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Partager le résultat de cette recherche Interroger des sources externesExtraction de la pepsine et utilisation dans la coagulation du lait en vue d’une valorisation des proventricules de volailles au profit de la filière lait en Algérie / Férial Azziza Krid (Née Benyahia)
Titre : Extraction de la pepsine et utilisation dans la coagulation du lait en vue d’une valorisation des proventricules de volailles au profit de la filière lait en Algérie Type de document : texte imprimé Auteurs : Férial Azziza Krid (Née Benyahia), Auteur ; M.N. Zidoune, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2013 Importance : 152 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Tags : pepsine de poulet coagulation protéolyse rhéologie microstructure conservation chicken pepsin proteolysis rheology ?????? ?????? ????? ?????? ??? ?????????? ???????? ??? ???????? ?????? ???????? ??????? Index. décimale : 640 Industrie Alimentaire Résumé :
This study aimed the extraction of the pepsin from chicken proventriculus and characterization in order to ensure its use as a rennet substitute in the milk coagulation. For this purpose, we approached the study of its coagulant, proteolytic activities and biochemical, rheological and microstructural pepsin gel aspects with comparison to the rennet gel.
The chicken pepsin crude extract presented a strength coagulation of 13142. The partial purification by FPLC gave 45 fractions. The 18 fraction presented maximum coagulant activity (AC) and proteolytic activity (PA). The ration AC/AP of the pepsin crude extract increased from 7.15 to 34.25 after its partial purification. This increase is widely appreciated in cheese making.
The coagulant activity for chicken pepsin and rennet have been defined for temperature intervals included between 50 ° C and 55 ° C, pH 5.0 and 5.6 and 0.04 M CaCl2 respectively.
The coagulation was further estimated by the turbidimetry and the conductimetry. The turbidimetry showed similarity (p>0.05) between the micelles fusion evolution in the formation of the pepsin or rennet gel. However, the conductimetry has shown a difference (p< 0.05) between the minerals conductivity distributed between the aqueous and the micellar phase during gelation.
Rheological approach allowed to study the pepsin and rennet gel behavior by application of different shear rates. The apparent viscosity in non-destructive mode showed a similar viscous character evolution after, it tended to its maximum to indicate the formation of the two gels. Flow curves showed a plastic character for the two gels (Bingham liquid). On the other hand, the rennet gel seems to be viscoelastic ( = 0.55) relatively notable than gel pepsin ( = 0.60). The rennet and pepsin gels breaking points are reached respectively to 0.34 N and 0.38 N. Syneresis of the two gels showed at the beginning of coagulation rapid expulsion of whey. This expulsion tends to increase for gel pepsin but for rennet gel a stabilisation is shown for the same time of coagulation.
Proteolysis study was evaluated by the estimation of NPN/TN and NCN/TN fractions.
NPN fractions have not shown a significant difference (p> 0.05) ; 11.4% versus 11% for pepsin and rennet respectively. Nevertheless, the NCN fractions have presented differences (p<0.05) of 58.4 % for the pepsin gel and 49.8 % for the rennet gel.
In urea-PAGE, pepsin degradation products αs1I-CN and β I-CN of αs1-CN and et β-CN caseins respectively were observed in the early stages of incubation. Those of rennet appeared late from 6 hours of incubation. In SDS-PAGE, only para κ-CN was obtained as a κ-CN degradation product after pepsin or rennet hydrolysis.
The interactions study revealed the bonds type involved in the formation of two gels. The rate of their proteins dissociation showed an abundance in hydrophobic interactions, followed by
hydrogen and calcium bonds. The difference between the rate of dissociated proteins of two gels is
not significant (p>0.05).
The microscopic study of gels showed the evolution of the micelles fusion and the sol - gel system transition. Similarity of pepsin and rennet gels protein structure networks is visualized. This resemblance is characterized by compactness and the appearance of many cavities of heterogeneous size and amorphous zones. The spatial structure of two gels seems to be homogeneous.
