Photosensitized Oxidative Desulfurization of Thiophene by Riboflavin

Photosensitized oxidative desulfurization of thiophene in n-octane/water extraction system with riboflavin as photosensitizer and O₂ in air as oxidant was studied. A 500 W high pressure Hg lamp was used as the light source for irradiation and air was introduced by a gas pump for supplying O₂. The desulfurization yield of thiophene was 85.4% for a 5 h photoirradiation under the conditions with the air flow at 150 ml-min^-1, water/oil ratio at 1:1 and riboflavin concentration at 30 mumol-L^-1. The mechanism of photosensitized oxidative of thiophene is ¹O₂ exited from ³O₂ by the addition of riboflavin. Under above conditions, the photooxidation kinetics of thiophene with O₂/riboflavin is first-order with rate constant of 0.3277 h^-1 and half-time of 1.37 h.