Effect of Surfactants on Reverse Osmosis Membrane Performance

Abstract

The aim of this study was to evaluate the performance of a reverse osmosis (RO) membrane in surfactant removal using various surfactant model aqueous solutions. The separation tests were performed with laboratory scale units in a dead-end configuration. Cellulose Acetate (CA) and Polyamide (PA) RO membranes were used with nonionic, anionic, or cationic surfactants at a wide range of concentrations. Membrane performance was evaluated using permeate flux and total organic carbon (TOC) rejection. The effects of surfactant type and concentration on RO membranes were assessed. Permeate flux of the PA membrane depended on the surfactant type and concentration. The separation of cationic surfactant aqueous solutions yielded the lowest permeate flux, followed by nonionic and anionic surfactant aqueous solutions, respectively. Surfactant adsorption on the membrane surface occurred at very low concentration of cationic and nonionic surfactants due to electrostatic and hydrophobic interactions, respectively, which affected permeate flux, and micelles did not affect the permeate flux of PA membrane. However, for CA membrane the permeate flux was not affected by the feed solution. Both membranes exhibited satisfactory TOC rejection (92–99%). This study highlights the importance of assessing interactions between membrane material and surfactant molecules to mitigate membrane fouling and guarantee a better performance of the RO membrane.

Keywords

• reverse osmosis
• surfactant
• fouling
• permeate flux
• TOC rejection