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Biohydrogen recovery and purification by gas separation method
Desalination 200 (2006) 227–229
Biohydrogen recovery and purification by gas separation method Dénes Búcsúa*, Zbynek Pientkab, Sándor Kovácsa, Katalin Bélafi-Bakóa a
Research Institute of Chemical and Process Engineering, University of Veszprém Egyetem u. 2., Veszprém 8200, Hungary email: [email protected] b Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovsky sq. 2., Praha 16206, Czech Republic Received 29 October 2005; accepted 4 March 2006
1. Introduction Biohydrogen fermenter and a gas separation system were coupled to recover and purify biohydrogen in an integrated system. Biohydrogen was produced by an anaerobic photosynthetic bacterium called Thiocapsa roseopersicina. It converts light energy into H2 using reduced sulphur compounds or organic sources under anaerobic conditions (nitrogen atmosphere). Thus the aims were (1) to recover the gaseous mixture containing biohydrogen from the head space of the fermenter and (2) to separate hydrogen from nitrogen. A lab-scale gas separation system was designed and built to achieve the tasks.
The upstream gas mixture was pressurized in vessels by hydraulic (liquid, water) seal system (right side). Nitrogen was used as a pressurizing gas. Permeate was collected in the vessel on the left which was controlled similarly by a liquid seal system. A dense polyethersulphone–polyimide membrane was applied, its parameters have been already described [1,2]. The effective permeation area was 12 cm2 and the top layer thickness was 0.11 mm. Samples were analyzed by gas chromatography and by gas pipette. Phototropic fermentation was carried out with the strain Thiocapsa roseopersicina, illuminated with continuous light at 30°C, under anaerobic (nitrogen) atmosphere.
2. Experimental A hollow fiber gas separation membrane module was manufactured. The module was built into a complete apparatus, where pure gases and model gas mixtures were applied to test the membrane (Fig. 1).
*Corresponding author.
3. Results and discussion First pure model gases were applied to determine permeances at 25°C. The value for hydrogen was P1 = 42 GPU and for nitrogen P2 = 1.0 GPU. Further experiments with various feed gas compositions were carried out at 4 bar upstream pressure, and the flux and composition
Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2006.03.305
228
D. Búcsú et al. / Desalination 200 (2006) 227–229
The model (Fig. 2) and its results were utilized to determine the optimized conditions for real separation. Based on the measured and calculated results with model gases, an integrated system has been constructed, where the gas separation apparatus was coupled to the phototropic fermentation with special care on the sterile condition. In the fermenter pressure increased gradually, signing H2 formation. The gas space of the fermenter was removed regularly and stored in an elastic-wall reservoir. The hydrogen content of the gaseous mixture varied between 5% and 18%. The gas mixture was fed into the hollow fiber membrane module and hydrogen rich permeate was collected in a gas burette. Having carried out several experiments, it was found that the average 11% hydrogen content in the feed was managed to increase upto 37% (in average), the flux obtained was 0.17 cm3 min–1. These results fit well to those measured with model gases and have proven that the special gas separation apparatus with liquid seal system is suitable to connect to the phototropic biohydrogen fermentation by Thiocapsa rosepersicina and is able to recover and concentrate hydrogen.
Feed gaseous mixture Permeate
Retentate Membrane module
Fig. 1. Scheme of the gas separation apparatus.
of permeates as a function of pressure was studied to check if the real permeability and separation factor differs from the ideal ones. Simulation of the gas separation process was carried out to model the behavior of the membrane. In steady state the flux is determined by partial pressures — estimated from Fick’s law:
J i = Pi
S ( pui - p pi ) l
(1)
S is the membrane surface area, pu the pressure of upstream, pp the pressure of downstream, l the membrane thickness.
100 J [cm3/min]
C [%]
80 60 40 20 0 1
2 3 4 5 Pressure [bar] 5% 10% 20%
6
20% measured 10% measured 5% measured
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 1
2
3 4 5 Pressure [bar]
5% 10% 20%
6
20% measured 10% measured 5% measured
Fig. 2. Calculated and measured permeance compositions and fluxes under different conditions.
D. Búcsú et al. / Desalination 200 (2006) 227–229
Acknowledgements
References
The research work was supported by the Czech-Hungarian Bilateral Research Programme, TéT, No. CZN-16/2005 (2006–2007). We also acknowledge the contributions of Prof. K.L. Kovács (University of Szeged, Hungary) and Prof. M. Wessling (Twente University, The Netherlands).
[1]
[2]
229
D. Wang, K. Li and W.K. Teo, Polyethersulphone hollow fiber gas separation membranes prepared from NMP/alcohol solvent systems, J. Membr. Sci., 115 (1996) 85–91. G.C. Kapantaidakis and G.H. Koops, High flux polyethersulphone–polyimide blend hollow fiber membranes for gas separation, J. Membr. Sci., 204 (2002) 153–171.
