| dc.description.abstract | Hydrogen is considered to be one of the best alternative fuels to petroleum. Most of pollutants of our environment are resulted from widely using petroleum as fuels. Hydrogen is also the cleanest energy because its product is water after burning with oxygen. It is believed that hydrogen will replace the petroleum as the major fuel in the next era.
Scientists have found many different approaches in hydrogen production since the last two decades.Among these approaches, it is believed that utilizing the solar energy to hydrogen production is the most appealing concept.Three methods including chemical, physical, and biological approaches can utilize solar energy for hydrogen production. Biological approach is considered to be better than the other two methods. Among all known biological system, photosynthetic bacteria (PSB) is the most efficient hydrogen producer.
PSB can utilize the solar energy for carbon dioxide fixation and hydrogen production. Several purple non-sulfur PSB have been reported to be the best hydrogen producers.
One of the common problems using PSB for hydrogen production is the instability of hydrogen producing capability of PSB. There is limited understanding of the instability in the academia. Thus, one common solution to this instability is by gel immobilization. Although gel immobilization can solve the instability problems, it creates other problems such as substrate diffusion difficulty, shading effects from immobilized cells, and scale-up problems.
Thus, the major focus of this project is to study the feasibility of using alternative immobilization method – adsorption on cotton fiber for hydrogen production and carbon dioxide fixation. Adsorption immobilization as compared with gel immobilization is considered to be most suitable for large-scale production due to its less mass transfer difficulty and lower operational cost. Thus, higher hydrogen production is expected.
Experimental results of this project are presented in four sections: four PSB strains are collected and isolated, design and manufacture of photobioreactors, characterization of PSB by batch fermentation, and performance of immobilized photobioreactors.Experimental data indicated that both reactor design and environmental conditions such as medium composition and light intensity play important role in carbon dioxide fixation and hydrogen production. | en_US |