To ensure stability of the chicken pepsin crude extract during a 135-day storage, two modes of drying were studied and compared, freeze-drying (lyophilization) and drying under
reduced vacuum. While the partial vacuum drying generated residual activity of 45.8% which decreased to 26.2% after 135 days of storage, freeze-drying ensured better results with 48.5% at the
end of drying operation and more than 41% for the same conservation period. The residual activity
seems to be better if the pepsinogen is activated after lyophilization. Furthermore, the addition of
lactose to the pepsin extract provides more interesting residual coagulant activity.
Theses results tend and converge towards the rennet substitution possibility by chicken pepsin in the milk coagulation. Also, it would be possible to use it in other areas for biological interest or industrial technology purposes.Diplôme : Doctorat en sciences En ligne : ../theses/agronomie/BEN6636.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9770 Extraction de la pepsine et utilisation dans la coagulation du lait en vue d’une valorisation des proventricules de volailles au profit de la filière lait en Algérie [texte imprimé] / Férial Azziza Krid (Née Benyahia), Auteur ; M.N. Zidoune, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2013 . - 152 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : pepsine de poulet coagulation protéolyse rhéologie microstructure conservation chicken pepsin proteolysis rheology ?????? ?????? ????? ?????? ??? ?????????? ???????? ??? ???????? ?????? ???????? ??????? Index. décimale : 640 Industrie Alimentaire Résumé :
This study aimed the extraction of the pepsin from chicken proventriculus and characterization in order to ensure its use as a rennet substitute in the milk coagulation. For this purpose, we approached the study of its coagulant, proteolytic activities and biochemical, rheological and microstructural pepsin gel aspects with comparison to the rennet gel.
The chicken pepsin crude extract presented a strength coagulation of 13142. The partial purification by FPLC gave 45 fractions. The 18 fraction presented maximum coagulant activity (AC) and proteolytic activity (PA). The ration AC/AP of the pepsin crude extract increased from 7.15 to 34.25 after its partial purification. This increase is widely appreciated in cheese making.
The coagulant activity for chicken pepsin and rennet have been defined for temperature intervals included between 50 ° C and 55 ° C, pH 5.0 and 5.6 and 0.04 M CaCl2 respectively.
The coagulation was further estimated by the turbidimetry and the conductimetry. The turbidimetry showed similarity (p>0.05) between the micelles fusion evolution in the formation of the pepsin or rennet gel. However, the conductimetry has shown a difference (p< 0.05) between the minerals conductivity distributed between the aqueous and the micellar phase during gelation.
Rheological approach allowed to study the pepsin and rennet gel behavior by application of different shear rates. The apparent viscosity in non-destructive mode showed a similar viscous character evolution after, it tended to its maximum to indicate the formation of the two gels. Flow curves showed a plastic character for the two gels (Bingham liquid). On the other hand, the rennet gel seems to be viscoelastic ( = 0.55) relatively notable than gel pepsin ( = 0.60). The rennet and pepsin gels breaking points are reached respectively to 0.34 N and 0.38 N. Syneresis of the two gels showed at the beginning of coagulation rapid expulsion of whey. This expulsion tends to increase for gel pepsin but for rennet gel a stabilisation is shown for the same time of coagulation.
Proteolysis study was evaluated by the estimation of NPN/TN and NCN/TN fractions.
NPN fractions have not shown a significant difference (p> 0.05) ; 11.4% versus 11% for pepsin and rennet respectively. Nevertheless, the NCN fractions have presented differences (p<0.05) of 58.4 % for the pepsin gel and 49.8 % for the rennet gel.
In urea-PAGE, pepsin degradation products αs1I-CN and β I-CN of αs1-CN and et β-CN caseins respectively were observed in the early stages of incubation. Those of rennet appeared late from 6 hours of incubation. In SDS-PAGE, only para κ-CN was obtained as a κ-CN degradation product after pepsin or rennet hydrolysis.
The interactions study revealed the bonds type involved in the formation of two gels. The rate of their proteins dissociation showed an abundance in hydrophobic interactions, followed by
hydrogen and calcium bonds. The difference between the rate of dissociated proteins of two gels is
not significant (p>0.05).
