Water disinfection treatment using photocatalysts
The SOLWATER project developed methods for the purification of drinking water for remote and isolated communities in Latin America. Researchers studied the disinfection of drinking water by photocatalysis using titanium dioxide (TiO2) and ruthenium Ru (II) complexes in a solar photoreactor. Both TiO2 and Ru (II) complexes were shown to be successful when applied individually. The combined effect of using both compounds, one after the other, was not found to be more efficient than using them separately. In experiments where Ru (II) complexes were immoblised on polymer strips the concentration of E. coli bacteria decreased four decimal places within an hour. When a control was used, which comprised only light and no catalyst it was clear that Ru (II) complex had a major impact on bacterial deactivation. The results showed that Ru (II) caused a rapid drop in bacteria concentration but remained the same for the control. The disinfection capability of Ru (II) complexes immobilised on paper was also compared with TiO2 immobilised on Ahlstrom paper matrixes. Photosensitised disinfection was more rapid for Ru (II) due to a higher reaction constant, giving a better disinfection performance. The effect of using Ru (II) together with TiO2 was investigated. The two different catalysts were connected in series so that researchers could determine how a hybrid catalysed system would perform. It was found that the experiment where only Ru (II) was used gave the best results for disinfection. This was followed by experiments using TiO2. No synergistic effect was detected when the two catalysts were used in series.
