrial catalyst for methane conversion manufactured by INS Pulawy (Poland). The effects of discharge power, initial concentration of toluene, gas flow rate and the presence of the bed of the G-0117 catalyst on the conversion of C7H8, a model tars compounds were investigated. Conversion of coluene increases with discharge power and the highest one was noted in the coupled plasma-catalytic system. It was higher than that in the homogeneous system of gliding discharge. When applying a reactor with reduced G-0117 and CO (0.15 mol%), CO2 (0.15 mol%), H2 (0.30 mol%), N2 (0.40 mol%), 4000 ppm of toluene and gas flow rate of 1.5 Nm3/h, the conversion of toluene was higher than 99%. In the coupled plasma-catalytic system with G-0117 methanation of carbon oxides was observed.

Keywords

  • gliding discharge
  • non-equilibrium plasma
  • plasma-catalytic system
  • tar decompositio
Open Access

Analysis of tank safety with propane-butane on LPG distribution station

Published Online: 29 Dec 2017
Page range: 99 - 102

Abstract

Abstract

An analysis of the risk of failure in the safety valve – tank with propane-butane (LPG) system has been conducted. An uncontrolled outflow of liquid LPG, caused by a failure of the above mentioned system has been considered as a threat. The main research goal of the study is the hazardous analysis of propane-butane gas outflow for the safety valve – LPG tank system. The additional goal is the development of an useful method to fast identify the hazard of a mismatched safety valve. The results of the research analysis have confirmed that safety valves are basic protection of the installation (tank) against failures that can lead to loss of life, material damage and further undesired costs of their unreliability. That is why a new, professional computer program has been created that allows for the selection of safety valves or for the verification of a safety valve selection in installations where any technical or technological changes have been made.

Keywords

  • safety valve
  • risk analysis
  • emergency scenarios
  • LPG
Open Access

Conditions of synthesis and structure of metakaolin-based geopolymers: application as heavy metal cation sorbent

Published Online: 29 Dec 2017
Page range: 103 - 109

Abstract

Abstract

This study presents the synthesis of geopolymer materials designed for application as self-supporting zeolite membranes. For this purpose, batches of metakaolin activated with sodium silicate and sodium hydroxide were used. During synthesis, it was assumed that low temperatures are sufficient to receive the membranes. The composition of raw materials and temperature of activation were selected in such a way so as to correspond to the basic chemical compositions and synthesis conditions of sodalite as well as zeolites A and X. Additionally, the structural and textural properties of geopolymers were determined. The results show that it is possible to obtain composite zeolite structures in an amorphous matrix. A number of synthesized materials were used in the sorption of selected heavy metal cations (Ni2+, Zn2+, Pb2+ and Cd2+). It was concluded that the investigated geopolymerization process may be applied to obtain a material with potential use as a heavy metal sorbent.

Keywords

  • metakaolin
  • geopolymers
  • structural and textural properties
  • heavy metal sorbent
Open Access

Antibacterial activity of iron oxide nanoparticles synthesized by co-precipitation technology against Bacillus cereus and Klebsiella pneumoniae

Published Online: 29 Dec 2017
Page range: 110 - 115

Abstract

Abstract

The present study investigates the synthesis and characterization of iron oxide nanoparticles (Fe3O4-NPs) for their antibacterial potential against Bacillus cereus and Klebsiella pneumonia by modified disc diffusion and broth agar dilution methods. DLS and XRD results revealed the average size of synthesized Fe3O4-NPs as 24 nm while XPS measurement exhibited the spin-orbit peak of Fe 2p3/2 binding energy at 511 eV. Fe3O4-NPs inhibited the growth of K. pneumoniae and B. cereus in both liquid and soild agar media, and displayed 26 mm and 22 mm zone of inhibitions, respectively. MIC of Fe3O4-NPs was found to be 5 μg/mL against these strains. However, MBC for these strains was observed at 40 μg/mL concentration of Fe3O4-NPs for exhibiting 40–50% loss in viable bacterial cells and 80 μg/mL concentration of Fe3O4-NPs acted as bactericidal for causing 90–99% loss in viability. Hence, these nanoparticles can be explored for their additional antimicrobial and biomedical applications.

