Photodegradation of 2,4,6-Trinitrotoluene By a Titanium Dioxide Nanoparticle Photocatalyst

Using the intrinsic property of photocatalysis semiconductors generate charge carriers which have highly oxidative effects upon organic, inorganic, and biological contaminants found in various waste and process water. Explosive contamination, disposal of industrial waste water and the disposal of process water poses a significant ecological risk. An inexpensive, ecologically sound solution to mitigate these environmental issues is required. An application of pertinent historical methods of photodegrading cyanide using TiO₂ as well as the methods found in the construction of dye sensitised solar cells (DSSC) were use to construct a prototype reactor. Helianthene B was used to characterise and obtain rates of degradation after UV irradiation at 1, 2 and 4 hour intervals within two respective reactors. The changes in concentration were determined by standard UV-Vis spectrophotometry and used to determine the k, constant molar rate of disappearance. The median value, for the rate of disappearance, between the two reactors was used to generate a kinetic model and to calculate the half-life.

A standard-scientific method was applied to establish and characterise the effectiveness of the photocatalytic effect of titanium dioxide on the organic dye helianthine B. The organic dye was shown to degrade, due to the photocatalytic effect of TiO₂, by experimental process, at an average half-life of 1.15 hours for a 5mg/L solution and 2.69 hours for a 50mg/L solution. With respect to the 2,4,6-trinitrotoluene solution, the half-life for a 35.992mg/L solution was 46.2 hours. Based upon the experimental results obtained, the effective degradation of large organic molecules and explosive compounds by TiO₂ is possible. Application of systems which immobilise the photocatalytic nanoparticles, such as thin film depositions upon an appropriate substrate, can be recommended. The successful degradation of the explosive in an aqueous solution also recomends the application of the nanoparticle photocatalyst to assist in the mitigation of contaminated water sources.

These experimental results utilised undoped anatase TiO₂ to establish comparative analytical results to which the selectivity and effectiveness of future tests using doped particles may be relevant. Future iterations of the reactor design will be implementing doped TiO₂, many of which have already been investigated and been found to have affinities, with respects to oxidising potentials, to specific contaminating compounds like phenols, acetone and aromatics.