A pervaporation-crystallization (PC) process for simultaneous recovery of ethanol and sodium pyruvate from waste centrifugal mother liquid

Abstract

Abstract Sodium pyruvate is an important intermediate chemical in the fine chemical, food and pharmaceutical industries. Efficient treatment for waste centrifugal mother liquid (mainly containing ethanol, water and residual sodium pyruvate) generated during the production of sodium pyruvate is highly important to improve the process economy. A pervaporation-crystallization (PC) process is presented in this study for simultaneous recovery of ethanol and sodium pyruvate products from waste centrifugal mother liquid. The PC process contains two-step operation, i.e., the first step is low-temperature pervaporation for water removal, and the second step is cooling crystallization followed by filtration to collect ethanol and crude sodium pyruvate. Mass-produced NaA zeolite membranes show remarkable pervaporation performance for separating ethanol/water/sodium pyruvate mixtures with the water/ethanol separation factor always over 10,000 under various operational conditions. The potential deposition of sodium pyruvate on the outer membrane surface during the long-term use would decrease the total flux. However, the pervaporation performance of NaA zeolite membrane could be easily recovered by water washing regeneration. A pilot-scale study on the PC process for treatment of actual waste centrifugal mother liquid is successfully performed, suggesting the good technical feasibility of PC process for industrial application.