The microscopic study of gels showed the evolution of the micelles fusion and the sol - gel system transition. Similarity of pepsin and rennet gels protein structure networks is visualized. This resemblance is characterized by compactness and the appearance of many cavities of heterogeneous size and amorphous zones. The spatial structure of two gels seems to be homogeneous.
To ensure stability of the chicken pepsin crude extract during a 135-day storage, two modes of drying were studied and compared, freeze-drying (lyophilization) and drying under
reduced vacuum. While the partial vacuum drying generated residual activity of 45.8% which decreased to 26.2% after 135 days of storage, freeze-drying ensured better results with 48.5% at the
end of drying operation and more than 41% for the same conservation period. The residual activity
seems to be better if the pepsinogen is activated after lyophilization. Furthermore, the addition of
lactose to the pepsin extract provides more interesting residual coagulant activity.
Theses results tend and converge towards the rennet substitution possibility by chicken pepsin in the milk coagulation. Also, it would be possible to use it in other areas for biological interest or industrial technology purposes.Diplôme : Doctorat en sciences En ligne : ../theses/agronomie/BEN6636.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9770 Exemplaires
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Titre : Nouvelles procédures « vertes » dans la synthèse des dérivés de la 3,4-dihydropyrimidin-2(1H)-one, de la 1,4-dihydropyridine et du tétrahydrobenzo[b]pyrane Type de document : texte imprimé Auteurs : Imane Sehout, Auteur ; Abdelmadjid Debache, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2014 Importance : 207 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Tags : synthèse organique chimie verte acide ascorbique acide acétylsalicylique réactions à composants multiples la réaction de Biginelli Hantzsch et la synthèse des benzopyranes green chemistry ascorbic acid acetylsalicylic acid multicomponent reactions the reaction of Biginelli Hantzsch and synthesis of benzopyran ??????? ??? ?????????? ??? ?????? ??????????? ????????? ???????? ???????? ????? ???????? ? ?????? ??????????? Index. décimale : 540 Chimie et sciences connexes Résumé : In this manuscript, we explained the purpose of our study, and the results obtained. We are interested in developing new protocols that fall within the field of green chemistry (sustainable chemistry) , offering two new Brϕnsted acids of natural origin catalysts ( ascorbic acid and acetylsalicylic acid); the reactions on which we did our study are multi-component reactions : reaction Biginelli , Hantzsch and synthesis of benzopyran which are divided into
three chapters.
The three reactions are carried out in a dry environment , which was a plus for our research, we could obtain very good results , that am for returns or for necessary for the progress of the reactions , we have also enriched the library of molecules, the production of new molecules with very good yields in record time.
Diplôme : Doctorat En ligne : ../theses/chimie/SEH6706.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9917 Nouvelles procédures « vertes » dans la synthèse des dérivés de la 3,4-dihydropyrimidin-2(1H)-one, de la 1,4-dihydropyridine et du tétrahydrobenzo[b]pyrane [texte imprimé] / Imane Sehout, Auteur ; Abdelmadjid Debache, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2014 . - 207 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : synthèse organique chimie verte acide ascorbique acide acétylsalicylique réactions à composants multiples la réaction de Biginelli Hantzsch et la synthèse des benzopyranes green chemistry ascorbic acid acetylsalicylic acid multicomponent reactions the reaction of Biginelli Hantzsch and synthesis of benzopyran ??????? ??? ?????????? ??? ?????? ??????????? ????????? ???????? ???????? ????? ???????? ? ?????? ??????????? Index. décimale : 540 Chimie et sciences connexes Résumé : In this manuscript, we explained the purpose of our study, and the results obtained. We are interested in developing new protocols that fall within the field of green chemistry (sustainable chemistry) , offering two new Brϕnsted acids of natural origin catalysts ( ascorbic acid and acetylsalicylic acid); the reactions on which we did our study are multi-component reactions : reaction Biginelli , Hantzsch and synthesis of benzopyran which are divided into
three chapters.
The three reactions are carried out in a dry environment , which was a plus for our research, we could obtain very good results , that am for returns or for necessary for the progress of the reactions , we have also enriched the library of molecules, the production of new molecules with very good yields in record time.
