The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous sus... more The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view. The degradation was studied using different parameters such as types of TiO2, catalyst concentration, substrate concentration, reaction pH and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and potassium persulphate (K2S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatlyst ′′Degussa P-25′′ was found to be more efficient as compared with other photocatalysts. The results indicate the process follows Langmuir-Hinshelwood-type kinetics and inference is made of the reaction taking place on the semiconductor particle surface. An analysis of Total Organic Carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved.
Photochemical and Photobiological Sciences, May 1, 2006
The degradation of pesticide methomyl in aqueous solution by UV-irradiation in the presence of Ti... more The degradation of pesticide methomyl in aqueous solution by UV-irradiation in the presence of TiO 2 "Degussa P-25" has been studied. It was found that mineralisation to carbon dioxide, water, sulfate and ammonia took place during the process. The rate of photodecomposition of methomyl was measured using high performance liquid chromatography (HPLC), while its mineralization was followed using ion chromatography (IC), and total organic carbon (TOC) analysis. The identification of reaction intermediate products was carried out using coupled techniques HPLC-MS (electrospray ionization in positive mode) and a degradation pathway was proposed. Under our conditions, complete disappearance of 1.23 × 10 −4 mol l −1 of pure pesticide occurred within 45 min of illumination and 80% TOC removal occurred in less than 4 h. Three main intermediates were identified resulting from (i) the rupture of the ester bond (or the NO bond), (ii) the hydroxylation of methyl group borne by the nitrogen atom and (iii) the product resulting from the decarboxylation of the oxidized hydroxylated methyl group (photo-Kolbe reaction). In order to be sure that the photocatalytic results were consistent, hydrolysis and photolysis tests were performed. Photocatalysis proved to be an excellent new advanced oxidation technology (AOT) to eliminate methomyl present in water.
Separation and Purification Technology, Jun 6, 2008
The chemical degradation of pesticide methomyl in water by Fenton (H 2 O 2 /Fe 2+) and photo-Fent... more The chemical degradation of pesticide methomyl in water by Fenton (H 2 O 2 /Fe 2+) and photo-Fenton (H 2 O 2 /Fe 2+ /UV) processes was investigated. A laboratory setup was designed to evaluate and select the optimal oxidation process. The degradation rate is strongly dependent on the pH, initial concentrations of the pesticide, H 2 O 2 , Fe 2+ , and [H 2 O 2 ] 0 /[Fe 2+ ] 0 ratio. The effect of these parameters has been studied and the optimum operational conditions of these two processes were found. The optimum conditions were obtained at pH 3 for the H 2 O 2 /Fe 2+ and H 2 O 2 /Fe 2+ /UV. The kinetics of degradation was found to follow first-order reaction rules. The photo-Fenton system proved to be the most efficient and occurs at a much higher oxidation rate than Fenton system and allows achieving 100% degradation of methomyl in 30 min of reaction time. The results of the study showed that photo-Fenton process was an effective and economic treatment process for methomyl under acidic conditions by producing higher mineralisation efficiency in a relatively short radiation time compared to Fenton process.
In this work we used a new organic bio flocculant (BF), which we extracted from natural seeds of ... more In this work we used a new organic bio flocculant (BF), which we extracted from natural seeds of Lepidium Sativum (LS). This extract is known for it’s performance in various fields such as cosmetology, pharmacology and food products. Moreover, it does not present any danger to human health. The main purpose of our study is the exploitation of a new natural supports, as bio polymers in the treatment of water loaded with marl limestone suspended solids (SS) and trace elements, including Copper and zinc. We studied the effectiveness of this extract in comparison with other products usually used in the treatment and depollution of water; the preliminary tests were carried out on pseudo samples prepared at the laboratory level. The comparative study with a synthetic flocculant (Anionic polyacrylamide: APA), usually used in water treatment, provided a good competitiveness with an important flocculation power. The combination of the two steps of neutralization and coagulation by aluminum sulfate (AS), followed by a flocculation step by the new flocculant (LS), then a natural decantation, gave significant results, in the abatement of Cu2+, Zn2+ and (SS). For the solution rich in marl limestone, the turbidity passes from an average of 600 NTU to values close to 1 NTU. The sludge thus produced after treatment is submitted to an analysis by (SEM) and (XRD) and the retained chemical elements are detected. The study generally enters as a sustainable development strategy capable of improving long-term global water security and protecting the environment from synthetic products used excessively in water treatment.
