İnci Eroğlu - Academia.edu (original) (raw)
Papers by İnci Eroğlu
BioHydrogen, 1999
A bio-photoelectrochemical (bio-PEC) reactor containing the photosynthetic bacterium Halobacteriu... more A bio-photoelectrochemical (bio-PEC) reactor containing the photosynthetic bacterium Halobacterium halobium has been constructed. H. halobium contains a retinal protein, bacteriorhodopsin, in its purple membrane that gives protons upon illumination. In this ...
ABSTRACT In this study, the durability of the PEM fuel cell electrocatalysts was investigated by ... more ABSTRACT In this study, the durability of the PEM fuel cell electrocatalysts was investigated by using cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques. Accelerated degradation tests (ADTs) were applied to the commercial catalysts and the electrocatalysts prepared by microwave irradiation technique in order to determine the platinum dissolution/agglomeration and carbon corrosion characteristics. The parameters examined for the commercial catalysts were carbon to Nafion (C/N) ratio in the catalyst ink and Pt loading over the carbon support. The parameters examined for the home-made catalysts were the conditions altered in the microwave environment including the base concentration and microwave duration. The hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR) were examined before and after ADTs. The results showed that the catalyst properties differently affect the HOR and ORR activities of the catalysts before and after ADTs.
In the present research, the improvement of an alkaline fuel cell performance by changing the ele... more In the present research, the improvement of an alkaline fuel cell performance by changing the electrode structure and manufacturing method has been achieved by employing multilayer, Te¯on-bonded gas diusion type electrodes which were prepared by the rolling method. Active carbon or carbon black was used as the support material, platinum as the catalyst and nickel screen as the backing material. Double layer electrodes possessed the active and the diusion layers on the backing layer. However, the single layer electrodes only had the active layer on the backing layer. The electrode manufacturing method was ameliorated by applying dierent compaction loads and altering the sintering conditions. The electrodes were prepared by using dierent PTFE contents and platinum loadings. The voltage-current density characteristics of the fuel cell were measured at dierent temperatures (25± 708C) in a test module. The speci®c power density (mW/mg Pt) and the fuel cell eciency obtained by using the double layer electrodes were higher compared to the single layer electrodes.
Synthesis of zinc borate was conducted in a laboratory and a pilot scale batch reactor to see the... more Synthesis of zinc borate was conducted in a laboratory and a pilot scale batch reactor to see the influence of process variables on the reaction parameters and the final product, 2ZnO Á 3B 2 O 3 Á 3.5H 2 O. Effects of stirring speed, presence of baffles, amount of seed, particle size and purity of zinc oxide, and mole ratio of H 3 BO 3 :ZnO on the zinc borate formation reaction were examined at a constant temperature of 85 1C in a laboratory (4 L) and a pilot scale (85 L) reactor. Products obtained from the reaction in both reactors were characterized by chemical analysis, X-ray diffraction, particle size distribution analysis, thermal gravimetric analysis and scanning electron microscopy. The kinetic data for the zinc borate production reaction was fit by using the logistic model. The results revealed that the specific reaction rate, a model parameter, decreases with increase in particle size of zinc oxide and the presence of baffles, but increases with increase in stirring speed and purity of zinc oxide; however, it is unaffected with the changes in the amount of seed and reactants ratio. The reaction completion time is unaffected by scaling-up.
... Materials 2.2. Sulfonation of polysulfone 2.3. Polymer characterization 2.4. Membranepreparat... more ... Materials 2.2. Sulfonation of polysulfone 2.3. Polymer characterization 2.4. Membranepreparation and characterization 2.5. Proton conductivity analysis 2.6. Membrane electrode assembly (MEA) preparation 2.7. PEMFC performance tests 3. Results 3.1. ...
Zeolite beta Membrane electrode assembly (MEA) a b s t r a c t Sulfonated polyether-etherketone (... more Zeolite beta Membrane electrode assembly (MEA) a b s t r a c t Sulfonated polyether-etherketone (SPEEK) has a potential for proton exchange fuel cell applications. However, its conductivity and thermohydrolytic stability should be improved.