Diplôme : Doctorat En ligne : ../theses/chimie/SEH6706.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9917 Exemplaires
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Titre : Investigation phytochimique et biologique de l’espèce Astragalus armatus ssp. numidicus (Coss. et Dur.) Maire. et Synthèse catalytique de nouveaux dérivés julolidines Type de document : texte imprimé Auteurs : Amira Labed èp Kherrab, Auteur ; Ahmed Kabouche, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2016 Importance : 242 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Français (fre) Tags : Astragalus armatus ssp. numidicus (Coss. et Dur.) Maire. activité antioxydante antibactérienne immunomodulatrice, transfert d’hydrogène iridium julolidine ?-alkylation antioxidant antibacterial immunomodulatory hydrogen transfer ????? ??????? ????? ????????? ???????? ???????? ??? ?????????? ???????? .?- Index. décimale : 540 Chimie et sciences connexes Résumé : In the first part of this work, our study was devoted to the phytochemical and biological investigations of the pods of Astragalus armatus ssp. numidicus (Coss. et Dur.) Maire. (Fabaceae). Separation and purification of the ethyl acetate and the n- butanol fractions led to the isolation of six compounds (four flavonoids including two
triglycosyles, a saponin and a cyclitol). The structural elucidation of these compounds was determined using modern spectroscopic methods including ultraviolet spectroscopy UV, nuclear magnetic resonance spectroscopy (NMR) mono and bidimensional (1H, 13C, COSY, HSQC, HMBC and TOCSY) and with comparison with literature data.
The chloroform fraction exhibited the best antibacterial activity against E. coli, S. aureus and P. aeruginosa, while the ethyl acetate fraction showed the highest antioxidant activity by the use of DPPH, ABTS, CUPRAC and metal chelate methods. Furthermore, the evaluation of the immunomodulatory activity of the n-butanol fraction with Biozzi method showed that the butanolic fraction improved the phagocytic activity by stimulating the reticuloendothelial system.
In the second part, the synthesis of 12 new derivatives julolidines was carried out by hydrogen transfer process. The first transformation allowed the formation of julolidines by NC (sp2)-cyclisation of tetrahydroquinoline and propan-1,3-diols. Applying another hydrogen autotransfer process, the prepared julolidines were easily
functionalized at the C2 position in green conditions with the formation of water as the only by-product. The activation of C9 was also achived. The preparation of three new iridium catalysts was performed.
The structures of the synthesized compounds were mainly established by the use of NMR techniques (1H, 13C and DEPT), by high resolution mass spectrometry (HRMS) and by X-rays.Diplôme : Doctorat En ligne : ../theses/chimie/LAB6879.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10198 Investigation phytochimique et biologique de l’espèce Astragalus armatus ssp. numidicus (Coss. et Dur.) Maire. et Synthèse catalytique de nouveaux dérivés julolidines [texte imprimé] / Amira Labed èp Kherrab, Auteur ; Ahmed Kabouche, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2016 . - 242 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Français (fre)
Tags : Astragalus armatus ssp. numidicus (Coss. et Dur.) Maire. activité antioxydante antibactérienne immunomodulatrice, transfert d’hydrogène iridium julolidine ?-alkylation antioxidant antibacterial immunomodulatory hydrogen transfer ????? ??????? ????? ????????? ???????? ???????? ??? ?????????? ???????? .?- Index. décimale : 540 Chimie et sciences connexes Résumé : In the first part of this work, our study was devoted to the phytochemical and biological investigations of the pods of Astragalus armatus ssp. numidicus (Coss. et Dur.) Maire. (Fabaceae). Separation and purification of the ethyl acetate and the n- butanol fractions led to the isolation of six compounds (four flavonoids including two
triglycosyles, a saponin and a cyclitol). The structural elucidation of these compounds was determined using modern spectroscopic methods including ultraviolet spectroscopy UV, nuclear magnetic resonance spectroscopy (NMR) mono and bidimensional (1H, 13C, COSY, HSQC, HMBC and TOCSY) and with comparison with literature data.
