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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 20 (2018): Edizione 2 (June 2018)

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

15 Articoli
Accesso libero

Metals uptake behaviour in Miscanthus x giganteus plant during growth at the contaminated soil from the military site in Sliač, Slovakia

Pubblicato online: 25 Jul 2018
Pagine: 1 - 7

Astratto

Abstract

Peculiarities of metals uptake by the biofuel crop Miscanthus x giganteus were explored during plant growth at soil from the military site (Sliač, Slovakia). The experiment was carried out in greenhouse during two vegetation seasons. Research soil was predominantly elevated in Fe and Ti, while other metals (As, Cu, Mn, Sr, Zn and Zr) were presented at order of magnitude lower concentrations. No inhibition of plant growth was observed. The calculated Bioconcentration Factor showed that levels of metals’ accumulation by plant roots, stems and leaves were independent of metals’ concentrations in the soil. The accumulation of metals by stems and leaves was much lower than by roots. As, Zr, Ti were almost not accumulated by stems and leaves during both seasons; accumulation of Cu, Fe, Mn, Zn and Sr was not essential which confirmed that biomass of M. x giganteus might be processed for the energy purpose.

Parole chiave

  • military site
  • non-parametric statistics
  • metals uptake behavior
Accesso libero

Modification of substandard EPDM with amorphous thermoplastic polyesters (PETG and PEF): microstructure and physical properties

Pubblicato online: 25 Jul 2018
Pagine: 8 - 14

Astratto

Abstract

The phase morphology, thermal behavior and mechanical properties of two series of polymer blends based on ethylene/propylene/diene rubber (EPDM) and amorphous homologues of poly(ethylene terephthalate), i.e. glycol modified poly(ethylene terephthalate) (PETG) and poly(ethylene furanoate) (PEF), were investigated. The morphology of the blends shows a two phase structure in which the minor phase (amorphous polyester) is dispersed as domains in the major (EPDM) continuous matrix phase. Differential calorimetry studies confirmed that both systems were immiscible and exhibits two glass transitions. The melting peak area of EPDM in the blends decreased as the amount of the other component increased. The values of stress at strain of 100% were improved upon the increasing content of PETG in EPDM system, while only slight decrease of this value was observed. Moreover, the strong improvement of hardness and thermo-oxidative stability along with an increasing content of amorphous polyester phase was reported.

Parole chiave

  • polymer blends
  • substandard EPDM
  • PETG
  • PEF
  • phase morphology
  • mechanical properties
  • thermal stability
Accesso libero

Use of carbon and aluminosilicate nanofillers in XNBR composites designed for protective materials against oils

Pubblicato online: 25 Jul 2018
Pagine: 15 - 23

Astratto

Abstract

The objective of the work was to investigate the possibility of application of carbon and bentonite nanoparticles in carboxylated acrylonitrile-butadiene rubber (XNBR) and the related effects of the nanofillers on the structure, as well as mechanical and barrier properties, of the resulting composites. The composites were designed for use in protective clothing and gloves. XNBR compounds were modified with 2 phr of graphene flakes, graphene oxide, or modified bentonite, and crosslinked with sulfur-accelerator system. Rubber compounds were prepared using a conventional method with a laboratory rolling mill. The composites were studied in terms of structure (WAXS), surface morphology (AFM), the presence of functional groups (ATR-FTIR) barrier properties against chemical substances (mineral oil) and swelling properties, as well as mechanical properties (abrasion resistance and tensile strength). The composites were characterized by very high resistance to oil permeation (breakthrough time >480 min). The type of nanofiller added to the XNBR blend in the amount of 2 phr did not significantly affect mechanical parameters.

Parole chiave

  • carboxylated nitrile butadiene rubber
  • XNBR composites
  • graphene
  • graphene oxide
  • bentonite
Accesso libero

New bio-polyol based on white mustard seed oil for rigid PUR-PIR foams

Pubblicato online: 25 Jul 2018
Pagine: 24 - 31

Astratto

Abstract

A new bio-polyol based on white mustard oil (Synapis alba) and 2,2′-mercaptodiethanol (2,2′-MDE) was obtained. The synthesis was carried out by two-step method. In the first stage, the double bond of the unsaturated fatty acid residues was oxidized, and in the second step the epoxy rings were opened with 2,2’-MDE. The properties of the obtained bio-polyol for application as raw material in polyurethane-polyisocyanurate foams (PUR-PIR) - hydroxyl number, acid number, density, viscosity, pH, water content, FTIR, 1H NMR and 13C NMR were investigated. Based on the obtained results, foaming formulations containing 0 to 0.6 R of the new bio-polyol were prepared. Significant impact of bio-polyol on apparent density, compressive strength, brittleness, flammability, water absorption and thermal conductivity of polyurethane composites were noted. Modified foam had better functional properties than reference foam e.g. lower brittleness, better thermal insulation properties and better fire resistance.

