The combined removal of methyl mercaptan and hydrogen sulfide via an electro-reactor process using a low concentration of continuously regenerable Ag(II) active catalyst

Abstract

In this study, an electrocatalytic wet scrubbing process was developed for the simultaneous removal of synthetic odorous gases namely, methyl mercaptan (CH 3SH) and hydrogen sulfide (H 2S). The initial process consists of the absorption of CH 3SH and H 2S gases by an absorbing solution, followed by their mediated electrochemical oxidation using a low concentration of active Ag(II) in 6 M HNO 3. Experiments were conducted under different reaction conditions, such as CH 3SH and H 2S loadings, active Ag(II) concentrations and molar flow rates. The cyclic voltammetry for the oxidation of CH 3SH corroborated the electro-reactor results, in that the silver in the 6 M HNO 3 reaction solution significantly influences the oxidation of CH 3SH. At a low active Ag(II) concentration of 0.0012 M, the CH 3SH removal experiments demonstrated that the CH 3SH degradation was steady, with 100% removal at a CH 3SH loading of 5 g m −3 h −1. The electro-reactor and cyclic voltammetry results indicated that the removal of H 2S (100%) follows a mediated electrocatalytic oxidation reaction. The simultaneous removal of 100% of the CH 3SH and H 2S was achieved, even with a very low active Ag(II) concentration (0.0012 M), as a result of the high efficiency of the Ag(II). The parallel cyclic voltammetry results demonstrated that a process of simultaneous destruction of both CH 3SH and H 2S follows an H 2S influenced mediated electrocatalytic oxidation. The use of a very low concentration of the Ag(II) mediator during the electro-reactor process is promising for the complete removal of CH 3SH and H 2S.