Effects of Nano-TiO2 Mediated Photocatalysis on Microcystis aeruginosa Cells

Abstract

The effects of nano-TiO2 mediated photocatalysis on Microcystis aeruginosa, a common species that causes algal bloom, were studied. The metabolic activity of the M. aeruginosa cells was inhibited by nano-TiO2 mediated photocatalysis, as demonstrated by the significant decrease in metabolic heat with the increase in the time of photocatalysis. SEM images also showed that photocatalysis significantly altered the surface morphology of the cells, and the cell disruption was observed by treatment for 6 h. The nano-TiO2 mediated photocatalysis decreased the negative charge on the cell surface because the hydrophilic carboxylic acid groups and ammonium groups in the proteins were modified by free radicals. Metal cations of different valence and charge density could neutralize the negative charges on the cell surface to varying degrees. The adsorption heat of metal cations on the cell surface was higher for the control cells than the cells by photocatalysis, because the surface of the latter was modified and had lower charge density.