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Journal Details
Format
Journal
eISSN
1899-4741
ISSN
1509-8117
First Published
03 Jul 2007
Publication timeframe
4 times per year
Languages
English

Search

Volume 13 (2011): Issue 4 (December 2011)

Journal Details
Format
Journal
eISSN
1899-4741
ISSN
1509-8117
First Published
03 Jul 2007
Publication timeframe
4 times per year
Languages
English

Search

15 Articles
Open Access

Kinetic, Equilibrium and Thermodynamic studies on the removal of Cr(VI) by activated carbon prepared from Cajanus Cajan(L) Milsp seed shell

Published Online: 02 Jan 2012
Page range: 1 - 7

Abstract

Kinetic, Equilibrium and Thermodynamic studies on the removal of Cr(VI) by activated carbon prepared from Cajanus Cajan(L) Milsp seed shell

This paper presents the feasibility of the removal of hexavalent chromium ions from aqueous solutions by using activated carbon prepared from Cajanus Cajan(L) Milsp. It was carbonized and activated by treating it with concentrated sulfuric acid followed by heating for 5 h at 500°C. Batch adsorption experiments were carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature. The experimental data fitted well to the Freundlich isotherm. The thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were calculated, which indicated that the adsorption was spontaneous and endothermic in nature. The adsorbent used in this study was characterized by FT-IR and SEM before and after the adsorption of metal ions. The results indicate that Cajanus Cajan(L) Milsp can be employed as a low cost alternative and commercial adsorbents in the removal of chromium (VI) from water and waste water.

Keywords

  • Adsorption
  • isotherm
  • activated carbon
  • chromium and seed shell
Open Access

New photocatalyst for decomposition of humic acids in photocatalysis and photo-Fenton processes

Published Online: 02 Jan 2012
Page range: 8 - 14

Abstract

New photocatalyst for decomposition of humic acids in photocatalysis and photo-Fenton processes

Humic acid Leonardite IHSS standard was decomposed on TiO2 and TiO2 modified by FeC2O4 via the photocatalysis and photo-Fenton processes under UV irradiation. Humic acid (HA) were favorable adsorbed on TiO2 surface and followed decomposition during UV irradiation faster on TiO2 than on the modified samples. However, when H2O2 was added to the solution, the photo-Fenton process occurred on the prepared TiO2 samples, contained iron together with photocatalysis and high acceleration of HA decomposition was observed. In this case the mineralization degree was much higher than in the applied photocatalysis only, around 75% HA (with concentration of 18 mg/L) was mineralized after 3 h of adsorption and 5 h of UV irradiation in the presence of H2O2 and modified TiO2 whereas on TiO2 mineralisation of HA occurred in around 45% only. The measured fluorescence spectra of HA solutions showed that in the presence of H2O2 polycyclic aromatics were rapidly oxidized to the lower size products such as alcohols, aldehydes, ketones and carboxylic acids, what accelerated the process of HA decomposition.

Keywords

  • Humic acid (HA)
  • photodecomposition
  • photo-Fenton
  • TiO
  • FeCO
Open Access

Immobilization of Aspergillus oryzae β galactosidase on concanavalin A-layered calcium alginate-cellulose beads and its application in lactose hydrolysis in continuous spiral bed reactors

Published Online: 02 Jan 2012
Page range: 15 - 20

Abstract

Immobilization of <italic>Aspergillus oryzae</italic> β galactosidase on concanavalin A-layered calcium alginate-cellulose beads and its application in lactose hydrolysis in continuous spiral bed reactors

In this study, Aspergillus oryzae β galactosidase was immobilized on concanavalin A layered calcium alginate-cellulose beads as a bioaffinity support. Immobilized enzyme showed a remarkable broadening in temperature-activity profiles as compared to the native enzyme and exhibited 65% activity in the presence of 5% galactose. Michaelis constant (Km) was 2.57 mM and 5.38 mM for the free and the immobilized β galactosidase, respectively. Crosslinked β galactosidase showed greater catalytic activity in the presence of Mg2+ and was more stable during storage at 4°C for 6 weeks. Immobilized enzyme hydrolyzed 67% lactose in milk in 8 h and 85% lactose in whey in 9 h in the stirred batch process at 50°C. The continuous hydrolysis of lactose by crosslinked β galactosidase in spiral bed reactor exhibited 93% and 88% hydrolysis of lactose at flow rate of 20 ml/h and 30 ml/h, after 1 month operation, respectively.