Photofermentative hydrogen production Olive mill wastewater Physicochemical pretreatment Clay reg... more Photofermentative hydrogen production Olive mill wastewater Physicochemical pretreatment Clay regeneration Two-stage processes Wastewater treatment a b s t r a c t
CHEMICAL …, 2009
... It is capable of growing photo-heterotrophically by using light as primary energy Please cite... more ... It is capable of growing photo-heterotrophically by using light as primary energy Please cite this article as: Afsar N., Ozgur E., Gurgan M., De Vrije T., Yucel M. and Gunduz U., (2009), Hydrogen production by r. capsulatus ... 2, 1-15 Kars, G., Gündüz, U., Yücel, M., Türker, F. and ...
Biomass & Bioenergy, 2009
Olive oil extraction produces a dark-colored wastewater that contains nutrients that can be furth... more Olive oil extraction produces a dark-colored wastewater that contains nutrients that can be further processed using biotechnology, in parallel with treatment for disposal. For instance, olive mill wastewater (OMW) can be used as a substrate for photofermentative hydrogen production by purple bacteria. A comparative study was investigated with several OMW samples from different olive oil mills in Western-Anatolia, Turkey. The
Solar Energy Materials and Solar Cells, 2000
The performance characteristics of two photo-electrochemical cells with di!erent cell con"guratio... more The performance characteristics of two photo-electrochemical cells with di!erent cell con"gurations were investigated at 253C and within the illumination range of 70}100 W/m. These cells included a jacketed single cell (JSC) and a jacketed two-compartment cell (JTC). Ni-mesh was used as a counter electrode and as a backing material for semiconductor electrodes. Semiconductor electrodes were prepared by silk-screen painting technique using TiO , WO , PbO, Sb S , ZnO, Al O or CuO powder mixed with Te#on. The electrolyte contained aqueous methylene blue (MB) and Fe (II)/Fe(III) compounds. Voltage}current characteristics of the cells were measured at 253C. Energy conversion e$ciencies were calculated. A bestperforming cell was selected from each cell con"guration. The e!ects of Ni-mesh, semiconductor properties, and electrolyte modi"cation on cell performance were studied. Experimental observations are compared with those in the literature, and the performance of each cell con"guration is discussed. The best performance was obtained from Ni}TiO -MB/MB, Fe(II)//MB, Fe(II)/Ni}C cell con"guration with 13% e$ciency from JTC, Ni-PbO/MB, Fe(II)/Ni cell con"guration with 24% e$ciency from JSC.
Resources, Conservation and Recycling, 2010
... attractive process; however, it suffers from the insurmountable barriers of oxygen sensitivit... more ... attractive process; however, it suffers from the insurmountable barriers of oxygen sensitivity, intrinsic limitations in light conversion efficiencies, problems with gas capture and separation, and very onerous economics ([Hallenbeck and Benemann, 2002] and [Melis, 2002]). ...
Journal of Membrane Science, 1995
In the present work the photo responses of bacteriorhodopsin in purple membrane fragments were st... more In the present work the photo responses of bacteriorhodopsin in purple membrane fragments were studied under continuous high intensity light illumination in different ranges of pH, temperature and ionic strength. The activity of bacteriorhodopsin was measured as pH vs. time by using a combined pH electrode. The activity of the bacteriorhodopsin in purple membrane fragments at acidic pH was found to be more sensitive to temperature changes than it was at physiological or higher pH values. The activity of bacteriorhodopsin was also found to be the function of varing concentrations of different salts. The kinetic analyses of light reactions (proton dissociation) and dark reactions (proton association) were carded out at different pH, temperature and ionic strengths. The kinetic data revealed that the proton dissociation in the light and proton association in the dark followed the first order kinetics in the pH range of 6.7-7.2 at room temperature. Beyond these limits the kinetic behavior of bacteriorhodopsin was found to be much more complex.
