Design and multi-objective optimization of hybrid reactive-extractive distillation process for separating wastewater containing benzene and isopropanol

Abstract

The recycling of wastewater in chemical industry is of great significance because it can recover valuable organic solvents and prevent environmental pollution. In this work, benzene/isopropanol (IPA)/water ternary mixtures were separated by single and double reactive-extractive distillation column processes respectively. We conducted thermodynamic analysis on separation processes of ternary mixture to determine the feasible separation sequence. Furthermore, the processes are optimized by multi-objective genetic algorithm (MOGA) to obtain suitable operating conditions. And the processes were evaluated by the total annual cost (TAC), CO2 emissions (ECO2), extraction efficiency (Eext) and thermodynamic efficiency. The results showed that compared with the traditional triple column extractive distillation (TCED) process, the TAC and ECO2 of the double column reactive-extractive distillation (DCRED) process were dramatically reduced by 52.9% and 49.5%, respectively. Similarly, TAC and ECO2 decreased by 49.5% and 53.5% in reactive-extractive dividing wall column (REDWC) process compared with the traditional process. With application of intensive processes, the final proposed process is more economically and environmentally sustainable than the separation system proposed in currently available literatures. This study can provide reference for the efficient separation of industrial wastewater containing benzene and IPA.