The chloroform fraction exhibited the best antibacterial activity against E. coli, S. aureus and P. aeruginosa, while the ethyl acetate fraction showed the highest antioxidant activity by the use of DPPH, ABTS, CUPRAC and metal chelate methods. Furthermore, the evaluation of the immunomodulatory activity of the n-butanol fraction with Biozzi method showed that the butanolic fraction improved the phagocytic activity by stimulating the reticuloendothelial system.
In the second part, the synthesis of 12 new derivatives julolidines was carried out by hydrogen transfer process. The first transformation allowed the formation of julolidines by NC (sp2)-cyclisation of tetrahydroquinoline and propan-1,3-diols. Applying another hydrogen autotransfer process, the prepared julolidines were easily
functionalized at the C2 position in green conditions with the formation of water as the only by-product. The activation of C9 was also achived. The preparation of three new iridium catalysts was performed.
The structures of the synthesized compounds were mainly established by the use of NMR techniques (1H, 13C and DEPT), by high resolution mass spectrometry (HRMS) and by X-rays.Diplôme : Doctorat En ligne : ../theses/chimie/LAB6879.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10198 Exemplaires
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Titre : Préparation et étude de polymères a empreintes moléculaires pour l’extraction de proteines. Type de document : texte imprimé Auteurs : Hassane Ayadi, Auteur ; Fayçal Djazi, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2017 Importance : 89 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles.
Langues : Français (fre) Tags : Empreintes moléculaires séparation des protéines photopolymerisation billes de PVC Iniferter molecular imprinting photopolymerization poly(vinyl chloride) proteins ??? ?????????? ????? ????? ???? ?????? ?.PV Index. décimale : 540 Chimie et sciences connexes Résumé : Separation techniques based on molecular recognition have received much attention in chemistry and biology due to their high selectivity for target molecules. In this area, molecularly imprinted polymers (MIPs) have experienced considerable growth in recent years, particularly when they are prepared as thin films Ultrathin films of molecularly imprinted polymer were prepared by photoiniferter on PVC beads for the selective uptake of lysozyme, taken as a model protein. Acrylamide was selected as the functional monomer and N,N-methylenebisacrylamide as the crosslinking agent. The copolymerization process was confined to the surface of the PVC beads grafted with diethyldithiocarbamate iniferter initiator in the presence of lysozyme. After extraction of lysozyme from the shell of the PVC-MIP beads, the latter were then used as artificial receptors for the rebinding of lysozyme. The sequential steps of the modification of PVC beads were monitored by XPS, infrared and Raman spectroscopies.
The imprinting step was found to be essential as the PVC-MIP beads could recognize lysozyme but not the nonimprinted beads (PVC-NIP). The binding properties of PVC-MIP beads were determined using UV spectroscopy from adsorption isotherms of lysozyme, cytochrome, and myoglobin. The imprinted beads were found to be highly selective toward
lysozyme over the competitive proteins. This work shows the interest of photoiniferter as an efficient mean for the design ofmolecularly imprinted polymer beads for rapid, selective removal of proteins.
Diplôme : Doctorat en sciences En ligne : ../theses/chimie/AYA7184.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10736 Préparation et étude de polymères a empreintes moléculaires pour l’extraction de proteines. [texte imprimé] / Hassane Ayadi, Auteur ; Fayçal Djazi, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2017 . - 89 f. ; 30 cm.
2 copies imprimées disponibles.
Langues : Français (fre)
Tags : Empreintes moléculaires séparation des protéines photopolymerisation billes de PVC Iniferter molecular imprinting photopolymerization poly(vinyl chloride) proteins ??? ?????????? ????? ????? ???? ?????? ?.PV Index. décimale : 540 Chimie et sciences connexes Résumé : Separation techniques based on molecular recognition have received much attention in chemistry and biology due to their high selectivity for target molecules. In this area, molecularly imprinted polymers (MIPs) have experienced considerable growth in recent years, particularly when they are prepared as thin films Ultrathin films of molecularly imprinted polymer were prepared by photoiniferter on PVC beads for the selective uptake of lysozyme, taken as a model protein. Acrylamide was selected as the functional monomer and N,N-methylenebisacrylamide as the crosslinking agent. The copolymerization process was confined to the surface of the PVC beads grafted with diethyldithiocarbamate iniferter initiator in the presence of lysozyme. After extraction of lysozyme from the shell of the PVC-MIP beads, the latter were then used as artificial receptors for the rebinding of lysozyme. The sequential steps of the modification of PVC beads were monitored by XPS, infrared and Raman spectroscopies.
