Rivista e Edizione

Volume 24 (2022): Edizione 3 (September 2022)

Volume 24 (2022): Edizione 2 (June 2022)

Volume 24 (2022): Edizione 1 (March 2022)

Volume 23 (2021): Edizione 4 (December 2021)

Volume 23 (2021): Edizione 3 (September 2021)

Volume 23 (2021): Edizione 2 (June 2021)

Volume 23 (2021): Edizione 1 (March 2021)

Volume 22 (2020): Edizione 4 (December 2020)

Volume 22 (2020): Edizione 3 (September 2020)

Volume 22 (2020): Edizione 2 (June 2020)

Volume 22 (2020): Edizione 1 (March 2020)

Volume 21 (2019): Edizione 4 (December 2019)

Volume 21 (2019): Edizione 3 (September 2019)

Volume 21 (2019): Edizione 2 (June 2019)

Volume 21 (2019): Edizione 1 (March 2019)

Volume 20 (2018): Edizione 4 (December 2018)

Volume 20 (2018): Edizione 3 (September 2018)

Volume 20 (2018): Edizione 2 (June 2018)

Volume 20 (2018): Edizione 1 (March 2018)

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

Volume 19 (2017): Edizione 3 (September 2017)

Volume 19 (2017): Edizione 2 (June 2017)

Volume 19 (2017): Edizione 1 (March 2017)

Volume 18 (2016): Edizione 4 (December 2016)

Volume 18 (2016): Edizione 3 (September 2016)

Volume 18 (2016): Edizione 2 (June 2016)

Volume 18 (2016): Edizione 1 (March 2016)

Volume 17 (2015): Edizione 4 (December 2015)

Volume 17 (2015): Edizione 3 (September 2015)

Volume 17 (2015): Edizione 2 (June 2015)

Volume 17 (2015): Edizione 1 (March 2015)

Volume 16 (2014): Edizione 4 (December 2014)

Volume 16 (2014): Edizione 3 (September 2014)

Volume 16 (2014): Edizione 2 (June 2014)

Volume 16 (2014): Edizione 1 (March 2014)

Volume 15 (2013): Edizione 4 (December 2013)

Volume 15 (2013): Edizione 3 (September 2013)

Volume 15 (2013): Edizione 1 (March 2013)

Volume 14 (2012): Edizione 4 (December 2012)

Volume 14 (2012): Edizione 3 (October 2012)

Volume 14 (2012): Edizione 2 (June 2012)

Volume 14 (2012): Edizione 1 (March 2012)

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

Volume 13 (2011): Edizione 3 (September 2011)

Volume 13 (2011): Edizione 2 (June 2011)

Volume 13 (2011): Edizione 1 (March 2011)

Volume 12 (2010): Edizione 4 (December 2010)

Volume 12 (2010): Edizione 3 (September 2010)

Volume 12 (2010): Edizione 2 (June 2010)

Volume 12 (2010): Edizione 1 (March 2010)

Volume 11 (2009): Edizione 4 (December 2009)

Volume 11 (2009): Edizione 3 (September 2009)

Volume 11 (2009): Edizione 2 (June 2009)

Volume 11 (2009): Edizione 1 (March 2009)

Volume 10 (2008): Edizione 4 (December 2008)

Volume 10 (2008): Edizione 3 (September 2008)

Volume 10 (2008): Edizione 2 (June 2008)

Volume 10 (2008): Edizione 1 (March 2008)

Volume 9 (2007): Edizione 4 (December 2007)

Volume 9 (2007): Edizione 3 (September 2007)

Volume 9 (2007): Edizione 2 (June 2007)

Volume 9 (2007): Edizione 1 (March 2007)

Dettagli della rivista
Formato
Rivista
eISSN
1899-4741
Pubblicato per la prima volta
03 Jul 2007
Periodo di pubblicazione
4 volte all'anno
Lingue
Inglese

Cerca

Volume 16 (2014): Edizione 4 (December 2014)

Dettagli della rivista
Formato
Rivista
eISSN
1899-4741
Pubblicato per la prima volta
03 Jul 2007
Periodo di pubblicazione
4 volte all'anno
Lingue
Inglese

Cerca

20 Articoli
Accesso libero

The influence of pH adjusted with different acids on the dyeability of polyester fabric

Pubblicato online: 11 Dec 2014
Pagine: 1 - 5

Astratto

Abstract

The influence of using formic, oxalic, citric, tartaric, hydrochloric, nitric, sulphuric and phosphoric acid for dyebath pH adjustment was investigated upon the dyeing of polyester fabric with CI Disperse Yellow 60. The positions of colour in CIELab coordinates of the samples dyed with the addition of tested acids were assessed and compared to those dyed with the addition of acetic acid. It was found that the differences in dyeabilities obtained with the addition of citric, oxalic, hydrochloric, nitric and sulphuric acid are entirely acceptable according to both M&S 83A and CMC (2:1) standards in comparison to the dyeability obtained with the addition of acetic acid.

Keywords

  • polyester
  • dyeing
  • disperse dyes
  • pH
  • acids
Accesso libero

Nano sized carbonized waste biomass for heavy metal ion remediation

Pubblicato online: 11 Dec 2014
Pagine: 6 - 13

Astratto

Abstract

Utilization of agricultural waste material with approach to enhance the heavy metal remediation properties by carbonizing the biomass at nano size particles has been explored in present investigation from aqueous solutions. In this study the lignocellulosic, nitrogenous agricultural waste biomass Delbergia sissoo pods (DSP) has been tried for sequestering of Cd (II), Pb (II) and Ni (II) metal ions from aqueous solutions. Batch experiments were performed for removal of targeted metal ions keeping in consideration the preliminary affecting parameters such as effect of adsorption dose, pH, initial metal ion concentration, stirring speed and contact time. The sorption studies were analyzed by using, Freundlic isotherm and Langmuir isotherm models. The kinetics of the process was evaluated by pseudo pseudo-first order and pseudo second order kinetic models. Studies reveal that the equilibrium was achieved with in 30 min of the contact time at optimized parameters. Analytical studies of biosorbent were done by means of FT-IR, SEM and XRD. Desorption experiments were carried out using HCl solution with a view to regenerate the spent adsorbent and to recover the adsorbed metal ions.

