Azam Ghavi - Academia.edu (original) (raw)
Papers by Azam Ghavi
![Research paper thumbnail of Corrigendum to “Pure CuCr2O4 nanoparticles: Synthesis, characterization and their morphological and size effects on the catalytic thermal decomposition of ammonium perchlorate” [Solid State Sci. 37(November 2014) 72–79]](https://attachments.academia-assets.com/114550557/thumbnails/1.jpg)
](Solid State Sciences, Jul 1, 2015
Environmental Sciences Europe, Oct 11, 2021
Background: This work studied the performance of UV/PS/TiO 2 NPs and UV/PI/TiO 2 NPs as hybrid ad... more Background: This work studied the performance of UV/PS/TiO 2 NPs and UV/PI/TiO 2 NPs as hybrid advanced oxidation processes for degradation of paraquat in aqueous solution, because this very toxic herbicide is used third most widely. Results: The effects of several factors such as UV irradiation, initial oxidant concentration, TiO 2 nanoparticles dosage, and pH on the degradation efficiency were investigated. The process optimization was performed by the central composite design as a tool of response surface methodology for 30 mgL −1 of the herbicide initial concentration at 25 ℃ and 40 min of degradation process. Based on the results, a degradation efficiency of 77% and 90% were obtained for the UV/PS/TiO 2 NPs and UV/PI/TiO 2 NPs processes, respectively, in the optimum conditions. The mineralization efficiency of the paraquat solution using UV/PS/TiO 2 NPs and UV/PI/TiO 2 NPs processes are about 32% and 55%, respectively, after 40 min. The kinetic studies show that both processes follow a pseudo-first-order kinetic model, and the kinetic constants are 0.0299 min −1 for the PS process and 0.0604 min −1 for the PI process. The electrical energy consumption was estimated to be about 481.60 kWhm −3 for the PS process and 238.41 kWhm −3 for the PI process. Conclusions: The degradation and mineralization efficiency of the paraquat solution using the UV/PI/TiO 2 NPs process was more than that of the UV/PS/TiO 2 NPs process at the optimum conditions after 40 min.
α-Fe2O3 nanoparticles have been successfully produced by the wet high-energy ball-milling method.... more α-Fe2O3 nanoparticles have been successfully produced by the wet high-energy ball-milling method. Phase and nanostructure characterizations of as-crushed powders have been done by X-ray diffraction and field emission scanning electron microscopy techniques. Average particle sizes of 56 and 51 nm are obtained after 20 and 40 hours of wet ball milling process, respectively. The catalytic property of the synthesised α-Fe2O3 nanoparticles in the thermal decomposition reaction of ammonium perchlorate has been evaluated by thermogravimetry and differential scanning calorimetry. Thermal analysis confirms that adding 5 wt.% α-Fe2O3 nanoparticles (51 nm) decreases the decomposition temperature of ammonium perchlorate from 422.0 °C to 360.0 °C and increases the ΔH of the decomposition reaction from 880 J g-1 to 1408.1 J g-1. Finally, the catalytic effects of α-Fe2O3 NPs on kinetic and thermodynamic parameters of thermal decomposition reaction of treated AP particles have been studied by Kissi...
International Journal of Energetic Materials and Chemical Propulsion, 2016
Journal of Thermal Analysis and Calorimetry, 2016
In this research, the catalytic effects of nano-Co 3 O 4 with diverse average particle sizes and ... more In this research, the catalytic effects of nano-Co 3 O 4 with diverse average particle sizes and specific surface area on thermal decomposition property of ammonium perchlorate (AP) particles were investigated. Field emission scanning electron microscopy, differential scanning calorimetry and thermogravimetry analysis techniques were used to evaluate the coating quality and thermal decomposition property of AP/Co 3 O 4 nanocomposites. The primary evaluations of the results show that the catalytic effects will be increased by decreasing average particle sizes of nano-Co 3 O 4. Also, kinetic parameters of thermal decomposition reaction AP/Co 3 O 4 nanocomposites were calculated by Kissinger, Friedman and Ozawa methods. However, nano-Co 3 O 4 with the smallest average particle size (10-30 nm) and the highest specific surface area (50-150 m 2 g-1) has the most significant catalytic effect including decrease in decomposition temperature of AP/Co 3 O 4 nanocomposite by 160°C, increase in the heat of decomposition from 540 to 1182 J g-1 and decrease in activation energy from 179 to 126 kJ mol-1 .