Keywords

  • antibacterial activity
  • co-precipitation
  • iron oxide nanoparticles
  • Klebsiella pneumoniae
  • physico-chemical characterization
Open Access

The structure and properties of eucalyptus fiber/phenolic foam composites under N-β(aminoethyl)-γ-aminopropyl trimethoxy silane pretreatments

Published Online: 29 Dec 2017
Page range: 116 - 121

Abstract

Abstract

Eucalyptus fibers were modified with N-β(aminoethyl)-γ-aminopropyl trimethoxy silane to research the fiber surface’s changes and the influence of the treatment on the mechanical properties, flame resistance, thermal conductivity and microstructure of eucalyptus fiber composite phenolic foams (EFCPFs). The results showed that the partial of hemicelluloses, waxes, lignin and impurities from the fiber surface were dissolved and removed. Compared with untreated EFCPFs, the mechanical properties of treated EFCPFs were increased dramatically; The size of cells was smaller and the distribution was more uniform; The thermal conductivities were basically reduced; Especially the ratio of mass loss decreased obviously. However limited oxygen indexs (LOIs) reduced. And the mechanical properties and LOIs of EFCPFs were basically decreased with the increase of eucalyptus fibers. By comprehensive analysis, the results showed that the interfacial compatibility has been significantly improved between eucalyptus fibers and phenolic resin. And the suitable dosage of eucalyptus fibers was about 5%.

Keywords

  • eucalyptus fiber
  • pheonlic foam
  • N-β(aminoethyl)-γ-aminopropyl trimethoxy silane
  • surface modification
  • composites
Open Access

Iridoids from Cornus mas L. and their potential as innovative ingredients in cosmetics

Published Online: 29 Dec 2017
Page range: 122 - 127

Abstract

Abstract

Dogwood berries represent a valuable source of a variety of active ingredients. A group that deserves special attention comprises iridoids – compounds with potent antioxidant, antiinflammatory and antibacterial properties. The present study is an attempt to obtain an innovative plant material from dogwood berries. To this end, water and water/ethanol-based extracts (1:1) were prepared and, as the next step, an iridoids-rich fraction was isolated. The total content of iridoids was determined spectrophotometrically, and antioxidant properties of the isolates were concurrently assessed. Additionally, skin whitening activity of isolated fractions was assessed on the basis of tyrosinase inhibition measurement. The testing schedule also involved the formulation of model washing systems based on anionic surfactants. The effect of adding the fractions obtained by the above method on the irritant potential was assessed by determining the zein number

Keywords

  • dogwood
  • antioxidant activity
  • zein test
  • tyrosinase inhibition
  • iridoids
Open Access

Green synthesis, characterization and antibacterial activities of silver nanoparticles from strawberry fruit extract

Published Online: 29 Dec 2017
Page range: 128 - 136

Abstract

Abstract

Silver nanoparticles (AgNPs) have been synthesized in the presence of Strawberry fruit extract (SBFE) at room temperature. The synthesized AgNPs was characterized by UV-vis spectroscopy, SEM, EDS, XRD, TEM and FTIR. The UV-vis spectra of the AgNPs show SPR band at 450 nm. TEM results indicate that AgNPs are spherical in shape and size range between 7–65 nm. Antibacterial activity of the synthesized AgNPs has been assessed against Pseudomonas aeruginosa and Bacillus licheniformis. The results show that AgNPs exhibit inhibitory effect and effect is a function of AgNPs concentration. The antibacterial activity of the prepared AgNPs has been compared with two antibiotics, amoxicillin and ciprofloxacin. It is found that the antibiotics perform better than AgNPs.

