Abstract
Crystalline TiO2 has shown its great photocatalytic properties in bacterial inactivation. This work presents a design fabrication of low-cost, layered TiO2 films assembled reactors and a study of their performance for a better understanding to elucidate the photocatalytic effect on inactivation of E. coli in water. The ability to reduce the number of bacteria in water samples for the layered TiO2 composing reactors has been investigated as a function of time, while varying the parameters of light sources, initial concentration of bacteria, and ratios of TiO2 film area and volume of water. Herein, the layered TiO2 films have been fabricated on the glass plates by thermal spray coating prior to screen printing, allowing a good adhesion of the films. Surface topology and crystallographic phase of TiO2 for the screen-printed active layer have been characterized, resulting in the ratio of anatase:rutile being 80:20. Under exposure to sunlight and a given condition employed in this study, the optimized film area:water volume of 1:2.62 has shown a significant ability to reduce the E. coli cells in water samples. The ratio of surface area of photocatalytic active base to volume of water medium is believed to play a predominant role facilitating the cells inactivation. The kinetic rate of inactivation and its behavior are also described in terms of adsorption of reaction species at different contact times.
Highlights
Escherichia coli bacteria found in the contaminated wastewater is known to significantly affect human health
The entire surface of the glass plates was prepared by sand blasting and thermal spray coated with TiO2 (Amperit Flame and Plasma Spray sand blasting andMunich, thermalGermany)
The double-layered TiO2 films with good adhesion were successfully produced by thermal spray coating and screen printing
Summary
Escherichia coli bacteria found in the contaminated wastewater is known to significantly affect human health. E. coli inactivation can be done by a variety of methods, such as boiling, solar heating, radiating, filtering with filter paper or sheet, and applying certain chemicals to annihilate the cells of microorganisms [1,2,3,4,5]. Solar irradiation is an effectively convenient method of inactivation. Conroy et al [6] used batch processing of solar inactivation for improving the quality of biologically contaminated drinking water in developing countries. The technique involved storing the contaminated drinking water in the transparent containers, e.g., plastic bags, plastic bottles, and glass bottles that were placed directly under sunlight for eight hours before consumption. McGuigan et al [7] has shown the high effectiveness of irradiation on cell inactivation against a broad range of bacterial pathogens
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