Photo-mineralization of aqueous gram positive and gram negative bacteria together with their organic components using sensitized ZnO nano-particles
جابر, سوسن فتحي عبد السلام
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Photo-degradation is one of the most attractive methods. It involves excitation of the suitable semiconductor by light, followed by mineralization of biological and chemical pollutants in water. ZnO nanoparticles (ZnO NPs) are being used for photo-degradation of widely spread water organic pollutants. Due to its wide broad band gap (~3.2 eV), ZnO photo-catalytic activity is limited to shorter wavelengths which located in UV region. As only ~4% of the solar spectrum falls in the UV region, smaller band gap natural dyes, such as natural dyes(Anthocyanin) are examined to sensitize ZnO particles for visible solar light. In this work disinfection of water by complete deactivation and mineralization of G +ve and G -ve bacteria, together with their organic components, using ZnO NPs was investigated. ZnO NPs are known as antibacterial agents, noxious to microorganisms, and hold good biocompatibility to human cells. Both naked ZnO and ZnO\Anthocyanin are tested against G –ve K. Pneumoniae and G +ve S. aureus bacteria by using direct solar light simulator. The efficiency of ZnO-NPs revealed that using both synthesized and commercial ZnO-NPs, with and without Anthocyanin dye sensitizer under sun light simulator were used for deactivated bacteria, finding that after 60 min G +ve S. aureus and G –ve K. pneumoniae bacteria were totally deactivated. While after 3 hrs. 98.7% of G + ve S. aureus and 45.2% of G –ve K. pneumoniae bacteria organic matters were mineralized by using ZnO-NPs. These results confirm the ability of ZnO-NPs to behave as effective catalyst in photo mineralization of the two bacteria in water. It is therefore recommended to expand the present study and include other types of biological pollutants, in addition to study other factors that might impact photo mineralization reaction.