Modeling and simulation of VOCs removal by nonthermal plasma discharge with photocatalysis in a continuous reactor: Synergetic effect and mass transfer

• A synergetic effect was observed by combining plasma SDBD and photocatalysis.
• A model based on chemical and mass transfer steps was developed.
• The model describes successfully the degradation of isovaleraldehyde by each process.
• By-products formation was well simulated by the model.
• Synergetic effect is taken into account by acting on the mass transfer coefficient.

This paper deals with photocatalysis (TiO2 + UV), nonthermal plasma (NTP) and their combinations. These processes have been widely studied for isovaleraldehyde (Isoval) treatment. Isoval removal, selectivity of CO2 and CO, and ozone formation are investigated in order to evaluate the performance of the combined process. The results show that the performance of the process has enhanced and a synergetic effect is observed.On the other hand, this work aims at investigating kinetic modeling of combined process with taking into account the mass transfer step. The model is based on mass balances in three types of region: bulk region, discharge zone and solid phase which contains the photocatalyst. The oxidation in discharge and solid phases is described in two stages. Firstly, the removal of Isoval gives an equivalent intermediate (EI). Secondly, EI is oxidized into carbon dioxide (CO2) and carbon monoxide (CO). This simplified approach of removal allows for an agreement between modeling and empirical data in terms of degradation and mineralization. It also allows for the simulation of NTP and photocatalytic kinetics without knowing the plausible pathway. Moreover, the synergetic effect can be represented correctly by increasing mass transfer constant.

General scheme for combined NTP and photocatalysis.Figure optionsDownload as PowerPoint slide