Parole chiave

  • polyurethane foam
  • white mustard seed oil
  • 2,2’-mercaptodiethanol
  • bio-polyol
Accesso libero

Batch removal of Pb (ΙΙ) ions from aqueous medium using gamma-Al2O3 nanoparticles/ethyl cellulose adsorbent fabricated via electrospinning method: An equilibrium isotherm and characterization study

Pubblicato online: 25 Jul 2018
Pagine: 32 - 39

Astratto

Abstract

The aim of the present work is to study the efficiency of a biocompatible polymer-based adsorbent for the removal of Pb (II) ions whose devastating effects on people’s health is a matter of great concern from aqueous solution. In this study, ethyl cellulose and gamma-Al2O3 nanoparticles/ethyl cellulose electrospun adsorbents were prepared for the batch removal of Pb (II) ions from aqueous solution. Both samples were characterized using contact angle analysis, N2 adsorption/desorption technique, FT-IR and SEM. The Freundlich model (R-square = 0.935 and RMSD (%) = 6.659) and the Dubinin-Radushkevich model (R-square = 0.944 and RMSD (%) = 6.145) were found to be more reliable in predicting the experimental data from the adsorption of Pb (II) ions onto the electrospun gamma-Al2O3 nanoparticles/ethyl cellulose than the Langmuir model (R-square = 0.685 and RMSD (%) = 14.61) and also the Temkin model (R-square = 0.695 and RMSD (%) = 14.38).

Parole chiave

  • Adsorption
  • Pb (II) ions
  • Ethyl cellulose
  • Gamma-AlO nanoparticles
  • Electrospinning
Accesso libero

Extraction of rubidium and cesium from brine solutions using a room temperature ionic liquid system containing 18-crown-6

Pubblicato online: 25 Jul 2018
Pagine: 40 - 46

Astratto

Abstract

Application of 1-butyl-3-metyhlimidazaolium hexafluorophosphate ([C4mim][PF6]), in the extraction of rubidium and cesium from brine solutions using 1,4,7,10,13,16-hexaoxacyclooctadecane (18C6) as extractant was investigated. Parameters that affect the extraction including pH of aqueous phase, equilibration time, dosage of the ionic liquid, phase ratio, concentration of 18C6 were studied. Under the optimal conditions, the single extraction efficiency of rubidium ions and cesium ions were up 84.11% and 94.99%, respectively. The stripping of alkali metal ions from the loaded organic phase with different stripping agents and concentrations were also investigated. The initial value of the K/Cs and K/Rb ratios were 93.0 and 104.3, respectively, which have dropped 91.21% and 88.01%, respectively, after the extraction and stripping experiments. It was taken a big step in the separation and enrichment of cesium (rubidium) ion and potassium ion. The extraction mechanism was revealed most likely to be a cation exchange mode in this system.

Parole chiave

  • Rubidium
  • Cesium
  • Ionic liquid
  • 18-crown-6
  • Solvent extraction
Accesso libero

A novel DOPO-g-KH550 modification wood fibers and its effects on the properties of composite phenolic foams

Pubblicato online: 25 Jul 2018
Pagine: 47 - 53

Astratto

Abstract

A novel 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) graft γ-amino propyl triethoxy silane (KH550) was synthesized and introduced on the surface of wood fiber. Finally DOPO-g-KH550 treated wood fiber (DKTWF) was used to prepare DKTWF composite phenolic foams (DKTWFCPF). The structures of DOPO-g- KH550 was acknowledged by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (1H-NMR). The structures of DKTWF were confirmed by FT-IR. Compared with wood fiber, the diffraction peaks’ position was basically unchanged, but the crystallinity was slightly increased and thermal stability were dramatically improved, T5% and Tmax increased by 21.9o and 36.1o respectively. But the char yield (800o) was slightly reduced. With the dosage of DKWF, there were different degrees of improvement including the mechanical properties, flame retardancy and microstructure of DKTWFCPF. Comprehensive analysis, the interfacial compatibility was significantly improved between DKTWF and phenolic resin, and the suitable content of DKTWF was 4%.