Powder Technology, 2015
In this study, mesoporous α-Fe 2 O 3 catalysts were synthesized from mesoporous silica SBA-15 as ... more In this study, mesoporous α-Fe 2 O 3 catalysts were synthesized from mesoporous silica SBA-15 as the hard template and iron nitrate as the iron oxide source via nanocasting strategy. In order to access the highest loading of iron oxide in the template pores, different weight ratios of Fe(NO 3) 3 •9H 2 O/SBA-15 were used in the pore-filling step by two solvents process. The structural and textural properties of the SBA-15 template and α-Fe 2 O 3-2.0 catalyst were characterized by means of X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption techniques. The findings indicated that the resulting iron oxides are crystalline and to some extent, have negative replica structures of mesoporous SBA-15 template. The catalytic performance of mesoporous α-Fe 2 O 3 towards thermal decomposition of ammonium perchlorate was evaluated by differential scanning calorimetry technique. The specific heat released from the AP decomposition in the presence of catalyst was improved by increasing the precursor to template weight ratio. Therefore, the specific resulting heat released from the composite of AP and mesoporous α-Fe 2 O 3-2.0 (1110 J g −1) was~3 folds of that for pure AP (423 J g −1).
Journal of Thermal Analysis and Calorimetry, 2014
ABSTRACT The present study is aimed at introducing the application of design of experiment (DOE) ... more ABSTRACT The present study is aimed at introducing the application of design of experiment (DOE) with artificial neural networks (ANN) in couple over Cu–Cr–O nanocomposites, which can be used as catalysts in the combustion of ammonium perchlorate (AP), as well as a method of data collection/fitting for the experiments. To this end, a practical scheme has been proposed to select the characterization parameters of Cu–Cr–O nanocomposites as the catalytic combustion of AP propellant. Moreover, a calculation model has been established to identify the primary combustion characteristics based on backpropagation neural networks. The model was subsequently validated and then used to predict the primary combustion characteristics of the aforementioned propellant. In addition, due to the complex nature of the system, neural networks were employed as an efficient and accurate tool to model the behavior of the system. Response surface methodology (RSM) and ANN methods were also constructed based upon the DOE’s points and were then utilized to generate extra simulated data. The data sets, including the original experimental data and the simulation results yielded by the ANN and RSM methods were subsequently used to fit the combustion rate expression for AP. A comparison of the results of kinetic modeling with the simulated data sets from ANN and RSM models was then made, which indicated that both methods could satisfactorily fit the experimental data presented in the literature. The results also revealed that the error of burning rate calculation is less than ±5 % and the variations of the calculation results were consistent with those of the experimental results.
Solid State Sciences, 2014
Transmission electron microscopy (a) and X-ray diffraction spectrum (b) of pure copper chromite n... more Transmission electron microscopy (a) and X-ray diffraction spectrum (b) of pure copper chromite nanoparticles calcined at 600 ℃ for 3 h in air (as the best catalyst in this study).
Additional file 1. Degradation of paraquat herbicide using hybrid AOP process: statistical optimi... more Additional file 1. Degradation of paraquat herbicide using hybrid AOP process: statistical optimization, kinetic study, and estimation of electrical energy consumption.
Environmental Sciences Europe, 2021
Background This work studied the performance of UV/PS/TiO2NPs and UV/PI/TiO2NPs as hybrid advance... more Background This work studied the performance of UV/PS/TiO2NPs and UV/PI/TiO2NPs as hybrid advanced oxidation processes for degradation of paraquat in aqueous solution, because this very toxic herbicide is used third most widely. Results The effects of several factors such as UV irradiation, initial oxidant concentration, TiO2 nanoparticles dosage, and pH on the degradation efficiency were investigated. The process optimization was performed by the central composite design as a tool of response surface methodology for 30 mgL−1 of the herbicide initial concentration at 25 ℃ and 40 min of degradation process. Based on the results, a degradation efficiency of 77% and 90% were obtained for the UV/PS/TiO2NPs and UV/PI/TiO2NPs processes, respectively, in the optimum conditions. The mineralization efficiency of the paraquat solution using UV/PS/TiO2NPs and UV/PI/TiO2NPs processes are about 32% and 55%, respectively, after 40 min. The kinetic studies show that both processes follow a pseudo-...
