Optimal separation of acetonitrile and pyridine from industrial wastewater

A mixture of water, pyridine and acetonitrile is obtained as a by-product during the pharmaceutical industry. Azeotropic-extractive distillation (AED) and azeotropic-pressure swing distillation (APSD) are used to separate this mixture. In this work, we perform an optimization study of the total energy consumption of both processes by using a single factor analysis and response surface methodology (RSM). Compared to single factor optimization, the results showed that the energy saving optimized by RSM of AED and APSD was 37.27% and 27.36% respectively. The heat exchange network is optimized according to ASPEN ENERGY ANALYSIS. The results showed that the energy saving of AED and APSD after heat transfer optimization was 12.3% and 33%, respectively. By comparing the energy consumption of the two processes, it was found that the optimized AED process had an energy saving of about 1.05% compared with APSD. However, since there is no extractant entrainment in the APSD process, the APSD process is finally selected.