Parole chiave

  • DOPO
  • Wood Fiber
  • Γ-amino propyl triethoxy silane
  • Composites
  • Characterization
Accesso libero

Production of (R)-styrene oxide by recombinant whole-cell biocatalyst in aqueous and biphasic system

Pubblicato online: 25 Jul 2018
Pagine: 54 - 60

Astratto

Abstract

The enantioselective resolution of racemic styrene oxide (rac-SO) to (R)-SO by whole cells of a recombinant Escherichia coli expressing epoxide hydrolase (EH) activity in aqueous and biphasic system were studied. Some parameters that may alter this bio-resolution, such as the concentration of recombinant cell, substrate and product were evaluated. The effect of the addition of different additives on the course of rac-SO biotransformation was also investigated. The results showed that the yield and the enantiomeric excess (ee) of (R)-SO were dependent on these variables. When the kinetic resolution was conducted with 350 mM of rac-SO, enantiopure (R)-SO with high (≥99%) ee was obtained with a yield of 38.2% yield at 12.2 h in the presence of 10% (v/v) Tween 80. An isooctane/aqueous system was developed to overcome the adverse factors in the aqueous phase, resulting in an improvement of yield from 38.2% to 42.9%. The results will provide a useful guidance for further application of this enzyme in the biocatalytic production of chiral synthons.

Parole chiave

  • Kinetic resolution
  • Epoxide hydrolase
  • Enantioselectivity
  • ()-styrene oxide
Accesso libero

Statistical optimization of the synthesis of plant-derived fatty acid esters of TMP over homogeneous organometallic tin catalyst

Pubblicato online: 25 Jul 2018
Pagine: 61 - 70

Astratto

Abstract

A class of very important industrial-grade biolubricants was synthesized from plant-derived fatty acids (oleic and isostearic acid) by direct esterification of trimethylolpropane according to novel effective and high selective method using Sn bis(2-ethylhexanoate) as catalyst. Model transesterification reactions were performed with oleic and isostearic acids to optimize the reaction conditions to obtain maximum content of TMP triesters. Used specific homogeneous Sn catalyst allows to obtain TMP esters with very high content of triesters, above of 94 wt% without deep vacuum purifying distillation. Both TMP esters were evaluated for their physicochemical and tribological properties using ASTM standards. Both TMP esters exhibited high viscosity indexes and excellent low temperature properties.

Parole chiave

  • tin catalyst
  • trimethylolpropane esters
  • statistical optimization
  • tribology
Accesso libero

Carbon nanotubes with controlled length – preparation, characterization and their cytocompatibility effects

Pubblicato online: 25 Jul 2018
Pagine: 71 - 79

Astratto

Abstract

Multiwalled carbon nanotubes (MWCNTs) have attracted huge attention due to their multifunctionality. Their unique properties allows for covalent and noncovalent modifications. The most simple method for functionalization of carbon nanotubes is their decoration with the oxygen containing moieties which can be further simultaneously functionalized for design of new class carriers for targeting and imaging. Here, we present methodology for chopping nanotubes, characterization of MWCNTs, the effect of size on the biocompatibility in culture of L929 mouse fibroblasts using WST-1, LDH and apoptosis assays. The analysis provides the optimal carbon nanotubes length and concentration which can be used for functionalization in order to minimize the effect of the secondary agglomeration when interacting with cells.

Parole chiave

  • Multiwalled carbon nanotubes
  • cutting carbon nanotubes
  • size effect
  • mitochondrial activity
  • biocompatibility
  • apoptosis
  • necrosis
Accesso libero

Removal of Pb(II) ions from aqueous solution using complexation-ultrafiltration

Pubblicato online: 25 Jul 2018
Pagine: 80 - 84

Astratto

Abstract

Ligand-modified micellar-enhanced ultrafiltration (LM-MEUF) is a membrane technique based on a separation process which can be used for removal of target metals from an aqueous solution. This method involves adding both a metal complexing ligand and surfactant molecule to the aqueous solution under conditions where most of the molecules are present as micelles. This ligand can be attached to the surface of micelles by solubilization and forms the ligand complexes with the metal ion. The aqueous solution is then treated through a membrane which has to be smaller pore sizes than those of the complexes. Hence, permeate water is then purified from the heavy metals. In this study, divalent lead is the target ion in a solution. Filtration experiments were performed with ultrafiltration membrane system, equipped with a regenerated cellulose membrane with a 5000 Daltons cutoff. The pressure was fixed at 4.0 bar with a permeate flow rate of 500 mL min−1. Complexes of Pb2+ ions with three ligands were investigated in micellar medium of different surfactants at different pH values to determine the ligands which could provide separation. Different parameters affecting the percentage rejection of the Pb2+, such as pH and surfactant concentration were also discussed. Results have shown that the maximum percentage of the Pb2+ ions rejection were obtained using sodium dodecyl sulfate (SDS) as a surfactant and dithizone (DZ) as the lead-specific ligand. A waste stream sample from a battery plant was subjected to LM-MEUF process in the optimum conditions determined in this study and it was shown that Pb2+ ions in a waste stream could be removed by LM-MEUF effectively.

