Photo Catalytic Inactivation of Escherichia coli Using Titanium (IV) Oxide-Tungsten (VI) Oxide Nanoparticles Composite

The resulting nanoparticles were calcined at 575° C and characterized through X-Ray Fluorescence and X-Ray Diffraction. The particle size diameter of the nanoparticles was found to be 18.99nm. The photocatalytic inactivation efficacy of Escherichia coli in water was tested using the synthesized nanoparticles. A 3M Petrifilm from 3M Microbiology Products, U.S.A., was used for Escherichia coli colony forming units' counts. An ATUV 8W G8 T5 lamp from PHILIPS emitting between 350-600nm was used as the energy source. The catalyst reduced Escherichia coli count by log 3.415 at an optimum catalyst amount of 0.75 g/L at pH 7.3 using the Chick-Watson model for disinfection kinetics. The study demonstrated that photocatalysis is a promising technology in water purification, particularly for small-scale point-of-use water purification units. The use of nanoparticles can provide solutions in the treatment of drinking water, especially for poor communities living in the tropics. The results of this study suggest that the TiO2/WO3 composite can be an effective photocatalyst for the inactivation of Escherichia coli in water. The African water resources contain high levels of microbiological pathogens, including bacteria, viruses, and protozoa, as well as chemical contaminants like pesticides, heavy metals, and persistent organic pollutants. Escherichia coli and related bacteria constitute about 0.1% of gut flora, and fecal-oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Cells are able to survive outside the body for a limited amount of time, making them ideal indicator organisms to test environmental samples for fecal contamination. The USEPA gives Maximum Contaminant Level Goal (MCLG) for Total Coliforms (including fecal coliform and Escherichia coli) as zero and a Maximum Contaminant Level (MCL) as 5%. Water treatment processes like filtration and adsorption are widely used, but these purification processes only transfer the removed pollutants from one matrix (water) into another (filter or adsorbent). This necessitates further remediation of the adsorbent or filter for subsequent use. A conclusive water treatment method is therefore crucial in total elimination of organic and inorganic pollutants in drinking water without the danger of inter-matrix transfer of the pollutants. Heterogeneous photo catalysis has emerged as an alternative process to advanced oxidation processes (AOP) for bacteria inactivation and oxidation of organic pollutants. The process utilizes semiconductor materials and a UV energy source. Pin-Ching et al., (1999) carried out experiments on inactivation of Escherichia coli on Titanium (IV) Oxide photo catalysts and concluded that TiO2 photo catalysis promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced major disorder in the Escherichia coli cell membrane. Coupling TiO2 with tungsten trioxide (WO3) has been widely studied to improve the photocatalytic performances of TiO2, since WO3 can serve as an electron accepting species.