Zeyede Aregahegn - Academia.edu (original) (raw)

Uploads

Papers by Zeyede Aregahegn

Bulletin of The Chemical Society of Ethiopia, Nov 21, 2017

The efficiency of two catalysts (TiO2 and TiO2 supported on zeolite) for the photocatalytic degra... more The efficiency of two catalysts (TiO2 and TiO2 supported on zeolite) for the photocatalytic degradation of methyl orange dye and wastewaters from Ethiopian textile industry was evaluated by chemometric methods from UV/Vis data of the reaction mixtures at different times. Multivariate curve resolution statistical analysis combined with an alternating least squares algorithm (MCR-ALS) proved to be an efficient method to resolve the different intermediates present during the photocatalytic degradation of the pollutants and to provide information about their evolution with time. Methyl orange photodegradation at pH = 3 showed different intermediate and concentration profiles than at pH = 6. The evolution of intermediates from textile wastewater photodegradation could also be resolved by this method. From the concentration profile or the reactants, a kinetic study was done. Results revealed that all the photodegradation reactions followed a first order kinetics. When TiO2 supported in Zeolite is used, reactions are in general slower, probably due to a mechanism of adsorption/desorption.

Applied and Environmental Soil Science, Feb 6, 2021

Awash River water has been impaired by various types of pollution owing to waste released from di... more Awash River water has been impaired by various types of pollution owing to waste released from different socioeconomic activities in its basin. is study aimed to evaluate the water quality of the Awash River and its tributaries in the basin used for irrigation purposes. Sampling sites were identified based on the pollution sources, accessibility, and land-use coverage. A total of 17 sampling sites were chosen along the Awash River, and samplings were collected four times a year through different seasons. e overall water quality and suitability for irrigation are explained using multiple water quality parameters such as pH, EC, SAR, RSC, Na + , K + , Ca + Mg, CO 3 2− , HCO 3 − , and Cl −. e obtained results showed that all quality parameters at Beseka Lake exceed the maximum permissible limit of suitability for irrigation. It is generally conceivable that the physicochemical characteristic of the Awash River varies in different water quality parameters at different sites. Only Beseka Lake and Meteka hot spring water exceeded pH and SAR permissible limit, and EC at Mojo, Wonji, Beseka, Melkasedi, Werer, Ambash, Meteka, and Meteka hot spring shows medium-to-high salinity scale, while RSC was very high at Beseka,

Journal of Soil Science and Environmental Management, Feb 29, 2020

Soil organic matter represents the remains of roots, plant materials, dead organisms in varies st... more Soil organic matter represents the remains of roots, plant materials, dead organisms in varies stages of decomposition and synthesis and is variable in composition. Walkley-Black method for the determination of organic matter is the most common method; however, it requires a lot of reagents and chemicals including potassium dichromate which is toxic especially when it is in a hexavalent form. It is very important to be able to reduce the amount of chemicals used during the analysis of organic carbon and it is also very important to reduce environmental pollution since the chemicals released to the environment becomes toxic. As the weight of sample decreases from 1 g (a Walkley-Black recommendation) proportionally with volume of reagents, there is no significant difference shown on the value of organic matter. Using orthophosphuric acid during organic matter determination did not have an impact on the results; however, it helps to observe a sharp endpoint. When the volume of diphenylamine indicator reduces from 15 to 4 drops, the result of organic matter has no significant difference.

Analytica Chimica Acta, 2007

To determine butyl-and phenyl-tins in fish muscle, a method including base digestion pretreatment... more To determine butyl-and phenyl-tins in fish muscle, a method including base digestion pretreatment, followed by a simultaneous ethylation-extraction procedure and gas chromatograph-flame photometric detector (GC-FPD) analysis is outlined. Key parameters that influence analyte recovery were investigated and optimized. A solution of 3% (w/v) potassium hydroxide (KOH) and 1 h digestion time at 60 • C were chosen in the base digestion step, to ensure complete solubilization of fish muscle and the decomposition of organotins was found to be insignificant. We found that the ratio of fish muscle/reaction solution should not exceed 0.2 g (dry weight) per 100 mL in order to avoid the matrix effect caused by the binding of hydrolyzed fish tissue with organotin ions. Ethylation of organotins were conducted at pH 6-7 with a 1% (w/v) sodium tetraethylborate (NaBEt 4) solution for 1 h. This simple and timesaving procedure should be able to be applied to the routine analysis of organotins in other bio-tissues.

