Triclinic ZnMoO4 catalyst for atmospheric pressure non-thermal pulsating corona plasma degradation of reactive dye; role of the catalyst in plasma degradation process

Abstract

Microcrystalline α-ZnMoO4 catalyst for degradation of Reactive Black 5 by self-made open air atmospheric pressure pulsating corona plasma reactor was synthesized by electrodeposition, followed by thermal treatment. The effect of electrodeposition current density on the catalyst’ characteristics was examined by SEM, EDX, FTIR XRD and TG. The catalyst enhanced plasma decolourization rate by 7.5 times. The role of the catalyst in the consumption of plasma generated H2O2 and in dye degradation was examined in details for the first time to the best of our knowledge; the catalyst enhanced the generation of ⋅OH radical, a principle dye degradation reagent, by enhancing decomposition of plasma–generated H2O2. The catalyst’ excitation mostly proceeded by the strikes of plasma–generated active species accelerated by electric field, which transferred their energy to the catalyst, causing the creation of electron – holes pairs which attacked H2O2. Decolourization followed pseudo – first order kinetics. Decolourization rate increases with the increase of discharge current density and reactor input voltage. The ratio between cylindrical reactor cell’s diameter and the liquid level in it didn’t affect the decolourization rate. Relatively high energy yield of 1.86 gkWh−1 was achieved for 50% decolourization. TOC removal was 85.4% after 180 min of the treatment.