Journal of Environmental Chemistry and Ecotoxicology, 2018
Ammonium perchlorate (AP) has long been of chemical interest as oxidizers, and has found excellen... more Ammonium perchlorate (AP) has long been of chemical interest as oxidizers, and has found excellent application in propellants, explosives, and pyrotechnics. Many investigations have been carried out on the catalytic improvement of thermal decomposition properties of AP particles by different nano catalysis additives such as metals powders, metal oxides and Spinels. However, there is no report on the effect of particle size of Co 3 O 4 nano Spinels on the heat of decomposition, kinetic parameters and thermal decomposition temperature of AP particles. The present investigation is intended to study the effect of the particle size of nano Co 3 O 4 on the thermal decomposition of AP particles. Co 3 O 4 nano particles with different particles size (10-30, 30-50 and higher than 50 nm) were used to prepare AP/Co 3 O 4 nanocomposites by a novel solvent evaporation method. The preliminary evaluation of results revealed that a significant variation in the catalytic activity was observed according to the range of the particle size used. The results showed that, as the particle size of Co 3 O 4 increased, the thermal decomposition temperature of AP/Co 3 O 4 nanocomposites and the decomposition activation energies ranges enhanced. The results revealed that smallest nanosized Co 3 O 4 with 10-30 nm diameters shows strong catalytic property for AP thermal decomposition. Adding 5% of Co 3 O 4 with 10-30 nm to AP, decreased the exothermic peak temperature of thermal decomposition by 130 C and increased the heat of decomposition from 880 to 1260 J g -1 . Also, the values of S # , H # , and G # for thermal decomposition processes of pure and treated AP particles have been estimated by non-isothermal methods that proposed by Friedman and Ozawa. C li c k h e r e t o b u y AB B Y Y P D F Trans fo r m e r 3 .0 w w w .A B B Y Y .c o m C li c k h e r e t o b u y AB B Y Y P D F Trans fo r m e r 3 .0 w w w .A B B Y Y .c o m
Perchlorate (ClO 4 -) is used as an oxidizer in flares, pyrotechnics, explosives and the recent d... more Perchlorate (ClO 4 -) is used as an oxidizer in flares, pyrotechnics, explosives and the recent detection of environmental contamination has primarily been associated with its use in rocket propellants and missile motors. Perchlorate is a concern because it can interfere with iodide uptake by the thyroid gland. Because iodide is an essential component of thyroid hormones, perchlorate exposure may result in decreased thyroid hormone production. It is highly water soluble, non-complexity, non-volatile and chemically stable for its unique chemistry, it has been highly challenging to remove perchlorate from water by traditional water treatment approaches[1]. In recent years, various treatment technologies have been developed and tested, including biological reduction ion exchange, tailored activated, carbon sorption, filtration and chemical reduction. However, these technologies are limited by some critical technical and economic drawbacks such as slow degradation kinetics and production of large volumes of concentrated process waste residuals. In recent years, zero-valent iron (ZVI) has attracted increasing interest for abiotic dechlorination of chlorinated organic compounds removal of nitrate, reduction of chromate, and sorption of arsenic). ZVI was also tested for reduction of perchlorate. It has been reported that decreasing the size of ZVI particles to the nano scale can greatly enhance the reaction rates for perchlorate a stabilizer are actually agglomerates of ZVI particles in the micron scale [2]. In this work, starch solution was used to modify particle size (dispersion those better and avoid getting lumps) and stability is preserved. The results of the analysis XRD (X-ray diffraction), DLS (dynamic light scattering) and TEM (transmission electron microscopy) show that ZVI nanoparticles synthesized with particle size distribution of 28-54 nm. Under optimum conditions (0.45 g/lit of NZVI, pH=5-6, time= 50 s and T=65 C), removal of perchlorate was nearly complete. The activation energy of perchlorate reduction using ZVI was obtained 39.83 kJ/mole and rate constant increase from 0.0147 to 0.057 min -1 at different temperature. C li c k h e r e t o b u y AB B Y Y P D F Trans fo r m e r 3 .0 w w w .A B B Y Y .c o m C li c k h e r e t o b u y AB B Y Y P D F Trans fo r m e r 3 .0 w w w .A B B Y Y .c o m