Silica gel supported titanium dioxide particles (TiO2–SiO2) prepared by sol–gel method was as pho... more Silica gel supported titanium dioxide particles (TiO2–SiO2) prepared by sol–gel method was as photocatalyst in the degradation of β-naphthol in water under UV-illumination. The prepared sample has been characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The supported catalyst had large surface area and good sedimentation ability. The photodegradation rate of β-naphthol under UV-irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The experiments were measured by high performance liquid chromatography (HPLC). The photodegradation rate of β-naphthol using 60% TiO2–SiO2 particles was faster than that using TiO2 “Degussa P-25”, TiO2 “PC-50” and TiO2 “Aldrich” as photocatalyst by 2.7, 4 and 7.8 times, respectively. The kinetics of photocatalytic β-naphthol degradation was found to follow a pseudo-first-order rate law. The effect of the TiO2 loading on the photoactivity of TiO2–SiO2 particles was also discussed. With good photocatalytic activity under UV-irradiation and the ability to be readily separated from the reaction system, this novel kind of catalyst exhibited the potential effective in the treatment of organic pollutants in aqueous systems.
Titanium dioxide TiO 2 powder photocatalysts were prepared at the laboratory by two methods: hydr... more Titanium dioxide TiO 2 powder photocatalysts were prepared at the laboratory by two methods: hydrolysis of titanium tetraisopropoxide (TTIP) and the precipitation of a precursor starting from titanium tetrachloride TiCl 4 in basic medium. The products obtained are calcined at temperatures around 800 • C. Their characterization was carried out by both diffraction X-ray (XRD) and thermogravimetric analysis (TGA). The photocatalytic activity of the elaborate solids (TiO 2) is evaluated. It is compared with that given for commercial TiO 2 "Degussa P-25" in the degradation of-naphthol chosen as an model molecule in aqueous suspension. These reactions are done at room temperature in a photochemical reactor.
In December 2019, the world experienced a new coronavirus, SARS-CoV-2, causing coronavirus diseas... more In December 2019, the world experienced a new coronavirus, SARS-CoV-2, causing coronavirus disease 2019 originating from Wuhan.The virus has crossed national borders and now affects more than 200 countries and territories. Hydroxychloroquine has been considered as a drug capable of treating COVID-19. The objective of this work is to establish a simple platform for electrocatalytic detection of hydroxychloroquine in human urine samples and pharmaceutical samples (tablets) using a ZnO@CPE sensor constructed by simple and inexpensive hydrothermal methods using a square wave voltammetry method. The best results are obtained in a PBS electrolyte with irreversible behavior of the hydroxychloroquine complement and controlled by diffusion coupled with absorption phenomena. The ZnO@CPE shifts the oxidation potential of hydroxychloroquine with the formation of a single very intense peak at the position of Epa = 0.5 V/(vs Ag/AgCl) with a shift is ΔEp = 0.1 V(vs Ag/AgCl) compared to the unmodified electrode. The obtained ZnO@CPE hybrid nanocomposite was characterized by different techniques and showed excellent electrocatalytic activity and higher active surface area compared to the bare carbon paste electrode. Under the optimized experimental conditions, the ZnO@CPE sensor showed good analytical performance for the determination of trace amounts of hydroxychloroquine, a wide linearity range from 10-3 M to 0.8 × 10-6 M with a very low detection limit in the range of 1.33 × 10-7 M, satisfactory selectivity, acceptable repeatability and reproducibility. The calculated recovery and coefficient of variation for the two samples analyzed are very satisfactory, ranging from 97.6 to 102% and 1.2 to 2.3% respectively. The proposed applied method and the fabricated sensor offer the possibility to analyze traces of hydroxychloroquine in real human urine and water samples.
In this work we used a new organic bio flocculant (BF), which we extracted from natural seeds of ... more In this work we used a new organic bio flocculant (BF), which we extracted from natural seeds of Lepidium Sativum (LS). This extract is known for it’s performance in various fields such as cosmetology, pharmacology and food products. Moreover, it does not present any danger to human health. The main purpose of our study is the exploitation of a new natural supports, as bio polymers in the treatment of water loaded with marl limestone suspended solids (SS) and trace elements, including Copper and zinc. We studied the effectiveness of this extract in comparison with other products usually used in the treatment and depollution of water; the preliminary tests were carried out on pseudo samples prepared at the laboratory level. The comparative study with a synthetic flocculant (Anionic polyacrylamide: APA), usually used in water treatment, provided a good competitiveness with an important flocculation power. The combination of the two steps of neutralization and coagulation by aluminum s...