Keywords

  • nitrogenous waste materials
  • carbon
  • heavy metal ions
  • kinetic studies
  • Delbergia sisso pods
Accesso libero

Polyurethanes from the crystalline prepolymers resistant to abrasive wear

Pubblicato online: 11 Dec 2014
Pagine: 14 - 20

Astratto

Abstract

The research aimed at the selection of polyurethanes synthesized from poly(tetramethylene ether) glycol (PTMEG), as well as from two different isocyanates 4,4′-methylenebis(cyclohexyl)isocyanate (HMDI) and 4.4′-methylenebis(phenyl isocyanate) (MDI) in order to obtain polyurethane with increased resistance to abrasive wear and degradation for bio-medical application. Polyurethanes were fabricated from crystalline prepolymers extended by water. The paper presents preliminary results on polyurethane surface wettability, friction coefficient for different couples of the co-working materials such as polyurethane-polyurethane, polyurethane-titanium alloy, polyurethane-alumina, in comparison to commonly used polyethylene-titanium alloy. Shear strength of polyurethane-alumina joint, as well as viscosity of prepolymers were also measured. The values of friction coefficient were compared to literature data on commercially available polyurethane with the trade name Pellethane. Polyurethanes obtained are characterized by low abrasive wear and low friction coefficient in couple with the titanium alloy, what makes them attractive as possible components of ceramic-polymer endoprosthesis joints.

Keywords

  • polyurethane
  • crystalline prepolymer
  • abrasive wear
  • adhesion
  • friction coefficient
  • endoprosthesis
Accesso libero

Study on the improvement of hydrophilic character on polyvinylalcohol treated polyester fabric

Pubblicato online: 11 Dec 2014
Pagine: 21 - 27

Astratto

Abstract

Polyester fabric was treated with polyvinyl alcohol in alkaline medium. The moisture regain, water retention and wettability of the PVA treated polyester fabric were tested. The PVA treated PET fabric was dyed with disperse dye. The presence of PVA in the treated PET fabric was assessed by spot test. The treated fabric was also characterized by scanning electron microscope, FTIR and differential scanning calorimetry. The PVA treated polyester fabric showed improved hydrophilic character over intact and sodium hydroxide treated PET fabrics.

Keywords

  • Polyester fabric
  • PVA
  • SEM
  • FTIR
  • DSC
  • hydrophilic character
Accesso libero

The heat insulating properties of potato starch extruded with addition of chosen by- products of food industry

Pubblicato online: 11 Dec 2014
Pagine: 28 - 32

Astratto

Abstract

The study was aimed at determination of time of heat transition through the layer of quince, apple, linen, rose pomace and potato pulp, as well as layer of potato starch and potato starch extruded with addition of above mentioned by-products. Additionally the attempt of creation a heat insulating barrier from researched raw material was made. The heat conductivity of researched materials was dependent on the type of material and its humidity. Extruded potato starch is characterized by smaller heat conductivity than potato starch extruded with addition of pomace. The obtained rigid extruded starch moulders were characterized by higher heat insulating properties than the loose beads. It is possible to use starch and by-products of food industry for production of heat insulating materials.

Keywords

  • potato starch
  • extruded potato starch
  • fruit pomace
  • potato pulp
  • heat insulation
Accesso libero

Adsorption of anionic dyes onto natural, thermally and chemically modified smectite clays

Pubblicato online: 11 Dec 2014
Pagine: 33 - 40

Astratto

Abstract

The aim of this study was to determine the adsorption capacity of the smectite clays (from the overburden of the lignite deposit in Belchatow) for two anionic dyes, i.e. Reactive Blue 81 (RB-81) and Direct Blue 74 (DB-74). Additionally, the influence of the thermal and chemical (acid and alkali) clay modifications on the amount of bonded dyes was investigated. The adsorption capacity of the clay (natural and modified) was different for studied dyes and depended on the initial concentration and modification type. All the modified clays adsorbed the dyes at pH>pHPZC as the negatively charged surfaces of their particles (in accordance with the formula: AOH ↔ AO- + H+) prevented the formation of electrostatic bonds between the anionic dyes and the clay surface. The dyes were mainly bound with the hydrogen bonds forming between the donor groups in the dyes and the acceptor groups (-SiO and -Al2OH) in the clays. The coefficients in the adsorption isotherms were estimated with the linear and non-linear regression. The linear regression method was found that the Freundlich and Dubinin-Radushkevich isotherms described the dye sorption much better than the Langmuir model. On the other hand, all three models described well the experimental data in the non-linear regression method. Furthermore, the 1/n value (<1) obtained from the Freundlich equation for all the dye-sorbent systems indicated the favorable sorption.

Keywords

  • smectite clay
  • modified clay
  • Reactive Blue 81
  • Direct Blue 74
  • sorption isotherms
  • linear regression
  • non-linear regression
Accesso libero

Modification of Salix americana willow bark for removal of heavy metal ions from aqueous solutions

Pubblicato online: 11 Dec 2014
Pagine: 41 - 44

Astratto

Abstract

Salix americana willow bark is a waste arising in the process of wicker decortication that so far has not found any practical application. The bark can adsorb metal ions, because in its composition among others are phenolic groups which may be involved in the removal of metal ions from water solutions. The results of sorption of copper(II) and zinc(II) on modified willow bark of Salix americana were presented. The bark was modified with nitric and sulfuric acids at concentrations ranging from 5 to 15%. The best adsorption results were obtained using 15% nitric acid for modification. Adsorption of metal ions from aqueous solutions at concentrations raging from 20 to 100 mg/dm3 was studied. It was found that an increase in the initial concentration of copper(II) and zinc(II) resulted in an increase in their adsorption on the modified cortex.

