Energy-efficient acetic acid-water separation: solvent design, process optimization and assessment

In the production processes of acetic acid ethylene, acetate esters, and acetone in chemical industry, a significant amount of dilute acetic acid (AcOH) is generated as wastewater discharge. This not only leads to considerable resource wastage but also results in serious environmental pollution. To support the development of the AcOH recovery industry, research on the separation of AcOH and water has garnered significant attention. In this work, we propose an energy-efficient, economical, and low-carbon AcOH-water separation by introducing a tailor-made ionic liquid (IL) solvent. Firstly, a computer-aided ionic liquid design (CAILD) method was coupled with novel design objectives to tailor high-performance ILs. By solving a CAILD-based mixed-integer nonlinear programming (MINLP) problem, pyridinium trifluoroacetate ([PY][TFA]) was identified as the candidate with the highest separation performance. Subsequently, rigorous simulations for the proposed IL-based AcOH-water separation process were performed, followed by a comprehensive process assessment covering energy, economic, and environmental performance. The results indicate that compared to the conventional distillation separation process, the [PY][TFA]-based AcOH-water separation process can reduce 57.08 ​% energy consumption, 23.99 ​% total annual cost, and 57.02 ​% carbon emissions. These findings suggest that the potential industrial application of ILs in the AcOH recovery. • A tailor-made IL ([PY][TFA]) is first introduced to separate acetic acid and water. • Structure optimization of IL is performed by formulating and solving a CAILD-based MINLP problem. • An optimized IL-based distillation process is proposed for the acetic acid/water separation. • The IL-based distillation process has 57.08 ​% energy savings and 23.99 ​% cost reduction.