Use of peroxymonosulfate in wet scrubbing process for efficient odor control

• PMS was firstly utilized as an oxidant for odor removal in wet scrubbing process.
• The removal of CH3SH(G) (∼80 ppm/v) maintained high levels of >95%.
• PMS reacted with not only CH3S− but also CH3SH(aq).
• The stability of PMS was well maintained by adding Na2SiO3 even at high pH.
• Three mol of PMS would be necessary to oxidize one mol of CH3SH.

Peroxymonosulfate (PMS) was utilized as an oxidant for methyl mercaptan odor (CH3SH(G), ∼80 ppm/v) removal in wet scrubbing process, and the proposed reaction mechanism was investigated in detail. Under alkaline condition (pH ∼ 12) with PMS, the removal of CH3SH(G) maintained high levels of >95%. The reaction was so quick that no methyl mercaptan ion (CH3S−) in aqueous solution was detected before the depletion of PMS. PMS not only reacted with CH3S−, which was dissociated from the dissolved CH3SH(aq) in alkaline solution, but also directly oxidized the dissolved CH3SH(aq). It was found that 3 mol of PMS would be necessary to oxidize 1 mol of CH3SH. The major product of the oxidation of CH3SH was methanesulfonic acid (CH3SO3−). Additionally, the stability of PMS, by adding sodium silicate (Na2SiO3), was very well maintained even under strong alkaline conditions (less than 5% decomposition). In conclusion, PMS was extremely suitable for CH3SH(G) removal in wet scrubbing process with the existence of Na2SiO3, especially under alkaline condition (pH ∼ 12).