Keywords

  • strawberry fruit
  • silver nanoparticles
  • biosynthesis
  • characterization
  • antibacterial activity
20 Articles
Open Access

Change in dust collection efficiency of liquid collectors in conditions of dedusting liquid recirculation

Published Online: 29 Dec 2017
Page range: 1 - 7

Abstract

Abstract

The high efficiency of industrial wet scrubbers is the result of a simultaneous formation of dust particle collectors. Collectors can be understood as droplets of atomised liquid, bubbles formed in the conditions of intensive barbotage, liquid surface and wet surfaces. All collectors are formed during the operation of a circulating unit. The efficiency of dust collection process also depends on the ability of dust particles to be absorbed by collectors. The study provides an experimental analysis of the effect of the increasing concentration of a dust collection liquid in the conditions of full liquid recirculation on the efficiency of dust collection process in the examined types of collectors.

Keywords

  • dust collectors
  • dust removal efficiency
  • wet scrubbers
Open Access

Simulation of SOFCs based power generation system using Aspen

Published Online: 29 Dec 2017
Page range: 8 - 15

Abstract

Abstract

This study presents a thermodynamic Aspen simulation model for Solid Oxide Fuel Cells, SOFCs, based power generation system. In the first step, a steady-state SOFCs system model was developed. The model includes the electrochemistry and the diffusion phenomena. The electrochemical model gives good agreement with experimental data in a wide operating range. Then, a parametric study has been conducted to estimate effects of the oxygen to carbon ratio, O/C, on reformer temperature, fuel cell temperature, fuel utilization, overall fuel cell performance, and the results are discussed in this paper. In the second step, a dynamic analysis of SOFCs characteristic has been developed. The aim of dynamic modelling was to find the response of the system against the fuel utilization and the O/C ratio variations. From the simulations, it was concluded that both developed models in the steady and dynamic state were reasonably accurate and can be used for system level optimization studies of the SOFC based power generation system.

Keywords

  • Solid Oxide Fuel Cell system
  • modelling
  • methane
  • reforming
  • CPO
Open Access

Flow behavior in weakly permeable micro-tube with varying viscosity near the wall

Published Online: 29 Dec 2017
Page range: 16 - 21

Abstract

Abstract

Weakly permeable micro-tubes are employed in many applications involving heat and/or mass transfer. During these processes, either solute concentration builds up (mass transfer) or steep change in temperature (heat transfer) takes place near the permeable wall causing a change in the viscosity of the fluid. Results of the present work suggest that such change in viscosity leads to a considerable alteration in the flow behavior, and the commonly assumed parabolic velocity profile no longer exists. To solve the problem numerically, the equation of motion was simplified to represent permeation of incompressible, Newtonian fluid with changing viscosity through a micro-tube. Even after considerable simplification, the accuracy of the results was the same as that obtained by previously reported results for some specific cases using rigorous formulation. The algorithm developed in the present work is found to be numerically robust and simple so that it can be easily integrated with other simulations.

Keywords

  • hollow-fiber
  • micro-tube
  • permeation
  • algorithm
  • variable viscosity
  • velocity profile
  • equation of motion
  • navier-stokes equation
Open Access

Galvanic coupling effects for module-mounting elements of ground-mounted photovoltaic power station

Published Online: 29 Dec 2017
Page range: 22 - 27

Abstract

Abstract

This communication reports on the concerns associated with possible generation of galvanic coupling effects for construction materials that are used to manufacture mounting assemblies for ground-mounted photovoltaic (PV) power stations. For this purpose, six macro-corrosion galvanic cells were assembled, including: hot-dip Zn/Magnelis®-coated steel/Al and stainless steel (SS)/Al cells. Corrosion experiments involved continuous, ca. three-month exposure of these couplings in 3 wt.% NaCl solution, conducted at room temperature for a stable pH value of around 8. All corrosion cells were subjected to regular assessment of galvanic current-density and potential parameters, where special consideration was given to compare the corrosion behaviour of Zn-coated steel samples with that of Magnelis®-coated electrodes. Characterization of surface condition and elemental composition for examined materials was carried-out by means of SEM and EDX spectroscopy techniques.