Keywords

  • waste
  • adsorption
  • heavy metals
  • willow bark
  • methods of modification
Accesso libero

Influence of expanded graphite (EG) and graphene oxide (GO) on physical properties of PET based nanocomposites

Pubblicato online: 11 Dec 2014
Pagine: 45 - 50

Astratto

Abstract

This work is the continuation and refinement of already published communications based on PET/EG nanocomposites prepared by in situ polymerization1, 2. In this study, nanocomposites based on poly(ethylene terephthalate) with expanded graphite were compared to those with functionalized graphite sheets (GO). The results suggest that the degree of dispersion of nanoparticles in the PET matrix has important effect on the structure and physical properties of the nanocomposites. The existence of graphene sheets nanoparticles enhances the crystallization rate of PET. It has been confirmed that in situ polymerization is the effective method for preparation nanocomposites which can avoid the agglomeration of nanoparticles in polymer matrices and improve the interfacial interaction between nanofiller and polymer matrix. The obtained results have shown also that due to the presence of functional groups on GO surface the interactions with PET matrix can be stronger than in the case of exfoliated graphene (EG) and matrix.

Keywords

  • in situ polymerization
  • PET
  • graphene oxide
  • expanded graphite
Accesso libero

The effect of selected supercritical CO2 plant extract addition on user properties of shower gels

Pubblicato online: 11 Dec 2014
Pagine: 51 - 54

Astratto

Abstract

The formulations of washing cosmetics i.e. shower gels, containing extracts obtained during supercritical CO2 extraction process as active ingredient, were developed. The subject of the study was the analysis of the physicochemical and user properties of the obtained products. In the work supercritical CO2 extracts of black currant seeds, strawberry seeds, hop cones and mint leafs were used. The formulation contains a mixture of surfactants (disodium cocoamphodiacetate, disodium laureth sulfosuccinate, cocoamide DEA, cocoamidepropyl betaine, Sodium Laureth Sulfate). Various thickener agents were applied to the obtained desired rheological properties of the cosmetics. Among others, sorbitol acetal derivatives, methylhydroxypropylcellulose and C10-30 alkyl acrylate crosspolymer were used. For stable products, the effect of extracts addition (black currants seeds, strawberries seeds, mint and hops, obtained from supercritical CO2 extraction process) on the cosmetics properties, such as pH, viscosity, detergency and foam ability, were determined. The obtained results showed that the extracts could be used as components of shower gels.

Keywords

  • supercritical CO2 extract
  • black currant seeds
  • strawberry seeds
  • hop cones
  • mint leafs
  • shower gel
Accesso libero

Ozone decomposition on ZnO catalysts obtained from different precursors

Pubblicato online: 11 Dec 2014
Pagine: 55 - 59

Astratto

Abstract

Kinetic investigations for ozone conversion on three different series of zinc oxide catalysts, containing pure ZnO and doped with Mn or Cu one with dopant content less than 1 wt.% were carried out. The different samples were obtained from carbonate, nitrate and acetate precursors. The as prepared catalysts were characterized by AAS, XRD, IR, EPR and BET methods. The mean size of the crystallites determined by XRD data is in the range 27÷68 nm. The presence of Mn2+ and Cu2+ ions into the ZnO matrix was established by EPR. The ozone decomposition was investigated for 30÷75°C temperature range. The zinc carbonate precursor samples show highest activity, while the nitrate precursor ones show lowest activity toward reaction decomposition of ozone in the whole temperature range. At 75°C two of the catalyst, obtained from carbonate precursor - ZnO and CuZnO show 100% conversion.

Keywords

  • ozone decomposition
  • zinc oxide catalyst
  • manganese doping
  • copper doping
  • nanosize
Accesso libero

An experimental study on drying characteristics and kinetics of figs (Ficuscarica)

Pubblicato online: 11 Dec 2014
Pagine: 60 - 65

Astratto

Abstract

In this study, the thin-layer drying characteristics of Figs (Ficus carica) are investigated in a pilot scale forced convective dryer. Experiments carried out under various operating conditions including air temperature (40, 50, 60, 70°C), air velocity (0.65, 2.1, 3.45, 4.85 m/s) and air humidity (0.005, 0.010, 0.015 kg/kg) and the effects of these operating conditions on the drying kinetics and the drying time determined. The obtained kinetics data are fitted into a conceptually developed model. The equilibrium moisture content of the dried figs is determined at different values of temperature and relative humidity of air. The values of effective moisture diffusivity (Deff) are obtained from the Fick’s second law and a temperature-dependent relation is proposed for this parameter.

Keywords

  • drying kinetics
  • figs
  • effective diffusivity
  • equilibrium moisture content
  • drying
Accesso libero

Time requirements in closed and open batch distillation arrangements for separation of a binary mixture

Pubblicato online: 11 Dec 2014
Pagine: 66 - 74

Astratto

Abstract

Batch time requirements are provided for the separation of binary zeotropic mixtures in two different multivessel columns (with and without vapor bypass), a non-cyclic two-vessel column and a regular batch column based on dynamic simulations. The first three columns are operated as closed (total reflux) systems and the regular batch column is operated as an open (partial reflux) system. We analyze the effects of feed composition, relative volatility and product specification on the time requirements. The multivessel arrangements perform better than the regular batch column, which requires from 4.00 to 34.67% more time to complete a given separation. The elimination of the vapor bypass in the multivessel column is impractical though it has a positive effect on the batch time requirements. Thus, the multivessel column, with the vapor stream bypassing the intermediate vessel, is proposed as the best candidate for a binary zeotropic mixture with low concentration of light component, low relative volatility and high product purity demand. Furthermore, an experimental multivessel column with vapor bypass is built and the corresponding experiments verify the simulations.

