Tailoring electrochemically assisted absorbers for the efficient removal of volatile organic compounds

Abstract

A new electrochemical cell is conceptualized, designed, manufactured using 3D printing technology, tested, and evaluated for the treatment of VOCs (for which benzene was used as model pollutant). This cell combines into a single device, a packed absorption column, where the pollutant is absorbed into an absorbent liquid, and an electrochemical cell equipped with a membrane-electrode assembly (MEA), for the continuous regeneration of the absorbent. The use of MEA technology allows to use of absorbents with low salt concentration. During operation, oxidants are produced on the electrodes of the electrochemical cell and distributed both in the liquid and gas phase, effectively degrading benzene. Computational Fluid Dynamics (CFD) modeling and experimental characterization of residence time distribution and mass transfer coefficient were also conducted. The results demonstrated that the use of electrochemically assisted absorbers in a single unit maximizes the utilization of the produced oxidants. The maximum removal efficiency of nearly 60% is reached working at 50 mA·cm−2. High current densities lead to pollutant desorption due to the significant increase in the gas phase outflow, resulting in reduced gas phase residence time and the pollutant leaving the system without undergoing reaction.