Parole chiave

  • Ligand-modified MEUF
  • Pb ions
  • DZ
  • and SDS
Accesso libero

Synthesis, characterization of Hollandite Ag2Mn8O16 on TiO2 nanotubes and their photocatalytic properties for Rhodamine B degradation

Pubblicato online: 25 Jul 2018
Pagine: 85 - 91

Astratto

Abstract

In this research Ag2Mn8O16 nanocrystals/TiO2 nanotubes, photoelectrodes were successfully prepared through anodization and annihilation steps, followed by electrodeposition of MnO2 and Ag in a three electrodes cell. The obtained photoelectrodes were dried, then annealed for crystallization, the morphology and structure of the fabricated electrodes were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The light absorption and harvesting properties were investigated through UV–visible diffuse reflectance spectrum (DRS), photocatalytic performances were evaluated by degradation of 50 mL of Rhodamine B (5 mg L−1) under Xenon light irradiation for 2 h. Results illustrated that the fabricated photoelectrodes show remarkable photo-degradation properties of organic pollutants in aqueous mediums.

Parole chiave

  • Ag-MnO/TiO
  • AgMnO
  • nanotubes
  • nanocrystals
  • Photoelectrode
  • electrochemical deposition
  • Rhodamine B
  • Photo-catalytic efficiency
Accesso libero

Synthesis of a novel environmental friendly plasticizer based on tung oil fatty acid for poly (vinyl chloride) blends

Pubblicato online: 25 Jul 2018
Pagine: 92 - 97

Astratto

Abstract

A novel environmental friendly plasticizer (TPE) derived from tung oil fatty acid with long fatty acid chain and high degree of branching was synthesized. Chemical structure of the obtained TPE was characterized with Fourier transform infrared spectroscopy (FT-IR) and 1H NMR. TPE was used to prepare plasticized PVC blends as main plasticizer. Thermal stability, mechanical properties and migration resistance of poly (vinyl chloride) plasticized with TPE were investigated. The results showed that torque data of plasticized PVC blends reached 12.4 N·m when the mass of the TPE was 50 wt.%. TPE improved the thermal stability of PVC blends obviously than dioctyl phthalate (DOP). The leaching tests showed that PVC plasticized with TPE were with higher migration resistance than that of DOP. The excellent thermal stability and high migration resistance of PVC blends showed high application value for TPE.

Parole chiave

  • Synthesis
  • plasticizer
  • migration resistance
  • poly (vinyl chloride)
Accesso libero

Experiment and prediction of water content of sour natural gas with an modified cubic plus association equation of state

Pubblicato online: 25 Jul 2018
Pagine: 98 - 106

Astratto

Abstract

In this work, new experimental value for water content in sour natural gas were reported. In addition, to predict the water content in sour natural gas, a modified cubic plus association equation of state (CPA-EoS) was also proposed. In this model, a new energy parameter a was proposed to make an accurate description of saturated liquid density. Additionally, a temperature dependent binary interaction parameter kij for six binary systems was also obtained. Lastly, a comparison between the prediction results of the modified CPA-EoS and the experimental data was presented, and the results showed that the modified CPA-EoS could predict the water content in sour natural gas with high accuracy, which has an AAD of 3.6722% with experimental data in literatures and an AAD of 1.946% for experimental data reported in this work.

Parole chiave

  • water content
  • sour natural gas
  • CPA-EoS
  • binary interaction parameter
  • PR
Accesso libero

Degradation of sertraline in water by suspended and supported TiO2

Pubblicato online: 25 Jul 2018
Pagine: 107 - 112

Astratto

Abstract

Pharmaceutical pollutants have been detected in many countries in surface and ground water after treatment in wastewater treatment plants. The presented studies concern the photocatalytic removal of one of SSRI antidepressants - sertraline from water using TiO2 photocatalyst. The process was conducted using two laboratory installations with periodic and flow reactors. Two forms of TiO2 was used in the photocatalytic reactions: suspended and supported onto a glass fabric. The studies shown that with increasing initial concentration of pharmaceutical, photoactivity decreases. For the initial concentration of 0.025 g/dm3, the best results – 94% removal – was achieved for the process conducted in the periodic reactor with TiO2 supported onto a glass fabric.