Keywords

  • PV mounting assembly
  • Zn-coated steel
  • Magnelis® coating
  • galvanic coupling
Open Access

Biological screening and assessment of certain substituted monoazo heterocycles containing sulphur and / or nitrogen and their seleno like moieties

Published Online: 29 Dec 2017
Page range: 28 - 35

Abstract

Abstract

The monoazo substituted five membered heterocycles, along with their seleno like moieties are still of interest in organic chemistry due to their medicinal and valuable applications. In continuation of our interest in the study of heterocyclic azo compounds containing sulphur and / or nitrogen heteroatoms, the synthesis of 5-aryl mono azo-thiazol-2-ylcarbamoyl-thiophene along with their seleno like derivatives of pyridine, pyridazine and quinolone, were accomplished. All the synthesized compounds were in vitro screening of their antioxidant activity, antitumor activity against Ehrlich ascites carcinoma cell EACC cell line and antimicrobial activity against various pathogenic microorganisms, such as Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) and fungi strains of Aspergillus flavus and Candida albicans. The structural–activity relationship was studied based on the obtained data.

Keywords

  • thiophene
  • antioxidant activities
  • antitumor agents
  • pathogenic microorganisms
  • selenium
Open Access

Preparation of Ag nanoparticles-reinforced polyamide 6 nanocomposites by in situ polymerization and investigation of its properties

Published Online: 29 Dec 2017
Page range: 36 - 40

Abstract

Abstract

Polyamide 6 (noted as PA6)/Ag nanocomposites were prepared by an in situ solution polymerization method. AgNO3 was used as filler and was directly reduced to silver nanoparticles resulting in uniformly dispersed nanoparticles in the PA6 matrix. The thermal stability, crystallization, melting performance, and dispersion properties of the PA6/Ag nanocomposites were studied using transmission electron microscopy (TEM), thermogravimetric analysis (TG), differential thermal scanning calorimetry (DSC), X-ray diffraction (XRD), and polarized light microscopy (POM). Furthermore, the mechanical and tribological behaviors of as-prepared nanocomposites were evaluated using universal tensile testing, impact testing, and friction testing machines. The results show that Ag-nanoparticles are evenly dispersed in PA6 and decrease in size with increasing Ag content. Whereas the crystallinity increased with increasing Ag content, the crystallization temperature of the nanocomposites did not change significantly. However, the mechanical and tribological properties of the nanocomposites increased compared with pure PA6.

Keywords

  • solution polymerization
  • Ag nanomaterials
  • nanocomposites
  • crystallization properties
  • mechanical properties
Open Access

Preparation and properties of cellulose membranes with graphene oxide addition

Published Online: 29 Dec 2017
Page range: 41 - 49

Abstract

Abstract

The paper presents results of research on the preparation of cellulose membranes with graphite oxide addition (GO/CEL). Initially, a cellulose (CEL) solution in 1-ethyl-3-methylimidazole acetate (EMIMAc) was obtained, to which graphene oxide (GO) dispersed in N,N-dimethylformamide (DMF) was added. From this solution, composite membranes were formed using phase inversion method. It was observed that the GO addition influences the physico-chemical properties of GO/CEL composite membranes, resulting in an increase in their mass per unit area, thickness and density, and a decrease in sorption properties. In addition, the study of transport properties has shown that GO/CEL membranes do not absorb BSA particles on their surface, which prevents the unfavorable phenomenon of fouling. An important feature of the obtained membranes is the specific permeate flux which reaches high values (~124 L/m2×h) at 3.8% of the GO addition to the cellulose matrix.