Bulletin of the Chemical Society of Ethiopia, 2017

The efficiency of two catalysts (TiO2 and TiO2 supported on zeolite) for the photocatalytic degra... more The efficiency of two catalysts (TiO2 and TiO2 supported on zeolite) for the photocatalytic degradation of methyl orange dye and wastewaters from Ethiopian textile industry was evaluated by chemometric methods from UV/Vis data of the reaction mixtures at different times. Multivariate curve resolution statistical analysis combined with an alternating least squares algorithm (MCR-ALS) proved to be an efficient method to resolve the different intermediates present during the photocatalytic degradation of the pollutants and to provide information about their evolution with time. Methyl orange photodegradation at pH = 3 showed different intermediate and concentration profiles than at pH = 6. The evolution of intermediates from textile wastewater photodegradation could also be resolved by this method. From the concentration profile or the reactants, a kinetic study was done. Results revealed that all the photodegradation reactions followed a first order kinetics. When TiO2 supported in Zeolite is used, reactions are in general slower, probably due to a mechanism of adsorption/desorption.

Introduction The amide functionality is a common feature in small or complex synthetic or natural... more Introduction The amide functionality is a common feature in small or complex synthetic or natural molecules existing everywhere in life [1]. The reactivity of amides is related to their structure and their tautomeric equilibria (SCHEME 1). Therefore, it can be useful to determine their spectral behavior in different conditions in order to study their tautomeric distribution [2]. Propylamide can form amide imidol tautomer [3,4]. Although enols are thermodynamically unstable species in comparison with their carbonyl isomers, some of them have a long enough lifetime so as to be detected by some instrumental methods [5,6]. R NH 2 O R NH OH SCHEME 1. Tautomeric equilibria of amides. Abstract Solvent effects and sample concentration effects on the structural changes of propylamide have been investigated by FT-IR measurement using principal component analysis. The absorption peaks observed at higher frequency and higher intensity when using chloroform and dichloromethane compared to benzen...

Applied and Environmental Soil Science, 2021

Awash River water has been impaired by various types of pollution owing to waste released from di... more Awash River water has been impaired by various types of pollution owing to waste released from different socioeconomic activities in its basin. This study aimed to evaluate the water quality of the Awash River and its tributaries in the basin used for irrigation purposes. Sampling sites were identified based on the pollution sources, accessibility, and land-use coverage. A total of 17 sampling sites were chosen along the Awash River, and samplings were collected four times a year through different seasons. The overall water quality and suitability for irrigation are explained using multiple water quality parameters such as pH, EC, SAR, RSC, Na+, K+, Ca + Mg, CO32−, HCO3−, and Cl−. The obtained results showed that all quality parameters at Beseka Lake exceed the maximum permissible limit of suitability for irrigation. It is generally conceivable that the physicochemical characteristic of the Awash River varies in different water quality parameters at different sites. Only Beseka Lake...

Solvent effects and sample concentration effects on the structural changes of propylamide have be... more Solvent effects and sample concentration effects on the structural changes of propylamide have been investigated by FT-IR measurement using principal component analysis. The absorption peaks observed at higher frequency and higher intensity when using chloroform and dichloromethane compared to benzene. The concentration study reveals that propylamide form a high degree of association in benzene. Shifting the composition of the solvent from benzene to chloroform or dichloromethane, the intensity that comes from the association of molecule decreases since association is more favored in non-polar solvents. In spectra of propylamide in mixtures of benzene and dichloromethane an increment in the intensity of bands as well as a solvatochromic effect (blue shift) is observed upon increasing the polarity of the medium (solvatochromic effect).