Journal of Crystal Growth, 2009
Zinc borate is a flame retardant additive used in polymers, wood applications and textile product... more Zinc borate is a flame retardant additive used in polymers, wood applications and textile products. There are different types of zinc borate having different chemical compositions and structures. In this study, the production of zinc borate having the molecular formula of 2ZnO Á 3B 2 O 3 Á 3.5H 2 O was reexamined by studying the effects of reaction parameters on the properties of product as well as the reaction kinetics. Production of zinc borate from the reaction of boric acid and zinc oxide in the presence of seed crystals was performed in a continuously stirred, temperature-controlled batch reactor having a volume of 1.5 L. Samples taken in regular time intervals during the experiments were analyzed for the concentration of zinc oxide and boron oxide in the solid as well as for the conversion of zinc oxide to zinc borate versus time. The zinc borate production reaction was fit to the logistic model. The reaction rate, reaction completion time, composition and particle size distribution of zinc borate product were determined by varying the following parameters: the boric acid to zinc oxide ratio (H 3 BO 3 :ZnO=3:1, 3.5:1, 5:1 and 7:1), the particle size of zinc oxide (10 and 25 mm), stirring rate (275, 400, 800 and 1600 rpm), temperature (75, 85 and 95 1C) and the size of seed crystals (10 and 2 mm). The products were also analyzed for particle size distribution. The experimental results showed that the reaction rate increases with the increase in H 3 BO 3 :ZnO ratio, particle size of zinc oxide, stirring rate and temperature. Concomitantly, the reaction completion time is decreased by increasing the H 3 BO 3 :ZnO ratio, stirring rate and temperature. The average particle sizes of the zinc borate products are in the range 4.3-16.6 mm (wet dispersion analysis).
Journal of Cleaner Production, 2010
... Ebru Özgür a , Corresponding Author Contact Information , E-mail The Corresponding Author ,Ni... more ... Ebru Özgür a , Corresponding Author Contact Information , E-mail The Corresponding Author ,Nilüfer Afsar a , Truus de Vrije b , Meral ... An uptake hydrogenase deficient mutant (hup − ) of R. capsulatus (Öztürk et al., 2006) was employed and a higher hydrogen productivity (1.37 ...
Journal of Cleaner Production, 2010
The purpose of this study was to develop a pilot scale tubular photo bioreactor (80L) for photo f... more The purpose of this study was to develop a pilot scale tubular photo bioreactor (80L) for photo fermentative hydrogen production by photosynthetic purple-non-sulfur bacterium, Rhodobacter capsulatus, operating in outdoor conditions, using acetate as the carbon source. The reactor was operated continuously in fed-batch mode for 30 days throughout December 2008 in Ankara. It was placed in a greenhouse in order
Journal of Biotechnology, 1999
Hydrogen gas can be produced electrochemically by leading a current through two electrodes immers... more Hydrogen gas can be produced electrochemically by leading a current through two electrodes immersed in a NaCl solution. Bacteriorhodopsin (BR) a protein found in the purple membrane of Halobacterium halobium, is known to pump protons across the membrane upon illumination. In this study, the effect of BR on photoelectrochemical hydrogen production was investigated. A batch type bio-photoelectrochemical reactor was designed and constructed. The photoelectrochemical hydrogen production experiments were performed with free H. halobium packed cells or immobilised H. halobium cells. The cells were either immobilised in polyacrylamide gel (PAG) or on cellulose acetate membrane (CAM). Experiments were also performed with purple membrane fragments of H. halobium immobilised on cellulose acetate membrane. It was found that the presence of bacteriorhodopsin (BR) in the reactor enhances the hydrogen production rate upon illumination. Immobilisation increased the amount of hydrogen produced per mole of BR. Compared to control experiments without BR, the power requirement of the photoelectrochemical reactor per amount of hydrogen produced decreased fourfold when purple membrane fragments immobilised on CAM were used. The presence of BR regulates the pH of the system, increases the hydrogen production rate and causes light-induced proton dissociation, which lowers the electrical power requirement for the electrochemical conversion.
