MAFRAM—A new fate and risk assessment methodology for non-volatile organic chemicals
- ملخص البحث
The main goal of this paper was to introduce an environmental fate and risk assessment methodology for comparing and establishing the general features of new and existing non-volatile organic chemicals (NVOCs) used in agricultural activities, based on simple and readily available properties. This methodology is a computer program called the multimedia agricultural fate and risk assessment model (MAFRAM). This model is a combination of the EQC-2V model, which describes the fate of NVOCs, with the ecological relative risk (EcoRR) approach, which assesses the ecotoxicological risk to agro-ecosystems. MAFRAM divides the agricultural environment into two main zones, which are the on- and off-farm zones. Each zone is subdivided into six compartments, including the air, water, soil, sediment, aboveground plants, and roots. The required input data are the chemical–physical properties of the pesticide, biota data, and environmental properties. The MAFRAM output includes the inter-compartmental transport and transfer rates, the primary loss mechanisms, chemical concentration, amount, residence time, and the rank of risk in each compartment. In addition, it can provide several secondary results. The MAFRAM application was illustrated using typical homogenous region properties and was run with an illustrative emission rate of 1 kg/h into air, using spinosad as a case study.
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- الكلمات المفتاحية
Agro-ecosystem; Chemical comparing and ranking; Environmental fate; Risk assessment; NVOCs
Elemental characterization of PM10 in UKM campus
- ملخص البحث
There is wide acceptance of the hypothesis that links health effects with the presence of atmospheric suspended particles. The goal of this paper was to study the elemental analysis of atmospheric particles in the Universiti Kebangsaan Malaysia (UKM) campus. Sampling was performed in one of UKM's students resident areas called college Zaa'ba. Samples were collected as PM10 for 24 h using high-volume air sampler from August 13 to 28, 2009. The obtained concentration of the suspended particles was 438.78 ¿g/m3. Particles were analyzed by SEM-EDS and then classified by their chemical composition and morphology in order of their abundance. Analysis results showed that there are no heavy metals or chlorinated compounds were found in the air of selected area. The detected elements in the samples were F, Na, Mg, Al, Si, K, Fe, Ca, Ti, and Zn.
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- الكلمات المفتاحية
Air pollution; SEM; Particulate Matter
Effect of air and oxyfuel staged combustion on oil shale fly ash formation with direct in-furnace limestone addition for sulphur retention
- ملخص البحث
El-Lajjun oil shale fly ash formation and S retention during in-furnace limestone injection were investigated in this work. Staged air-firing and 27% O2/CO2 combustion was performed at 1200 °C in a vertical once through reactor. Ash samples were collected at 2.5 m far from the burner and from the conductive section of the reactor. Limestone was added with oil shale before burning in both combustion modes. Ultimate, proximate, and XRF analyses were done for all collected samples, while XRD and SEM analyses were performed for some of them. Sulphur retention in the convective section increased by 13% compared to the radiative section of the reactor. Sulphur retention in the collected ashes ranged from 22 to 32% and 35 to 45% at 2.5 m from the burner and at the candle filter, respectively. The combustion mode had a slight effect on the collected ashes chemical composition. In both combustion modes, the ash samples were enriched with lime and depleted in sulphur, which proved sulphur capture. Fly ash particles were spherical in shape with some aggregates. XRD analysis showed that the main crystalline phases formed in the produced fly ashes were the same regardless the combustion mode and environment, some differences in the relative intensities of anhydrite and lime peaks were present.
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- الكلمات المفتاحية
Ash Formation; Desulphurisation; Oxyfuel; Staging; Oil Shale
Experimental and numerical performance analysis and optimization of single slope, double slope and pyramidal shaped solar stills
- ملخص البحث
In this work, the annual performance of single basin single slope, double slope and pyramidal shaped solar stills has been investigated experimentally and theoretically. Experiments were conducted in Ma'an area in Jordan throughout the year from January 2015 to December 2015 on clear days using solar stills with different orientations and different tilt angles of 15°, 30° and 45°. Mathematical models of solar radiation and solar desalination were developed to simulate the availability of solar radiation in Ma'an region, Jordan (Latitude: 30.7 N, Longitude: 35.7 E), and the performance of the solar stills. The average basin area was found to be of 0.64 m2 and 0.82 m2 in January and July, respectively. Model simulations were validated against experimental measurements and a reasonably good agreement was obtained. Annual optimal tilt angles of 30.3°, 45°, and 65° were suggested for south oriented single slope, double slope and pyramidal shaped solar stills, respectively. Under optimal settings, the single slope solar still was found to be the best system with improvement in productivity of about 28%. On a seasonal basis, a south oriented double slope solar still with tilt angle of 35° was found to perform, slightly, better than the other stills in summer.