This work analyzes the degradation of toxic perchlorate from wastewater and its conversion to non... more This work analyzes the degradation of toxic perchlorate from wastewater and its conversion to non-toxic chloride ion through nano-scale zero valent iron (nZVI) coating. To prevent its agglomeration and to provide the required stabilization and more removal efficiency, it was coated with various coating agents which are co-friendly (green agents) and inexpensive. At first, nZVI was synthesized using green method. Thereafter, it was used for the removal of perchlorate. NZVI was characterized by X-ray diffraction (XRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM) techniques. Data show that nZVI coated with starch had the size range of 20 to 60 nm and spherical morphology and thickness of about 60 nm. Analysis results of UV-Spectrophotometry and ion chromatography showed that perchlorate was removed with more efficiency (up over 90%) under optimal conditions, and for one week, it was coated with nZVI using starch. Also, the parameters of the removal efficiency include temperature, time reaction, pH and amount of nZVI. Activation energy (E a) of 16.77 kJ mol-1 and constant rate (k) of 0.0242 min-1 were obtained from the removal of perchlorate under optimal conditions. The study shows that the obtained results improved more than previously.
α-Fe 2 O 3 nanoparticles have been successfully produced by the wet high-energy ball-milling meth... more α-Fe 2 O 3 nanoparticles have been successfully produced by the wet high-energy ball-milling method. Phase and nanostructure characterizations of as-crushed powders have been done by X-ray diffraction and field emission scanning electron microscopy techniques. Average particle sizes of 56 and 51 nm are obtained after 20 and 40 hours of wet ball milling process, respectively. The catalytic property of the synthesised α-Fe 2 O 3 nanoparticles in the thermal decomposition reaction of ammonium perchlorate has been evaluated by thermogravimetry and differential scanning calorimetry. Thermal analysis confirms that adding 5 wt.% α-Fe 2 O 3 nanoparticles (51 nm) decreases the decomposition temperature of ammonium perchlorate from 422.0 °C to 360.0 °C and increases the ΔH of the decomposition reaction from 880 J g-1 to 1408.1 J g-1. Finally, the catalytic effects of α-Fe 2 O 3 NPs on kinetic and thermodynamic parameters of thermal decomposition reaction of treated AP particles have been studied by Kissinger, Boswell, Ozawa and Starink methods.
In this study, mesoporous α-Fe 2 O 3 catalysts were synthesized from mesoporous silica SBA-15 as ... more In this study, mesoporous α-Fe 2 O 3 catalysts were synthesized from mesoporous silica SBA-15 as the hard template and iron nitrate as the iron oxide source via nanocasting strategy. In order to access the highest loading of iron oxide in the template pores, different weight ratios of Fe(NO 3) 3 ·9H 2 O/SBA-15 were used in the pore-filling step by two solvents process. The structural and textural properties of the SBA-15 template and α-Fe 2 O 3-2.0 catalyst were characterized by means of X-ray diffraction, transmission electron microscopy and nitrogen adsorption–desorption techniques. The findings indicated that the resulting iron oxides are crystalline and to some extent, have negative replica structures of mesoporous SBA-15 template. The catalytic performance of mesoporous α-Fe 2 O 3 towards thermal decomposition of ammonium perchlorate was evaluated by differential scanning calorimetry technique. The specific heat released from the AP decomposition in the presence of catalyst was improved by increasing the precursor to template weight ratio. Therefore, the specific resulting heat released from the composite of AP and mesoporous α-Fe 2 O 3-2.0 (1110 J g −1) was ~ 3 folds of that for pure AP (423 J g −1).