Journal of Biotechnology, 1999
Rhodobacter sphaeroides O.U. 001 is able to produce hydrogen anaerobically upon illumination. The... more Rhodobacter sphaeroides O.U. 001 is able to produce hydrogen anaerobically upon illumination. The cells were screened for the presence of valuable by-products such as poly-b-hydroxy (PHB) butyric acid aiming to improve the feasibility of the system. Also waste water from a sugar refinery was used for bacterial growth to further increase the feasibility. Under aerobic conditions the standard growth media containing L-malic acid and sodium glutamate in 7.5/10 and 15/2 molar ratios and a medium containing 30% waste water from sugar refinery were used. In this case the maximum concentration of PHB produced were approximately 0.2 g l − 1 in both of the standard media whereas it was 0.3 g l − 1 in medium containing 30% waste water. By using the medium containing 30% waste water, PHB and hydrogen productions were determined under anaerobic conditions. The maximum concentration of PHB produced was around 0.5 g l − 1 and the amount of gas collected was 35 ml in 108 h. From these results it can be concluded that PHB can be collected during hydrogen production. The use of waste water from sugar refinery increased the yield.
Journal of Biotechnology, 1999
The effect of L-malic acid and sodium glutamate, which serve as the carbon and nitrogen source, r... more The effect of L-malic acid and sodium glutamate, which serve as the carbon and nitrogen source, respectively, on hydrogen production by Rhodobacter sphaeroides O.U.001 has been investigated in a batch water jacketed glass column photobioreactor (PBR), which has an inner volume of 400 ml. The PBR was operated at different carbon to nitrogen ratios at 32°C with a tungsten lamp at a light intensity of 200 W m − 2 . Carbon to nitrogen ratio was found to be an important parameter for bio-hydrogen production. Moreover, hydrogen gas production was dependent on certain threshold concentrations of sodium glutamate. L-malic acid consumption was found to be first order with respect to L-malic acid concentration, whereas sodium glutamate consumption was found to be second order with respect to glutamate concentration. It was concluded that there is a close relationship between the hydrogen production rate and substrate consumption rates. A kinetic model is developed, which relates hydrogen gas production per amount of biomass, L-malic acid, and sodium glutamate concentrations.
International Journal of Hydrogen Energy, 2011
Olive mill wastewater Iron Molybdenum Wastewater treatment Rhodobacter sphaeroides a b s t r a c ... more Olive mill wastewater Iron Molybdenum Wastewater treatment Rhodobacter sphaeroides a b s t r a c t Photofermentative hydrogen production from olive mill wastewater (OMW) by Rhodobacter sphaeroides O.U.001 was assessed under iron and molybdenum supplementation. Control cultures were only grown with 2% OMW containing media. The analysis included measurements of biomass accumulation, hydrogen production, pH variations of the medium, and changes in the chemical oxygen demand (COD) of the wastewater. Growth under control and Mo-supplemented experiments yielded about the same amount of biomass (w0.4 g dry cell weight per L culture). On the other hand, Mo addition slightly enhanced the total volume of H 2 gas production (62 mL H 2 ), in comparison with the control reactor (40 mL H 2 ). Fe-supplemented cultures showed a significant increase on H 2 production (125 mL H 2 ), tough having a longer lag time for the observation of the first H 2 bubbles (24 h), compared to the control (15 h) and Mo-supplemented ones (15 h). Fe-added cultures also yielded better wastewater treatment by achieving 48.1% degradation of the initial chemical oxygen demand (COD) value compared to the control reactor having 30.2% COD removal efficiency. Advances described in this work have the potential to find applications in hydrogen industry while attempting an effective management of cheap feedstock utilization. (E. Eroglu).
Fuel and Energy Abstracts, 2000
Rhodobacter capsulatus produces molecular hydrogen under the photoheterotrophic growth condition ... more Rhodobacter capsulatus produces molecular hydrogen under the photoheterotrophic growth condition with reduced carbon sources (organic acids). Under this condition, ubiquinol pool is over reduced and excess reducing equivalents are primarily consumed via the reduction of CO2 through the Calvin–Benson–Bassham (CBB) pathway, the dimethylsulfoxide reductase (DMSOR) system or by the reduction of protons into hydrogen gas with the use of nitrogenase
BioHydrogen, 1999
A bio-photoelectrochemical (bio-PEC) reactor containing the photosynthetic bacterium Halobacteriu... more A bio-photoelectrochemical (bio-PEC) reactor containing the photosynthetic bacterium Halobacterium halobium has been constructed. H. halobium contains a retinal protein, bacteriorhodopsin, in its purple membrane that gives protons upon illumination. In this ...