The imprinting step was found to be essential as the PVC-MIP beads could recognize lysozyme but not the nonimprinted beads (PVC-NIP). The binding properties of PVC-MIP beads were determined using UV spectroscopy from adsorption isotherms of lysozyme, cytochrome, and myoglobin. The imprinted beads were found to be highly selective toward
lysozyme over the competitive proteins. This work shows the interest of photoiniferter as an efficient mean for the design ofmolecularly imprinted polymer beads for rapid, selective removal of proteins.
Diplôme : Doctorat en sciences En ligne : ../theses/chimie/AYA7184.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10736 Exemplaires
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Titre : Simulated sunlight photodegradation of an organic pollutant by heterogeneous photo-Fenton-like processes: case of 2-mercaptobenzothiazole using a local natural clay powder. Titre original : Photodégradation d'un polluant organique sous la lumière solaire simulée, par un processus type photo-Fenton hétérogène: cas de photodégradation du 2-mercaptobenzothiazole en présence d’une poudre argileuse naturelle locale. Type de document : texte imprimé Auteurs : Zakaria Redouane Salah, Auteur ; Moulay Abderrahmane Malouki, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2018 Importance : 163 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles
Langues : Anglais (eng) Tags : MBT heterogeneous photo-Fenton process natural clay powder (NCP) photodegradation hydroxyl radical simulated sunlight irradiation procédé photo-Fenton hétérogène poudre d'argile naturelle photodégradation radical hydroxyle irradiation solaire simulée ??? ????? ???? ????? ??? ??????? ????? ????? ??????? ???? ???? ??? ?????????? ?????? ???? ????? ???? ????? ??????? ? ???? ??????? Index. décimale : 540 Chimie et sciences connexes Résumé : The problem of water pollution has been an environmental concern for many years, which lead researchers around the world to looking for effective methods to solve this issue. The incapability of conventional methods to remove effectively biorecalcitrant and toxic pollutants, have promoted the research of more efficient and ecologically friendly water treatment technologies.
In the same aspect, this thesis is a small contribution to the development of a new advanced oxidation process considered as promising and clean method for the destruction of water pollutants. In this process we investigated the efficiency of untreated local natural clay rich in iron oxides as a cost-free photocatalyst for the
degradation of a persistent organic pollutant under simulated sunlight irradiation. The targeted pollutant was: 2-mercaptobenzothiazole (MBT). The study showed that:
Firstly, the adsorption capacity, kinetics and isotherms models were examined in thedark.
Secondly, experiments of degradation by heterogeneous Fenton process under variousoperational parameters were investigated.And then, we focused our research on the photodegradation of MBT by heterogeneous photo-Fenton process using the same natural clay powder (NCP) as photocatalyst and under simulated sunlight irradiation. Experiments were conducted at natural pH with a bath reactor equipped with a medium-pressure Hg lamp emitting mainly at 366 nm. The natural clay was crushed into small homogeneous particles (powder) and then characterized by SEM-EDS, UV-Vis diffuse reflectance spectroscopy, XRF and XRD analysis. The specific BET surface area measured for the clay was 30.22 m²·g-1.
Our main results indicated that, the photodegradation of MBT follows first order (for direct photolysis) or pseudo-first order kinetics (for photocatalysis) Direct photolysis of MBT showed a negligible effect both upon 254 and 365 nm irradiation, while 42.5% and 62% of MBT was eliminated in 3 h under 310 nm irradiation in the presence of H2O2, and under sunlight irradiation (using NCP), respectively. Kinetic runs carried out with 5,0.10-5M MBT and 0.5g·L-1clay showed higher MBT conversion and photodegradation rate at basic pH and in oxygenated
media.
