Solar photocatalytic disinfection of a group of bacteria and fungi aqueous suspensions with TiO2, ZnO and Sahara desert dust

This photocatalytic method was aimed to destroy bacteria, to prevent fungi in some industrial products and to create desirable hygienic medium under solar irradiation. The efficiencies of disinfection with the photoactive metal oxides and the Sahara desert dust was investigated. We have studied photocatalytic disinfection of two-groups of microorganisms which are known as bacteria and fungus in pathogenic-organisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Saccharomyces cerevisiae, Candida albicans, Aspergillius niger. Aqueous suspension of the microorganisms (1.10(5) cfu/ml), in the presence of TiO2, ZnO and Sahara desert dust were irradiated with a 400 W sodium lamp for various time periods in order to simulate solar radiation. Minimum catalyst concentration was used as 0.01 mg/ml. Sahara desert dust that contain some photoactive/inactive metal oxides (ZnO, Fe2O3, etc.) and some organics, is known as fertilizer of bioactivities in nature. In accordance with, no microbicidal effect of Sahara dust. Efficient microbicidal effects of TiO2 and ZnO were detected under sodium light irradiations. Except for A. niger, all selected bacteria and fungus were disinfected in a short period by using 400 W sodium lamp in the presence of photocatalysts. Three strains of bacteria were destroyed in 40 min, two strains of fungi were also destroyed in 120 min at the same conditions. Photocatalytical method is an advantageous and an alternative one in comparison with former literatures. (C) 2004 Elsevier B.V. All rights reserved.