Parole chiave

  • photocatalysis
  • titanium dioxide
  • pharmaceuticals
  • sertraline
  • water treatment
15 Articoli
Accesso libero

Metals uptake behaviour in Miscanthus x giganteus plant during growth at the contaminated soil from the military site in Sliač, Slovakia

Pubblicato online: 25 Jul 2018
Pagine: 1 - 7

Astratto

Abstract

Peculiarities of metals uptake by the biofuel crop Miscanthus x giganteus were explored during plant growth at soil from the military site (Sliač, Slovakia). The experiment was carried out in greenhouse during two vegetation seasons. Research soil was predominantly elevated in Fe and Ti, while other metals (As, Cu, Mn, Sr, Zn and Zr) were presented at order of magnitude lower concentrations. No inhibition of plant growth was observed. The calculated Bioconcentration Factor showed that levels of metals’ accumulation by plant roots, stems and leaves were independent of metals’ concentrations in the soil. The accumulation of metals by stems and leaves was much lower than by roots. As, Zr, Ti were almost not accumulated by stems and leaves during both seasons; accumulation of Cu, Fe, Mn, Zn and Sr was not essential which confirmed that biomass of M. x giganteus might be processed for the energy purpose.

Parole chiave

  • military site
  • non-parametric statistics
  • metals uptake behavior
Accesso libero

Modification of substandard EPDM with amorphous thermoplastic polyesters (PETG and PEF): microstructure and physical properties

Pubblicato online: 25 Jul 2018
Pagine: 8 - 14

Astratto

Abstract

The phase morphology, thermal behavior and mechanical properties of two series of polymer blends based on ethylene/propylene/diene rubber (EPDM) and amorphous homologues of poly(ethylene terephthalate), i.e. glycol modified poly(ethylene terephthalate) (PETG) and poly(ethylene furanoate) (PEF), were investigated. The morphology of the blends shows a two phase structure in which the minor phase (amorphous polyester) is dispersed as domains in the major (EPDM) continuous matrix phase. Differential calorimetry studies confirmed that both systems were immiscible and exhibits two glass transitions. The melting peak area of EPDM in the blends decreased as the amount of the other component increased. The values of stress at strain of 100% were improved upon the increasing content of PETG in EPDM system, while only slight decrease of this value was observed. Moreover, the strong improvement of hardness and thermo-oxidative stability along with an increasing content of amorphous polyester phase was reported.

Parole chiave

  • polymer blends
  • substandard EPDM
  • PETG
  • PEF
  • phase morphology
  • mechanical properties
  • thermal stability
Accesso libero

Use of carbon and aluminosilicate nanofillers in XNBR composites designed for protective materials against oils

Pubblicato online: 25 Jul 2018
Pagine: 15 - 23

Astratto

Abstract

The objective of the work was to investigate the possibility of application of carbon and bentonite nanoparticles in carboxylated acrylonitrile-butadiene rubber (XNBR) and the related effects of the nanofillers on the structure, as well as mechanical and barrier properties, of the resulting composites. The composites were designed for use in protective clothing and gloves. XNBR compounds were modified with 2 phr of graphene flakes, graphene oxide, or modified bentonite, and crosslinked with sulfur-accelerator system. Rubber compounds were prepared using a conventional method with a laboratory rolling mill. The composites were studied in terms of structure (WAXS), surface morphology (AFM), the presence of functional groups (ATR-FTIR) barrier properties against chemical substances (mineral oil) and swelling properties, as well as mechanical properties (abrasion resistance and tensile strength). The composites were characterized by very high resistance to oil permeation (breakthrough time >480 min). The type of nanofiller added to the XNBR blend in the amount of 2 phr did not significantly affect mechanical parameters.

Parole chiave

  • carboxylated nitrile butadiene rubber
  • XNBR composites
  • graphene
  • graphene oxide
  • bentonite
Accesso libero

New bio-polyol based on white mustard seed oil for rigid PUR-PIR foams

Pubblicato online: 25 Jul 2018
Pagine: 24 - 31

Astratto

Abstract

A new bio-polyol based on white mustard oil (Synapis alba) and 2,2′-mercaptodiethanol (2,2′-MDE) was obtained. The synthesis was carried out by two-step method. In the first stage, the double bond of the unsaturated fatty acid residues was oxidized, and in the second step the epoxy rings were opened with 2,2’-MDE. The properties of the obtained bio-polyol for application as raw material in polyurethane-polyisocyanurate foams (PUR-PIR) - hydroxyl number, acid number, density, viscosity, pH, water content, FTIR, 1H NMR and 13C NMR were investigated. Based on the obtained results, foaming formulations containing 0 to 0.6 R of the new bio-polyol were prepared. Significant impact of bio-polyol on apparent density, compressive strength, brittleness, flammability, water absorption and thermal conductivity of polyurethane composites were noted. Modified foam had better functional properties than reference foam e.g. lower brittleness, better thermal insulation properties and better fire resistance.