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- الكلمات المفتاحية
Solar desalination; Solar radiation; Optimization
MAM-An Aquivalence-based Dynamic Mass Balance Model for the Fate of Non-Volatile Organic Chemicals in the Agricultural Environment
- ملخص البحث
A Multimedia Agricultural Model (MAM) for predicting the fate and transport of Non-Volatile Organic Chemicals (NVOCs) in the agricultural environment was presented. It is an expanded and modified version of the three compartmental model introduced by Batiha and co-authors in 2007, which is an aquivalence-based level IV. MAM considered five environmental compartments to include the air, water, soil, sediment and vegetation. It calculates the complete steady-state mass budgets for the air, water and particulate organic carbon between the model compartments. MAM compartments were connected by advective and intermedia transport processes. Degradation can take place in every compartment. The mass balances for each of the compartments result in a system of five differential equations, solved numerically to yield estimates of concentrations, masses, transport fluxes and reaction rates as a function of time. All the equations required for MAM calculations were provided.
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- الكلمات المفتاحية
Agro-ecosystem, MAM, NVOCs, Sediment, Vegetation
The Fate of Non-Volatile Organic Chemicals in The Agricultural Environment
- ملخص البحث
Multimedia dynamic model of the fate of non-volatile organic chemicals (NVOC) in the agricultural environment is described. The modeled environment, consisting of up to three major surfaces environmental compartments, includes air, agricultural soil, and surface water. This model is based on the aquivalence approach suggested by Mackay and co-workers in 1989. As the movement of chemicals in the environment is closely associated with the movement of air, water and organic matter, the complete steady state mass budgets for air, water and particulate organic carbon (POC) between the model compartments are described. All of the model equations, which are expressed in aquivalence notation, the mass balance for NVOC in the environmental surfaces compartments at dynamic state, and equations for the calculation of partitioning, overall persistence, total amount, total concentrations at dynamic state and intermedia fluxes of organic chemicals between air, water, and soil at steady-state are provided.
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- الكلمات المفتاحية
Non-volatile organic chemicals; Aquivalence; Multimedia model; Dynamic; Partitioning
Structures and thermodynamic stability of cobalt molybdenum oxide (CoMoO4-II)
- ملخص البحث
This contribution reports density functional theory (DFT) calculations on structural and electronic properties of bulk and surfaces of cobalt molybdenum oxide CoMoO4-II; i.e., a material that enjoys a wide array of chemical catalytic and optical applications. Estimated lattice constants and atomic charges for bulk CoMoO4-II reproduce limited analogous experimental measurements. Bader's charges confirm the ionic nature for metal-O bonds in bulk and surfaces of CoMoO4-II. Plotted partial density of states reveal a narrow band gap of 1.8 eV for bulk CoMoO4-II. We found that cleaving bulk of CoMoO4-II along the low-Miller indices afford twelve distinct surfaces. Upward displacement of oxygen atom becomes evident when contrasting bulk positioning of atoms with relaxed surfaces. The two mixed Mo/O- and Co/O–terminated surfaces dominate the thermodynamic stability diagram at 1 atm and 300 – 1400 K, and across a wide range of oxygen chemical potential. The presence of surface oxygen atoms in these stable surfaces is expected to facilitate the occurrence of oxygen reduction reactions as experimentally demonstrated. Likewise, the adjacent surface cations (Mo4+/Co2+) and anions (O2−) serve as Lewis-acid pairs; i.e., very potent active sites in prominent catalysis reactions.
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- الكلمات المفتاحية
CoMoO4-II; Lattice constants; DFT + U; Surfaces; Thermodynamic stability
Oxyfuel technology: Oil shale desulfurization behavior during staged combustion
- ملخص البحث
A high sulfur content in Jordanian oil shale is considered one of the biggest challenges preventing its full utilization. To resolve this issue, direct limestone injection during staged combustion has been investigated for the simultaneous control of NO and SO2 emissions. Staged El-Lajjun oil shale combustion under oxyfuel conditions and conventional air-firing conditions was performed at 1200 °C in a 20-kW vertical reactor. Limestone was mixed with oil shale before combustion. Three different molar ratios of Ca/S, three different burner oxygen ratios (0.75, 0.85 and 0.95) and different positions of the burnout oxidant probe were tested in both firing conditions to determine the optimum conditions for the lowest SO2 and NO emissions. The SO2 emissions were significantly lowered by adding limestone during staged air-firing and OF27 (27% O2/73% CO2 environment) combustion. The desulfurization efficiencies ranged from 32 to 61% and from 25 to 60% during the staged air-firing and staged OF27 combustion, respectively. The staging level, the Ca/S molar ratio and the position of the secondary oxidant are important parameters that affect the desulfurization efficiency. Higher desulfurization efficiencies were obtained during OF27 combustion compared with air-firing at burner oxygen ratios of 0.85 and 0.95. At a burner oxygen ratio of 0.75, the opposite trend was observed. The SO2 emissions during staged combustion were significantly higher than those during unstaged combustion in air and during OF27 combustion. This was due to high competition among many reactions, which minimized the desulfurization efficiency. The maximum desulfurization efficiency during staged OF27 combustion was 60% with λ = 0.85 and Ca/S = 2 at 1 m from the burner. During air-firing combustion, the maximum desulfurization efficiency was 61% with λ = 0.85 and Ca/S = 3 at 1.5 m from the burner. Based on the current and previous studies, the authors recommend that oxyfuel technology be used for oil shale combustion so that CO2, SO2 and NOx emissions can be simultaneously controlled.