[
Corrigendum Corrigendum to " Pure CuCr 2 O 4 nanoparticles: Synthesis, characterization and their... more Corrigendum Corrigendum to " Pure CuCr 2 O 4 nanoparticles: Synthesis, characterization and their morphological and size effects on the catalytic thermal decomposition of ammonium perchlorate " [Solid State Sci. 37(November 2014) 72e79]
Solid State Sciences, Jul 1, 2015
Environmental Sciences Europe, Oct 11, 2021
Background: This work studied the performance of UV/PS/TiO 2 NPs and UV/PI/TiO 2 NPs as hybrid ad... more Background: This work studied the performance of UV/PS/TiO 2 NPs and UV/PI/TiO 2 NPs as hybrid advanced oxidation processes for degradation of paraquat in aqueous solution, because this very toxic herbicide is used third most widely. Results: The effects of several factors such as UV irradiation, initial oxidant concentration, TiO 2 nanoparticles dosage, and pH on the degradation efficiency were investigated. The process optimization was performed by the central composite design as a tool of response surface methodology for 30 mgL −1 of the herbicide initial concentration at 25 ℃ and 40 min of degradation process. Based on the results, a degradation efficiency of 77% and 90% were obtained for the UV/PS/TiO 2 NPs and UV/PI/TiO 2 NPs processes, respectively, in the optimum conditions. The mineralization efficiency of the paraquat solution using UV/PS/TiO 2 NPs and UV/PI/TiO 2 NPs processes are about 32% and 55%, respectively, after 40 min. The kinetic studies show that both processes follow a pseudo-first-order kinetic model, and the kinetic constants are 0.0299 min −1 for the PS process and 0.0604 min −1 for the PI process. The electrical energy consumption was estimated to be about 481.60 kWhm −3 for the PS process and 238.41 kWhm −3 for the PI process. Conclusions: The degradation and mineralization efficiency of the paraquat solution using the UV/PI/TiO 2 NPs process was more than that of the UV/PS/TiO 2 NPs process at the optimum conditions after 40 min.
α-Fe2O3 nanoparticles have been successfully produced by the wet high-energy ball-milling method.... more α-Fe2O3 nanoparticles have been successfully produced by the wet high-energy ball-milling method. Phase and nanostructure characterizations of as-crushed powders have been done by X-ray diffraction and field emission scanning electron microscopy techniques. Average particle sizes of 56 and 51 nm are obtained after 20 and 40 hours of wet ball milling process, respectively. The catalytic property of the synthesised α-Fe2O3 nanoparticles in the thermal decomposition reaction of ammonium perchlorate has been evaluated by thermogravimetry and differential scanning calorimetry. Thermal analysis confirms that adding 5 wt.% α-Fe2O3 nanoparticles (51 nm) decreases the decomposition temperature of ammonium perchlorate from 422.0 °C to 360.0 °C and increases the ΔH of the decomposition reaction from 880 J g-1 to 1408.1 J g-1. Finally, the catalytic effects of α-Fe2O3 NPs on kinetic and thermodynamic parameters of thermal decomposition reaction of treated AP particles have been studied by Kissi...
International Journal of Energetic Materials and Chemical Propulsion, 2016
Journal of Thermal Analysis and Calorimetry, 2016
In this research, the catalytic effects of nano-Co 3 O 4 with diverse average particle sizes and ... more In this research, the catalytic effects of nano-Co 3 O 4 with diverse average particle sizes and specific surface area on thermal decomposition property of ammonium perchlorate (AP) particles were investigated. Field emission scanning electron microscopy, differential scanning calorimetry and thermogravimetry analysis techniques were used to evaluate the coating quality and thermal decomposition property of AP/Co 3 O 4 nanocomposites. The primary evaluations of the results show that the catalytic effects will be increased by decreasing average particle sizes of nano-Co 3 O 4. Also, kinetic parameters of thermal decomposition reaction AP/Co 3 O 4 nanocomposites were calculated by Kissinger, Friedman and Ozawa methods. However, nano-Co 3 O 4 with the smallest average particle size (10-30 nm) and the highest specific surface area (50-150 m 2 g-1) has the most significant catalytic effect including decrease in decomposition temperature of AP/Co 3 O 4 nanocomposite by 160°C, increase in the heat of decomposition from 540 to 1182 J g-1 and decrease in activation energy from 179 to 126 kJ mol-1 .
