Scale-up of a BTX electrochemically assisted reactive absorption

Abstract

Electrochemical technologies have proven highly efficient in remediating polluted gas with benzene, toluene, and xylene (BTX). However, their scalability has yet to be explored to determine the best configurations to maintain optimal removals and energetic efficiencies. Here, we report a straightforward scale-up of an electro-absorption process that combines the absorption of BTX in 0.05 M H₂SO₄ (electrolyte) and their electrochemical oxidation in the electrolyte. The electrochemical cell was upsized by stacking eight single-compartment cells, permitting the circulation of the absorbent in series. The results showed the successful removal of BTX from a synthetic gas stream, which increased at high current densities and low gas flow rates. Average removals over 60 % were achieved in the electro-absorption with 50 mA cm⁻². Analysis of the contaminants in the electrolyte confirmed the absorption of BTXs and their electrochemical oxidation by mineralisation, which was enhanced at larger gas flows and current densities. Nevertheless, a comparison of equivalent scaled and baseline systems indicated an inferior current efficiency on the larger scale due to mass transfer inefficiencies, which are affected by circulating the absorbent in series. These findings suggest that the replication of single electrochemical cells (parallel) can optimise the performance of the electro-absorption degradation of BTX at larger scales.