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- الكلمات المفتاحية
Desulfurization; Oxyfuel combustion; Staging; Oil shale
Modeling the fate and transport of non-volatile organic chemicals in the agro-ecosystem: A case study of Cameron Highlands, Malaysia
- ملخص البحث
Many pesticides used in agricultural activities are considered environmentally non-volatile. The main purpose of this paper is to develop multimedia model to be used as a tool to predict the overall fate and transport of non-volatile organic chemicals (NVOCs) dynamic in the agro-ecosystem. The model was developed based on the EQuilibrium Criterion (EQC) model for type 2 chemicals introduced by Mackay and colleagues in 1996. Mackay’s model only considered four environmental compartments, which are air, water, soil and sediment. The present model adds the vegetation compartment, in addition to previous compartments that shape the agro-ecosystem. The vegetation compartment is described by two sub-compartments consisting of the above ground plant (AGP) and roots. The model was parameterized for the Cameron Highlands region, Malaysia, and runs with an illustrative emission rate of 1 kg h−1 into the air for three selected pesticides, namely, mancozeb, spinosad and chlorosulfuron. The simulation results with and without vegetation compartment were compared. The estimated results indicating that the AGP captures 99.9% of introduced NVOCs (i.e., of 100% or 1 kg h−1) and transfers them to the ground below due to the slight degradation losses of 10−4% and the non-volatility property of the evaluated chemicals. Root uptake of chlorosulfuron accounted the highest removal process from soil while degradation of spinosad in the soil is the major loss mechanism. Leaching to groundwater loss for mancozeb is about 2-fold greater than that of degradation, which together accounted the major removal process from soil. Based on the estimated results of mass distribution on the overall system, vegetation compartment accumulates 0.04%, 0.5% and 2.02% of the mancozeb, spinosad and chlorosulfuron, respectively.
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- الكلمات المفتاحية
Agricultural pollution; Mass balance model; NVOCs; Pesticide; Vegetation
The Effectiveness of Zn Leaching from EAFD Using Caustic Soda
- ملخص البحث
Electric arc furnace dust (EAFD) is a toxic waste which is mainly rich in iron oxide, zinc, and lead. Hydrometallurgical extraction of zinc from Jordanian EAFD in alkaline medium was investigated; NaOH, NaHCO3, and Na2CO3 were used as leaching agents. The pH values for the prepared solutions were 8.3, 8.2, and 12.55 for NaHCO3, Na2CO3, and NaOH, respectively. The effect of NaOH concentration (1, 3, 5, 7, and 9 M), contact time (5 min to 3 h), temperature (20, 40, and 60), and solid-to-liquid ratio (SLR; 20, 40, 80, and 120 mg/ml) on the leachability of zinc from EAFD were tested. The initial EAFD and the resulting leach residues were characterized using X-ray diffraction (XRD) and X-ray fluorescence (XRF). EAFD contained 25.9% Zn, 18.0% Fe, and 3.2% Pb. A maximum zinc recovery of 92.9% was achieved using 6 M NaOH at 60 °C with solid loading of 20 g/L and 3 h leaching time. NaHCO3 and Na2CO3 were not efficient leaching agents for Zn extraction since the recoveries were only 2.6 and 4.5%, respectively. Zn and Pb were depleted in the residues with an E-factor of 0.5–0.6 and 0.1–0.25, respectively. Iron was enriched in the residues; the E-factor was around 2. The EAFD contained mainly zincite, franklinite, and magnetite. After 3 h leaching, only traces of zincite exist in the residues, while sylvite and halite were completely dissolved.
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- الكلمات المفتاحية
Alkaline leaching; Electric arc furnace dust; Jordan; Zinc extraction
Effect of Pyridine and Tribenzylamine on the Hydrolysis Kinetics of Benzoyl Chloride in Water-Dioxane System
- ملخص البحث
The aim of this paper was to study the effect of tribenzylamine and pyridine on the kinetics of the hydrolysis reaction of benzoyl chloride in water-dioxane solution. The benzoyl chloride and water initial concentrations were 0.005 and 1 mol/L, respectively. While, the initial concentrations of pyridine and tribenzylamine varied in the range of 0.005-0.02 mol/L and 0.007-0.014 mol/L, respectively. It was found that the addition of tribenzylamine to benzoyl chloride hydrolysis reaction has no catalytic effect and hence the rate constant can be calculated using a first-order rate equation. In the presence of pyridine, reaction obeyed second-order rate. The relationship between the reaction rate constant and pyridine initial concentration was found to be linear with a rate constant of 0.752 × 10–3 min–1.
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- الكلمات المفتاحية
Benzoyl chloride; Hydrolysis kinetics; Tertiary amines; Tribenzylamine; Water-dioxane solutions.