Parole chiave

  • polyurethane foam
  • white mustard seed oil
  • 2,2’-mercaptodiethanol
  • bio-polyol
Accesso libero

Batch removal of Pb (ΙΙ) ions from aqueous medium using gamma-Al2O3 nanoparticles/ethyl cellulose adsorbent fabricated via electrospinning method: An equilibrium isotherm and characterization study

Pubblicato online: 25 Jul 2018
Pagine: 32 - 39

Astratto

Abstract

The aim of the present work is to study the efficiency of a biocompatible polymer-based adsorbent for the removal of Pb (II) ions whose devastating effects on people’s health is a matter of great concern from aqueous solution. In this study, ethyl cellulose and gamma-Al2O3 nanoparticles/ethyl cellulose electrospun adsorbents were prepared for the batch removal of Pb (II) ions from aqueous solution. Both samples were characterized using contact angle analysis, N2 adsorption/desorption technique, FT-IR and SEM. The Freundlich model (R-square = 0.935 and RMSD (%) = 6.659) and the Dubinin-Radushkevich model (R-square = 0.944 and RMSD (%) = 6.145) were found to be more reliable in predicting the experimental data from the adsorption of Pb (II) ions onto the electrospun gamma-Al2O3 nanoparticles/ethyl cellulose than the Langmuir model (R-square = 0.685 and RMSD (%) = 14.61) and also the Temkin model (R-square = 0.695 and RMSD (%) = 14.38).

Parole chiave

  • Adsorption
  • Pb (II) ions
  • Ethyl cellulose
  • Gamma-AlO nanoparticles
  • Electrospinning
Accesso libero

Extraction of rubidium and cesium from brine solutions using a room temperature ionic liquid system containing 18-crown-6

Pubblicato online: 25 Jul 2018
Pagine: 40 - 46

Astratto

Abstract

Application of 1-butyl-3-metyhlimidazaolium hexafluorophosphate ([C4mim][PF6]), in the extraction of rubidium and cesium from brine solutions using 1,4,7,10,13,16-hexaoxacyclooctadecane (18C6) as extractant was investigated. Parameters that affect the extraction including pH of aqueous phase, equilibration time, dosage of the ionic liquid, phase ratio, concentration of 18C6 were studied. Under the optimal conditions, the single extraction efficiency of rubidium ions and cesium ions were up 84.11% and 94.99%, respectively. The stripping of alkali metal ions from the loaded organic phase with different stripping agents and concentrations were also investigated. The initial value of the K/Cs and K/Rb ratios were 93.0 and 104.3, respectively, which have dropped 91.21% and 88.01%, respectively, after the extraction and stripping experiments. It was taken a big step in the separation and enrichment of cesium (rubidium) ion and potassium ion. The extraction mechanism was revealed most likely to be a cation exchange mode in this system.

Parole chiave

  • Rubidium
  • Cesium
  • Ionic liquid
  • 18-crown-6
  • Solvent extraction
Accesso libero

A novel DOPO-g-KH550 modification wood fibers and its effects on the properties of composite phenolic foams

Pubblicato online: 25 Jul 2018
Pagine: 47 - 53

Astratto

Abstract

A novel 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) graft γ-amino propyl triethoxy silane (KH550) was synthesized and introduced on the surface of wood fiber. Finally DOPO-g-KH550 treated wood fiber (DKTWF) was used to prepare DKTWF composite phenolic foams (DKTWFCPF). The structures of DOPO-g- KH550 was acknowledged by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (1H-NMR). The structures of DKTWF were confirmed by FT-IR. Compared with wood fiber, the diffraction peaks’ position was basically unchanged, but the crystallinity was slightly increased and thermal stability were dramatically improved, T5% and Tmax increased by 21.9o and 36.1o respectively. But the char yield (800o) was slightly reduced. With the dosage of DKWF, there were different degrees of improvement including the mechanical properties, flame retardancy and microstructure of DKTWFCPF. Comprehensive analysis, the interfacial compatibility was significantly improved between DKTWF and phenolic resin, and the suitable content of DKTWF was 4%.

