Related Experiment Video
Updated: Aug 26, 2025

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification
Published on: April 7, 2017
Introduction of poly(acrylic acid) sodium into traditional draw solution to enhance its driving capacity in forward
Pin Zhao1,2, Ruiping Liu1, Huijuan Liu1
1Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
Abstract:
In this study, poly(acrylic acid) sodium (PAA-Na) salt was selected as representative polymer additive and the effect on forward osmosis (FO) performance of traditional draw solute NaCl was investigated. Results showed that PAA-Na increased water flux in both FO and PRO mode at 25 °C (up to 50%). Water flux and specific RSF firstly increased and then kept stable with the increasing concentration of PAA-Na additive. However, PAA-Na cannot enhance water permeation effectively at 35 and 45 °C. PAA-Na influenced FO performance by (1) increasing membrane hydrophilicity, which can increase water permeation, and was dominant at low temperature, and (2) causing pore-clogging, leading water flux decline, which was significant at high temperature. Furthermore, the influence of PAA-Na was compared with another polymer PAM and divalent salts MgCl2. The addition of PAM increased water flux slightly (lower than 25%), but increased RSF at the same time, due to the negative charge. Although MgCl2 decreased RSF and kept water flux fixed, its role was not obvious. In all, PAA-Na had advantages to improve FO performance.
Related Concept Videos
Anionic Chain-Growth Polymerization: Overview
Ion Exchange
Osmosis and Osmotic Pressure of Solutions
Dialysis
Osmosis
Water, like other substances, moves from a high concentration of...