Keywords

  • cellulose
  • ionic liquid
  • graphene oxide
  • membranes
  • transport properties
Open Access

Montmorillonite as the catalyst in oxidation of limonene with hydrogen peroxide and in isomerization of limonene

Published Online: 29 Dec 2017
Page range: 50 - 58

Abstract

Abstract

In our studies montmorillonite (MMT) was used as the heterogeneous, natural catalyst. This material was previously prepared by bentonite purification with help of the sedimentation method. The obtained catalyst was characterized by: XRD, SEM, BET and EDX. Catalytic tests with montmorillonite as the catalyst were performed with the natural terpene – R-(+)-limonene. This compound was oxidized with hydrogen peroxide and, moreover, in the separate process it was also isomerized. As the main products of limonene oxidation were detected: (1,2-8,9)-diepoxide, perillyl alcohol, carvone, carveol, 1,2-epoxylimonene and 1,2-epoxylimonene diol. In the isomerization of R-(+)-limonene were formed: terpinenes, terpinolene and p-cymene. Conversions of limonene in these processes reached 70–80%. The application of montmorillonite (the natural of origin) in the studied processes (oxidation and isomerization) is environmentally friendly, it allows to reduce the cost of the studied processes. The resulting products of the processes of oxidation and isomerization of R-(+)-limonene have many applications.

Keywords

  • montmorillonite
  • R-(+)-limonene
  • oxidation
  • isomerization
  • hydrogen peroxide
  • heterogeneous catalysis
Open Access

Adsorption of propan-1-ol vapour on Sorbonorit 4 activated carbon – equilibrium and dynamic studies

Published Online: 29 Dec 2017
Page range: 59 - 64

Abstract

Abstract

The study examined the adsorption of propan-1-ol (1PN) vapour on Sorbonorit 4 (S4) activated carbon in cyclic Electrothermal Temperature Swing Adsorption (ETSA) process. Dynamic adsorption capacity and breakthrough time were determined based on column studies. Thomas model was used to describe experimental breakthrough curves. Adsorption isotherms for 1PN vapour on S4 activated carbon were tested at 293 to 413 K. The experimental data were examined by using three multi-temperature isotherm models: Toth, Sips and hybrid Langmuir-Sips. Results indicate that S4 activated carbon is a heterogeneous adsorbent and the hybrid Langmuir-Sips model provides the best-fit experimental data. The energy requirement for 1PN electrothermal desorption from S4 bed (ca. 170–200 kJ/mol) was about 3 to 3.5 times larger than the isosteric heat of adsorption (56.8 kJ/mol), which was calculated using Toth adsorption isotherm.

Keywords

  • activated carbon
  • propan-1-ol
  • multi-temperature isotherms
  • electrothermal desorption
  • breakthrough curve
Open Access

Removal of Rhodamine B from aqueous solution by ZnFe2O4 nanocomposite with magnetic separation performance

Published Online: 29 Dec 2017
Page range: 65 - 74

Abstract

Abstract

Magnetic ZnFe2O4 nanocomposite (ZnFe-NC) was used as an adsorbent for the removal of Rhodamine B (RB) from aqueous solution. The synthesized nanocomposite was characterized by XRD, SEM, HRTEM, BET and FTIR. The effects of various parameters such as initial RB concentration (5–25 mg L−1), pH (3.4–11.1) and temperature (20–60°C) were investigated. The adsorption capacity at equilibrium increased from 5.02 to 9.83 mg g−1, with the increase in the initial concentration of RB from 5 to 25 mg L−1 at pH 7.0 and at 20°C. The experimental results indicated that the maximum RB removal could be attained at a solution pH of 4.4 and the adsorption capacity obtained was 6.02 mg g−1. Kinetic adsorption data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order model and the intraparticle diffusion model. The adsorption kinetics well fitted using a pseudo-second-order kinetic model. The experimental isotherm data were analyzed using two isotherm models, namely, Langmuir and Freundlich. The results revealed that the adsorption behavior of the RB onto ZnFe-NC fitted well with the Langmuir isotherm model. In addition, various thermodynamic parameters, such as standard Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) have been calculated.