Removal of iron and copper from aqueous solutions using Jordanian kaolin and zeolitic tuff
- ملخص البحث
The goal of this paper is to investigate the removal of iron and copper from aqueous solutions using adsorption. Zeolitic tuff and kaolin were used as adsorbents and were collected from different areas in Jordan. Batch adsorption experiments using synthetic Fe3+ and Cu2+ solutions were employed to study the effects of adsorbent dose, initial concentration, particle size, pH, and temperature on metal uptake. Zeolitic tuff had higher Fe3+ and Cu2+ adsorption capacities (20.70 and 20.83 mg/g, respectively) compared with kaolin (14.68 and 9.81 mg/g, respectively). The optimum pH values for Fe3+ and Cu2+ removal on kaolin were found to be 4 and 6, respectively. For the initial metal concentration of 100 ppm, 100% of Fe3+ and 62% of Cu2+ were adsorbed. As the temperature increased from 25 to 55°C, the adsorption capacity of Fe3+ on kaolin increased, thereby indicating the endothermic nature of the process. At the highest investigated temperature of 55°C, the Fe3+ removal using kaolin was 95.5%. The kinetic data obtained for Cu2+ removal confirmed the pseudo-second-order model. Fe3+ removal using zeolitic tuff was not affected by the particle size, while Cu2+ removal increased as the particle size decreased. This study suggests that zeolitic tuff and kaolin can be used as low-cost adsorbents for Fe3+ and Cu2+ removal with high efficiency. Kaolin was modified by pillaring with Al13 polyoxycation and acid activation. The mineralogy of the kaolin, analyzed using X-ray diffraction, confirmed that its structure was not changed significantly due to Al-pillared activation. Both pillaring and acid activation decreased the adsorption capacity.
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- الكلمات المفتاحية
Adsorption; Copper; Iron; Jordan; Kaolin; Kinetics; Zeolitic tuff
High performance thermoplastic elastomer (TPE) nanocomposite based on graphene nanoplates (GNPs)
- ملخص البحث
This paper examines the enhancement in the properties of thermoplastic elastomer (TPE) reinforced by graphene nanoplates (GNPs). TPE is a blend of polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR), which is used as a compatibiliser at a percentage of volume ratio 70:10:20, respectively. Using TPE as the host matrix, TPE/GNPs nanocomposites are processed, and the mechanical, electrical and structural properties are characterised. The results extracted from the tensile and the impact tests showed that the tensile strength, Young’s modulus and the impact strength of the nanocomposites also increased as the filler loading increased until an optimum value of filler loading was reached. Based on the experimental results, GNPs strongly affected the electrical conductivity due to disruption of the GNPs percolated network. It is believed that the high aspect ratio of GNPs is a critical issue concerning the constitution of a special interface region between the GNPs and TPE matrix and the high performance of the composites.
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- الكلمات المفتاحية
Graphene nanoplates; Nanocomposites; Thermoplastics; Electrical conductivity; Thermoplastic elastomer
Generalization of the MAFRAM Methodology for Semi-Volatile Organic Agro-Chemicals
- ملخص البحث
A wide variety of semi-volatile organic chemicals (SVOCs) are still in use in agricultural practices. A proper understanding of the environmental fate and ecotoxicological risk associated with these compounds can aid decision making, particularly regarding product registration and licensing. The aim of this paper is to expand the use of a previously developed Multimedia Agricultural Fate and Risk Assessment Model (MAFRAM) to SVOCs by adopting the fugacity concept as a second criterion to the existing MAFRAM partitioning criterion (i.e., aquivalence). Volatilization processes from surface compartments into the atmosphere were also included. For example, the application of the generalized model was illustrated using an average annual application rate of 4.48 kg/ha of chlorpyrifos over a typical homogeneous region. Chlorpyrifos emissions were assumed to take place in three environmental compartments (i.e., soil, air, and aboveground plants) with fractions of 0.1, 0.3, and 0.6, respectively. The trends seen in the modeling results were in good agreement with the existing experimental data. Validation issues in MAFRAM were also discussed. Comprehensive experimental validation is unattainable because of the large scale of the areas covered, the lack of boundaries for the system considered, and the uncertainty in the input parameters.
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- الكلمات المفتاحية
Environmental fate prediction; Ecotoxicological risk assessment; Multimedia model; Semi-volatile organic chemicals; Model validation problems
Effect of Tertiary Amines on the Hydrolysis Kinetics of Benzoyl Chloride in Water-Dioxane Solutions
- ملخص البحث
The main object of this study was to study the effect of pyridine, 2-methyl pyridine, 3-methyl pyridine, 2,6-dimethyl pyridine, quinoline and tribenzylamine on the hydrolysis kinetics of benzoyl chloride in water-dioxane solutions. The investigation has been made by means of gas-liquid chromatography measurements. Almost equal rate constants have been determined for the hydrolysis reaction of benzoyl chloride in dioxane solutions. The catalytic effect of the studied range of tertiary amines on the hydrolysis reaction of benzoyl chloride was determined.
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- الكلمات المفتاحية
Benzoyl chloride; Hydrolysis kinetics; Tertiary amines; Water-dioxane solutions.
