A correction method for the incomplete dissociation of sulfuric acid in the Villermaux-Dushman reaction system

Abstract

The Villermaux-Dushman reaction system is the most popular method for characterizing the micromixing performance of various reactors, which traditionally uses sulfuric acid as the proton source. However, the accurate initial proton concentration (IPC) in this system is hardly accessible owing to the two-step dissociation of the sulfuric acid, resulting in the inaccuracy of the segregation index (XS). In this work, a novel strategy was proposed to correct XS obtained by sulfuric acid as the proton resource via comparing with that obtained by perchloric acid. Under the same theoretical IPC, the micromixing experiments using sulfuric acid and perchloric acid were conducted in different types of reactors, respectively. The conclusions were consistent that an increase of approximately 1.3 times in XS was observed using perchloric acid relative to sulfuric acid. Hence, 1.3 could be considered as the correction coefficient to acquire the exact XS when sulfuric acid, with the concentration ranges from 0.05 to 0.195 mol/L, was used as the proton source. The deviation between the corrected and experimental XS was within ±15%. Overall, this work provides a secure and feasible strategy to accurately evaluate the micromixing performance.