Powder Technology, 2015
In this study, mesoporous α-Fe 2 O 3 catalysts were synthesized from mesoporous silica SBA-15 as ... more In this study, mesoporous α-Fe 2 O 3 catalysts were synthesized from mesoporous silica SBA-15 as the hard template and iron nitrate as the iron oxide source via nanocasting strategy. In order to access the highest loading of iron oxide in the template pores, different weight ratios of Fe(NO 3) 3 •9H 2 O/SBA-15 were used in the pore-filling step by two solvents process. The structural and textural properties of the SBA-15 template and α-Fe 2 O 3-2.0 catalyst were characterized by means of X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption techniques. The findings indicated that the resulting iron oxides are crystalline and to some extent, have negative replica structures of mesoporous SBA-15 template. The catalytic performance of mesoporous α-Fe 2 O 3 towards thermal decomposition of ammonium perchlorate was evaluated by differential scanning calorimetry technique. The specific heat released from the AP decomposition in the presence of catalyst was improved by increasing the precursor to template weight ratio. Therefore, the specific resulting heat released from the composite of AP and mesoporous α-Fe 2 O 3-2.0 (1110 J g −1) was~3 folds of that for pure AP (423 J g −1).
Journal of Thermal Analysis and Calorimetry, 2014
ABSTRACT The present study is aimed at introducing the application of design of experiment (DOE) ... more ABSTRACT The present study is aimed at introducing the application of design of experiment (DOE) with artificial neural networks (ANN) in couple over Cu–Cr–O nanocomposites, which can be used as catalysts in the combustion of ammonium perchlorate (AP), as well as a method of data collection/fitting for the experiments. To this end, a practical scheme has been proposed to select the characterization parameters of Cu–Cr–O nanocomposites as the catalytic combustion of AP propellant. Moreover, a calculation model has been established to identify the primary combustion characteristics based on backpropagation neural networks. The model was subsequently validated and then used to predict the primary combustion characteristics of the aforementioned propellant. In addition, due to the complex nature of the system, neural networks were employed as an efficient and accurate tool to model the behavior of the system. Response surface methodology (RSM) and ANN methods were also constructed based upon the DOE’s points and were then utilized to generate extra simulated data. The data sets, including the original experimental data and the simulation results yielded by the ANN and RSM methods were subsequently used to fit the combustion rate expression for AP. A comparison of the results of kinetic modeling with the simulated data sets from ANN and RSM models was then made, which indicated that both methods could satisfactorily fit the experimental data presented in the literature. The results also revealed that the error of burning rate calculation is less than ±5 % and the variations of the calculation results were consistent with those of the experimental results.
Solid State Sciences, 2014
Transmission electron microscopy (a) and X-ray diffraction spectrum (b) of pure copper chromite n... more Transmission electron microscopy (a) and X-ray diffraction spectrum (b) of pure copper chromite nanoparticles calcined at 600 ℃ for 3 h in air (as the best catalyst in this study).
Additional file 1. Degradation of paraquat herbicide using hybrid AOP process: statistical optimi... more Additional file 1. Degradation of paraquat herbicide using hybrid AOP process: statistical optimization, kinetic study, and estimation of electrical energy consumption.
Environmental Sciences Europe, 2021
Background This work studied the performance of UV/PS/TiO2NPs and UV/PI/TiO2NPs as hybrid advance... more Background This work studied the performance of UV/PS/TiO2NPs and UV/PI/TiO2NPs as hybrid advanced oxidation processes for degradation of paraquat in aqueous solution, because this very toxic herbicide is used third most widely. Results The effects of several factors such as UV irradiation, initial oxidant concentration, TiO2 nanoparticles dosage, and pH on the degradation efficiency were investigated. The process optimization was performed by the central composite design as a tool of response surface methodology for 30 mgL−1 of the herbicide initial concentration at 25 ℃ and 40 min of degradation process. Based on the results, a degradation efficiency of 77% and 90% were obtained for the UV/PS/TiO2NPs and UV/PI/TiO2NPs processes, respectively, in the optimum conditions. The mineralization efficiency of the paraquat solution using UV/PS/TiO2NPs and UV/PI/TiO2NPs processes are about 32% and 55%, respectively, after 40 min. The kinetic studies show that both processes follow a pseudo-...