ABSTRACT In this study, the durability of the PEM fuel cell electrocatalysts was investigated by ... more ABSTRACT In this study, the durability of the PEM fuel cell electrocatalysts was investigated by using cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques. Accelerated degradation tests (ADTs) were applied to the commercial catalysts and the electrocatalysts prepared by microwave irradiation technique in order to determine the platinum dissolution/agglomeration and carbon corrosion characteristics. The parameters examined for the commercial catalysts were carbon to Nafion (C/N) ratio in the catalyst ink and Pt loading over the carbon support. The parameters examined for the home-made catalysts were the conditions altered in the microwave environment including the base concentration and microwave duration. The hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR) were examined before and after ADTs. The results showed that the catalyst properties differently affect the HOR and ORR activities of the catalysts before and after ADTs.
In the present research, the improvement of an alkaline fuel cell performance by changing the ele... more In the present research, the improvement of an alkaline fuel cell performance by changing the electrode structure and manufacturing method has been achieved by employing multilayer, Te¯on-bonded gas diusion type electrodes which were prepared by the rolling method. Active carbon or carbon black was used as the support material, platinum as the catalyst and nickel screen as the backing material. Double layer electrodes possessed the active and the diusion layers on the backing layer. However, the single layer electrodes only had the active layer on the backing layer. The electrode manufacturing method was ameliorated by applying dierent compaction loads and altering the sintering conditions. The electrodes were prepared by using dierent PTFE contents and platinum loadings. The voltage-current density characteristics of the fuel cell were measured at dierent temperatures (25± 708C) in a test module. The speci®c power density (mW/mg Pt) and the fuel cell eciency obtained by using the double layer electrodes were higher compared to the single layer electrodes.
Synthesis of zinc borate was conducted in a laboratory and a pilot scale batch reactor to see the... more Synthesis of zinc borate was conducted in a laboratory and a pilot scale batch reactor to see the influence of process variables on the reaction parameters and the final product, 2ZnO Á 3B 2 O 3 Á 3.5H 2 O. Effects of stirring speed, presence of baffles, amount of seed, particle size and purity of zinc oxide, and mole ratio of H 3 BO 3 :ZnO on the zinc borate formation reaction were examined at a constant temperature of 85 1C in a laboratory (4 L) and a pilot scale (85 L) reactor. Products obtained from the reaction in both reactors were characterized by chemical analysis, X-ray diffraction, particle size distribution analysis, thermal gravimetric analysis and scanning electron microscopy. The kinetic data for the zinc borate production reaction was fit by using the logistic model. The results revealed that the specific reaction rate, a model parameter, decreases with increase in particle size of zinc oxide and the presence of baffles, but increases with increase in stirring speed and purity of zinc oxide; however, it is unaffected with the changes in the amount of seed and reactants ratio. The reaction completion time is unaffected by scaling-up.
... Materials 2.2. Sulfonation of polysulfone 2.3. Polymer characterization 2.4. Membranepreparat... more ... Materials 2.2. Sulfonation of polysulfone 2.3. Polymer characterization 2.4. Membranepreparation and characterization 2.5. Proton conductivity analysis 2.6. Membrane electrode assembly (MEA) preparation 2.7. PEMFC performance tests 3. Results 3.1. ...
Zeolite beta Membrane electrode assembly (MEA) a b s t r a c t Sulfonated polyether-etherketone (... more Zeolite beta Membrane electrode assembly (MEA) a b s t r a c t Sulfonated polyether-etherketone (SPEEK) has a potential for proton exchange fuel cell applications. However, its conductivity and thermohydrolytic stability should be improved.