Keywords

  • adsorption
  • Rhodamine B
  • ZnFeO
  • kinetics
  • thermodynamics
Open Access

Ionic [Ru] complex with recyclability by electro-adsorption for efficient catalytic transfer hydrogenation of aryl ketones

Published Online: 29 Dec 2017
Page range: 75 - 79

Abstract

Abstract

The efficient reuse of homogeneous catalyst is important. Cation complex of [Ru(η6-p-cymene)(PPh3)(CH3CN) Cl]PF6 with different ligands was synthesized and characterized by infrared spectroscopy (IR), 1H-, 13C- and 31P-nuclear magnetic resonance spectroscopy (1H-, 13C- and 31P-NMR), element analysis (EA), and high resolution mass spectrometry (HR-MS). The complex was used as a catalyst for the hydrogen transfer reduction of carbonyl for the first time, presenting an excellent catalytic performance of 89%–98% conversion of acetophenone and its derivatives. The catalyst may be efficiently reused by the electro-adsorption of 10 times to one catalyst recovery. The cation [Ru] complex presented advantages of both homogeneous and heterogeneous catalysts.

Keywords

  • ionic Ru complex
  • transfer hydrogenation
  • electron-adsorption
  • catalyst recovery
Open Access

The research of anti corrosive properties of various compositions on samples of standard metals

Published Online: 29 Dec 2017
Page range: 80 - 86

Abstract

Abstract

In this proceeding. the compositions of the T-30 turbine oil with liquid rubber. Co. Ni. Zn. Mg and Ba salts of the natural petroleum acids (NPA) boiling in the range 220–340°C and nitro compounds which are produced on the basis of C14H28 α-olefins have been investigated in different ratio and contents as metalworking fluids (MWF). The physical and chemical properties of the produced compositions have been studied. and the morphology of inhibited carbon steel surface was analyzed and characterized by using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) techniques. The effect of the temperature on the inhibition efficiency and thermodynamic parameters have also been reported. The thermal analyzer was used for the thermogravimetric analysis (TG/DTA) of the prepared MWF. The experiments have been operated with different concentrations of the inhibitor on the steel plates in condensation and environment phases in the experiment chamber.

Keywords

  • metalworking fluids and lubricants
  • corrosion
  • liquid rubber
  • natural petroleum acids
Open Access

Effect of textural and chemical characteristics of activated carbons on phenol adsorption in aqueous solutions

Published Online: 29 Dec 2017
Page range: 87 - 93

Abstract

Abstract

The effect of textural and chemical properties such as: surface area, pore volume and chemical groups content of the granular activated carbon and monoliths on phenol adsorption in aqueous solutions was studied. Granular activated carbon and monolith samples were produced by chemical activation. They were characterized by using N2 adsorption at 77 K, CO2 adsorption at 273 K, Boehm Titrations and immersion calorimetry in phenol solutions. Microporous materials with different pore size distribution, surface area between 516 and 1685 m2 g−1 and pore volumes between 0.24 and 0.58 cm3 g−1 were obtained. Phenol adsorption capacity of the activated carbon materials increased with increasing BET surface area and pore volume, and is favored by their surface functional groups that act as electron donors. Phenol adsorption capacities are in ranged between 73.5 and 389.4 mg · g−1.