Keywords

  • β galactosidase
  • Immobilization
  • Cellulose-alginate
  • Concanavalin A
  • Spiral bed reactor
  • Lactose hydrolysis
Open Access

Influence of wet chemistry treatment on the mechanical performance of natural fibres

Published Online: 02 Jan 2012
Page range: 21 - 27

Abstract

Influence of wet chemistry treatment on the mechanical performance of natural fibres

The paper presents determination of the effect of various chemical treatment on the strength of 288 tex jute yarn arisen from the plain weave fabric produced by LENTEX, Poland. The yarn was put to alternative treatments in: NaOH and KOH water solutions with various concentration (from 1 to 15%) and treatment duration (from 0.5 to 6 hours), vinyl acetate, methanol and toluene diisocyanate. After the treatment it was put to tensile tests. Yarn diameter and elementary fibre twist angle were also measured using MICRO PROF FRT optical profilographometer. The SEM micro-photographs have also been performed in order to evaluate the structural changes of the yarn after the treatment.

Optimal conditions of alcali-treatment are: 5% concentration and 2h duration for NaOH, 3% concentration and 4h duration for KOH. Such treatments give a growth in yarn rupture force up to 10% and they are well applicable in composite materials manufacturing. Also interaction with vinyl acetate and toluene diisocyanate has practically not negative influence on the mechanical performance of the yarn. Two effects were observed which can explain the influence of chemical treatment on mechanical performance of jute yarn: swelling and change in the orientation of elementary fibres.

Keywords

  • natural fibres
  • jute fibres
  • surface treatment
  • mechanical performance
  • fibre reinforced composites
Open Access

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

Published Online: 02 Jan 2012
Page range: 28 - 33

Abstract

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

A method was developed to attach 2,2-bipyridine (BP) onto a silica gel surface by a two-step reaction. The first step consisted of a reaction between the matrix and a silylating agent, 3-chloropropyltrimethoxysilane. In the second step of the reaction, a ligand molecule was attached onto Si-CPTS, yielding the product Si-BP. The modified material contained 0.431±0.01 mmol of 2,2-bipyridine per gram of modified silica, as confirmed by FT-IR spectra of the proposed structure. The surface modification was characterized by the BET technique, which revealed a decrease in the surface area from 614 to 450 m2 g-1. The series of adsorption isotherms for the metal ions were adjusted to fit a modified Langmuir equation. The maximum number of moles of copper, cadmium and lead ions adsorbed was 0.64, 0.53, and 0.54 mmol g-1, respectively. The surface saturation was calculated as φ fraction and the values obtained, Cu(II) = 1.160, Cd(II) = 1.044 and Pb(II) = 0.997, suggest a type 1:1 metal-ligand complex.

Keywords

  • 2, 2-Bipyridine
  • silica gel
  • adsorption
  • metal ions
Open Access

Modelling of heat transfer in a packed bed column

Published Online: 02 Jan 2012
Page range: 34 - 41

Abstract

Modelling of heat transfer in a packed bed column

The CFD modelling of heat transfer in the packed bed column in the laminar and turbulent flow regimes has been presented. Three numerical grids with different densities were generated for the packed bed column. The modelling was performed with the use of the Porous Media Model for treating the flow inside a porous structure. The standard k-ε model along with the logarithmic wall functions for the turbulent flow range was used. The influence of the mesh size on the accuracy of the fluid flow was studied. Both radial and axial direction temperature distributions have been compared with the experimental data1 and the values calculated from a 2DADPF model. A good agreement between the experimental and the predicted values of the pressure drop, temperature distributions and heat transfer coefficient was obtained.

Keywords

  • Packed bed column
  • Porous media model
  • Heat transfer
  • Computational Fluid Dynamics
Open Access

Preparation and properties of porous carbon material containing magnesium oxide

Published Online: 02 Jan 2012
Page range: 42 - 46

Abstract

Preparation and properties of porous carbon material containing magnesium oxide

Porous carbons loaded with magnesium oxide were prepared through one-step process. Poly(ethylene terephthalate) and natural magnesite were used as carbon source and MgO precursor, respectively. An impact of a temperature and relative amounts of raw components used for preparations on the textural parameters of resulting hybrid materials is presented and discussed. As found, pore structure parameters tend to decrease along with MgO loading and temperature used during preparation process. Micropore area is the parameter being reduced primarily.

