Journal of Environmental Biology

Photocatalytic inactivation of cyanobacteria with ZnO/g-Al₂O₃

composite under solar light

Author Details

 

Winn-Jung Huang (Corresponding author)

Department of Safety, Health and Environmental Engineering, Hungkuang University, 34 Chung

Chie Road, Shalu, Taichung-43302, Taiwan, ROC

e-mail: huangwj@sunrise.hk.edu.tw

Tzu-Ping Lin

Department of Safety, Health and Environmental Engineering, Hungkuang University, 34 Chung

Chie Road, Shalu, Taichung-43302, Taiwan, ROC

Jih-Sheng Chen

Department of Safety, Health and Environmental Engineering, Hungkuang University, 34 Chung

Chie Road, Shalu, Taichung-43302, Taiwan, ROC

 

Fu-Hsiang Shih

Department of Safety, Health and Environmental Engineering, Hungkuang University, 34 Chung

Chie Road, Shalu, Taichung-43302, Taiwan, ROC

 

 

Publication Data

Paper received:

29 April 2009

 

Revised received:

10 January 2010

 

Re-revised received:

27 May 2010

 

Accepted:

15 July 2010

 

Abstract

Cyanobacteria were inactivated by using zinc oxide (ZnO) coated on the surface of g-Al₂O₃ as a photocatalyst and combining with sunlight. In vitro experiments indicate that axenic cultures of planktonic cyanobacteria lost their photosynthetic activity after photocatalyzed with sunlight exposure exceeding 24 hr. As for Oscillatoria tenuisa, nearly 92% of the cells lost their photosynthetic activity and the cell morphology was severely damaged during 24 hr of the reaction. However, in the case of Microcystis aeruginosa, lower photocatalytic inactivity efficiency was observed, which was attributed to extracellular polymeric secretions (EPSs) surrounding the cells. With a high dosage ZnO catalyst, the dissolved organic carbon (DOC) concentration of the Oscillatoria tenuisa suspension was increased by up to about 190% during photocatalysis. The increased suspension of DOC was attributed to increase liberation of extracellular organic and cell-wall polysaccharides during photocatalysis.

 

Key words

Cyanobacteria, Inactivation, Photocatalysis, ZnO film in g-Al₂O₃

 

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