Bulletin of The Chemical Society of Ethiopia, Nov 21, 2017

The efficiency of two catalysts (TiO2 and TiO2 supported on zeolite) for the photocatalytic degra... more The efficiency of two catalysts (TiO2 and TiO2 supported on zeolite) for the photocatalytic degradation of methyl orange dye and wastewaters from Ethiopian textile industry was evaluated by chemometric methods from UV/Vis data of the reaction mixtures at different times. Multivariate curve resolution statistical analysis combined with an alternating least squares algorithm (MCR-ALS) proved to be an efficient method to resolve the different intermediates present during the photocatalytic degradation of the pollutants and to provide information about their evolution with time. Methyl orange photodegradation at pH = 3 showed different intermediate and concentration profiles than at pH = 6. The evolution of intermediates from textile wastewater photodegradation could also be resolved by this method. From the concentration profile or the reactants, a kinetic study was done. Results revealed that all the photodegradation reactions followed a first order kinetics. When TiO2 supported in Zeolite is used, reactions are in general slower, probably due to a mechanism of adsorption/desorption.

Applied and Environmental Soil Science, Feb 6, 2021

Awash River water has been impaired by various types of pollution owing to waste released from di... more Awash River water has been impaired by various types of pollution owing to waste released from different socioeconomic activities in its basin. is study aimed to evaluate the water quality of the Awash River and its tributaries in the basin used for irrigation purposes. Sampling sites were identified based on the pollution sources, accessibility, and land-use coverage. A total of 17 sampling sites were chosen along the Awash River, and samplings were collected four times a year through different seasons. e overall water quality and suitability for irrigation are explained using multiple water quality parameters such as pH, EC, SAR, RSC, Na + , K + , Ca + Mg, CO 3 2− , HCO 3 − , and Cl −. e obtained results showed that all quality parameters at Beseka Lake exceed the maximum permissible limit of suitability for irrigation. It is generally conceivable that the physicochemical characteristic of the Awash River varies in different water quality parameters at different sites. Only Beseka Lake and Meteka hot spring water exceeded pH and SAR permissible limit, and EC at Mojo, Wonji, Beseka, Melkasedi, Werer, Ambash, Meteka, and Meteka hot spring shows medium-to-high salinity scale, while RSC was very high at Beseka,

Journal of Soil Science and Environmental Management, Feb 29, 2020

Soil organic matter represents the remains of roots, plant materials, dead organisms in varies st... more Soil organic matter represents the remains of roots, plant materials, dead organisms in varies stages of decomposition and synthesis and is variable in composition. Walkley-Black method for the determination of organic matter is the most common method; however, it requires a lot of reagents and chemicals including potassium dichromate which is toxic especially when it is in a hexavalent form. It is very important to be able to reduce the amount of chemicals used during the analysis of organic carbon and it is also very important to reduce environmental pollution since the chemicals released to the environment becomes toxic. As the weight of sample decreases from 1 g (a Walkley-Black recommendation) proportionally with volume of reagents, there is no significant difference shown on the value of organic matter. Using orthophosphuric acid during organic matter determination did not have an impact on the results; however, it helps to observe a sharp endpoint. When the volume of diphenylamine indicator reduces from 15 to 4 drops, the result of organic matter has no significant difference.

Analytica Chimica Acta, 2007

To determine butyl-and phenyl-tins in fish muscle, a method including base digestion pretreatment... more To determine butyl-and phenyl-tins in fish muscle, a method including base digestion pretreatment, followed by a simultaneous ethylation-extraction procedure and gas chromatograph-flame photometric detector (GC-FPD) analysis is outlined. Key parameters that influence analyte recovery were investigated and optimized. A solution of 3% (w/v) potassium hydroxide (KOH) and 1 h digestion time at 60 • C were chosen in the base digestion step, to ensure complete solubilization of fish muscle and the decomposition of organotins was found to be insignificant. We found that the ratio of fish muscle/reaction solution should not exceed 0.2 g (dry weight) per 100 mL in order to avoid the matrix effect caused by the binding of hydrolyzed fish tissue with organotin ions. Ethylation of organotins were conducted at pH 6-7 with a 1% (w/v) sodium tetraethylborate (NaBEt 4) solution for 1 h. This simple and timesaving procedure should be able to be applied to the routine analysis of organotins in other bio-tissues.

