Thin-Film Composite Polyamide Membranes for Forward Osmosis Processes in the Various pH Conditions of Feed Solution

Forward osmosis (FO) works depending on the osmotic pressure difference between the feed solution and the draw solution instead of hydraulic pressure. It utilizes an osmotic pressure gradient as a driving force, thus it has the potential to produce water with less energy consumption. As increasing cost of energy, Forward osmosis (FO) technology is becoming important recently. And also the FO process has attracted much attraction for its applications in various fields, such as wastewater treatment, pharmaceutical and juice concentration process. The FO membranes for applying in those fields should have high water permeability and resistance of various feed conditions.  

The objective of this study is to compare to cellulose FO membrane and our newly developed polyamide FO membrane in the various pH conditions of feed solution. FO membrane, composed of a polyamide active layer coated onto the porous support layer made of hydrophilic polymer was used in this study. The changed performances of membranes were measured and compared with those of the cellulose FO membrane in terms of water flux, reversible diffusion of salts (RDS). And those membranes were characterized by surface analytical instruments. When using strong acid and base as feed solution, two types of membranes have different behaviors of water permeabilites and RDS. Polyamide based FO membrane has stable performances at strong feed solution. This study showed that polyamide baced membrane was a comparative advantage in wide pH ranges than cellulose FO membrane