Reactive extraction of propionic acid using trioctylamine in 1–decanol by response surface methodology optimization technique

Reactive extraction, a novel technique, was experimentally investigated for the removal of propionic acid, which is usually present in low concentrations in aqueous solutions. The experiments were conducted according to statistical design to develop an appropriate regression model. This was aimed at analyzing and optimizing the process variables and extraction efficiency for propionic acid reactive extraction from dilute aqueous streams using trioctylamine as extractant and 1-decanol as organic diluent. Response surface methodology in combination with Box–Behnken design involving 17 experimental runs was utilized for the propionic acid reactive extraction in this study. Three independent process variables were chosen as temperature (T), initial propionic acid concentration (CPAO) in the aqueous phase and trioctylamine composition (CTOA) in the organic phase. The statistical design analysis demonstrated that the propionic acid concentration and TOA composition had a significant effect while temperature had an insignificant effect on the response value as well as an interactive and quadratic effect on the response. The optimum conditions for propionic acid extraction were established as T = 300.752 K, CTOA = 18.252 %v/v, CPAO = 0.408 kmol/m3. Under these optimum conditions, the propionic acid experimental extraction yield was 89.788 %, which was in close conformity with the predicted yield value of 91.939 %.