Keywords

  • time requirements
  • closed operation
  • multivessel column
  • binary mixture
Accesso libero

Thermal stability for the effective use of commercial catalase

Pubblicato online: 11 Dec 2014
Pagine: 75 - 79

Astratto

Abstract

Catalase with the commercial catalase name Terminox Ultra is widely used in the textile industry in bleaching processes. This enzyme is used to catalyse the decomposition of residual hydrogen peroxide into oxygen and water. In this study catalase was kept for about 30 hours in water baths in a temperature range from 35 to 70°C. For the first time, the kinetics of thermal deactivation of this enzyme was examined using an oxygen electrode. Stability of the enzyme depends strongly on temperature and its half-life times are 0.0014 h and 7.6 h, at 35 and 70°C, respectively.

Keywords

  • catalase
  • Terminox Ultra
  • thermal deactivation
  • energy of thermal deactivation
  • hydrogen peroxide
Accesso libero

Behavior of arsenic in hydrometallurgical zinc production and environmental impact

Pubblicato online: 11 Dec 2014
Pagine: 80 - 86

Astratto

Abstract

The presence of arsenic in zinc sulphide concentrates is particularly harmful, because it creates problems in zinc electrolysis. The main source of arsenic in non-ferrous metallurgy is arsenopyrite (FeAsS). In oxidative roasting of zinc concentrates, FeAsS oxidizes to arsenic oxides (As2O3, As2O5). In this connection a natural FeAsS was examined, and also the distribution of arsenic in the products of the roasting process, the cycle of sulphuric acid obtaining and the leaching of zinc calcine were studied. The arsenic contamination of soils in the vicinity of nonferrous metals smelter KCM SA, Plovdiv, Bulgaria as a result of zinc and lead productions has been studied.

Keywords

  • arsenic
  • arsenopyrite
  • zinc concentrates
  • roasting
  • leaching
Accesso libero

Simulation and sensitivity analysis for heavy linear paraffins production in LAB production Plant

Pubblicato online: 11 Dec 2014
Pagine: 87 - 94

Astratto

Abstract

Linear alkyl benzene (LAB) is vastly utilized for the production of biodegradable detergents and emulsifiers. Predistillation unit is a part of LAB production plant in which that produced heavy linear paraffins (nC10-nC13). In this study, a mathematical model has been developed for heavy linear paraffins production in distillation columns, which has been solved using a commercial code. The models have been validated by the actual data. The effects of process parameters such as reflux rate, and reflux temperature using Gradient Search technique has been investigated. The sensitivity analysis shows that optimum reflux in columns are achieved.

Keywords

  • LAB plant
  • pre-distillation unit
  • columns
  • sensitivity analysis
  • commercial code
Accesso libero

Impact of heating rate and solvent on Ni-based catalysts prepared by solution combustion method for syngas methanation

Pubblicato online: 11 Dec 2014
Pagine: 95 - 100

Astratto

Abstract

Ni-Al2O3 catalysts prepared by solution combustion method for syngas methanation were enhanced by employing various heating rate and different solvent. The catalytic properties were tested in syngas methanation. The result indicates that both of heating rate and solvent remarkably affect Ni particle size, which is a key factor to the catalytic activity of Ni-Al2O3 catalysts for syngas methanation. Moreover, the relationship between Ni particle size and the production rate of methane per unit mass was correlated. The optimal Ni-Al2O3 catalyst prepared in ethanol at 2°C/min, achieves a maximum production rate of methane at the mean size of 20.8 nm.

Keywords

  • nickel catalysts
  • syngas methanation
  • solution combustion method
Accesso libero

Hydrodechlorination of tetrachloromethane over silica-supported palladium-gold alloys

Pubblicato online: 11 Dec 2014
Pagine: 101 - 105

Astratto

Abstract

Compared with the monometallic palladium, bimetallic Pd-Au/SiO2 catalysts show much higher activity and better stability in the reaction of hydrodechlorination of tetrachloromethane, also providing higher selectivity to longer than methane hydrocarbon products. Reasonably mixed Pd-Au particles show better catalytic performance during ~60 h operation, whereas the monometallic palladium and very rich in palladium catalysts suffer rapid deactivation. Smaller amounts of carbon- and chlorine-containing deposits found after reaction on Pd-Au catalysts correspond to their superior catalytic behavior.

Keywords

  • Pd-Au/SiO2
  • CCl4 hydrodechlorination
  • synergy
  • selectivity for hydrocarbons
  • catalyst deactivation
Accesso libero

Effect of the ruthenium loading and barium addition on the activity of ruthenium/carbon catalysts in carbon monoxide methanation

Pubblicato online: 11 Dec 2014
Pagine: 106 - 110

Astratto

Abstract

A group of supported ruthenium catalysts was prepared and tested in methanation of small CO amounts (7000 ppm) in hydrogen-rich streams. High surface area graphitized carbon (484 m2/g) was used as a support for ruthenium and RuCl3 was used as a Ru precursor. Some of the Ru/C systems were additionally doped with barium (Ba(NO3)2 was barium precursor). The catalysts were characterized by the chemisorption technique using CO as an adsorbate. To determine the resistance of the catalysts to undesired carbon support methanation, the TG-MS experiments were performed. They revealed that the barium addition inhibits support losses. The studies of CO methanation (fl ow reactor, atmospheric pressure) have shown that some of the supported ruthenium catalysts exhibit high activities referred to the metal mass. The catalytic properties of ruthenium proved to be dependent on metal dispersion. Some of the Ru/C and Ba-Ru/C systems exhibit higher activity in CO hydrogenation than the commercial nickel-based catalyst.