Keywords

  • porous carbon
  • MgO
  • porosity
Open Access

Mathematical modeling of air duct heater using the finite difference method

Published Online: 02 Jan 2012
Page range: 47 - 52

Abstract

Mathematical modeling of air duct heater using the finite difference method

In this research, mathematical modeling of a duct heater has been performed using energy conservation law, Stefan-Boltzman law in thermal radiation, Fourier's law in conduction heat transfer, and Newton's law of cooling in convection heat transfer. The duct was divided to some elements with equal length. Each element has been studied separately and air physical properties in each element have been used based on its temperature. The derived equations have been solved using the finite difference method and consequently air temperature, internal and external temperatures of the wall, internal and external convection heat transfer coefficients, and the quantity of heat transferred have been calculated in each element and effects of the variation of heat transfer parameters have been surveyed. The results of modelling presented in this paper can be used for the design and optimization of heat exchangers.

Keywords

  • Duct heater
  • Modeling
  • Variable physical properties
  • Finite difference
  • Log mean temperature difference
Open Access

Utilization of the post - filtration lye from the soda-chlorine-saltpetre method of soda production

Published Online: 02 Jan 2012
Page range: 53 - 56

Abstract

Utilization of the post - filtration lye from the soda-chlorine-saltpetre method of soda production

The optimal conditions were determined for the precipitation of ammonium metavanadate from the solutions of ammonium nitrate with the use of sodium metavanadate. The experiments were performed with the molar ratio of salts NH4NO3: NaVO3 1.5:1 at temperatures 293, 303, 313 and 323 K. Based on the obtained results, the optimal time of the process was determined as 5 h at 293-303K. Under these conditions, the achieved yield of the precipitation process was ~98.7%, while the contents of the vanadium salts in the post - filtration solution was ~0.02%.

Keywords

  • SCS method
  • double exchange
  • ammonium nitrate and ammonium metavanadate
Open Access

Activity of monolithic Pd/Al2O3 catalysts in the combustion of mine ventilation air methane

Published Online: 02 Jan 2012
Page range: 57 - 62

Abstract

Activity of monolithic Pd/Al<sub>2</sub>O<sub>3</sub> catalysts in the combustion of mine ventilation air methane

The activity of Pd/Al2O3 catalysts increases when Pd content is increased from 1% to 2%. Among these catalysts, 2%Pd/Al2O3 shows the highest methane combustion activity. In a reduced form, the catalyst displays a higher activity than in the oxidized form. 24-hour ageing at 600°C to 800°C lowers the catalytic activity of 2%Pd/Al2O3 due to Pd crystallite sintering. After 110-hour oxidation of 1% methane in air over 2%Pd/Al2O3, conversion decreases from 100% to 88%. Upon reduction with hydrogen (performed after 24-hour ageing at 700°C and 110-hour methane oxidation), the 2%Pd/Al2O3 catalyst regains its initial activity. The high activity of Pd catalysts renders them suitable for methane removal from coal mine ventilation air at high gas flow velocities and temperatures lower than 600°C.

Keywords

  • catalytic oxidation of methane
  • monolithic catalysts
  • mine ventilation air
Open Access

The simplex optimization for high porous carbons preparation

Published Online: 02 Jan 2012
Page range: 63 - 70

Abstract

The simplex optimization for high porous carbons preparation

The microporous carbon materials were prepared by chemical activation of Polish coal with potassium hydroxide using the simplex design method for planning the experiments. The experimental parameters were varied to identify the optimum conditions. Coal can be an excellent starting material for the preparation of high porous carbons for natural gas storage. The porosity of the resultant carbons was characterized by nitrogen adsorption (-196°C). Methane adsorption was investigated in a volumetric laboratory installation at range pressures from 1 to 3.5 MPa (25°C).

The best results of methane storage capacity (557 cm3 · g-1) were obtained when using an impregnation ratio 3.41/1 KOH/precursor and temperature at 592°C, (SLANG = 2091 m2 · g-1). The parameters of the preparation of high porosity and high methane adsorption carbon were determined by a fast and simple method.