Biohydrogen recovery and purification by gas separation method Dénes Búcsúa*, Zbynek Pientkab, Sándor Kovácsa, Katalin Bélafi-Bakóa a
Research Institute of Chemical and Process Engineering, University of Veszprém Egyetem u. 2., Veszprém 8200, Hungary email: [email protected] b Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovsky sq. 2., Praha 16206, Czech Republic Received 29 October 2005; accepted 4 March 2006
1. Introduction Biohydrogen fermenter and a gas separation system were coupled to recover and purify biohydrogen in an integrated system. Biohydrogen was produced by an anaerobic photosynthetic bacterium called Thiocapsa roseopersicina. It converts light energy into H2 using reduced sulphur compounds or organic sources under anaerobic conditions (nitrogen atmosphere). Thus the aims were (1) to recover the gaseous mixture containing biohydrogen from the head space of the fermenter and (2) to separate hydrogen from nitrogen. A lab-scale gas separation system was designed and built to achieve the tasks.
The upstream gas mixture was pressurized in vessels by hydraulic (liquid, water) seal system (right side). Nitrogen was used as a pressurizing gas. Permeate was collected in the vessel on the left which was controlled similarly by a liquid seal system. A dense polyethersulphone–polyimide membrane was applied, its parameters have been already described [1,2]. The effective permeation area was 12 cm2 and the top layer thickness was 0.11 mm. Samples were analyzed by gas chromatography and by gas pipette. Phototropic fermentation was carried out with the strain Thiocapsa roseopersicina, illuminated with continuous light at 30°C, under anaerobic (nitrogen) atmosphere.
2. Experimental A hollow fiber gas separation membrane module was manufactured. The module was built into a complete apparatus, where pure gases and model gas mixtures were applied to test the membrane (Fig. 1).
*Corresponding author.
3. Results and discussion First pure model gases were applied to determine permeances at 25°C. The value for hydrogen was P1 = 42 GPU and for nitrogen P2 = 1.0 GPU. Further experiments with various feed gas compositions were carried out at 4 bar upstream pressure, and the flux and composition
Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2006.03.305
228
D. Búcsú et al. / Desalination 200 (2006) 227–229
The model (Fig. 2) and its results were utilized to determine the optimized conditions for real separation. Based on the measured and calculated results with model gases, an integrated system has been constructed, where the gas separation apparatus was coupled to the phototropic fermentation with special care on the sterile condition. In the fermenter pressure increased gradually, signing H2 formation. The gas space of the fermenter was removed regularly and stored in an elastic-wall reservoir. The hydrogen content of the gaseous mixture varied between 5% and 18%. The gas mixture was fed into the hollow fiber membrane module and hydrogen rich permeate was collected in a gas burette. Having carried out several experiments, it was found that the average 11% hydrogen content in the feed was managed to increase upto 37% (in average), the flux obtained was 0.17 cm3 min–1. These results fit well to those measured with model gases and have proven that the special gas separation apparatus with liquid seal system is suitable to connect to the phototropic biohydrogen fermentation by Thiocapsa rosepersicina and is able to recover and concentrate hydrogen.
Feed gaseous mixture Permeate
Retentate Membrane module
Fig. 1. Scheme of the gas separation apparatus.
of permeates as a function of pressure was studied to check if the real permeability and separation factor differs from the ideal ones. Simulation of the gas separation process was carried out to model the behavior of the membrane. In steady state the flux is determined by partial pressures — estimated from Fick’s law:
J i = Pi
S ( pui - p pi ) l
(1)
S is the membrane surface area, pu the pressure of upstream, pp the pressure of downstream, l the membrane thickness.
100 J [cm3/min]
C [%]
80 60 40 20 0 1
2 3 4 5 Pressure [bar] 5% 10% 20%
6
20% measured 10% measured 5% measured
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 1
2
3 4 5 Pressure [bar]
5% 10% 20%
6
20% measured 10% measured 5% measured
Fig. 2. Calculated and measured permeance compositions and fluxes under different conditions.
D. Búcsú et al. / Desalination 200 (2006) 227–229
Acknowledgements
References
The research work was supported by the Czech-Hungarian Bilateral Research Programme, TéT, No. CZN-16/2005 (2006–2007). We also acknowledge the contributions of Prof. K.L. Kovács (University of Szeged, Hungary) and Prof. M. Wessling (Twente University, The Netherlands).
[1]
[2]
229
D. Wang, K. Li and W.K. Teo, Polyethersulphone hollow fiber gas separation membranes prepared from NMP/alcohol solvent systems, J. Membr. Sci., 115 (1996) 85–91. G.C. Kapantaidakis and G.H. Koops, High flux polyethersulphone–polyimide blend hollow fiber membranes for gas separation, J. Membr. Sci., 204 (2002) 153–171.