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

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

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

Search

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

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

Search

7 Articles
access type Open Access

(-)-Menthol-β-cyclodextrin inclusion complex production and characterization

Published Online: 20 Jul 2022
Page range: 1 - 7

Abstract

Abstract

(-)-Menthol has been widely used in clinical medicine, flavor, and fragrance. However, high volatility, short retention time, low solubility in water, and whisker growth of menthol are crucial problems for its application. In this paper, (-)-menthol-β-cyclodextrin inclusion complex was fabricated to solve these problems. The product was characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The results showed that menthol was successfully encapsulated in the cavity of β-cyclodextrin. Menthol itself vaporized almost completely at around 120 oC, while the maximum menthol release rate occurred at 267.5 oC after the formation of the inclusion complex. The stability and retention time were improved. The menthol release reaction order, apparent activation energy and the pre-exponential factor were obtained and their values were 0, 142.9 kJ/mol and 1.6 × 1013 respectively. The structure of menthol-β-cyclodextrin inclusion complex was investigated by molecular simulation and the minimum energy, –116.7 kJ/mol, was obtained at –0.8 × 10–10 m.

Keywords

  • Menthol-β-cyclodextrin inclusion complex
  • Preparation
  • Characterization
  • Kinetics
  • Molecular mechanics
access type Open Access

Retrofitting Heat Exchanger Network of Industrial Ethylene Glycol Plant using Heat Integration based on Pinch Analysis

Published Online: 20 Jul 2022
Page range: 8 - 20

Abstract

Abstract

Heat integration by pinch method is used to modify the heat exchanger network of an industrial ethylene glycol plant. The aim is to reduce the energy cost by operating the plant close to the maximum energy recovery. Pinch analysis identified a pinch temperature of 483 K, a minimum heating utility of 13,490.9 MJ/ton EO, and a minimum cooling utility of 25,697 MJ/ton EO. Using the pinch decomposition diagram and the standard procedure for matching hot and cold streams, a retrofit of the heat exchangers network is developed. The modified heat exchanger network reduces the external cooling duty by 45.5% and the external heating duty by 93.3%. This promising cost savings provide enough justification for restructuring the existing ethylene glycol plant. Moreover, an additional 6% reduction in the external cooling duty can be achieved by integrating the steam turbine below the pinch point.

Keywords

  • Heat Integration
  • Pinch Analysis
  • Ethylene Glycol
  • Minimum Utility
access type Open Access

Study on synthesis and photoelectric properties of AgInS2 quantum dots

Published Online: 20 Jul 2022
Page range: 21 - 26

Abstract

Abstract

AgInS2 Quantum dots (AIS QDs) have high quantum yield and catalytic performance, which is promising materials in photo-catalytic and optoelectronic fields. In the paper, it adopted a simple and non-toxic method to synthesize AIS QDs. The effect of reaction temperature on the growth mechanism, optical and physical properties of AIS had been extensively investigated by using L-cysteine as the sulfur source, and their application in catalytic hydrogen production was also studied. The results demonstrated that the fluorescence properties will be quenched with the increase of temperature, indicating that the separation speed of electron hole pairs of samples obtained at higher temperature was faster. Meantime, the electron transport capacity and the photocurrent had also improved with the increase of reaction temperature. Finally, the sample obtained at 100 oC had higher hydrogen production rate.

Keywords

  • AgInS
  • Quantum dots
  • Optical properties
  • Photocatalytic hydrogen production
access type Open Access

Enhancement of Thermal Stability, Conductivity and Smoke Suppression of Polyethylene Composites with Exfoliated MoS2 Functionalized with Magnetite

Published Online: 20 Jul 2022
Page range: 27 - 34

Abstract

Abstract

This work reports a facile fabrication method to modify exfoliated molybdenum disulfide (e-MoS2) nanosheets with magnetite nanoparticles with various size distribution. The obtained materials have been utilized as nanofillers of polyethylene to enhance its thermal properties and flame retardance. The incorporation of magnetite modified MoS2 nanosheets leads to the reduction of the peak heat release rate. The best thermal conductivity has been noticed for composites with e-MoS2/Fe3O4 with 2 wt. % of nanofillers. The lowest CO emission was observed for the PE/e-MoS2 composite containing also 2 wt. % of Fe3O4. All composites with exfoliated MoS2 exhibited greater thermal properties in respect to the pristine polyethylene.

Keywords

  • flammability
  • polyethylene
  • molybdenum disulfide nanocomposites
  • flame retardants
access type Open Access

Estimation of the upper flammability limits for alkanes in air at increased pressures

Published Online: 20 Jul 2022
Page range: 35 - 41

Abstract

Abstract

A method is proposed to predict the upper flammability limits for alkanes in air at increased pressures. The upper flammability limits for methane, ethane, propane and n-butane/air mixtures at ambient temperature and initial pressure of 0.3 MPa–2.0 MPa are identified through the adiabatic flame temperature calculation model. The association of calculated adiabatic flame temperature with pressure is presented to determine the upper flammability limit. Research shows the good agreement between the forecast upper flammability limits with pressure dependence and the experimental upper flammability limit values. The average relative error of the estimated upper flammability limits for alkanes in air at high pressures reaches 2.52%.