Keywords

  • porous carbon
  • chemical activation
  • simplex method
  • methane adsorption
Open Access

Influence of reduction time of copper based catalysts: Cu/Al2O3 and CuCr2O4 on hydrogenolysis of glycerol

Published Online: 02 Jan 2012
Page range: 71 - 76

Abstract

Influence of reduction time of copper based catalysts: Cu/Al<sub>2</sub>O<sub>3</sub> and CuCr<sub>2</sub>O<sub>4</sub> on hydrogenolysis of glycerol

High activity of copper based catalysts for C-O bond hydro-dehydrogenation and their poor activity for C-C bond cleavage1 have prompted an attempt to apply such catalysts in the hydrogenolysis of glycerol to 1,2- and 1,3-propanediol. In the present study the influence of hydrogen reduction time of the Cu/Al2O3 and CuCr2O4 copper catalysts on glycerol conversion and selectivity of transformation to propanediols and by-products was studied. At first a general comparison was made between the commercial catalysts and those prepared by the co-precipitation method. As better results were obtained in the presence of catalysts prepared by co-precipitation, they were selected for further detailed studies of the influence of reduction time. For both prepared catalysts Cu/Al2O3 and CuCr2O4 the reduction time of 8 h was optimal. In the presence of Cu/Al2O3 catalyst the conversion of glycerol was 59.0%, selectivity of transformation to 1,2-propanediol 77.4% and selectivity to 1,3-propanediol 1.9%. In the presence of CuCr2O4 the glycerol conversion was 30.3% and selectivity to 1,2-propanediol 67.3%.

Keywords

  • hydrogenolysis
  • 1, 2-propanediol
  • 1, 3-propanediol
  • glycerol
Open Access

Electrically conductive acrylic pressure-sensitive adhesives containing carbon black

Published Online: 02 Jan 2012
Page range: 77 - 81

Abstract

Electrically conductive acrylic pressure-sensitive adhesives containing carbon black

Acrylic pressure-sensitive adhesives (PSA) are non electrical conductive materials. The electrical conductivity is incorporated into acrylic self-adhesive polymer after adding electrically conductive additives like carbon black, especially nano carbon black. After an addition of electrical conductive carbon black, the main and typical properties of pressure-sensitive adhesives such as tack, peel adhesion and shear strength, are deteriorated. The investigations reveals that the acrylic pressure-sensitive adhesives basis must be synthesised with ameliorated initial performances, like high tack, excellent adhesion and very good cohesion. Currently, the electrical conductive solvent-borne acrylic PSA containing carbon black are not commercially available on the market. They are promising materials which can be applied for the manufacturing of diverse technical high performance self-adhesive products, such as broadest line of special electrically conductive sensitive tapes.

Keywords

  • Acrylic pressure-sensitive adhesives
  • carbon black
  • electrical conductive materials
Open Access

Adsorption behavior of Pb(II) onto xanthated rubber (Hevea brasiliensis) leaf powder

Published Online: 02 Jan 2012
Page range: 84 - 88

Abstract

Adsorption behavior of Pb(II) onto xanthated rubber (<italic>Hevea brasiliensis</italic>) leaf powder

A plant waste, rubber (Hevea brasiliensis) leaf powder was modified with carbon disulfide (xanthation) for the purpose of introducing sulfur groups, and the adsorbent performance in removing Pb(II) ion was evaluated. Pb(II) adsorption was confirmed by spectroscopic analysis, which involved Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The amount of Pb(II) adsorbed increased with increasing pH, contact time and concentration but slightly decreased with increasing ionic strength. Adsorption equilibrium was achieved in less than 60 min and followed the pseudo-second order model. The isotherm data indicated that Pb(II) adsorption on xanthated rubber leaf (XRL) fitted well with Langmuir isotherm model. The maximum adsorption capacity computed from the Langmuir isotherm model was 166.7 mg/g. Pb(II) adsorption occurred via ion-exchange and complexation mechanisms.