Photofermentative hydrogen production Olive mill wastewater Physicochemical pretreatment Clay reg... more Photofermentative hydrogen production Olive mill wastewater Physicochemical pretreatment Clay regeneration Two-stage processes Wastewater treatment a b s t r a c t
CHEMICAL …, 2009
... It is capable of growing photo-heterotrophically by using light as primary energy Please cite... more ... It is capable of growing photo-heterotrophically by using light as primary energy Please cite this article as: Afsar N., Ozgur E., Gurgan M., De Vrije T., Yucel M. and Gunduz U., (2009), Hydrogen production by r. capsulatus ... 2, 1-15 Kars, G., Gündüz, U., Yücel, M., Türker, F. and ...
Biomass & Bioenergy, 2009
Olive oil extraction produces a dark-colored wastewater that contains nutrients that can be furth... more Olive oil extraction produces a dark-colored wastewater that contains nutrients that can be further processed using biotechnology, in parallel with treatment for disposal. For instance, olive mill wastewater (OMW) can be used as a substrate for photofermentative hydrogen production by purple bacteria. A comparative study was investigated with several OMW samples from different olive oil mills in Western-Anatolia, Turkey. The
Solar Energy Materials and Solar Cells, 2000
The performance characteristics of two photo-electrochemical cells with di!erent cell con"guratio... more The performance characteristics of two photo-electrochemical cells with di!erent cell con"gurations were investigated at 253C and within the illumination range of 70}100 W/m. These cells included a jacketed single cell (JSC) and a jacketed two-compartment cell (JTC). Ni-mesh was used as a counter electrode and as a backing material for semiconductor electrodes. Semiconductor electrodes were prepared by silk-screen painting technique using TiO , WO , PbO, Sb S , ZnO, Al O or CuO powder mixed with Te#on. The electrolyte contained aqueous methylene blue (MB) and Fe (II)/Fe(III) compounds. Voltage}current characteristics of the cells were measured at 253C. Energy conversion e$ciencies were calculated. A bestperforming cell was selected from each cell con"guration. The e!ects of Ni-mesh, semiconductor properties, and electrolyte modi"cation on cell performance were studied. Experimental observations are compared with those in the literature, and the performance of each cell con"guration is discussed. The best performance was obtained from Ni}TiO -MB/MB, Fe(II)//MB, Fe(II)/Ni}C cell con"guration with 13% e$ciency from JTC, Ni-PbO/MB, Fe(II)/Ni cell con"guration with 24% e$ciency from JSC.
Resources, Conservation and Recycling, 2010
... attractive process; however, it suffers from the insurmountable barriers of oxygen sensitivit... more ... attractive process; however, it suffers from the insurmountable barriers of oxygen sensitivity, intrinsic limitations in light conversion efficiencies, problems with gas capture and separation, and very onerous economics ([Hallenbeck and Benemann, 2002] and [Melis, 2002]). ...
Journal of Membrane Science, 1995
In the present work the photo responses of bacteriorhodopsin in purple membrane fragments were st... more In the present work the photo responses of bacteriorhodopsin in purple membrane fragments were studied under continuous high intensity light illumination in different ranges of pH, temperature and ionic strength. The activity of bacteriorhodopsin was measured as pH vs. time by using a combined pH electrode. The activity of the bacteriorhodopsin in purple membrane fragments at acidic pH was found to be more sensitive to temperature changes than it was at physiological or higher pH values. The activity of bacteriorhodopsin was also found to be the function of varing concentrations of different salts. The kinetic analyses of light reactions (proton dissociation) and dark reactions (proton association) were carded out at different pH, temperature and ionic strengths. The kinetic data revealed that the proton dissociation in the light and proton association in the dark followed the first order kinetics in the pH range of 6.7-7.2 at room temperature. Beyond these limits the kinetic behavior of bacteriorhodopsin was found to be much more complex.