Nanotechnology for Environmental Engineering, 2022
The Zn–Al–Cl Layered Double Hydroxide (Zn–Al–Cl LDH) was synthesized at constant pH by coprecipit... more The Zn–Al–Cl Layered Double Hydroxide (Zn–Al–Cl LDH) was synthesized at constant pH by coprecipitation method and then used as an adsorbent for the removal of a reactive azo dye Remazol Red 23 (RR-23). The structural and morphological properties of the synthesized Zn–Al–Cl LDH were determined using X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Brunauer–Emmett–Teller surface area, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Thermogravimetry Analysis, and Differential Thermal Analysis, and the determination of the point of zero charge pHpzc. The adsorption characteristics were studied by optimizing different parameters such as solution pH, contact time, and initial dye concentration. The maximum adsorption capacity was obtained in the pH ranging from 4 to 7. XRD and FTIR results of Zn–Al–Cl LDH before and after adsorption showed that the removal of the dye is due to its adsorption on the surface of the LDH and that there is no intercalation of the dye since no change in the basal spacing was observed. The kinetic data obtained were examined using the pseudo-first and pseudo-second-order equations. The equilibrium adsorption data were studied using the Freundlich and Langmuir models. The adsorption behavior of Zn–Al–Cl LDH fits perfectly the Langmuir isotherm and the pseudo second-order kinetic model. Thermodynamic studies revealed that the RR-23 dye adsorption on Zn–Al–Cl LDH was exothermic and governed by a physisorption (ΔadsH0<0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\Delta_{{{\text{ads}}}} H^{0} < 0)$$\end{document}, spontaneous (ΔadsG0<0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\Delta_{{{\text{ads}}}} G^{0} < 0)$$\end{document} and increased the randomness (ΔadsS0>0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\Delta_{{{\text{ads}}}} S^{0} > 0)$$\end{document} in the adsorbent/adsorbate system. The regeneration study was also conducted in three cycles with 98, 91, and 74% removal efficiency of RR-23.
The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous sus... more The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view. The degradation was studied using different parameters such as types of TiO2, catalyst concentration, substrate concentration, reaction pH and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and potassium persulphate (K2S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatlyst ′′Degussa P-25′′ was found to be more efficient as compared with other photocatalysts. The results indicate the process follows Langmuir-Hinshelwood-type kinetics and inference is made of the reaction taking place on the semiconductor particle surface. An analysis of Total Organic Carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved.
Photochemical and Photobiological Sciences, May 1, 2006
The degradation of pesticide methomyl in aqueous solution by UV-irradiation in the presence of Ti... more The degradation of pesticide methomyl in aqueous solution by UV-irradiation in the presence of TiO 2 "Degussa P-25" has been studied. It was found that mineralisation to carbon dioxide, water, sulfate and ammonia took place during the process. The rate of photodecomposition of methomyl was measured using high performance liquid chromatography (HPLC), while its mineralization was followed using ion chromatography (IC), and total organic carbon (TOC) analysis. The identification of reaction intermediate products was carried out using coupled techniques HPLC-MS (electrospray ionization in positive mode) and a degradation pathway was proposed. Under our conditions, complete disappearance of 1.23 × 10 −4 mol l −1 of pure pesticide occurred within 45 min of illumination and 80% TOC removal occurred in less than 4 h. Three main intermediates were identified resulting from (i) the rupture of the ester bond (or the NO bond), (ii) the hydroxylation of methyl group borne by the nitrogen atom and (iii) the product resulting from the decarboxylation of the oxidized hydroxylated methyl group (photo-Kolbe reaction). In order to be sure that the photocatalytic results were consistent, hydrolysis and photolysis tests were performed. Photocatalysis proved to be an excellent new advanced oxidation technology (AOT) to eliminate methomyl present in water.
