Investigation of the Formation and Photo-activity of Titanium Dioxide and Polyelectrolytes

Anatase titanium dioxide was synthesized using a hydrothermal treatment of bis(ammonium lactato) titanium dihydroxide (ALT) under a variety conditions. Heating the precursor produces highly crystalline particles that do not undergo a crystal phase transition upon calcination; however, it does remove a layer of surface adsorbed lactate. Three titanium-polyelectrolyte composites (PAA, PAH, and PEI) were formed through electrostatic polymer chain collapse. In order to gain a measure of the relative photo-activity of these various samples the interaction and de-colouration of methylene blue (MB) was investigated. The composite particles were not active whereas the non-composite titanium dioxide and solution phase PAA were individually active. MB was found to form dimers with anionic PAA through electrostatic interaction; however, there was no difference in the de-colouration rate of these dimers versus the monomers. Finally, it was found that pre-irradiating the polyelectrolyte prior to combining with MB decreases the de-colouration rate.MAS