Keywords

  • CO methanation
  • ruthenium catalyst
  • barium
  • carbon support
Accesso libero

Characterization of FeCo based catalyst for ammonia decomposition. The effect of potassium oxide

Pubblicato online: 11 Dec 2014
Pagine: 111 - 116

Astratto

Abstract

FeCo fused catalyst was obtained by fusing iron and cobalt oxides with an addition of calcium, aluminium, and potassium oxides (CaO, Al2O3, K2O). An additional amount of potassium oxide was inserted by wet impregnation. Chemical composition of the prepared catalysts was determined with an aid of the XRF method. On the basis of XRD analysis it was found that cobalt was built into the structure of magnetite and solid solution of CoFe2O4 was formed. An increase in potassium content develops surface area of the reduced form of the catalyst, number of adsorption sites for hydrogen, and the ammonia decomposition rate. The nitriding process of the catalyst slows down the ammonia decomposition.

Keywords

  • ammonia decomposition
  • hydrogen
  • FeCo catalyst
Accesso libero

The study of glycerol-based fermentation and broth downstream by nanofiltration

Pubblicato online: 11 Dec 2014
Pagine: 117 - 122

Astratto

Abstract

In this work, the glycerol fermentation was carried out using Citrobacter freundii bacteria. The influence of glycerol and metabolites concentrations, and the pH changes on the efficiency of 1,3-propanediol production, during batch and fed-batch processes, was presented. The nanofiltration was used for the separation of obtained post-fermentation solutions. The resulted 1,3-PD solutions were significantly desalted, which may facilitate further downstream processes during 1,3-PD production.

Keywords

  • glycerol fermentation
  • 1,3-propanediol
  • nanofiltration
  • Citrobacter freundii
20 Articoli
Accesso libero

The influence of pH adjusted with different acids on the dyeability of polyester fabric

Pubblicato online: 11 Dec 2014
Pagine: 1 - 5

Astratto

Abstract

The influence of using formic, oxalic, citric, tartaric, hydrochloric, nitric, sulphuric and phosphoric acid for dyebath pH adjustment was investigated upon the dyeing of polyester fabric with CI Disperse Yellow 60. The positions of colour in CIELab coordinates of the samples dyed with the addition of tested acids were assessed and compared to those dyed with the addition of acetic acid. It was found that the differences in dyeabilities obtained with the addition of citric, oxalic, hydrochloric, nitric and sulphuric acid are entirely acceptable according to both M&S 83A and CMC (2:1) standards in comparison to the dyeability obtained with the addition of acetic acid.

Keywords

  • polyester
  • dyeing
  • disperse dyes
  • pH
  • acids
Accesso libero

Nano sized carbonized waste biomass for heavy metal ion remediation

Pubblicato online: 11 Dec 2014
Pagine: 6 - 13

Astratto

Abstract

Utilization of agricultural waste material with approach to enhance the heavy metal remediation properties by carbonizing the biomass at nano size particles has been explored in present investigation from aqueous solutions. In this study the lignocellulosic, nitrogenous agricultural waste biomass Delbergia sissoo pods (DSP) has been tried for sequestering of Cd (II), Pb (II) and Ni (II) metal ions from aqueous solutions. Batch experiments were performed for removal of targeted metal ions keeping in consideration the preliminary affecting parameters such as effect of adsorption dose, pH, initial metal ion concentration, stirring speed and contact time. The sorption studies were analyzed by using, Freundlic isotherm and Langmuir isotherm models. The kinetics of the process was evaluated by pseudo pseudo-first order and pseudo second order kinetic models. Studies reveal that the equilibrium was achieved with in 30 min of the contact time at optimized parameters. Analytical studies of biosorbent were done by means of FT-IR, SEM and XRD. Desorption experiments were carried out using HCl solution with a view to regenerate the spent adsorbent and to recover the adsorbed metal ions.

Keywords

  • nitrogenous waste materials
  • carbon
  • heavy metal ions
  • kinetic studies
  • Delbergia sisso pods
Accesso libero

Polyurethanes from the crystalline prepolymers resistant to abrasive wear

Pubblicato online: 11 Dec 2014
Pagine: 14 - 20

Astratto

Abstract

The research aimed at the selection of polyurethanes synthesized from poly(tetramethylene ether) glycol (PTMEG), as well as from two different isocyanates 4,4′-methylenebis(cyclohexyl)isocyanate (HMDI) and 4.4′-methylenebis(phenyl isocyanate) (MDI) in order to obtain polyurethane with increased resistance to abrasive wear and degradation for bio-medical application. Polyurethanes were fabricated from crystalline prepolymers extended by water. The paper presents preliminary results on polyurethane surface wettability, friction coefficient for different couples of the co-working materials such as polyurethane-polyurethane, polyurethane-titanium alloy, polyurethane-alumina, in comparison to commonly used polyethylene-titanium alloy. Shear strength of polyurethane-alumina joint, as well as viscosity of prepolymers were also measured. The values of friction coefficient were compared to literature data on commercially available polyurethane with the trade name Pellethane. Polyurethanes obtained are characterized by low abrasive wear and low friction coefficient in couple with the titanium alloy, what makes them attractive as possible components of ceramic-polymer endoprosthesis joints.