Keywords

  • Upper flammability limit
  • Adiabatic flame temperature
  • High pressure
  • Alkanes
access type Open Access

The analysis of pressure drop, spray angle, and sprinkling intensity distribution in the spray stream produced by the water-foam nozzle

Published Online: 20 Jul 2022
Page range: 42 - 49

Abstract

Abstract

This paper summarises a series of large-scale fire suppression tests conducted to simulate a fire in the big surface and/or surface sprinkling. The subject of this paper is the research on water spraying with the use of the Turbo Jet 2011 water-foam nozzle manufactured by Supon Białystok. The results discuss the pressure losses caused by the flow through the discharge hose, spray angle, and the intensity of surface sprinkling. The greatest stream ranges and the highest maximum values of the sprinkling intensity were obtained at the capacity of 400 l/min, and a solid spray angle. The smallest values were obtained at 200 l/min, a pressure of 5 bar, and a solid spray angle. The actual pressures taking into account the losses in the hose section were calculated. As for the highest firefighting effectiveness of the stream, the authors recommended the following parameters: semi spray angle, 200 l/min, and 2.5 bar.

Keywords

  • fire safety
  • harvest fire prevention
  • atomization
  • spraying intensity
  • pressure drops
access type Open Access

High performance fluidized bed photoreactor for ethylene decomposition

Published Online: 20 Jul 2022
Page range: 50 - 56

Abstract

Abstract

Removal of C2H4 in the air was carried out in the continuous flow reactor with the photocatalytic bed (expanded polystyrene spheres coated by TiO2 or SiO2/TiO2) under irradiation of UV light. Continuous flow of a gas stream through the reactor was realised at the static bed and under bed fluidization. The required flow of a gas stream through the reactor for bed fluidisation was 500–700 ml/min, whereas for the static bed the flow rate of 20 ml/min was used. Fluidized bed reactor appeared to be much more efficient in ethylene removal than that with the stationary bed. It was caused by the increased speed of C2H4 mass transfer to the photocatalyst surface and better utilization of the incident UV light. In the fluidized bed reactor calculated rate of C2H4 degradation was around 10 μg/min whereas in the stationary state 1.2 μg/min only.

Keywords

  • ethylene degradation
  • photocatalytic bed reactor
  • fluidization
  • TiO
7 Articles
access type Open Access

(-)-Menthol-β-cyclodextrin inclusion complex production and characterization

Published Online: 20 Jul 2022
Page range: 1 - 7

Abstract

Abstract

(-)-Menthol has been widely used in clinical medicine, flavor, and fragrance. However, high volatility, short retention time, low solubility in water, and whisker growth of menthol are crucial problems for its application. In this paper, (-)-menthol-β-cyclodextrin inclusion complex was fabricated to solve these problems. The product was characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The results showed that menthol was successfully encapsulated in the cavity of β-cyclodextrin. Menthol itself vaporized almost completely at around 120 oC, while the maximum menthol release rate occurred at 267.5 oC after the formation of the inclusion complex. The stability and retention time were improved. The menthol release reaction order, apparent activation energy and the pre-exponential factor were obtained and their values were 0, 142.9 kJ/mol and 1.6 × 1013 respectively. The structure of menthol-β-cyclodextrin inclusion complex was investigated by molecular simulation and the minimum energy, –116.7 kJ/mol, was obtained at –0.8 × 10–10 m.

Keywords

  • Menthol-β-cyclodextrin inclusion complex
  • Preparation
  • Characterization
  • Kinetics
  • Molecular mechanics
access type Open Access

Retrofitting Heat Exchanger Network of Industrial Ethylene Glycol Plant using Heat Integration based on Pinch Analysis

Published Online: 20 Jul 2022
Page range: 8 - 20

Abstract

Abstract

Heat integration by pinch method is used to modify the heat exchanger network of an industrial ethylene glycol plant. The aim is to reduce the energy cost by operating the plant close to the maximum energy recovery. Pinch analysis identified a pinch temperature of 483 K, a minimum heating utility of 13,490.9 MJ/ton EO, and a minimum cooling utility of 25,697 MJ/ton EO. Using the pinch decomposition diagram and the standard procedure for matching hot and cold streams, a retrofit of the heat exchangers network is developed. The modified heat exchanger network reduces the external cooling duty by 45.5% and the external heating duty by 93.3%. This promising cost savings provide enough justification for restructuring the existing ethylene glycol plant. Moreover, an additional 6% reduction in the external cooling duty can be achieved by integrating the steam turbine below the pinch point.

