Grafted cellulose acetate reverse osmosis membrane using 2-acrylamido-2-methylpropanesulfonic acid for water desalination Ashraf Morsy, Shaker Ebrahim, El-Refaie Kenawy, Tarek Abdel-Fattah and Sherif Kandil ABSTRACT Reverse osmosis (RO) membranes based on cellulose acetate (CA), were prepared using a phase inversion technique. To improve the hydrophilicity, salt rejection and water flux of these membranes, a novel grafting of 2-acrylamido-2-methylpropanesulfonic acid (AMPSA) was added on the top surface of the CA-RO membranes. The grafted CA-RO membranes were characterized by Fourier transform infrared spectroscopy (FTIR), contact angle, and scanning electron microscopy techniques. It was found that the contact angles were 58 W and 45 W for pristine CA and 15 wt% grafted CA-RO membranes, respectively, which suggest an increase in the membrane surface hydrophilicity after grafting. The morphological studies of the surface of the pristine CA-RO membrane revealed a typical ridge- and-valley morphology and displayed a relatively high surface roughness of 337 nm, and a significant decrease at 15 wt% of grafted CA-RO membrane to 7 nm. The effect of the grafting percentages of AMPSA on the water flux and salt rejection was studied using a cross flow RO unit. The salt rejection and water flux of the grafted CA-RO membrane with 15 wt% were 99.03% and 6 L/m 2 h, respectively. Ashraf Morsy Shaker Ebrahim (corresponding author) Sherif Kandil Materials Science Department, Institute of Graduate Studies & Research, 163 Horreya Avenue, El-Shatby, Alexandria, Egypt E-mail: shaker.ebrahim@alexu.edu.eg Ashraf Morsy Department of Chemistry, Egyptian Petrochemicals Company, Alexandria, Egypt El-Refaie Kenawy Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt Tarek Abdel-Fattah Applied Research Center, Thomas Jefferson National Accelerator Facility and Department of Molecular Biology, and Chemistry, Christopher Newport University, Newport News, VA 23606, USA Key words | 2-acrylamide-2-methylpropane sulfonic acid, cellulose acetate, desalination, membrane INTRODUCTION Water scarcity is one of the most serious global challenges; one-third of the world’s population are living in water- stressed countries; by the year 2030, this figure is predicted to rise to nearly two-thirds. The challenge of providing ample, safe drinking water is farther complicated by popu- lation growth, contamination of available freshwater resources, and climate change (Elimelech & Phillip ). Many decades of successful implementations demonstrate how desalination technology can provide supplementary or main water sources. The desalination process can be roughly categorized into two major types: thermal and mem- brane separation (Zhou et al. ). Reverse osmosis (RO) is currently the most widely used desalination technology due to continuous technological improvements and substantial cost reductions. This technology has the advantages of having modular construction and small carbon footprint, which allows for the combination of additional treatment processes. Presently, two main types of polymeric RO mem- branes exist in the market: cellulose acetate (CA) membranes and polyamide thin film composite (TFC) mem- branes. However, TFC membranes, which are the most commonly used type of RO membranes, cannot withstand chlorine exposure, even at low ppm concentrations. On the other hand, CA membranes exhibit some resistance against chlorine at concentrations of up to 5 mg Cl 2 /L and 0.2 mg Cl 2 /L for short and long exposure times, respectively. Consequently, CA membranes are used in most of the RO plants located in the Middle East Region while the elevated seawater temperature and water quality promote the risk of membrane biofouling (Khan et al. ). 1046 © IWA Publishing 2016 Water Science & Technology: Water Supply | 16.4 | 2016 doi: 10.2166/ws.2016.025 Downloaded from https://iwaponline.com/ws/article-pdf/16/4/1046/411878/ws016041046.pdf by guest on 11 June 2020