Controlling Swelling Behavior of Poly (vinyl) Alcohol via Networked Cellulose and its Application as a Reverse Osmosis Membrane

Abstract

Water scarcity is a global growing threat. It has affected many countries including the UAE. As a consequence, many countries are now relying on desalination technologies for producing potable water from sea and brackish water. The importance of treating seawater has led to the inception of different membrane technologies among which reverse osmosis (RO) has become the leading membrane desalination method. Continual process improvements in RO have been due to improved membrane performances. Poly (vinyl) alcohol (PVA) represents one such material which is continually being researched for improved performance parameters. The hydrophilic nature of PVA makes it a promising membrane material for water treatment applications, but its use is restricted by its high swelling capacity in water. In this work, the swelling behavior of PVA was controlled using a novel process of aqueous blending of PVA with a modified form of cellulose, namely, networked-cellulose (NC). Dense PVA-NC membranes were obtained by varying the NC concentration. The incorporation of NC in PVA imparts its physical integrity which otherwise require heat treatment or crosslinking. Fabricated membranes were characterized for their mechanical, thermal and structural properties. The swelling capacity of PVA was reduced from 340% to 150% while the tensile strength of wet PVA-15 wt. % was improved by 1520%. The fabricated membranes were tested for desalination by reverse osmosis (RO) using aqueous solution of sodium chloride. A 272 µm thick membrane allowed a water flux value of 1.2 L h−1 m−2 with a salt rejection of 98.8%. Further experimentation showed that the flux doubled with approximately 50% decrease in thickness while maintaining the salt rejection rate attesting to the future potential of these fabricated PVA-NC membranes in RO technology.

Date of Award	May 2014
Original language	American English
Supervisor	Raed Hashaikeh (Supervisor)