Bulletin of the Chemical Society of Ethiopia, 2017

The efficiency of two catalysts (TiO2 and TiO2 supported on zeolite) for the photocatalytic degra... more The efficiency of two catalysts (TiO2 and TiO2 supported on zeolite) for the photocatalytic degradation of methyl orange dye and wastewaters from Ethiopian textile industry was evaluated by chemometric methods from UV/Vis data of the reaction mixtures at different times. Multivariate curve resolution statistical analysis combined with an alternating least squares algorithm (MCR-ALS) proved to be an efficient method to resolve the different intermediates present during the photocatalytic degradation of the pollutants and to provide information about their evolution with time. Methyl orange photodegradation at pH = 3 showed different intermediate and concentration profiles than at pH = 6. The evolution of intermediates from textile wastewater photodegradation could also be resolved by this method. From the concentration profile or the reactants, a kinetic study was done. Results revealed that all the photodegradation reactions followed a first order kinetics. When TiO2 supported in Zeolite is used, reactions are in general slower, probably due to a mechanism of adsorption/desorption.

Introduction The amide functionality is a common feature in small or complex synthetic or natural... more Introduction The amide functionality is a common feature in small or complex synthetic or natural molecules existing everywhere in life [1]. The reactivity of amides is related to their structure and their tautomeric equilibria (SCHEME 1). Therefore, it can be useful to determine their spectral behavior in different conditions in order to study their tautomeric distribution [2]. Propylamide can form amide imidol tautomer [3,4]. Although enols are thermodynamically unstable species in comparison with their carbonyl isomers, some of them have a long enough lifetime so as to be detected by some instrumental methods [5,6]. R NH 2 O R NH OH SCHEME 1. Tautomeric equilibria of amides. Abstract Solvent effects and sample concentration effects on the structural changes of propylamide have been investigated by FT-IR measurement using principal component analysis. The absorption peaks observed at higher frequency and higher intensity when using chloroform and dichloromethane compared to benzen...

Applied and Environmental Soil Science, 2021

Awash River water has been impaired by various types of pollution owing to waste released from di... more Awash River water has been impaired by various types of pollution owing to waste released from different socioeconomic activities in its basin. This study aimed to evaluate the water quality of the Awash River and its tributaries in the basin used for irrigation purposes. Sampling sites were identified based on the pollution sources, accessibility, and land-use coverage. A total of 17 sampling sites were chosen along the Awash River, and samplings were collected four times a year through different seasons. The overall water quality and suitability for irrigation are explained using multiple water quality parameters such as pH, EC, SAR, RSC, Na+, K+, Ca + Mg, CO32−, HCO3−, and Cl−. The obtained results showed that all quality parameters at Beseka Lake exceed the maximum permissible limit of suitability for irrigation. It is generally conceivable that the physicochemical characteristic of the Awash River varies in different water quality parameters at different sites. Only Beseka Lake...

Solvent effects and sample concentration effects on the structural changes of propylamide have be... more Solvent effects and sample concentration effects on the structural changes of propylamide have been investigated by FT-IR measurement using principal component analysis. The absorption peaks observed at higher frequency and higher intensity when using chloroform and dichloromethane compared to benzene. The concentration study reveals that propylamide form a high degree of association in benzene. Shifting the composition of the solvent from benzene to chloroform or dichloromethane, the intensity that comes from the association of molecule decreases since association is more favored in non-polar solvents. In spectra of propylamide in mixtures of benzene and dichloromethane an increment in the intensity of bands as well as a solvatochromic effect (blue shift) is observed upon increasing the polarity of the medium (solvatochromic effect).