Titanium oxide (TiO2) nano-materials are an emerging technology in the field of water treatment research and photonic energy transfer. In particular, TiO2 photocatalysis is an Advanced Oxidation Process (AOP) that can be used to remove trace amounts of organic compounds from wastewater after traditional treatment processes. TiO2 responds to UV light and is effective at degrading small-molecule organic contaminants in model laboratory studies and wastewater samples. One way to achieve improved TiO2 performance is to modify the chemistry of the photocatalyst surface, thereby modulating how contaminants adhere to the surface. Moreover, coating the photocatalyst surface in particular chemical functionalities allows contaminants to orient towards the surface in specific ways, altering the degradation pathway. Our study focuses on nano-sized TiO2 particles (made in-house) modified with three different coatings: salicylic acid (SA), arginine (Arg), and phenylalanine (Phe). These photocatalysts, along with the bare (uncoated) nano-TiO2 and commercially available TiO2 (Degussa P25) are used to degrade three contaminants: caffeine, diclofenac, and carbamazepine. The relative degradation rates for these contaminants (which each contain different functional groups, and thus may interact differently with the modified surfaces) are examined, both in experiments with one contaminant, and in experiments with mixtures of multiple contaminants. The reactions are monitored by HPLC-MS with a short (12min) gradient that allows for simultaneously tracking of contaminants and degradation products. A comparison of products formed from catalysis with different surface-modified TiO2 samples is presented. These results offer insight into the chemical interactions that govern photocatalytic degradation of organic molecules.

Selective photo-degradation of small molecule contaminants with surface-modified TiO2 nanoparticles

256th National Meeting (2018)

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