# The Enrichment of Acetic Acid Using an Integrated Reverse Osmosis–Electrodialysis Process

## TL;DR

This paper presents a new method to concentrate dilute acetic acid using a combination of reverse osmosis and electrodialysis.

## Contribution

The novel integration of RO and ED processes is shown to efficiently enrich low-concentration acetic acid.

## Key findings

- Reverse osmosis increased acetic acid concentration from 1.5% to 6.5% with low energy consumption.
- Electrodialysis further enriched the solution to 19.02% acetic acid concentration.
- The integrated RO–ED process reduces water energy consumption and cost compared to traditional methods.

## Abstract

In this study, the integrated process of reverse osmosis (RO) and electrodialysis (ED) is developed to concentrate the dilute solution of acetic acid (HAc). The key parameters, such as RO pressure, ED voltage, and ED volume ratio, were systematically evaluated and the operation conditions of the processes were optimized. Under an operating pressure of 5 MPa, RO can enrich low-concentration HAc from 1.5 wt.% to 6.5% wt.% and the energy consumption is 0.37 kW·h·kg−1. Next, RO-concentrated water was used as the ED feed and the first ED with a volume ratio of the concentrated to dilute chamber of 1:4 was carried out under the conditions of a flow rate of 30 L/h and an operating voltage of 12 V; the HAc concentration reached 12.50 wt.%. The second ED with a volume ratio of 1:5 made the final HAc concentration reach 19.02 wt.%. This study shows that using RO-concentrated water instead of initial water for the ED process can reduce water energy consumption and cost markedly, and the RO–ED integrated process can efficiently pre-enrich low-concentration HAc aqueous solution, and the enriched HAc concentration meets the requirements for the further distillation of HAc.