Keywords

  • polyurethane
  • crystalline prepolymer
  • abrasive wear
  • adhesion
  • friction coefficient
  • endoprosthesis
Accesso libero

Study on the improvement of hydrophilic character on polyvinylalcohol treated polyester fabric

Pubblicato online: 11 Dec 2014
Pagine: 21 - 27

Astratto

Abstract

Polyester fabric was treated with polyvinyl alcohol in alkaline medium. The moisture regain, water retention and wettability of the PVA treated polyester fabric were tested. The PVA treated PET fabric was dyed with disperse dye. The presence of PVA in the treated PET fabric was assessed by spot test. The treated fabric was also characterized by scanning electron microscope, FTIR and differential scanning calorimetry. The PVA treated polyester fabric showed improved hydrophilic character over intact and sodium hydroxide treated PET fabrics.

Keywords

  • Polyester fabric
  • PVA
  • SEM
  • FTIR
  • DSC
  • hydrophilic character
Accesso libero

The heat insulating properties of potato starch extruded with addition of chosen by- products of food industry

Pubblicato online: 11 Dec 2014
Pagine: 28 - 32

Astratto

Abstract

The study was aimed at determination of time of heat transition through the layer of quince, apple, linen, rose pomace and potato pulp, as well as layer of potato starch and potato starch extruded with addition of above mentioned by-products. Additionally the attempt of creation a heat insulating barrier from researched raw material was made. The heat conductivity of researched materials was dependent on the type of material and its humidity. Extruded potato starch is characterized by smaller heat conductivity than potato starch extruded with addition of pomace. The obtained rigid extruded starch moulders were characterized by higher heat insulating properties than the loose beads. It is possible to use starch and by-products of food industry for production of heat insulating materials.

Keywords

  • potato starch
  • extruded potato starch
  • fruit pomace
  • potato pulp
  • heat insulation
Accesso libero

Adsorption of anionic dyes onto natural, thermally and chemically modified smectite clays

Pubblicato online: 11 Dec 2014
Pagine: 33 - 40

Astratto

Abstract

The aim of this study was to determine the adsorption capacity of the smectite clays (from the overburden of the lignite deposit in Belchatow) for two anionic dyes, i.e. Reactive Blue 81 (RB-81) and Direct Blue 74 (DB-74). Additionally, the influence of the thermal and chemical (acid and alkali) clay modifications on the amount of bonded dyes was investigated. The adsorption capacity of the clay (natural and modified) was different for studied dyes and depended on the initial concentration and modification type. All the modified clays adsorbed the dyes at pH>pHPZC as the negatively charged surfaces of their particles (in accordance with the formula: AOH ↔ AO- + H+) prevented the formation of electrostatic bonds between the anionic dyes and the clay surface. The dyes were mainly bound with the hydrogen bonds forming between the donor groups in the dyes and the acceptor groups (-SiO and -Al2OH) in the clays. The coefficients in the adsorption isotherms were estimated with the linear and non-linear regression. The linear regression method was found that the Freundlich and Dubinin-Radushkevich isotherms described the dye sorption much better than the Langmuir model. On the other hand, all three models described well the experimental data in the non-linear regression method. Furthermore, the 1/n value (<1) obtained from the Freundlich equation for all the dye-sorbent systems indicated the favorable sorption.

Keywords

  • smectite clay
  • modified clay
  • Reactive Blue 81
  • Direct Blue 74
  • sorption isotherms
  • linear regression
  • non-linear regression
Accesso libero

Modification of Salix americana willow bark for removal of heavy metal ions from aqueous solutions

Pubblicato online: 11 Dec 2014
Pagine: 41 - 44

Astratto

Abstract

Salix americana willow bark is a waste arising in the process of wicker decortication that so far has not found any practical application. The bark can adsorb metal ions, because in its composition among others are phenolic groups which may be involved in the removal of metal ions from water solutions. The results of sorption of copper(II) and zinc(II) on modified willow bark of Salix americana were presented. The bark was modified with nitric and sulfuric acids at concentrations ranging from 5 to 15%. The best adsorption results were obtained using 15% nitric acid for modification. Adsorption of metal ions from aqueous solutions at concentrations raging from 20 to 100 mg/dm3 was studied. It was found that an increase in the initial concentration of copper(II) and zinc(II) resulted in an increase in their adsorption on the modified cortex.

Keywords

  • waste
  • adsorption
  • heavy metals
  • willow bark
  • methods of modification
Accesso libero

Influence of expanded graphite (EG) and graphene oxide (GO) on physical properties of PET based nanocomposites

Pubblicato online: 11 Dec 2014
Pagine: 45 - 50

Astratto

Abstract

This work is the continuation and refinement of already published communications based on PET/EG nanocomposites prepared by in situ polymerization1, 2. In this study, nanocomposites based on poly(ethylene terephthalate) with expanded graphite were compared to those with functionalized graphite sheets (GO). The results suggest that the degree of dispersion of nanoparticles in the PET matrix has important effect on the structure and physical properties of the nanocomposites. The existence of graphene sheets nanoparticles enhances the crystallization rate of PET. It has been confirmed that in situ polymerization is the effective method for preparation nanocomposites which can avoid the agglomeration of nanoparticles in polymer matrices and improve the interfacial interaction between nanofiller and polymer matrix. The obtained results have shown also that due to the presence of functional groups on GO surface the interactions with PET matrix can be stronger than in the case of exfoliated graphene (EG) and matrix.