Keywords

  • Adsorption
  • Isotherm
  • Kinetic
  • Lead
  • Xanthated rubber leaf powder
Open Access

Comments on "3-aminopropyltriethoxysilane functionalized nanoscale zero-valent iron for the removal of dyes from aqueous solution"

Published Online: 02 Jan 2012
Page range: 89 - 89

Abstract

Comments on "3-aminopropyltriethoxysilane functionalized nanoscale zero-valent iron for the removal of dyes from aqueous solution"
15 Articles
Open Access

Kinetic, Equilibrium and Thermodynamic studies on the removal of Cr(VI) by activated carbon prepared from Cajanus Cajan(L) Milsp seed shell

Published Online: 02 Jan 2012
Page range: 1 - 7

Abstract

Kinetic, Equilibrium and Thermodynamic studies on the removal of Cr(VI) by activated carbon prepared from Cajanus Cajan(L) Milsp seed shell

This paper presents the feasibility of the removal of hexavalent chromium ions from aqueous solutions by using activated carbon prepared from Cajanus Cajan(L) Milsp. It was carbonized and activated by treating it with concentrated sulfuric acid followed by heating for 5 h at 500°C. Batch adsorption experiments were carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature. The experimental data fitted well to the Freundlich isotherm. The thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were calculated, which indicated that the adsorption was spontaneous and endothermic in nature. The adsorbent used in this study was characterized by FT-IR and SEM before and after the adsorption of metal ions. The results indicate that Cajanus Cajan(L) Milsp can be employed as a low cost alternative and commercial adsorbents in the removal of chromium (VI) from water and waste water.

Keywords

  • Adsorption
  • isotherm
  • activated carbon
  • chromium and seed shell
Open Access

New photocatalyst for decomposition of humic acids in photocatalysis and photo-Fenton processes

Published Online: 02 Jan 2012
Page range: 8 - 14

Abstract

New photocatalyst for decomposition of humic acids in photocatalysis and photo-Fenton processes

Humic acid Leonardite IHSS standard was decomposed on TiO2 and TiO2 modified by FeC2O4 via the photocatalysis and photo-Fenton processes under UV irradiation. Humic acid (HA) were favorable adsorbed on TiO2 surface and followed decomposition during UV irradiation faster on TiO2 than on the modified samples. However, when H2O2 was added to the solution, the photo-Fenton process occurred on the prepared TiO2 samples, contained iron together with photocatalysis and high acceleration of HA decomposition was observed. In this case the mineralization degree was much higher than in the applied photocatalysis only, around 75% HA (with concentration of 18 mg/L) was mineralized after 3 h of adsorption and 5 h of UV irradiation in the presence of H2O2 and modified TiO2 whereas on TiO2 mineralisation of HA occurred in around 45% only. The measured fluorescence spectra of HA solutions showed that in the presence of H2O2 polycyclic aromatics were rapidly oxidized to the lower size products such as alcohols, aldehydes, ketones and carboxylic acids, what accelerated the process of HA decomposition.

Keywords

  • Humic acid (HA)
  • photodecomposition
  • photo-Fenton
  • TiO
  • FeCO
Open Access

Immobilization of Aspergillus oryzae β galactosidase on concanavalin A-layered calcium alginate-cellulose beads and its application in lactose hydrolysis in continuous spiral bed reactors

Published Online: 02 Jan 2012
Page range: 15 - 20

Abstract

Immobilization of <italic>Aspergillus oryzae</italic> β galactosidase on concanavalin A-layered calcium alginate-cellulose beads and its application in lactose hydrolysis in continuous spiral bed reactors

In this study, Aspergillus oryzae β galactosidase was immobilized on concanavalin A layered calcium alginate-cellulose beads as a bioaffinity support. Immobilized enzyme showed a remarkable broadening in temperature-activity profiles as compared to the native enzyme and exhibited 65% activity in the presence of 5% galactose. Michaelis constant (Km) was 2.57 mM and 5.38 mM for the free and the immobilized β galactosidase, respectively. Crosslinked β galactosidase showed greater catalytic activity in the presence of Mg2+ and was more stable during storage at 4°C for 6 weeks. Immobilized enzyme hydrolyzed 67% lactose in milk in 8 h and 85% lactose in whey in 9 h in the stirred batch process at 50°C. The continuous hydrolysis of lactose by crosslinked β galactosidase in spiral bed reactor exhibited 93% and 88% hydrolysis of lactose at flow rate of 20 ml/h and 30 ml/h, after 1 month operation, respectively.