Keywords

  • activated carbon monoliths
  • phenol adsorption
  • textural and chemical characteristics
  • immersion calorimetry
Open Access

Purification of the gas after pyrolysis in coupled plasma-catalytic system

Published Online: 29 Dec 2017
Page range: 94 - 98

Abstract

Abstract

Gliding discharge and coupled plasma-catalytic system were used for toluene conversion in a gas composition such as the one obtained during pyrolysis of biomass. The chosen catalyst was G-0117, which is an industrial catalyst for methane conversion manufactured by INS Pulawy (Poland). The effects of discharge power, initial concentration of toluene, gas flow rate and the presence of the bed of the G-0117 catalyst on the conversion of C7H8, a model tars compounds were investigated. Conversion of coluene increases with discharge power and the highest one was noted in the coupled plasma-catalytic system. It was higher than that in the homogeneous system of gliding discharge. When applying a reactor with reduced G-0117 and CO (0.15 mol%), CO2 (0.15 mol%), H2 (0.30 mol%), N2 (0.40 mol%), 4000 ppm of toluene and gas flow rate of 1.5 Nm3/h, the conversion of toluene was higher than 99%. In the coupled plasma-catalytic system with G-0117 methanation of carbon oxides was observed.

Keywords

  • gliding discharge
  • non-equilibrium plasma
  • plasma-catalytic system
  • tar decompositio
Open Access

Analysis of tank safety with propane-butane on LPG distribution station

Published Online: 29 Dec 2017
Page range: 99 - 102

Abstract

Abstract

An analysis of the risk of failure in the safety valve – tank with propane-butane (LPG) system has been conducted. An uncontrolled outflow of liquid LPG, caused by a failure of the above mentioned system has been considered as a threat. The main research goal of the study is the hazardous analysis of propane-butane gas outflow for the safety valve – LPG tank system. The additional goal is the development of an useful method to fast identify the hazard of a mismatched safety valve. The results of the research analysis have confirmed that safety valves are basic protection of the installation (tank) against failures that can lead to loss of life, material damage and further undesired costs of their unreliability. That is why a new, professional computer program has been created that allows for the selection of safety valves or for the verification of a safety valve selection in installations where any technical or technological changes have been made.

Keywords

  • safety valve
  • risk analysis
  • emergency scenarios
  • LPG
Open Access

Conditions of synthesis and structure of metakaolin-based geopolymers: application as heavy metal cation sorbent

Published Online: 29 Dec 2017
Page range: 103 - 109

Abstract

Abstract

This study presents the synthesis of geopolymer materials designed for application as self-supporting zeolite membranes. For this purpose, batches of metakaolin activated with sodium silicate and sodium hydroxide were used. During synthesis, it was assumed that low temperatures are sufficient to receive the membranes. The composition of raw materials and temperature of activation were selected in such a way so as to correspond to the basic chemical compositions and synthesis conditions of sodalite as well as zeolites A and X. Additionally, the structural and textural properties of geopolymers were determined. The results show that it is possible to obtain composite zeolite structures in an amorphous matrix. A number of synthesized materials were used in the sorption of selected heavy metal cations (Ni2+, Zn2+, Pb2+ and Cd2+). It was concluded that the investigated geopolymerization process may be applied to obtain a material with potential use as a heavy metal sorbent.

Keywords

  • metakaolin
  • geopolymers
  • structural and textural properties
  • heavy metal sorbent
Open Access

Antibacterial activity of iron oxide nanoparticles synthesized by co-precipitation technology against Bacillus cereus and Klebsiella pneumoniae

Published Online: 29 Dec 2017
Page range: 110 - 115

Abstract

Abstract

The present study investigates the synthesis and characterization of iron oxide nanoparticles (Fe3O4-NPs) for their antibacterial potential against Bacillus cereus and Klebsiella pneumonia by modified disc diffusion and broth agar dilution methods. DLS and XRD results revealed the average size of synthesized Fe3O4-NPs as 24 nm while XPS measurement exhibited the spin-orbit peak of Fe 2p3/2 binding energy at 511 eV. Fe3O4-NPs inhibited the growth of K. pneumoniae and B. cereus in both liquid and soild agar media, and displayed 26 mm and 22 mm zone of inhibitions, respectively. MIC of Fe3O4-NPs was found to be 5 μg/mL against these strains. However, MBC for these strains was observed at 40 μg/mL concentration of Fe3O4-NPs for exhibiting 40–50% loss in viable bacterial cells and 80 μg/mL concentration of Fe3O4-NPs acted as bactericidal for causing 90–99% loss in viability. Hence, these nanoparticles can be explored for their additional antimicrobial and biomedical applications.

