Direct photolysis of pyridine in solution with 206nm UV irradiation

A new-type electrodeless UV lamp (EDUVL). namely 206nm UV, from discharge of mixtures of Kr/I(2) by microwave (MW) energy, was employed. EDUVL was optimized by investigating start-up characteristics of lamp, MW energy coupling character, and irradiation intensity at 206 nm under different conditions, including the inserting depth in cavity, lamp structure and amount of filled Kr/I(2) mixture. Experiments showed that 206 nm irradiation intensity was enhanced by the decline of Kr and 12 filled in the lamp and the advisable amount of Kr and I(2) was 266 Pa and 0.5 mg, respectively. In addition, photochemical degradation of simulating pyridine wastewater under 206 nm irradiation was conducted. The following results were obtained that removal efficiency of pyridine was greatly increased with irradiation time, the decrease of initial pyridine concentration, bubbling with N(2) or Air and the rise of microwave power. The removal of pyridine after 1 h irradiation reached 73.1% under the experimental conditions with solution volume of 150 mL, initial pH of 7.0, and initial pyridine concentration of 120 mgL(-1) and 75 w of microwave power. At last, we analyzed degradation products via GC/MS and azacyclopropane and N-1-propenyl-azacyclopropane were detected. On the basis of which, degradation pathway were concluded. Therefore, this study was presumed to provide the referable information about the proper application of 206 nm UV radiation for the direct photolysis of coking wastewater.