Journal of Crystal Growth, 2009
Zinc borate is a flame retardant additive used in polymers, wood applications and textile product... more Zinc borate is a flame retardant additive used in polymers, wood applications and textile products. There are different types of zinc borate having different chemical compositions and structures. In this study, the production of zinc borate having the molecular formula of 2ZnO Á 3B 2 O 3 Á 3.5H 2 O was reexamined by studying the effects of reaction parameters on the properties of product as well as the reaction kinetics. Production of zinc borate from the reaction of boric acid and zinc oxide in the presence of seed crystals was performed in a continuously stirred, temperature-controlled batch reactor having a volume of 1.5 L. Samples taken in regular time intervals during the experiments were analyzed for the concentration of zinc oxide and boron oxide in the solid as well as for the conversion of zinc oxide to zinc borate versus time. The zinc borate production reaction was fit to the logistic model. The reaction rate, reaction completion time, composition and particle size distribution of zinc borate product were determined by varying the following parameters: the boric acid to zinc oxide ratio (H 3 BO 3 :ZnO=3:1, 3.5:1, 5:1 and 7:1), the particle size of zinc oxide (10 and 25 mm), stirring rate (275, 400, 800 and 1600 rpm), temperature (75, 85 and 95 1C) and the size of seed crystals (10 and 2 mm). The products were also analyzed for particle size distribution. The experimental results showed that the reaction rate increases with the increase in H 3 BO 3 :ZnO ratio, particle size of zinc oxide, stirring rate and temperature. Concomitantly, the reaction completion time is decreased by increasing the H 3 BO 3 :ZnO ratio, stirring rate and temperature. The average particle sizes of the zinc borate products are in the range 4.3-16.6 mm (wet dispersion analysis).
Journal of Cleaner Production, 2010
... Ebru Özgür a , Corresponding Author Contact Information , E-mail The Corresponding Author ,Ni... more ... Ebru Özgür a , Corresponding Author Contact Information , E-mail The Corresponding Author ,Nilüfer Afsar a , Truus de Vrije b , Meral ... An uptake hydrogenase deficient mutant (hup − ) of R. capsulatus (Öztürk et al., 2006) was employed and a higher hydrogen productivity (1.37 ...
Journal of Cleaner Production, 2010
The purpose of this study was to develop a pilot scale tubular photo bioreactor (80L) for photo f... more The purpose of this study was to develop a pilot scale tubular photo bioreactor (80L) for photo fermentative hydrogen production by photosynthetic purple-non-sulfur bacterium, Rhodobacter capsulatus, operating in outdoor conditions, using acetate as the carbon source. The reactor was operated continuously in fed-batch mode for 30 days throughout December 2008 in Ankara. It was placed in a greenhouse in order
Journal of Biotechnology, 1999
Hydrogen gas can be produced electrochemically by leading a current through two electrodes immers... more Hydrogen gas can be produced electrochemically by leading a current through two electrodes immersed in a NaCl solution. Bacteriorhodopsin (BR) a protein found in the purple membrane of Halobacterium halobium, is known to pump protons across the membrane upon illumination. In this study, the effect of BR on photoelectrochemical hydrogen production was investigated. A batch type bio-photoelectrochemical reactor was designed and constructed. The photoelectrochemical hydrogen production experiments were performed with free H. halobium packed cells or immobilised H. halobium cells. The cells were either immobilised in polyacrylamide gel (PAG) or on cellulose acetate membrane (CAM). Experiments were also performed with purple membrane fragments of H. halobium immobilised on cellulose acetate membrane. It was found that the presence of bacteriorhodopsin (BR) in the reactor enhances the hydrogen production rate upon illumination. Immobilisation increased the amount of hydrogen produced per mole of BR. Compared to control experiments without BR, the power requirement of the photoelectrochemical reactor per amount of hydrogen produced decreased fourfold when purple membrane fragments immobilised on CAM were used. The presence of BR regulates the pH of the system, increases the hydrogen production rate and causes light-induced proton dissociation, which lowers the electrical power requirement for the electrochemical conversion.