MAFRAM—A new fate and risk assessment methodology for non-volatile organic chemicals
- ملخص البحث
The main goal of this paper was to introduce an environmental fate and risk assessment methodology for comparing and establishing the general features of new and existing non-volatile organic chemicals (NVOCs) used in agricultural activities, based on simple and readily available properties. This methodology is a computer program called the multimedia agricultural fate and risk assessment model (MAFRAM). This model is a combination of the EQC-2V model, which describes the fate of NVOCs, with the ecological relative risk (EcoRR) approach, which assesses the ecotoxicological risk to agro-ecosystems. MAFRAM divides the agricultural environment into two main zones, which are the on- and off-farm zones. Each zone is subdivided into six compartments, including the air, water, soil, sediment, aboveground plants, and roots. The required input data are the chemical–physical properties of the pesticide, biota data, and environmental properties. The MAFRAM output includes the inter-compartmental transport and transfer rates, the primary loss mechanisms, chemical concentration, amount, residence time, and the rank of risk in each compartment. In addition, it can provide several secondary results. The MAFRAM application was illustrated using typical homogenous region properties and was run with an illustrative emission rate of 1 kg/h into air, using spinosad as a case study.
- رابط البحث
- الكلمات المفتاحية
Agro-ecosystem; Chemical comparing and ranking; Environmental fate; Risk assessment; NVOCs
Elemental characterization of PM10 in UKM campus
- ملخص البحث
There is wide acceptance of the hypothesis that links health effects with the presence of atmospheric suspended particles. The goal of this paper was to study the elemental analysis of atmospheric particles in the Universiti Kebangsaan Malaysia (UKM) campus. Sampling was performed in one of UKM's students resident areas called college Zaa'ba. Samples were collected as PM10 for 24 h using high-volume air sampler from August 13 to 28, 2009. The obtained concentration of the suspended particles was 438.78 ¿g/m3. Particles were analyzed by SEM-EDS and then classified by their chemical composition and morphology in order of their abundance. Analysis results showed that there are no heavy metals or chlorinated compounds were found in the air of selected area. The detected elements in the samples were F, Na, Mg, Al, Si, K, Fe, Ca, Ti, and Zn.
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- الكلمات المفتاحية
Air pollution; SEM; Particulate Matter
Oxyfuel technology: Oil shale desulfurization behavior during staged combustion
- ملخص البحث
A high sulfur content in Jordanian oil shale is considered one of the biggest challenges preventing its full utilization. To resolve this issue, direct limestone injection during staged combustion has been investigated for the simultaneous control of NO and SO2 emissions. Staged El-Lajjun oil shale combustion under oxyfuel conditions and conventional air-firing conditions was performed at 1200 °C in a 20-kW vertical reactor. Limestone was mixed with oil shale before combustion. Three different molar ratios of Ca/S, three different burner oxygen ratios (0.75, 0.85 and 0.95) and different positions of the burnout oxidant probe were tested in both firing conditions to determine the optimum conditions for the lowest SO2 and NO emissions. The SO2 emissions were significantly lowered by adding limestone during staged air-firing and OF27 (27% O2/73% CO2 environment) combustion. The desulfurization efficiencies ranged from 32 to 61% and from 25 to 60% during the staged air-firing and staged OF27 combustion, respectively. The staging level, the Ca/S molar ratio and the position of the secondary oxidant are important parameters that affect the desulfurization efficiency. Higher desulfurization efficiencies were obtained during OF27 combustion compared with air-firing at burner oxygen ratios of 0.85 and 0.95. At a burner oxygen ratio of 0.75, the opposite trend was observed. The SO2 emissions during staged combustion were significantly higher than those during unstaged combustion in air and during OF27 combustion. This was due to high competition among many reactions, which minimized the desulfurization efficiency. The maximum desulfurization efficiency during staged OF27 combustion was 60% with λ = 0.85 and Ca/S = 2 at 1 m from the burner. During air-firing combustion, the maximum desulfurization efficiency was 61% with λ = 0.85 and Ca/S = 3 at 1.5 m from the burner. Based on the current and previous studies, the authors recommend that oxyfuel technology be used for oil shale combustion so that CO2, SO2 and NOx emissions can be simultaneously controlled.
- رابط البحث
- الكلمات المفتاحية
Desulfurization; Oxyfuel combustion; Staging; Oil shale
Effect of air and oxyfuel staged combustion on oil shale fly ash formation with direct in-furnace limestone addition for sulphur retention
- ملخص البحث
El-Lajjun oil shale fly ash formation and S retention during in-furnace limestone injection were investigated in this work. Staged air-firing and 27% O2/CO2 combustion was performed at 1200 °C in a vertical once through reactor. Ash samples were collected at 2.5 m far from the burner and from the conductive section of the reactor. Limestone was added with oil shale before burning in both combustion modes. Ultimate, proximate, and XRF analyses were done for all collected samples, while XRD and SEM analyses were performed for some of them. Sulphur retention in the convective section increased by 13% compared to the radiative section of the reactor. Sulphur retention in the collected ashes ranged from 22 to 32% and 35 to 45% at 2.5 m from the burner and at the candle filter, respectively. The combustion mode had a slight effect on the collected ashes chemical composition. In both combustion modes, the ash samples were enriched with lime and depleted in sulphur, which proved sulphur capture. Fly ash particles were spherical in shape with some aggregates. XRD analysis showed that the main crystalline phases formed in the produced fly ashes were the same regardless the combustion mode and environment, some differences in the relative intensities of anhydrite and lime peaks were present.