Keywords

  • Heat Integration
  • Pinch Analysis
  • Ethylene Glycol
  • Minimum Utility
access type Open Access

Study on synthesis and photoelectric properties of AgInS2 quantum dots

Published Online: 20 Jul 2022
Page range: 21 - 26

Abstract

Abstract

AgInS2 Quantum dots (AIS QDs) have high quantum yield and catalytic performance, which is promising materials in photo-catalytic and optoelectronic fields. In the paper, it adopted a simple and non-toxic method to synthesize AIS QDs. The effect of reaction temperature on the growth mechanism, optical and physical properties of AIS had been extensively investigated by using L-cysteine as the sulfur source, and their application in catalytic hydrogen production was also studied. The results demonstrated that the fluorescence properties will be quenched with the increase of temperature, indicating that the separation speed of electron hole pairs of samples obtained at higher temperature was faster. Meantime, the electron transport capacity and the photocurrent had also improved with the increase of reaction temperature. Finally, the sample obtained at 100 oC had higher hydrogen production rate.

Keywords

  • AgInS
  • Quantum dots
  • Optical properties
  • Photocatalytic hydrogen production
access type Open Access

Enhancement of Thermal Stability, Conductivity and Smoke Suppression of Polyethylene Composites with Exfoliated MoS2 Functionalized with Magnetite

Published Online: 20 Jul 2022
Page range: 27 - 34

Abstract

Abstract

This work reports a facile fabrication method to modify exfoliated molybdenum disulfide (e-MoS2) nanosheets with magnetite nanoparticles with various size distribution. The obtained materials have been utilized as nanofillers of polyethylene to enhance its thermal properties and flame retardance. The incorporation of magnetite modified MoS2 nanosheets leads to the reduction of the peak heat release rate. The best thermal conductivity has been noticed for composites with e-MoS2/Fe3O4 with 2 wt. % of nanofillers. The lowest CO emission was observed for the PE/e-MoS2 composite containing also 2 wt. % of Fe3O4. All composites with exfoliated MoS2 exhibited greater thermal properties in respect to the pristine polyethylene.

Keywords

  • flammability
  • polyethylene
  • molybdenum disulfide nanocomposites
  • flame retardants
access type Open Access

Estimation of the upper flammability limits for alkanes in air at increased pressures

Published Online: 20 Jul 2022
Page range: 35 - 41

Abstract

Abstract

A method is proposed to predict the upper flammability limits for alkanes in air at increased pressures. The upper flammability limits for methane, ethane, propane and n-butane/air mixtures at ambient temperature and initial pressure of 0.3 MPa–2.0 MPa are identified through the adiabatic flame temperature calculation model. The association of calculated adiabatic flame temperature with pressure is presented to determine the upper flammability limit. Research shows the good agreement between the forecast upper flammability limits with pressure dependence and the experimental upper flammability limit values. The average relative error of the estimated upper flammability limits for alkanes in air at high pressures reaches 2.52%.

Keywords

  • Upper flammability limit
  • Adiabatic flame temperature
  • High pressure
  • Alkanes
access type Open Access

The analysis of pressure drop, spray angle, and sprinkling intensity distribution in the spray stream produced by the water-foam nozzle

Published Online: 20 Jul 2022
Page range: 42 - 49

Abstract

Abstract

This paper summarises a series of large-scale fire suppression tests conducted to simulate a fire in the big surface and/or surface sprinkling. The subject of this paper is the research on water spraying with the use of the Turbo Jet 2011 water-foam nozzle manufactured by Supon Białystok. The results discuss the pressure losses caused by the flow through the discharge hose, spray angle, and the intensity of surface sprinkling. The greatest stream ranges and the highest maximum values of the sprinkling intensity were obtained at the capacity of 400 l/min, and a solid spray angle. The smallest values were obtained at 200 l/min, a pressure of 5 bar, and a solid spray angle. The actual pressures taking into account the losses in the hose section were calculated. As for the highest firefighting effectiveness of the stream, the authors recommended the following parameters: semi spray angle, 200 l/min, and 2.5 bar.

Keywords

  • fire safety
  • harvest fire prevention
  • atomization
  • spraying intensity
  • pressure drops
access type Open Access

High performance fluidized bed photoreactor for ethylene decomposition

Published Online: 20 Jul 2022
Page range: 50 - 56

Abstract

Abstract

Removal of C2H4 in the air was carried out in the continuous flow reactor with the photocatalytic bed (expanded polystyrene spheres coated by TiO2 or SiO2/TiO2) under irradiation of UV light. Continuous flow of a gas stream through the reactor was realised at the static bed and under bed fluidization. The required flow of a gas stream through the reactor for bed fluidisation was 500–700 ml/min, whereas for the static bed the flow rate of 20 ml/min was used. Fluidized bed reactor appeared to be much more efficient in ethylene removal than that with the stationary bed. It was caused by the increased speed of C2H4 mass transfer to the photocatalyst surface and better utilization of the incident UV light. In the fluidized bed reactor calculated rate of C2H4 degradation was around 10 μg/min whereas in the stationary state 1.2 μg/min only.

Keywords

  • ethylene degradation
  • photocatalytic bed reactor
  • fluidization
  • TiO

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