Abstract

The application of nanotechnology in water treatment is of great importance as the need to purify water has become more evident due to factors like population growth, droughts, and inefficient purification methods. Titanium dioxide nanoparticles, (TiO2 NPs), have grown in interest because of their photocatalytic abilities, and chemical stability. TiO2 has three crystal structures: anatase, rutile, and brookite. Of the three polymorphs, studies show that brookite has greater surface energy, reacts under low levels of UV light, and decomposes organic matter more efficiently. This project analyzes the effect of pH, on the size and form of TiO2 NPs. A hydrothermal synthesis was used to set the pH of the samples to 1,6,7,10.5 or 12.5. Sodium hydroxide, NaOH, and nitric acid, HNO3, were used to alter basicity and acidity. Four samples were made for each pH value and heated for 24,48,72 or 96 hours to evaluate the effects of heating time on crystal structure and size of TiO2 nanoparticles. Particles were characterized using scanning electron microscopy, and powder x-ray diffraction. It was found that rutile mixed with anatase formed at a pH of 1.00. Anatase formed under acidic and neutral conditions, while brookite formed under basic conditions. The size of the particles did not increase with basicity or reaction time, but more agglomeration was observed. This method allowed for all crystal structures of TiO2, with an average size of 15.96 nm, to be synthesized by only altering the pH in the last step.

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