Keywords

  • β galactosidase
  • Immobilization
  • Cellulose-alginate
  • Concanavalin A
  • Spiral bed reactor
  • Lactose hydrolysis
Open Access

Influence of wet chemistry treatment on the mechanical performance of natural fibres

Published Online: 02 Jan 2012
Page range: 21 - 27

Abstract

Influence of wet chemistry treatment on the mechanical performance of natural fibres

The paper presents determination of the effect of various chemical treatment on the strength of 288 tex jute yarn arisen from the plain weave fabric produced by LENTEX, Poland. The yarn was put to alternative treatments in: NaOH and KOH water solutions with various concentration (from 1 to 15%) and treatment duration (from 0.5 to 6 hours), vinyl acetate, methanol and toluene diisocyanate. After the treatment it was put to tensile tests. Yarn diameter and elementary fibre twist angle were also measured using MICRO PROF FRT optical profilographometer. The SEM micro-photographs have also been performed in order to evaluate the structural changes of the yarn after the treatment.

Optimal conditions of alcali-treatment are: 5% concentration and 2h duration for NaOH, 3% concentration and 4h duration for KOH. Such treatments give a growth in yarn rupture force up to 10% and they are well applicable in composite materials manufacturing. Also interaction with vinyl acetate and toluene diisocyanate has practically not negative influence on the mechanical performance of the yarn. Two effects were observed which can explain the influence of chemical treatment on mechanical performance of jute yarn: swelling and change in the orientation of elementary fibres.

Keywords

  • natural fibres
  • jute fibres
  • surface treatment
  • mechanical performance
  • fibre reinforced composites
Open Access

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

Published Online: 02 Jan 2012
Page range: 28 - 33

Abstract

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

A method was developed to attach 2,2-bipyridine (BP) onto a silica gel surface by a two-step reaction. The first step consisted of a reaction between the matrix and a silylating agent, 3-chloropropyltrimethoxysilane. In the second step of the reaction, a ligand molecule was attached onto Si-CPTS, yielding the product Si-BP. The modified material contained 0.431±0.01 mmol of 2,2-bipyridine per gram of modified silica, as confirmed by FT-IR spectra of the proposed structure. The surface modification was characterized by the BET technique, which revealed a decrease in the surface area from 614 to 450 m2 g-1. The series of adsorption isotherms for the metal ions were adjusted to fit a modified Langmuir equation. The maximum number of moles of copper, cadmium and lead ions adsorbed was 0.64, 0.53, and 0.54 mmol g-1, respectively. The surface saturation was calculated as φ fraction and the values obtained, Cu(II) = 1.160, Cd(II) = 1.044 and Pb(II) = 0.997, suggest a type 1:1 metal-ligand complex.

Keywords

  • 2, 2-Bipyridine
  • silica gel
  • adsorption
  • metal ions
Open Access

Modelling of heat transfer in a packed bed column

Published Online: 02 Jan 2012
Page range: 34 - 41

Abstract

Modelling of heat transfer in a packed bed column

The CFD modelling of heat transfer in the packed bed column in the laminar and turbulent flow regimes has been presented. Three numerical grids with different densities were generated for the packed bed column. The modelling was performed with the use of the Porous Media Model for treating the flow inside a porous structure. The standard k-ε model along with the logarithmic wall functions for the turbulent flow range was used. The influence of the mesh size on the accuracy of the fluid flow was studied. Both radial and axial direction temperature distributions have been compared with the experimental data1 and the values calculated from a 2DADPF model. A good agreement between the experimental and the predicted values of the pressure drop, temperature distributions and heat transfer coefficient was obtained.

Keywords

  • Packed bed column
  • Porous media model
  • Heat transfer
  • Computational Fluid Dynamics
Open Access

Preparation and properties of porous carbon material containing magnesium oxide

Published Online: 02 Jan 2012
Page range: 42 - 46

Abstract

Preparation and properties of porous carbon material containing magnesium oxide

Porous carbons loaded with magnesium oxide were prepared through one-step process. Poly(ethylene terephthalate) and natural magnesite were used as carbon source and MgO precursor, respectively. An impact of a temperature and relative amounts of raw components used for preparations on the textural parameters of resulting hybrid materials is presented and discussed. As found, pore structure parameters tend to decrease along with MgO loading and temperature used during preparation process. Micropore area is the parameter being reduced primarily.

