Study on 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 3 h photoirradiation under the conditions with an air flow of 150 mL/min, water/oil ratio of 1:1 and riboflavin concentration of 30 μmol/L. The mechanism of photosensitized oxidation of thiophene is1O2 exited from 3O2 by the addition of riboflavin. Under the above conditions, the photooxidation kinetics of thiophene with O2/riboflavin is first-order with a rate constant of 0.3277 h−1 and half-time of 1.37 h.