Isopropanol concentration by osmotically assisted reverse osmosis

Isopropanol (IPA) is a versatile solvent used in a wide range of industrial and consumer applications, and its disposal may pose high costs and environmental concerns. In this work, the osmotically assisted reverse osmosis (OARO) technology was employed to demonstrate the effective treatment and concentration of IPA wastewater. The effect of various operating parameters, including feed solution concentration, number of membrane modules, flow rate, and applied pressure, was systematically investigated. Both permeance and IPA rejection decreased with an increase in IPA concentration, due to increase of feed solution osmotic pressure and occurrence of membrane swelling. By adjusting the feed flow rate and applied pressure, we can effectively control the final IPA concentration. Specifically, lowering the feed flow rate will result in higher IPA concentration, and increasing the applied pressure will also lead to higher IPA concentration. Long-term operational stability was also investigated, and results showed that the OARO process could maintain stable operation over an extended period of 180 days. Lastly, real IPA wastewater sourced from an electronics devices factory was treated using the OARO system and the wastewater sample was concentrated for more than four times. The results of this work exhibit the great practical application potential of the OARO process for the concentration of IPA wastewater.