Parole chiave

  • DOPO
  • Wood Fiber
  • Γ-amino propyl triethoxy silane
  • Composites
  • Characterization
Accesso libero

Production of (R)-styrene oxide by recombinant whole-cell biocatalyst in aqueous and biphasic system

Pubblicato online: 25 Jul 2018
Pagine: 54 - 60

Astratto

Abstract

The enantioselective resolution of racemic styrene oxide (rac-SO) to (R)-SO by whole cells of a recombinant Escherichia coli expressing epoxide hydrolase (EH) activity in aqueous and biphasic system were studied. Some parameters that may alter this bio-resolution, such as the concentration of recombinant cell, substrate and product were evaluated. The effect of the addition of different additives on the course of rac-SO biotransformation was also investigated. The results showed that the yield and the enantiomeric excess (ee) of (R)-SO were dependent on these variables. When the kinetic resolution was conducted with 350 mM of rac-SO, enantiopure (R)-SO with high (≥99%) ee was obtained with a yield of 38.2% yield at 12.2 h in the presence of 10% (v/v) Tween 80. An isooctane/aqueous system was developed to overcome the adverse factors in the aqueous phase, resulting in an improvement of yield from 38.2% to 42.9%. The results will provide a useful guidance for further application of this enzyme in the biocatalytic production of chiral synthons.

Parole chiave

  • Kinetic resolution
  • Epoxide hydrolase
  • Enantioselectivity
  • ()-styrene oxide
Accesso libero

Statistical optimization of the synthesis of plant-derived fatty acid esters of TMP over homogeneous organometallic tin catalyst

Pubblicato online: 25 Jul 2018
Pagine: 61 - 70

Astratto

Abstract

A class of very important industrial-grade biolubricants was synthesized from plant-derived fatty acids (oleic and isostearic acid) by direct esterification of trimethylolpropane according to novel effective and high selective method using Sn bis(2-ethylhexanoate) as catalyst. Model transesterification reactions were performed with oleic and isostearic acids to optimize the reaction conditions to obtain maximum content of TMP triesters. Used specific homogeneous Sn catalyst allows to obtain TMP esters with very high content of triesters, above of 94 wt% without deep vacuum purifying distillation. Both TMP esters were evaluated for their physicochemical and tribological properties using ASTM standards. Both TMP esters exhibited high viscosity indexes and excellent low temperature properties.

Parole chiave

  • tin catalyst
  • trimethylolpropane esters
  • statistical optimization
  • tribology
Accesso libero

Carbon nanotubes with controlled length – preparation, characterization and their cytocompatibility effects

Pubblicato online: 25 Jul 2018
Pagine: 71 - 79

Astratto

Abstract

Multiwalled carbon nanotubes (MWCNTs) have attracted huge attention due to their multifunctionality. Their unique properties allows for covalent and noncovalent modifications. The most simple method for functionalization of carbon nanotubes is their decoration with the oxygen containing moieties which can be further simultaneously functionalized for design of new class carriers for targeting and imaging. Here, we present methodology for chopping nanotubes, characterization of MWCNTs, the effect of size on the biocompatibility in culture of L929 mouse fibroblasts using WST-1, LDH and apoptosis assays. The analysis provides the optimal carbon nanotubes length and concentration which can be used for functionalization in order to minimize the effect of the secondary agglomeration when interacting with cells.

Parole chiave

  • Multiwalled carbon nanotubes
  • cutting carbon nanotubes
  • size effect
  • mitochondrial activity
  • biocompatibility
  • apoptosis
  • necrosis
Accesso libero

Removal of Pb(II) ions from aqueous solution using complexation-ultrafiltration

Pubblicato online: 25 Jul 2018
Pagine: 80 - 84

Astratto

Abstract

Ligand-modified micellar-enhanced ultrafiltration (LM-MEUF) is a membrane technique based on a separation process which can be used for removal of target metals from an aqueous solution. This method involves adding both a metal complexing ligand and surfactant molecule to the aqueous solution under conditions where most of the molecules are present as micelles. This ligand can be attached to the surface of micelles by solubilization and forms the ligand complexes with the metal ion. The aqueous solution is then treated through a membrane which has to be smaller pore sizes than those of the complexes. Hence, permeate water is then purified from the heavy metals. In this study, divalent lead is the target ion in a solution. Filtration experiments were performed with ultrafiltration membrane system, equipped with a regenerated cellulose membrane with a 5000 Daltons cutoff. The pressure was fixed at 4.0 bar with a permeate flow rate of 500 mL min−1. Complexes of Pb2+ ions with three ligands were investigated in micellar medium of different surfactants at different pH values to determine the ligands which could provide separation. Different parameters affecting the percentage rejection of the Pb2+, such as pH and surfactant concentration were also discussed. Results have shown that the maximum percentage of the Pb2+ ions rejection were obtained using sodium dodecyl sulfate (SDS) as a surfactant and dithizone (DZ) as the lead-specific ligand. A waste stream sample from a battery plant was subjected to LM-MEUF process in the optimum conditions determined in this study and it was shown that Pb2+ ions in a waste stream could be removed by LM-MEUF effectively.