Keywords

  • porous carbon
  • MgO
  • porosity
Open Access

Mathematical modeling of air duct heater using the finite difference method

Published Online: 02 Jan 2012
Page range: 47 - 52

Abstract

Mathematical modeling of air duct heater using the finite difference method

In this research, mathematical modeling of a duct heater has been performed using energy conservation law, Stefan-Boltzman law in thermal radiation, Fourier's law in conduction heat transfer, and Newton's law of cooling in convection heat transfer. The duct was divided to some elements with equal length. Each element has been studied separately and air physical properties in each element have been used based on its temperature. The derived equations have been solved using the finite difference method and consequently air temperature, internal and external temperatures of the wall, internal and external convection heat transfer coefficients, and the quantity of heat transferred have been calculated in each element and effects of the variation of heat transfer parameters have been surveyed. The results of modelling presented in this paper can be used for the design and optimization of heat exchangers.

Keywords

  • Duct heater
  • Modeling
  • Variable physical properties
  • Finite difference
  • Log mean temperature difference
Open Access

Utilization of the post - filtration lye from the soda-chlorine-saltpetre method of soda production

Published Online: 02 Jan 2012
Page range: 53 - 56

Abstract

Utilization of the post - filtration lye from the soda-chlorine-saltpetre method of soda production

The optimal conditions were determined for the precipitation of ammonium metavanadate from the solutions of ammonium nitrate with the use of sodium metavanadate. The experiments were performed with the molar ratio of salts NH4NO3: NaVO3 1.5:1 at temperatures 293, 303, 313 and 323 K. Based on the obtained results, the optimal time of the process was determined as 5 h at 293-303K. Under these conditions, the achieved yield of the precipitation process was ~98.7%, while the contents of the vanadium salts in the post - filtration solution was ~0.02%.

Keywords

  • SCS method
  • double exchange
  • ammonium nitrate and ammonium metavanadate
Open Access

Activity of monolithic Pd/Al2O3 catalysts in the combustion of mine ventilation air methane

Published Online: 02 Jan 2012
Page range: 57 - 62

Abstract

Activity of monolithic Pd/Al<sub>2</sub>O<sub>3</sub> catalysts in the combustion of mine ventilation air methane

The activity of Pd/Al2O3 catalysts increases when Pd content is increased from 1% to 2%. Among these catalysts, 2%Pd/Al2O3 shows the highest methane combustion activity. In a reduced form, the catalyst displays a higher activity than in the oxidized form. 24-hour ageing at 600°C to 800°C lowers the catalytic activity of 2%Pd/Al2O3 due to Pd crystallite sintering. After 110-hour oxidation of 1% methane in air over 2%Pd/Al2O3, conversion decreases from 100% to 88%. Upon reduction with hydrogen (performed after 24-hour ageing at 700°C and 110-hour methane oxidation), the 2%Pd/Al2O3 catalyst regains its initial activity. The high activity of Pd catalysts renders them suitable for methane removal from coal mine ventilation air at high gas flow velocities and temperatures lower than 600°C.

Keywords

  • catalytic oxidation of methane
  • monolithic catalysts
  • mine ventilation air
Open Access

The simplex optimization for high porous carbons preparation

Published Online: 02 Jan 2012
Page range: 63 - 70

Abstract

The simplex optimization for high porous carbons preparation

The microporous carbon materials were prepared by chemical activation of Polish coal with potassium hydroxide using the simplex design method for planning the experiments. The experimental parameters were varied to identify the optimum conditions. Coal can be an excellent starting material for the preparation of high porous carbons for natural gas storage. The porosity of the resultant carbons was characterized by nitrogen adsorption (-196°C). Methane adsorption was investigated in a volumetric laboratory installation at range pressures from 1 to 3.5 MPa (25°C).

The best results of methane storage capacity (557 cm3 · g-1) were obtained when using an impregnation ratio 3.41/1 KOH/precursor and temperature at 592°C, (SLANG = 2091 m2 · g-1). The parameters of the preparation of high porosity and high methane adsorption carbon were determined by a fast and simple method.

