Degradation of methyl mercaptan by a microwave-induced photoreaction process

In this research, microwave discharge electrodeless lamp (MDEL) was applied to treat methyl mercaptan (MM). The influence factors of microwave-induced photoreaction on the malodor removal and MM degradation were intensively studied. The decline of malodor and MM concentration suggested that MDEL treatment has strong capability of deodorization and MM degradation. In addition, the irradiation of ultraviolet ray and visible light emitted from MDEL could remove over 99% of malodor at initial MM concentration of 90 ppmv in air atmosphere. The MM degradation analysis showed that MDEL played a significant role on the MM removal in N₂, air and O₂ atmosphere. Humidity had little effect on photo degradation in this system. However, the increment of initial MM concentration would decrease the degradation rate of MM, and total MM removal required longer time. Direct photolysis could remove a limited concentration of MM by MDEL in N₂ atmosphere. When increasing O₂ concentration and extending retention time, MM removal reached higher value. By comparing the results in N₂ and air, it took shorter time to decompose MM completely in pure O₂ atmosphere. This study provides a proof of concept that the combination of microwave and ultraviolet to deodorize MM, and the result can be used to optimize pilot-scale and full-scale experiment.