Parole chiave

  • Ligand-modified MEUF
  • Pb ions
  • DZ
  • and SDS
Accesso libero

Synthesis, characterization of Hollandite Ag2Mn8O16 on TiO2 nanotubes and their photocatalytic properties for Rhodamine B degradation

Pubblicato online: 25 Jul 2018
Pagine: 85 - 91

Astratto

Abstract

In this research Ag2Mn8O16 nanocrystals/TiO2 nanotubes, photoelectrodes were successfully prepared through anodization and annihilation steps, followed by electrodeposition of MnO2 and Ag in a three electrodes cell. The obtained photoelectrodes were dried, then annealed for crystallization, the morphology and structure of the fabricated electrodes were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The light absorption and harvesting properties were investigated through UV–visible diffuse reflectance spectrum (DRS), photocatalytic performances were evaluated by degradation of 50 mL of Rhodamine B (5 mg L−1) under Xenon light irradiation for 2 h. Results illustrated that the fabricated photoelectrodes show remarkable photo-degradation properties of organic pollutants in aqueous mediums.

Parole chiave

  • Ag-MnO/TiO
  • AgMnO
  • nanotubes
  • nanocrystals
  • Photoelectrode
  • electrochemical deposition
  • Rhodamine B
  • Photo-catalytic efficiency
Accesso libero

Synthesis of a novel environmental friendly plasticizer based on tung oil fatty acid for poly (vinyl chloride) blends

Pubblicato online: 25 Jul 2018
Pagine: 92 - 97

Astratto

Abstract

A novel environmental friendly plasticizer (TPE) derived from tung oil fatty acid with long fatty acid chain and high degree of branching was synthesized. Chemical structure of the obtained TPE was characterized with Fourier transform infrared spectroscopy (FT-IR) and 1H NMR. TPE was used to prepare plasticized PVC blends as main plasticizer. Thermal stability, mechanical properties and migration resistance of poly (vinyl chloride) plasticized with TPE were investigated. The results showed that torque data of plasticized PVC blends reached 12.4 N·m when the mass of the TPE was 50 wt.%. TPE improved the thermal stability of PVC blends obviously than dioctyl phthalate (DOP). The leaching tests showed that PVC plasticized with TPE were with higher migration resistance than that of DOP. The excellent thermal stability and high migration resistance of PVC blends showed high application value for TPE.

Parole chiave

  • Synthesis
  • plasticizer
  • migration resistance
  • poly (vinyl chloride)
Accesso libero

Experiment and prediction of water content of sour natural gas with an modified cubic plus association equation of state

Pubblicato online: 25 Jul 2018
Pagine: 98 - 106

Astratto

Abstract

In this work, new experimental value for water content in sour natural gas were reported. In addition, to predict the water content in sour natural gas, a modified cubic plus association equation of state (CPA-EoS) was also proposed. In this model, a new energy parameter a was proposed to make an accurate description of saturated liquid density. Additionally, a temperature dependent binary interaction parameter kij for six binary systems was also obtained. Lastly, a comparison between the prediction results of the modified CPA-EoS and the experimental data was presented, and the results showed that the modified CPA-EoS could predict the water content in sour natural gas with high accuracy, which has an AAD of 3.6722% with experimental data in literatures and an AAD of 1.946% for experimental data reported in this work.

Parole chiave

  • water content
  • sour natural gas
  • CPA-EoS
  • binary interaction parameter
  • PR
Accesso libero

Degradation of sertraline in water by suspended and supported TiO2

Pubblicato online: 25 Jul 2018
Pagine: 107 - 112

Astratto

Abstract

Pharmaceutical pollutants have been detected in many countries in surface and ground water after treatment in wastewater treatment plants. The presented studies concern the photocatalytic removal of one of SSRI antidepressants - sertraline from water using TiO2 photocatalyst. The process was conducted using two laboratory installations with periodic and flow reactors. Two forms of TiO2 was used in the photocatalytic reactions: suspended and supported onto a glass fabric. The studies shown that with increasing initial concentration of pharmaceutical, photoactivity decreases. For the initial concentration of 0.025 g/dm3, the best results – 94% removal – was achieved for the process conducted in the periodic reactor with TiO2 supported onto a glass fabric.

Parole chiave

  • photocatalysis
  • titanium dioxide
  • pharmaceuticals
  • sertraline
  • water treatment

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