Separation and Purification Technology, Jun 6, 2008
The chemical degradation of pesticide methomyl in water by Fenton (H 2 O 2 /Fe 2+) and photo-Fent... more The chemical degradation of pesticide methomyl in water by Fenton (H 2 O 2 /Fe 2+) and photo-Fenton (H 2 O 2 /Fe 2+ /UV) processes was investigated. A laboratory setup was designed to evaluate and select the optimal oxidation process. The degradation rate is strongly dependent on the pH, initial concentrations of the pesticide, H 2 O 2 , Fe 2+ , and [H 2 O 2 ] 0 /[Fe 2+ ] 0 ratio. The effect of these parameters has been studied and the optimum operational conditions of these two processes were found. The optimum conditions were obtained at pH 3 for the H 2 O 2 /Fe 2+ and H 2 O 2 /Fe 2+ /UV. The kinetics of degradation was found to follow first-order reaction rules. The photo-Fenton system proved to be the most efficient and occurs at a much higher oxidation rate than Fenton system and allows achieving 100% degradation of methomyl in 30 min of reaction time. The results of the study showed that photo-Fenton process was an effective and economic treatment process for methomyl under acidic conditions by producing higher mineralisation efficiency in a relatively short radiation time compared to Fenton process.
In this work we used a new organic bio flocculant (BF), which we extracted from natural seeds of ... more In this work we used a new organic bio flocculant (BF), which we extracted from natural seeds of Lepidium Sativum (LS). This extract is known for it’s performance in various fields such as cosmetology, pharmacology and food products. Moreover, it does not present any danger to human health. The main purpose of our study is the exploitation of a new natural supports, as bio polymers in the treatment of water loaded with marl limestone suspended solids (SS) and trace elements, including Copper and zinc. We studied the effectiveness of this extract in comparison with other products usually used in the treatment and depollution of water; the preliminary tests were carried out on pseudo samples prepared at the laboratory level. The comparative study with a synthetic flocculant (Anionic polyacrylamide: APA), usually used in water treatment, provided a good competitiveness with an important flocculation power. The combination of the two steps of neutralization and coagulation by aluminum sulfate (AS), followed by a flocculation step by the new flocculant (LS), then a natural decantation, gave significant results, in the abatement of Cu2+, Zn2+ and (SS). For the solution rich in marl limestone, the turbidity passes from an average of 600 NTU to values close to 1 NTU. The sludge thus produced after treatment is submitted to an analysis by (SEM) and (XRD) and the retained chemical elements are detected. The study generally enters as a sustainable development strategy capable of improving long-term global water security and protecting the environment from synthetic products used excessively in water treatment.
Silica gel supported titanium dioxide particles (TiO2–SiO2) prepared by sol–gel method was as pho... more Silica gel supported titanium dioxide particles (TiO2–SiO2) prepared by sol–gel method was as photocatalyst in the degradation of β-naphthol in water under UV-illumination. The prepared sample has been characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The supported catalyst had large surface area and good sedimentation ability. The photodegradation rate of β-naphthol under UV-irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The experiments were measured by high performance liquid chromatography (HPLC). The photodegradation rate of β-naphthol using 60% TiO2–SiO2 particles was faster than that using TiO2 “Degussa P-25”, TiO2 “PC-50” and TiO2 “Aldrich” as photocatalyst by 2.7, 4 and 7.8 times, respectively. The kinetics of photocatalytic β-naphthol degradation was found to follow a pseudo-first-order rate law. The effect of the TiO2 loading on the photoactivity of TiO2–SiO2 particles was also discussed. With good photocatalytic activity under UV-irradiation and the ability to be readily separated from the reaction system, this novel kind of catalyst exhibited the potential effective in the treatment of organic pollutants in aqueous systems.
Titanium dioxide TiO 2 powder photocatalysts were prepared at the laboratory by two methods: hydr... more Titanium dioxide TiO 2 powder photocatalysts were prepared at the laboratory by two methods: hydrolysis of titanium tetraisopropoxide (TTIP) and the precipitation of a precursor starting from titanium tetrachloride TiCl 4 in basic medium. The products obtained are calcined at temperatures around 800 • C. Their characterization was carried out by both diffraction X-ray (XRD) and thermogravimetric analysis (TGA). The photocatalytic activity of the elaborate solids (TiO 2) is evaluated. It is compared with that given for commercial TiO 2 "Degussa P-25" in the degradation of-naphthol chosen as an model molecule in aqueous suspension. These reactions are done at room temperature in a photochemical reactor.