The photodegradation of MBT is mainly attributed to reaction with HO, leading to different intermediates that have been identified by HPLC-MS. A reaction mechanism is proposed at the end of our thesis. The highest TOC removals were obtained using UVA at low pHs, in the absence of O2 with 68% and 65% TOC removal respectively.
The presence of oxalic acid and H2O2 enhanced significantly MBT photodegradation.
Finally, the obtained results support the use of natural clay rich in iron oxides as a free, clean and efficient photocatalysts for water pollutants abatement.
Diplôme : Doctorat en sciences En ligne : ../theses/chimie/RED7300.pdf Format de la ressource électronique : Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10915 Simulated sunlight photodegradation of an organic pollutant by heterogeneous photo-Fenton-like processes: case of 2-mercaptobenzothiazole using a local natural clay powder. = Photodégradation d'un polluant organique sous la lumière solaire simulée, par un processus type photo-Fenton hétérogène: cas de photodégradation du 2-mercaptobenzothiazole en présence d’une poudre argileuse naturelle locale. [texte imprimé] / Zakaria Redouane Salah, Auteur ; Moulay Abderrahmane Malouki, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2018 . - 163 f. ; 30 cm.
2 copies imprimées disponibles
Langues : Anglais (eng)
Tags : MBT heterogeneous photo-Fenton process natural clay powder (NCP) photodegradation hydroxyl radical simulated sunlight irradiation procédé photo-Fenton hétérogène poudre d'argile naturelle photodégradation radical hydroxyle irradiation solaire simulée ??? ????? ???? ????? ??? ??????? ????? ????? ??????? ???? ???? ??? ?????????? ?????? ???? ????? ???? ????? ??????? ? ???? ??????? Index. décimale : 540 Chimie et sciences connexes Résumé : The problem of water pollution has been an environmental concern for many years, which lead researchers around the world to looking for effective methods to solve this issue. The incapability of conventional methods to remove effectively biorecalcitrant and toxic pollutants, have promoted the research of more efficient and ecologically friendly water treatment technologies.
In the same aspect, this thesis is a small contribution to the development of a new advanced oxidation process considered as promising and clean method for the destruction of water pollutants. In this process we investigated the efficiency of untreated local natural clay rich in iron oxides as a cost-free photocatalyst for the
degradation of a persistent organic pollutant under simulated sunlight irradiation. The targeted pollutant was: 2-mercaptobenzothiazole (MBT). The study showed that:
Firstly, the adsorption capacity, kinetics and isotherms models were examined in thedark.
Secondly, experiments of degradation by heterogeneous Fenton process under variousoperational parameters were investigated.And then, we focused our research on the photodegradation of MBT by heterogeneous photo-Fenton process using the same natural clay powder (NCP) as photocatalyst and under simulated sunlight irradiation. Experiments were conducted at natural pH with a bath reactor equipped with a medium-pressure Hg lamp emitting mainly at 366 nm. The natural clay was crushed into small homogeneous particles (powder) and then characterized by SEM-EDS, UV-Vis diffuse reflectance spectroscopy, XRF and XRD analysis. The specific BET surface area measured for the clay was 30.22 m²·g-1.
Our main results indicated that, the photodegradation of MBT follows first order (for direct photolysis) or pseudo-first order kinetics (for photocatalysis) Direct photolysis of MBT showed a negligible effect both upon 254 and 365 nm irradiation, while 42.5% and 62% of MBT was eliminated in 3 h under 310 nm irradiation in the presence of H2O2, and under sunlight irradiation (using NCP), respectively. Kinetic runs carried out with 5,0.10-5M MBT and 0.5g·L-1clay showed higher MBT conversion and photodegradation rate at basic pH and in oxygenated
media.
The photodegradation of MBT is mainly attributed to reaction with HO, leading to different intermediates that have been identified by HPLC-MS. A reaction mechanism is proposed at the end of our thesis. The highest TOC removals were obtained using UVA at low pHs, in the absence of O2 with 68% and 65% TOC removal respectively.
The presence of oxalic acid and H2O2 enhanced significantly MBT photodegradation.
Finally, the obtained results support the use of natural clay rich in iron oxides as a free, clean and efficient photocatalysts for water pollutants abatement.
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