Journal of Environmental Chemistry and Ecotoxicology, 2018
Ammonium perchlorate (AP) has long been of chemical interest as oxidizers, and has found excellen... more Ammonium perchlorate (AP) has long been of chemical interest as oxidizers, and has found excellent application in propellants, explosives, and pyrotechnics. Many investigations have been carried out on the catalytic improvement of thermal decomposition properties of AP particles by different nano catalysis additives such as metals powders, metal oxides and Spinels. However, there is no report on the effect of particle size of Co 3 O 4 nano Spinels on the heat of decomposition, kinetic parameters and thermal decomposition temperature of AP particles. The present investigation is intended to study the effect of the particle size of nano Co 3 O 4 on the thermal decomposition of AP particles. Co 3 O 4 nano particles with different particles size (10-30, 30-50 and higher than 50 nm) were used to prepare AP/Co 3 O 4 nanocomposites by a novel solvent evaporation method. The preliminary evaluation of results revealed that a significant variation in the catalytic activity was observed according to the range of the particle size used. The results showed that, as the particle size of Co 3 O 4 increased, the thermal decomposition temperature of AP/Co 3 O 4 nanocomposites and the decomposition activation energies ranges enhanced. The results revealed that smallest nanosized Co 3 O 4 with 10-30 nm diameters shows strong catalytic property for AP thermal decomposition. Adding 5% of Co 3 O 4 with 10-30 nm to AP, decreased the exothermic peak temperature of thermal decomposition by 130 C and increased the heat of decomposition from 880 to 1260 J g -1 . Also, the values of S # , H # , and G # for thermal decomposition processes of pure and treated AP particles have been estimated by non-isothermal methods that proposed by Friedman and Ozawa. C li c k h e r e t o b u y AB B Y Y P D F Trans fo r m e r 3 .0 w w w .A B B Y Y .c o m C li c k h e r e t o b u y AB B Y Y P D F Trans fo r m e r 3 .0 w w w .A B B Y Y .c o m
Perchlorate (ClO 4 -) is used as an oxidizer in flares, pyrotechnics, explosives and the recent d... more Perchlorate (ClO 4 -) is used as an oxidizer in flares, pyrotechnics, explosives and the recent detection of environmental contamination has primarily been associated with its use in rocket propellants and missile motors. Perchlorate is a concern because it can interfere with iodide uptake by the thyroid gland. Because iodide is an essential component of thyroid hormones, perchlorate exposure may result in decreased thyroid hormone production. It is highly water soluble, non-complexity, non-volatile and chemically stable for its unique chemistry, it has been highly challenging to remove perchlorate from water by traditional water treatment approaches[1]. In recent years, various treatment technologies have been developed and tested, including biological reduction ion exchange, tailored activated, carbon sorption, filtration and chemical reduction. However, these technologies are limited by some critical technical and economic drawbacks such as slow degradation kinetics and production of large volumes of concentrated process waste residuals. In recent years, zero-valent iron (ZVI) has attracted increasing interest for abiotic dechlorination of chlorinated organic compounds removal of nitrate, reduction of chromate, and sorption of arsenic). ZVI was also tested for reduction of perchlorate. It has been reported that decreasing the size of ZVI particles to the nano scale can greatly enhance the reaction rates for perchlorate a stabilizer are actually agglomerates of ZVI particles in the micron scale [2]. In this work, starch solution was used to modify particle size (dispersion those better and avoid getting lumps) and stability is preserved. The results of the analysis XRD (X-ray diffraction), DLS (dynamic light scattering) and TEM (transmission electron microscopy) show that ZVI nanoparticles synthesized with particle size distribution of 28-54 nm. Under optimum conditions (0.45 g/lit of NZVI, pH=5-6, time= 50 s and T=65 C), removal of perchlorate was nearly complete. The activation energy of perchlorate reduction using ZVI was obtained 39.83 kJ/mole and rate constant increase from 0.0147 to 0.057 min -1 at different temperature. C li c k h e r e t o b u y AB B Y Y P D F Trans fo r m e r 3 .0 w w w .A B B Y Y .c o m C li c k h e r e t o b u y AB B Y Y P D F Trans fo r m e r 3 .0 w w w .A B B Y Y .c o m