Keywords

  • antibacterial activity
  • co-precipitation
  • iron oxide nanoparticles
  • Klebsiella pneumoniae
  • physico-chemical characterization
Open Access

The structure and properties of eucalyptus fiber/phenolic foam composites under N-β(aminoethyl)-γ-aminopropyl trimethoxy silane pretreatments

Published Online: 29 Dec 2017
Page range: 116 - 121

Abstract

Abstract

Eucalyptus fibers were modified with N-β(aminoethyl)-γ-aminopropyl trimethoxy silane to research the fiber surface’s changes and the influence of the treatment on the mechanical properties, flame resistance, thermal conductivity and microstructure of eucalyptus fiber composite phenolic foams (EFCPFs). The results showed that the partial of hemicelluloses, waxes, lignin and impurities from the fiber surface were dissolved and removed. Compared with untreated EFCPFs, the mechanical properties of treated EFCPFs were increased dramatically; The size of cells was smaller and the distribution was more uniform; The thermal conductivities were basically reduced; Especially the ratio of mass loss decreased obviously. However limited oxygen indexs (LOIs) reduced. And the mechanical properties and LOIs of EFCPFs were basically decreased with the increase of eucalyptus fibers. By comprehensive analysis, the results showed that the interfacial compatibility has been significantly improved between eucalyptus fibers and phenolic resin. And the suitable dosage of eucalyptus fibers was about 5%.

Keywords

  • eucalyptus fiber
  • pheonlic foam
  • N-β(aminoethyl)-γ-aminopropyl trimethoxy silane
  • surface modification
  • composites
Open Access

Iridoids from Cornus mas L. and their potential as innovative ingredients in cosmetics

Published Online: 29 Dec 2017
Page range: 122 - 127

Abstract

Abstract

Dogwood berries represent a valuable source of a variety of active ingredients. A group that deserves special attention comprises iridoids – compounds with potent antioxidant, antiinflammatory and antibacterial properties. The present study is an attempt to obtain an innovative plant material from dogwood berries. To this end, water and water/ethanol-based extracts (1:1) were prepared and, as the next step, an iridoids-rich fraction was isolated. The total content of iridoids was determined spectrophotometrically, and antioxidant properties of the isolates were concurrently assessed. Additionally, skin whitening activity of isolated fractions was assessed on the basis of tyrosinase inhibition measurement. The testing schedule also involved the formulation of model washing systems based on anionic surfactants. The effect of adding the fractions obtained by the above method on the irritant potential was assessed by determining the zein number

Keywords

  • dogwood
  • antioxidant activity
  • zein test
  • tyrosinase inhibition
  • iridoids
Open Access

Green synthesis, characterization and antibacterial activities of silver nanoparticles from strawberry fruit extract

Published Online: 29 Dec 2017
Page range: 128 - 136

Abstract

Abstract

Silver nanoparticles (AgNPs) have been synthesized in the presence of Strawberry fruit extract (SBFE) at room temperature. The synthesized AgNPs was characterized by UV-vis spectroscopy, SEM, EDS, XRD, TEM and FTIR. The UV-vis spectra of the AgNPs show SPR band at 450 nm. TEM results indicate that AgNPs are spherical in shape and size range between 7–65 nm. Antibacterial activity of the synthesized AgNPs has been assessed against Pseudomonas aeruginosa and Bacillus licheniformis. The results show that AgNPs exhibit inhibitory effect and effect is a function of AgNPs concentration. The antibacterial activity of the prepared AgNPs has been compared with two antibiotics, amoxicillin and ciprofloxacin. It is found that the antibiotics perform better than AgNPs.

Keywords

  • strawberry fruit
  • silver nanoparticles
  • biosynthesis
  • characterization
  • antibacterial activity