Keywords

  • in situ polymerization
  • PET
  • graphene oxide
  • expanded graphite
Accesso libero

The effect of selected supercritical CO2 plant extract addition on user properties of shower gels

Pubblicato online: 11 Dec 2014
Pagine: 51 - 54

Astratto

Abstract

The formulations of washing cosmetics i.e. shower gels, containing extracts obtained during supercritical CO2 extraction process as active ingredient, were developed. The subject of the study was the analysis of the physicochemical and user properties of the obtained products. In the work supercritical CO2 extracts of black currant seeds, strawberry seeds, hop cones and mint leafs were used. The formulation contains a mixture of surfactants (disodium cocoamphodiacetate, disodium laureth sulfosuccinate, cocoamide DEA, cocoamidepropyl betaine, Sodium Laureth Sulfate). Various thickener agents were applied to the obtained desired rheological properties of the cosmetics. Among others, sorbitol acetal derivatives, methylhydroxypropylcellulose and C10-30 alkyl acrylate crosspolymer were used. For stable products, the effect of extracts addition (black currants seeds, strawberries seeds, mint and hops, obtained from supercritical CO2 extraction process) on the cosmetics properties, such as pH, viscosity, detergency and foam ability, were determined. The obtained results showed that the extracts could be used as components of shower gels.

Keywords

  • supercritical CO2 extract
  • black currant seeds
  • strawberry seeds
  • hop cones
  • mint leafs
  • shower gel
Accesso libero

Ozone decomposition on ZnO catalysts obtained from different precursors

Pubblicato online: 11 Dec 2014
Pagine: 55 - 59

Astratto

Abstract

Kinetic investigations for ozone conversion on three different series of zinc oxide catalysts, containing pure ZnO and doped with Mn or Cu one with dopant content less than 1 wt.% were carried out. The different samples were obtained from carbonate, nitrate and acetate precursors. The as prepared catalysts were characterized by AAS, XRD, IR, EPR and BET methods. The mean size of the crystallites determined by XRD data is in the range 27÷68 nm. The presence of Mn2+ and Cu2+ ions into the ZnO matrix was established by EPR. The ozone decomposition was investigated for 30÷75°C temperature range. The zinc carbonate precursor samples show highest activity, while the nitrate precursor ones show lowest activity toward reaction decomposition of ozone in the whole temperature range. At 75°C two of the catalyst, obtained from carbonate precursor - ZnO and CuZnO show 100% conversion.

Keywords

  • ozone decomposition
  • zinc oxide catalyst
  • manganese doping
  • copper doping
  • nanosize
Accesso libero

An experimental study on drying characteristics and kinetics of figs (Ficuscarica)

Pubblicato online: 11 Dec 2014
Pagine: 60 - 65

Astratto

Abstract

In this study, the thin-layer drying characteristics of Figs (Ficus carica) are investigated in a pilot scale forced convective dryer. Experiments carried out under various operating conditions including air temperature (40, 50, 60, 70°C), air velocity (0.65, 2.1, 3.45, 4.85 m/s) and air humidity (0.005, 0.010, 0.015 kg/kg) and the effects of these operating conditions on the drying kinetics and the drying time determined. The obtained kinetics data are fitted into a conceptually developed model. The equilibrium moisture content of the dried figs is determined at different values of temperature and relative humidity of air. The values of effective moisture diffusivity (Deff) are obtained from the Fick’s second law and a temperature-dependent relation is proposed for this parameter.

Keywords

  • drying kinetics
  • figs
  • effective diffusivity
  • equilibrium moisture content
  • drying
Accesso libero

Time requirements in closed and open batch distillation arrangements for separation of a binary mixture

Pubblicato online: 11 Dec 2014
Pagine: 66 - 74

Astratto

Abstract

Batch time requirements are provided for the separation of binary zeotropic mixtures in two different multivessel columns (with and without vapor bypass), a non-cyclic two-vessel column and a regular batch column based on dynamic simulations. The first three columns are operated as closed (total reflux) systems and the regular batch column is operated as an open (partial reflux) system. We analyze the effects of feed composition, relative volatility and product specification on the time requirements. The multivessel arrangements perform better than the regular batch column, which requires from 4.00 to 34.67% more time to complete a given separation. The elimination of the vapor bypass in the multivessel column is impractical though it has a positive effect on the batch time requirements. Thus, the multivessel column, with the vapor stream bypassing the intermediate vessel, is proposed as the best candidate for a binary zeotropic mixture with low concentration of light component, low relative volatility and high product purity demand. Furthermore, an experimental multivessel column with vapor bypass is built and the corresponding experiments verify the simulations.

Keywords

  • time requirements
  • closed operation
  • multivessel column
  • binary mixture
Accesso libero

Thermal stability for the effective use of commercial catalase

Pubblicato online: 11 Dec 2014
Pagine: 75 - 79

Astratto

Abstract

Catalase with the commercial catalase name Terminox Ultra is widely used in the textile industry in bleaching processes. This enzyme is used to catalyse the decomposition of residual hydrogen peroxide into oxygen and water. In this study catalase was kept for about 30 hours in water baths in a temperature range from 35 to 70°C. For the first time, the kinetics of thermal deactivation of this enzyme was examined using an oxygen electrode. Stability of the enzyme depends strongly on temperature and its half-life times are 0.0014 h and 7.6 h, at 35 and 70°C, respectively.

Keywords

  • catalase
  • Terminox Ultra
  • thermal deactivation
  • energy of thermal deactivation
  • hydrogen peroxide
Accesso libero

Behavior of arsenic in hydrometallurgical zinc production and environmental impact

Pubblicato online: 11 Dec 2014
Pagine: 80 - 86

Astratto

Abstract

The presence of arsenic in zinc sulphide concentrates is particularly harmful, because it creates problems in zinc electrolysis. The main source of arsenic in non-ferrous metallurgy is arsenopyrite (FeAsS). In oxidative roasting of zinc concentrates, FeAsS oxidizes to arsenic oxides (As2O3, As2O5). In this connection a natural FeAsS was examined, and also the distribution of arsenic in the products of the roasting process, the cycle of sulphuric acid obtaining and the leaching of zinc calcine were studied. The arsenic contamination of soils in the vicinity of nonferrous metals smelter KCM SA, Plovdiv, Bulgaria as a result of zinc and lead productions has been studied.