- رابط البحث
- الكلمات المفتاحية
Ash Formation; Desulphurisation; Oxyfuel; Staging; Oil Shale
Experimental and numerical performance analysis and optimization of single slope, double slope and pyramidal shaped solar stills
- ملخص البحث
In this work, the annual performance of single basin single slope, double slope and pyramidal shaped solar stills has been investigated experimentally and theoretically. Experiments were conducted in Ma'an area in Jordan throughout the year from January 2015 to December 2015 on clear days using solar stills with different orientations and different tilt angles of 15°, 30° and 45°. Mathematical models of solar radiation and solar desalination were developed to simulate the availability of solar radiation in Ma'an region, Jordan (Latitude: 30.7 N, Longitude: 35.7 E), and the performance of the solar stills. The average basin area was found to be of 0.64 m2 and 0.82 m2 in January and July, respectively. Model simulations were validated against experimental measurements and a reasonably good agreement was obtained. Annual optimal tilt angles of 30.3°, 45°, and 65° were suggested for south oriented single slope, double slope and pyramidal shaped solar stills, respectively. Under optimal settings, the single slope solar still was found to be the best system with improvement in productivity of about 28%. On a seasonal basis, a south oriented double slope solar still with tilt angle of 35° was found to perform, slightly, better than the other stills in summer.
- رابط البحث
- الكلمات المفتاحية
Solar desalination; Solar radiation; Optimization
MAM-An Aquivalence-based Dynamic Mass Balance Model for the Fate of Non-Volatile Organic Chemicals in the Agricultural Environment
- ملخص البحث
A Multimedia Agricultural Model (MAM) for predicting the fate and transport of Non-Volatile Organic Chemicals (NVOCs) in the agricultural environment was presented. It is an expanded and modified version of the three compartmental model introduced by Batiha and co-authors in 2007, which is an aquivalence-based level IV. MAM considered five environmental compartments to include the air, water, soil, sediment and vegetation. It calculates the complete steady-state mass budgets for the air, water and particulate organic carbon between the model compartments. MAM compartments were connected by advective and intermedia transport processes. Degradation can take place in every compartment. The mass balances for each of the compartments result in a system of five differential equations, solved numerically to yield estimates of concentrations, masses, transport fluxes and reaction rates as a function of time. All the equations required for MAM calculations were provided.
- رابط البحث
- الكلمات المفتاحية
Agro-ecosystem, MAM, NVOCs, Sediment, Vegetation
The Fate of Non-Volatile Organic Chemicals in The Agricultural Environment
- ملخص البحث
Multimedia dynamic model of the fate of non-volatile organic chemicals (NVOC) in the agricultural environment is described. The modeled environment, consisting of up to three major surfaces environmental compartments, includes air, agricultural soil, and surface water. This model is based on the aquivalence approach suggested by Mackay and co-workers in 1989. As the movement of chemicals in the environment is closely associated with the movement of air, water and organic matter, the complete steady state mass budgets for air, water and particulate organic carbon (POC) between the model compartments are described. All of the model equations, which are expressed in aquivalence notation, the mass balance for NVOC in the environmental surfaces compartments at dynamic state, and equations for the calculation of partitioning, overall persistence, total amount, total concentrations at dynamic state and intermedia fluxes of organic chemicals between air, water, and soil at steady-state are provided.
- رابط البحث
- الكلمات المفتاحية
Non-volatile organic chemicals; Aquivalence; Multimedia model; Dynamic; Partitioning
Structures and thermodynamic stability of cobalt molybdenum oxide (CoMoO4-II)
- ملخص البحث
This contribution reports density functional theory (DFT) calculations on structural and electronic properties of bulk and surfaces of cobalt molybdenum oxide CoMoO4-II; i.e., a material that enjoys a wide array of chemical catalytic and optical applications. Estimated lattice constants and atomic charges for bulk CoMoO4-II reproduce limited analogous experimental measurements. Bader's charges confirm the ionic nature for metal-O bonds in bulk and surfaces of CoMoO4-II. Plotted partial density of states reveal a narrow band gap of 1.8 eV for bulk CoMoO4-II. We found that cleaving bulk of CoMoO4-II along the low-Miller indices afford twelve distinct surfaces. Upward displacement of oxygen atom becomes evident when contrasting bulk positioning of atoms with relaxed surfaces. The two mixed Mo/O- and Co/O–terminated surfaces dominate the thermodynamic stability diagram at 1 atm and 300 – 1400 K, and across a wide range of oxygen chemical potential. The presence of surface oxygen atoms in these stable surfaces is expected to facilitate the occurrence of oxygen reduction reactions as experimentally demonstrated. Likewise, the adjacent surface cations (Mo4+/Co2+) and anions (O2−) serve as Lewis-acid pairs; i.e., very potent active sites in prominent catalysis reactions.