Journal of Biotechnology, 1999
Rhodobacter sphaeroides O.U. 001 is able to produce hydrogen anaerobically upon illumination. The... more Rhodobacter sphaeroides O.U. 001 is able to produce hydrogen anaerobically upon illumination. The cells were screened for the presence of valuable by-products such as poly-b-hydroxy (PHB) butyric acid aiming to improve the feasibility of the system. Also waste water from a sugar refinery was used for bacterial growth to further increase the feasibility. Under aerobic conditions the standard growth media containing L-malic acid and sodium glutamate in 7.5/10 and 15/2 molar ratios and a medium containing 30% waste water from sugar refinery were used. In this case the maximum concentration of PHB produced were approximately 0.2 g l − 1 in both of the standard media whereas it was 0.3 g l − 1 in medium containing 30% waste water. By using the medium containing 30% waste water, PHB and hydrogen productions were determined under anaerobic conditions. The maximum concentration of PHB produced was around 0.5 g l − 1 and the amount of gas collected was 35 ml in 108 h. From these results it can be concluded that PHB can be collected during hydrogen production. The use of waste water from sugar refinery increased the yield.
Journal of Biotechnology, 1999
The effect of L-malic acid and sodium glutamate, which serve as the carbon and nitrogen source, r... more The effect of L-malic acid and sodium glutamate, which serve as the carbon and nitrogen source, respectively, on hydrogen production by Rhodobacter sphaeroides O.U.001 has been investigated in a batch water jacketed glass column photobioreactor (PBR), which has an inner volume of 400 ml. The PBR was operated at different carbon to nitrogen ratios at 32°C with a tungsten lamp at a light intensity of 200 W m − 2 . Carbon to nitrogen ratio was found to be an important parameter for bio-hydrogen production. Moreover, hydrogen gas production was dependent on certain threshold concentrations of sodium glutamate. L-malic acid consumption was found to be first order with respect to L-malic acid concentration, whereas sodium glutamate consumption was found to be second order with respect to glutamate concentration. It was concluded that there is a close relationship between the hydrogen production rate and substrate consumption rates. A kinetic model is developed, which relates hydrogen gas production per amount of biomass, L-malic acid, and sodium glutamate concentrations.
International Journal of Hydrogen Energy, 2011
Olive mill wastewater Iron Molybdenum Wastewater treatment Rhodobacter sphaeroides a b s t r a c ... more Olive mill wastewater Iron Molybdenum Wastewater treatment Rhodobacter sphaeroides a b s t r a c t Photofermentative hydrogen production from olive mill wastewater (OMW) by Rhodobacter sphaeroides O.U.001 was assessed under iron and molybdenum supplementation. Control cultures were only grown with 2% OMW containing media. The analysis included measurements of biomass accumulation, hydrogen production, pH variations of the medium, and changes in the chemical oxygen demand (COD) of the wastewater. Growth under control and Mo-supplemented experiments yielded about the same amount of biomass (w0.4 g dry cell weight per L culture). On the other hand, Mo addition slightly enhanced the total volume of H 2 gas production (62 mL H 2 ), in comparison with the control reactor (40 mL H 2 ). Fe-supplemented cultures showed a significant increase on H 2 production (125 mL H 2 ), tough having a longer lag time for the observation of the first H 2 bubbles (24 h), compared to the control (15 h) and Mo-supplemented ones (15 h). Fe-added cultures also yielded better wastewater treatment by achieving 48.1% degradation of the initial chemical oxygen demand (COD) value compared to the control reactor having 30.2% COD removal efficiency. Advances described in this work have the potential to find applications in hydrogen industry while attempting an effective management of cheap feedstock utilization. (E. Eroglu).
Fuel and Energy Abstracts, 2000
Rhodobacter capsulatus produces molecular hydrogen under the photoheterotrophic growth condition ... more Rhodobacter capsulatus produces molecular hydrogen under the photoheterotrophic growth condition with reduced carbon sources (organic acids). Under this condition, ubiquinol pool is over reduced and excess reducing equivalents are primarily consumed via the reduction of CO2 through the Calvin–Benson–Bassham (CBB) pathway, the dimethylsulfoxide reductase (DMSOR) system or by the reduction of protons into hydrogen gas with the use of nitrogenase