In December 2019, the world experienced a new coronavirus, SARS-CoV-2, causing coronavirus diseas... more In December 2019, the world experienced a new coronavirus, SARS-CoV-2, causing coronavirus disease 2019 originating from Wuhan.The virus has crossed national borders and now affects more than 200 countries and territories. Hydroxychloroquine has been considered as a drug capable of treating COVID-19. The objective of this work is to establish a simple platform for electrocatalytic detection of hydroxychloroquine in human urine samples and pharmaceutical samples (tablets) using a ZnO@CPE sensor constructed by simple and inexpensive hydrothermal methods using a square wave voltammetry method. The best results are obtained in a PBS electrolyte with irreversible behavior of the hydroxychloroquine complement and controlled by diffusion coupled with absorption phenomena. The ZnO@CPE shifts the oxidation potential of hydroxychloroquine with the formation of a single very intense peak at the position of Epa = 0.5 V/(vs Ag/AgCl) with a shift is ΔEp = 0.1 V(vs Ag/AgCl) compared to the unmodified electrode. The obtained ZnO@CPE hybrid nanocomposite was characterized by different techniques and showed excellent electrocatalytic activity and higher active surface area compared to the bare carbon paste electrode. Under the optimized experimental conditions, the ZnO@CPE sensor showed good analytical performance for the determination of trace amounts of hydroxychloroquine, a wide linearity range from 10-3 M to 0.8 × 10-6 M with a very low detection limit in the range of 1.33 × 10-7 M, satisfactory selectivity, acceptable repeatability and reproducibility. The calculated recovery and coefficient of variation for the two samples analyzed are very satisfactory, ranging from 97.6 to 102% and 1.2 to 2.3% respectively. The proposed applied method and the fabricated sensor offer the possibility to analyze traces of hydroxychloroquine in real human urine and water samples.
In this work we used a new organic bio flocculant (BF), which we extracted from natural seeds of ... more In this work we used a new organic bio flocculant (BF), which we extracted from natural seeds of Lepidium Sativum (LS). This extract is known for it’s performance in various fields such as cosmetology, pharmacology and food products. Moreover, it does not present any danger to human health. The main purpose of our study is the exploitation of a new natural supports, as bio polymers in the treatment of water loaded with marl limestone suspended solids (SS) and trace elements, including Copper and zinc. We studied the effectiveness of this extract in comparison with other products usually used in the treatment and depollution of water; the preliminary tests were carried out on pseudo samples prepared at the laboratory level. The comparative study with a synthetic flocculant (Anionic polyacrylamide: APA), usually used in water treatment, provided a good competitiveness with an important flocculation power. The combination of the two steps of neutralization and coagulation by aluminum s...
Nanotechnology for Environmental Engineering, 2022
The Zn–Al–Cl Layered Double Hydroxide (Zn–Al–Cl LDH) was synthesized at constant pH by coprecipit... more The Zn–Al–Cl Layered Double Hydroxide (Zn–Al–Cl LDH) was synthesized at constant pH by coprecipitation method and then used as an adsorbent for the removal of a reactive azo dye Remazol Red 23 (RR-23). The structural and morphological properties of the synthesized Zn–Al–Cl LDH were determined using X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Brunauer–Emmett–Teller surface area, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Thermogravimetry Analysis, and Differential Thermal Analysis, and the determination of the point of zero charge pHpzc. The adsorption characteristics were studied by optimizing different parameters such as solution pH, contact time, and initial dye concentration. The maximum adsorption capacity was obtained in the pH ranging from 4 to 7. XRD and FTIR results of Zn–Al–Cl LDH before and after adsorption showed that the removal of the dye is due to its adsorption on the surface of the LDH and that there is no intercalation of the dye since no change in the basal spacing was observed. The kinetic data obtained were examined using the pseudo-first and pseudo-second-order equations. The equilibrium adsorption data were studied using the Freundlich and Langmuir models. The adsorption behavior of Zn–Al–Cl LDH fits perfectly the Langmuir isotherm and the pseudo second-order kinetic model. Thermodynamic studies revealed that the RR-23 dye adsorption on Zn–Al–Cl LDH was exothermic and governed by a physisorption (ΔadsH0<0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\Delta_{{{\text{ads}}}} H^{0} < 0)$$\end{document}, spontaneous (ΔadsG0<0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\Delta_{{{\text{ads}}}} G^{0} < 0)$$\end{document} and increased the randomness (ΔadsS0>0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\Delta_{{{\text{ads}}}} S^{0} > 0)$$\end{document} in the adsorbent/adsorbate system. The regeneration study was also conducted in three cycles with 98, 91, and 74% removal efficiency of RR-23.
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