6533b7d1fe1ef96bd125d7b6

RESEARCH PRODUCT

Adsorption and photocatalytic degradation of acetonitrile: FT-IR investigation

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Abstract The photocatalytic degradation of acetonitrile was carried out in liquid–solid regime in a batch reactor by using two types of commercial TiO 2 powders (Merck and Degussa P25) as photocatalysts. The concentration of acetonitrile and non-purgeable organic carbon (NPOC) were monitored. The initial rate of acetonitrile conversion was found higher on TiO 2 Merck than on TiO 2 P25. FT-IR spectroscopy was used to investigate the molecular features of the adsorption and photo-oxidation of acetonitrile on the two TiO 2 powders in a fully surface hydrated form. Acetonitrile was found adsorbed on Ti 4+ surface ions and hydroxyl groups for both types of TiO 2 . This interaction appeared fully reversible in the case of the Merck photocatalyst, whereas acetonitrile was more strongly stabilized on Ti 4+ ions of TiO 2 P25. Furthermore, the adsorption of CD 3 CN⋯Ti 4+ on this type of photocatalyst resulted in the formation of acetamide-like species, because of the presence of nucleophilic surface O 2− and hydroxyl groups. The formation of these species, strongly bound to the TiO 2 surface and recalcitrant to the photo-oxidation, could result in the poisoning of a part of the photocatalytic sites of TiO 2 P25, accounting for its lower initial acetonitrile conversion rate.