Details

Autor(en) / Beteiligte

• Czili, Hajnalka
• Horvath, Attila

Titel

Applicability of coumarin for detecting and measuring hydroxyl radicals generated by photoexcitation of TiO sub(2) nanoparticles

Ist Teil von

• Applied catalysis. B, Environmental, 2008-06, Vol.81 (3-4), p.295-302

Erscheinungsjahr

2008

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Applicability of coumarin (COU) as fluorescent probe to detect and measure hydroxyl radicals generated by UV irradiation of aqueous suspension of TiO sub(2) was investigated under aerobic and anaerobic conditions. The fluorescent 7-hydroxycoumarin (7HC) was formed in argon-saturated suspension when silver ion was used as electron acceptor. The luminescence intensity increased with irradiation time until the deposition of silver on the surface of TiO sub(2) was completed and then the luminescence intensity was constant and proportional to the initial concentration of the silver ion. The low yield of 7HC related to the deposited silver (0.32%) indicates the appearance of efficient side reactions of hydroxyl radicals and holes. It has also been demonstrated that efficient electron donors reacting directly with photogenerated holes such as oxalic acid significantly reduce the yield of 7HC. Using oxalic acid of relatively high concentration in aerated suspension leads to the production of hydroxyl radical in thermal reactions followed by primary electron transfer steps.