Keywords

  • porous carbon
  • chemical activation
  • simplex method
  • methane adsorption
Open Access

Influence of reduction time of copper based catalysts: Cu/Al2O3 and CuCr2O4 on hydrogenolysis of glycerol

Published Online: 02 Jan 2012
Page range: 71 - 76

Abstract

Influence of reduction time of copper based catalysts: Cu/Al<sub>2</sub>O<sub>3</sub> and CuCr<sub>2</sub>O<sub>4</sub> on hydrogenolysis of glycerol

High activity of copper based catalysts for C-O bond hydro-dehydrogenation and their poor activity for C-C bond cleavage1 have prompted an attempt to apply such catalysts in the hydrogenolysis of glycerol to 1,2- and 1,3-propanediol. In the present study the influence of hydrogen reduction time of the Cu/Al2O3 and CuCr2O4 copper catalysts on glycerol conversion and selectivity of transformation to propanediols and by-products was studied. At first a general comparison was made between the commercial catalysts and those prepared by the co-precipitation method. As better results were obtained in the presence of catalysts prepared by co-precipitation, they were selected for further detailed studies of the influence of reduction time. For both prepared catalysts Cu/Al2O3 and CuCr2O4 the reduction time of 8 h was optimal. In the presence of Cu/Al2O3 catalyst the conversion of glycerol was 59.0%, selectivity of transformation to 1,2-propanediol 77.4% and selectivity to 1,3-propanediol 1.9%. In the presence of CuCr2O4 the glycerol conversion was 30.3% and selectivity to 1,2-propanediol 67.3%.

Keywords

  • hydrogenolysis
  • 1, 2-propanediol
  • 1, 3-propanediol
  • glycerol
Open Access

Electrically conductive acrylic pressure-sensitive adhesives containing carbon black

Published Online: 02 Jan 2012
Page range: 77 - 81

Abstract

Electrically conductive acrylic pressure-sensitive adhesives containing carbon black

Acrylic pressure-sensitive adhesives (PSA) are non electrical conductive materials. The electrical conductivity is incorporated into acrylic self-adhesive polymer after adding electrically conductive additives like carbon black, especially nano carbon black. After an addition of electrical conductive carbon black, the main and typical properties of pressure-sensitive adhesives such as tack, peel adhesion and shear strength, are deteriorated. The investigations reveals that the acrylic pressure-sensitive adhesives basis must be synthesised with ameliorated initial performances, like high tack, excellent adhesion and very good cohesion. Currently, the electrical conductive solvent-borne acrylic PSA containing carbon black are not commercially available on the market. They are promising materials which can be applied for the manufacturing of diverse technical high performance self-adhesive products, such as broadest line of special electrically conductive sensitive tapes.

Keywords

  • Acrylic pressure-sensitive adhesives
  • carbon black
  • electrical conductive materials
Open Access

Adsorption behavior of Pb(II) onto xanthated rubber (Hevea brasiliensis) leaf powder

Published Online: 02 Jan 2012
Page range: 84 - 88

Abstract

Adsorption behavior of Pb(II) onto xanthated rubber (<italic>Hevea brasiliensis</italic>) leaf powder

A plant waste, rubber (Hevea brasiliensis) leaf powder was modified with carbon disulfide (xanthation) for the purpose of introducing sulfur groups, and the adsorbent performance in removing Pb(II) ion was evaluated. Pb(II) adsorption was confirmed by spectroscopic analysis, which involved Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The amount of Pb(II) adsorbed increased with increasing pH, contact time and concentration but slightly decreased with increasing ionic strength. Adsorption equilibrium was achieved in less than 60 min and followed the pseudo-second order model. The isotherm data indicated that Pb(II) adsorption on xanthated rubber leaf (XRL) fitted well with Langmuir isotherm model. The maximum adsorption capacity computed from the Langmuir isotherm model was 166.7 mg/g. Pb(II) adsorption occurred via ion-exchange and complexation mechanisms.

Keywords

  • Adsorption
  • Isotherm
  • Kinetic
  • Lead
  • Xanthated rubber leaf powder
Open Access

Comments on "3-aminopropyltriethoxysilane functionalized nanoscale zero-valent iron for the removal of dyes from aqueous solution"

Published Online: 02 Jan 2012
Page range: 89 - 89

Abstract

Comments on "3-aminopropyltriethoxysilane functionalized nanoscale zero-valent iron for the removal of dyes from aqueous solution"

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