- رابط البحث
- الكلمات المفتاحية
CoMoO4-II; Lattice constants; DFT + U; Surfaces; Thermodynamic stability
Modeling the fate and transport of non-volatile organic chemicals in the agro-ecosystem: A case study of Cameron Highlands, Malaysia
- ملخص البحث
Many pesticides used in agricultural activities are considered environmentally non-volatile. The main purpose of this paper is to develop multimedia model to be used as a tool to predict the overall fate and transport of non-volatile organic chemicals (NVOCs) dynamic in the agro-ecosystem. The model was developed based on the EQuilibrium Criterion (EQC) model for type 2 chemicals introduced by Mackay and colleagues in 1996. Mackay’s model only considered four environmental compartments, which are air, water, soil and sediment. The present model adds the vegetation compartment, in addition to previous compartments that shape the agro-ecosystem. The vegetation compartment is described by two sub-compartments consisting of the above ground plant (AGP) and roots. The model was parameterized for the Cameron Highlands region, Malaysia, and runs with an illustrative emission rate of 1 kg h−1 into the air for three selected pesticides, namely, mancozeb, spinosad and chlorosulfuron. The simulation results with and without vegetation compartment were compared. The estimated results indicating that the AGP captures 99.9% of introduced NVOCs (i.e., of 100% or 1 kg h−1) and transfers them to the ground below due to the slight degradation losses of 10−4% and the non-volatility property of the evaluated chemicals. Root uptake of chlorosulfuron accounted the highest removal process from soil while degradation of spinosad in the soil is the major loss mechanism. Leaching to groundwater loss for mancozeb is about 2-fold greater than that of degradation, which together accounted the major removal process from soil. Based on the estimated results of mass distribution on the overall system, vegetation compartment accumulates 0.04%, 0.5% and 2.02% of the mancozeb, spinosad and chlorosulfuron, respectively.
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- الكلمات المفتاحية
Agricultural pollution; Mass balance model; NVOCs; Pesticide; Vegetation
The Effectiveness of Zn Leaching from EAFD Using Caustic Soda
- ملخص البحث
Electric arc furnace dust (EAFD) is a toxic waste which is mainly rich in iron oxide, zinc, and lead. Hydrometallurgical extraction of zinc from Jordanian EAFD in alkaline medium was investigated; NaOH, NaHCO3, and Na2CO3 were used as leaching agents. The pH values for the prepared solutions were 8.3, 8.2, and 12.55 for NaHCO3, Na2CO3, and NaOH, respectively. The effect of NaOH concentration (1, 3, 5, 7, and 9 M), contact time (5 min to 3 h), temperature (20, 40, and 60), and solid-to-liquid ratio (SLR; 20, 40, 80, and 120 mg/ml) on the leachability of zinc from EAFD were tested. The initial EAFD and the resulting leach residues were characterized using X-ray diffraction (XRD) and X-ray fluorescence (XRF). EAFD contained 25.9% Zn, 18.0% Fe, and 3.2% Pb. A maximum zinc recovery of 92.9% was achieved using 6 M NaOH at 60 °C with solid loading of 20 g/L and 3 h leaching time. NaHCO3 and Na2CO3 were not efficient leaching agents for Zn extraction since the recoveries were only 2.6 and 4.5%, respectively. Zn and Pb were depleted in the residues with an E-factor of 0.5–0.6 and 0.1–0.25, respectively. Iron was enriched in the residues; the E-factor was around 2. The EAFD contained mainly zincite, franklinite, and magnetite. After 3 h leaching, only traces of zincite exist in the residues, while sylvite and halite were completely dissolved.
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- الكلمات المفتاحية
Alkaline leaching; Electric arc furnace dust; Jordan; Zinc extraction
Effect of Pyridine and Tribenzylamine on the Hydrolysis Kinetics of Benzoyl Chloride in Water-Dioxane System
- ملخص البحث
The aim of this paper was to study the effect of tribenzylamine and pyridine on the kinetics of the hydrolysis reaction of benzoyl chloride in water-dioxane solution. The benzoyl chloride and water initial concentrations were 0.005 and 1 mol/L, respectively. While, the initial concentrations of pyridine and tribenzylamine varied in the range of 0.005-0.02 mol/L and 0.007-0.014 mol/L, respectively. It was found that the addition of tribenzylamine to benzoyl chloride hydrolysis reaction has no catalytic effect and hence the rate constant can be calculated using a first-order rate equation. In the presence of pyridine, reaction obeyed second-order rate. The relationship between the reaction rate constant and pyridine initial concentration was found to be linear with a rate constant of 0.752 × 10–3 min–1.
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- الكلمات المفتاحية
Benzoyl chloride; Hydrolysis kinetics; Tertiary amines; Tribenzylamine; Water-dioxane solutions.