Keywords

  • arsenic
  • arsenopyrite
  • zinc concentrates
  • roasting
  • leaching
Accesso libero

Simulation and sensitivity analysis for heavy linear paraffins production in LAB production Plant

Pubblicato online: 11 Dec 2014
Pagine: 87 - 94

Astratto

Abstract

Linear alkyl benzene (LAB) is vastly utilized for the production of biodegradable detergents and emulsifiers. Predistillation unit is a part of LAB production plant in which that produced heavy linear paraffins (nC10-nC13). In this study, a mathematical model has been developed for heavy linear paraffins production in distillation columns, which has been solved using a commercial code. The models have been validated by the actual data. The effects of process parameters such as reflux rate, and reflux temperature using Gradient Search technique has been investigated. The sensitivity analysis shows that optimum reflux in columns are achieved.

Keywords

  • LAB plant
  • pre-distillation unit
  • columns
  • sensitivity analysis
  • commercial code
Accesso libero

Impact of heating rate and solvent on Ni-based catalysts prepared by solution combustion method for syngas methanation

Pubblicato online: 11 Dec 2014
Pagine: 95 - 100

Astratto

Abstract

Ni-Al2O3 catalysts prepared by solution combustion method for syngas methanation were enhanced by employing various heating rate and different solvent. The catalytic properties were tested in syngas methanation. The result indicates that both of heating rate and solvent remarkably affect Ni particle size, which is a key factor to the catalytic activity of Ni-Al2O3 catalysts for syngas methanation. Moreover, the relationship between Ni particle size and the production rate of methane per unit mass was correlated. The optimal Ni-Al2O3 catalyst prepared in ethanol at 2°C/min, achieves a maximum production rate of methane at the mean size of 20.8 nm.

Keywords

  • nickel catalysts
  • syngas methanation
  • solution combustion method
Accesso libero

Hydrodechlorination of tetrachloromethane over silica-supported palladium-gold alloys

Pubblicato online: 11 Dec 2014
Pagine: 101 - 105

Astratto

Abstract

Compared with the monometallic palladium, bimetallic Pd-Au/SiO2 catalysts show much higher activity and better stability in the reaction of hydrodechlorination of tetrachloromethane, also providing higher selectivity to longer than methane hydrocarbon products. Reasonably mixed Pd-Au particles show better catalytic performance during ~60 h operation, whereas the monometallic palladium and very rich in palladium catalysts suffer rapid deactivation. Smaller amounts of carbon- and chlorine-containing deposits found after reaction on Pd-Au catalysts correspond to their superior catalytic behavior.

Keywords

  • Pd-Au/SiO2
  • CCl4 hydrodechlorination
  • synergy
  • selectivity for hydrocarbons
  • catalyst deactivation
Accesso libero

Effect of the ruthenium loading and barium addition on the activity of ruthenium/carbon catalysts in carbon monoxide methanation

Pubblicato online: 11 Dec 2014
Pagine: 106 - 110

Astratto

Abstract

A group of supported ruthenium catalysts was prepared and tested in methanation of small CO amounts (7000 ppm) in hydrogen-rich streams. High surface area graphitized carbon (484 m2/g) was used as a support for ruthenium and RuCl3 was used as a Ru precursor. Some of the Ru/C systems were additionally doped with barium (Ba(NO3)2 was barium precursor). The catalysts were characterized by the chemisorption technique using CO as an adsorbate. To determine the resistance of the catalysts to undesired carbon support methanation, the TG-MS experiments were performed. They revealed that the barium addition inhibits support losses. The studies of CO methanation (fl ow reactor, atmospheric pressure) have shown that some of the supported ruthenium catalysts exhibit high activities referred to the metal mass. The catalytic properties of ruthenium proved to be dependent on metal dispersion. Some of the Ru/C and Ba-Ru/C systems exhibit higher activity in CO hydrogenation than the commercial nickel-based catalyst.

Keywords

  • CO methanation
  • ruthenium catalyst
  • barium
  • carbon support
Accesso libero

Characterization of FeCo based catalyst for ammonia decomposition. The effect of potassium oxide

Pubblicato online: 11 Dec 2014
Pagine: 111 - 116

Astratto

Abstract

FeCo fused catalyst was obtained by fusing iron and cobalt oxides with an addition of calcium, aluminium, and potassium oxides (CaO, Al2O3, K2O). An additional amount of potassium oxide was inserted by wet impregnation. Chemical composition of the prepared catalysts was determined with an aid of the XRF method. On the basis of XRD analysis it was found that cobalt was built into the structure of magnetite and solid solution of CoFe2O4 was formed. An increase in potassium content develops surface area of the reduced form of the catalyst, number of adsorption sites for hydrogen, and the ammonia decomposition rate. The nitriding process of the catalyst slows down the ammonia decomposition.

Keywords

  • ammonia decomposition
  • hydrogen
  • FeCo catalyst
Accesso libero

The study of glycerol-based fermentation and broth downstream by nanofiltration

Pubblicato online: 11 Dec 2014
Pagine: 117 - 122

Astratto

Abstract

In this work, the glycerol fermentation was carried out using Citrobacter freundii bacteria. The influence of glycerol and metabolites concentrations, and the pH changes on the efficiency of 1,3-propanediol production, during batch and fed-batch processes, was presented. The nanofiltration was used for the separation of obtained post-fermentation solutions. The resulted 1,3-PD solutions were significantly desalted, which may facilitate further downstream processes during 1,3-PD production.

Keywords

  • glycerol fermentation
  • 1,3-propanediol
  • nanofiltration
  • Citrobacter freundii

Pianifica la tua conferenza remota con Sciendo