Non-thermal plasma/ photocatalysis processes for dimethyl disulfide removal: Study and reduction of the catalyst poisoning

In this paper, the removal of gaseous dimethyl disulfide (DMDS) was performed by two oxidation processes: photocatalysis over TiO₂ supported on glass fiber tissue and in dielectric barrier discharge (DBD) plasma. A catalyst deactivation was confirmed when the photocatalysis was taken alone, and several regeneration procedures were conducted. Firstly, photocatalytic removal efficiency was followed at three different DMDS initial concentrations. Catalyst deactivation has started quickly and the removal efficiency reach a low plateau at 19.68 %, 22 % and 10 % for an initial concentration of 22, 45 and 60 mg.m⁻³, respectively. The FT-IR and XPS analysis, performed on the deactivated catalyst indicated the presence of partial oxidation products such as sulfonates, sulfates and sulfonic acids groups. In the plasma process alone, the effect of initial concentration and plasma energy (10–41 J.L⁻¹) were explored toward DMDS elimination and 89.60 % of degraded DMDS was achieved at 41 J.L⁻¹. In the second part, the catalyst regeneration was investigated. It was demonstrated that DBD coupled with UVA was an efficient method to recover the full catalyst performance due to the action of ozone decomposition and valorization in the regeneration process. An additional activation effect was highlighted by the highest degradation rate of 6.88 mg.h⁻¹. The degradation carried out by the combined plasma–photocatalysis system at 22 and 45 mg.m⁻³ exhibited interesting performances with a stable removal efficiency of 100 and 70 % for the two concentrations, respectively.