Removal of iron and copper from aqueous solutions using Jordanian kaolin and zeolitic tuff
- ملخص البحث
The goal of this paper is to investigate the removal of iron and copper from aqueous solutions using adsorption. Zeolitic tuff and kaolin were used as adsorbents and were collected from different areas in Jordan. Batch adsorption experiments using synthetic Fe3+ and Cu2+ solutions were employed to study the effects of adsorbent dose, initial concentration, particle size, pH, and temperature on metal uptake. Zeolitic tuff had higher Fe3+ and Cu2+ adsorption capacities (20.70 and 20.83 mg/g, respectively) compared with kaolin (14.68 and 9.81 mg/g, respectively). The optimum pH values for Fe3+ and Cu2+ removal on kaolin were found to be 4 and 6, respectively. For the initial metal concentration of 100 ppm, 100% of Fe3+ and 62% of Cu2+ were adsorbed. As the temperature increased from 25 to 55°C, the adsorption capacity of Fe3+ on kaolin increased, thereby indicating the endothermic nature of the process. At the highest investigated temperature of 55°C, the Fe3+ removal using kaolin was 95.5%. The kinetic data obtained for Cu2+ removal confirmed the pseudo-second-order model. Fe3+ removal using zeolitic tuff was not affected by the particle size, while Cu2+ removal increased as the particle size decreased. This study suggests that zeolitic tuff and kaolin can be used as low-cost adsorbents for Fe3+ and Cu2+ removal with high efficiency. Kaolin was modified by pillaring with Al13 polyoxycation and acid activation. The mineralogy of the kaolin, analyzed using X-ray diffraction, confirmed that its structure was not changed significantly due to Al-pillared activation. Both pillaring and acid activation decreased the adsorption capacity.
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- الكلمات المفتاحية
Adsorption; Copper; Iron; Jordan; Kaolin; Kinetics; Zeolitic tuff
High performance thermoplastic elastomer (TPE) nanocomposite based on graphene nanoplates (GNPs)
- ملخص البحث
This paper examines the enhancement in the properties of thermoplastic elastomer (TPE) reinforced by graphene nanoplates (GNPs). TPE is a blend of polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR), which is used as a compatibiliser at a percentage of volume ratio 70:10:20, respectively. Using TPE as the host matrix, TPE/GNPs nanocomposites are processed, and the mechanical, electrical and structural properties are characterised. The results extracted from the tensile and the impact tests showed that the tensile strength, Young’s modulus and the impact strength of the nanocomposites also increased as the filler loading increased until an optimum value of filler loading was reached. Based on the experimental results, GNPs strongly affected the electrical conductivity due to disruption of the GNPs percolated network. It is believed that the high aspect ratio of GNPs is a critical issue concerning the constitution of a special interface region between the GNPs and TPE matrix and the high performance of the composites.
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- الكلمات المفتاحية
Graphene nanoplates; Nanocomposites; Thermoplastics; Electrical conductivity; Thermoplastic elastomer
Generalization of the MAFRAM Methodology for Semi-Volatile Organic Agro-Chemicals
- ملخص البحث
A wide variety of semi-volatile organic chemicals (SVOCs) are still in use in agricultural practices. A proper understanding of the environmental fate and ecotoxicological risk associated with these compounds can aid decision making, particularly regarding product registration and licensing. The aim of this paper is to expand the use of a previously developed Multimedia Agricultural Fate and Risk Assessment Model (MAFRAM) to SVOCs by adopting the fugacity concept as a second criterion to the existing MAFRAM partitioning criterion (i.e., aquivalence). Volatilization processes from surface compartments into the atmosphere were also included. For example, the application of the generalized model was illustrated using an average annual application rate of 4.48 kg/ha of chlorpyrifos over a typical homogeneous region. Chlorpyrifos emissions were assumed to take place in three environmental compartments (i.e., soil, air, and aboveground plants) with fractions of 0.1, 0.3, and 0.6, respectively. The trends seen in the modeling results were in good agreement with the existing experimental data. Validation issues in MAFRAM were also discussed. Comprehensive experimental validation is unattainable because of the large scale of the areas covered, the lack of boundaries for the system considered, and the uncertainty in the input parameters.
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- الكلمات المفتاحية
Environmental fate prediction; Ecotoxicological risk assessment; Multimedia model; Semi-volatile organic chemicals; Model validation problems
Effect of Tertiary Amines on the Hydrolysis Kinetics of Benzoyl Chloride in Water-Dioxane Solutions
- ملخص البحث
The main object of this study was to study the effect of pyridine, 2-methyl pyridine, 3-methyl pyridine, 2,6-dimethyl pyridine, quinoline and tribenzylamine on the hydrolysis kinetics of benzoyl chloride in water-dioxane solutions. The investigation has been made by means of gas-liquid chromatography measurements. Almost equal rate constants have been determined for the hydrolysis reaction of benzoyl chloride in dioxane solutions. The catalytic effect of the studied range of tertiary amines on the hydrolysis reaction of benzoyl chloride was determined.
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- الكلمات المفتاحية
Benzoyl chloride; Hydrolysis kinetics; Tertiary amines; Water-dioxane solutions.