This work analyzes the degradation of toxic perchlorate from wastewater and its conversion to non... more This work analyzes the degradation of toxic perchlorate from wastewater and its conversion to non-toxic chloride ion through nano-scale zero valent iron (nZVI) coating. To prevent its agglomeration and to provide the required stabilization and more removal efficiency, it was coated with various coating agents which are co-friendly (green agents) and inexpensive. At first, nZVI was synthesized using green method. Thereafter, it was used for the removal of perchlorate. NZVI was characterized by X-ray diffraction (XRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM) techniques. Data show that nZVI coated with starch had the size range of 20 to 60 nm and spherical morphology and thickness of about 60 nm. Analysis results of UV-Spectrophotometry and ion chromatography showed that perchlorate was removed with more efficiency (up over 90%) under optimal conditions, and for one week, it was coated with nZVI using starch. Also, the parameters of the removal efficiency include temperature, time reaction, pH and amount of nZVI. Activation energy (E a) of 16.77 kJ mol-1 and constant rate (k) of 0.0242 min-1 were obtained from the removal of perchlorate under optimal conditions. The study shows that the obtained results improved more than previously.
α-Fe 2 O 3 nanoparticles have been successfully produced by the wet high-energy ball-milling meth... more α-Fe 2 O 3 nanoparticles have been successfully produced by the wet high-energy ball-milling method. Phase and nanostructure characterizations of as-crushed powders have been done by X-ray diffraction and field emission scanning electron microscopy techniques. Average particle sizes of 56 and 51 nm are obtained after 20 and 40 hours of wet ball milling process, respectively. The catalytic property of the synthesised α-Fe 2 O 3 nanoparticles in the thermal decomposition reaction of ammonium perchlorate has been evaluated by thermogravimetry and differential scanning calorimetry. Thermal analysis confirms that adding 5 wt.% α-Fe 2 O 3 nanoparticles (51 nm) decreases the decomposition temperature of ammonium perchlorate from 422.0 °C to 360.0 °C and increases the ΔH of the decomposition reaction from 880 J g-1 to 1408.1 J g-1. Finally, the catalytic effects of α-Fe 2 O 3 NPs on kinetic and thermodynamic parameters of thermal decomposition reaction of treated AP particles have been studied by Kissinger, Boswell, Ozawa and Starink methods.
In this study, mesoporous α-Fe 2 O 3 catalysts were synthesized from mesoporous silica SBA-15 as ... more In this study, mesoporous α-Fe 2 O 3 catalysts were synthesized from mesoporous silica SBA-15 as the hard template and iron nitrate as the iron oxide source via nanocasting strategy. In order to access the highest loading of iron oxide in the template pores, different weight ratios of Fe(NO 3) 3 ·9H 2 O/SBA-15 were used in the pore-filling step by two solvents process. The structural and textural properties of the SBA-15 template and α-Fe 2 O 3-2.0 catalyst were characterized by means of X-ray diffraction, transmission electron microscopy and nitrogen adsorption–desorption techniques. The findings indicated that the resulting iron oxides are crystalline and to some extent, have negative replica structures of mesoporous SBA-15 template. The catalytic performance of mesoporous α-Fe 2 O 3 towards thermal decomposition of ammonium perchlorate was evaluated by differential scanning calorimetry technique. The specific heat released from the AP decomposition in the presence of catalyst was improved by increasing the precursor to template weight ratio. Therefore, the specific resulting heat released from the composite of AP and mesoporous α-Fe 2 O 3-2.0 (1110 J g −1) was ~ 3 folds of that for pure AP (423 J g −1).
[
Corrigendum Corrigendum to " Pure CuCr 2 O 4 nanoparticles: Synthesis, characterization and their... more Corrigendum Corrigendum to " Pure CuCr 2 O 4 nanoparticles: Synthesis, characterization and their morphological and size effects on the catalytic thermal decomposition of ammonium perchlorate " [Solid State Sci. 37(November 2014) 72e79]