Spirulina coated with semiconducting compound can purify water and produce bio-fuel.
Many people use spirulina as a dietary supplement, but researchers at the Swiss Federal Material Science Laboratory have found a new way. They coat blue-green algae with a semiconductor compound to make these tiny spirulina more useful. They can be used to purify the water and clear pollutants, and their remains can be used to make bio-fuels.
Coating materials such as Nickel, Zinc Oxide and Zinc Sulfide on the surface of spirulina. This compound composition was first developed on the tiny structure similar to ferns. Scientists found that the spirulina treated by this process is good at absorbing light energy. Because the spiral shape of this unique algae can avoid the shading problem caused by the branch structure of micro ferns, thereby increasing light absorption.
Researchers spread a thin layer of nickel on the 4 micron spirals of the preserved spirulina, and then spread Zinc Oxide and Zinc Sulfide Nanoparticles. Facts have proved that the magnetic properties of nickel are very good at recovering small spirals to complete the application, while the Zinc coating shows "impressive photo-catalytic activity".
The process was developed to use the purification properties of plants to help producing clean water. Under light, the chemical reactions can oxidize and neutralize pollutants in the water. The combination of Zinc Oxide and Nano-Zinc Sulfide particles allowed the team to simultaneously use the visible and ultraviolet parts of the solar spectrum to improve efficiency.
After the coating spiral completes the water purification task, the Zinc and nickel compounds can be recycled and reused. The leftovers can then be used to produce bio-ethanol and bio-diesel. The preserved spirulina residue can also be processed into pellets, which can be burned to produce energy, and the ashes can be used as fertilizer to cultivate new populations.
Empa team said “the production cost of this kind of algae is relatively low, and it is also very easy. It only needs water, sunlight and fertilizer to reproduce quickly. More importantly, this single-celled organism consumes carbon dioxide and then throws the oxygen away as a waste product. By adding more carbon dioxide to the algae culture, this process will be further accelerated”.
Currently, this process has only been successfully demonstrated in a laboratory environment, but the researchers said that they are confident that they can achieve larger-scale applications.