Preparation and characterization of novel Polyamide-6/Chitosan blend dense membranes for desalination of brackish water

In this study, polyamide-6/chitosan blend dense membranes were prepared using solution casting technique. The membranes were then characterized by FTIR spectroscopy, TGA, SEM analysis and tensile testing. FTIR analysis confirmed hydrogen bonding between chitosan and polyamide. TGA analysis proved that all the membranes maintained thermal stability up to 370 °C. SEM analysis exhibited compact and dense structure of the membranes. The tensile properties of the membranes improved with the addition of hydrophilic chitosan. The membranes were then characterized for desalination properties using 2000 ppm NaCl solution by state-of-the-art dead-end membrane desalination equipment at 20 bar operating pressure. The effect of membrane thickness was then studied, and the best thickness of the membrane was determined for optimum water flux and salt rejection. The effect of chitosan concentration was also studied, and the best concentration was determined for optimum desalination properties. It has been found that the membrane having 200 micron thickness and 3 wt.% chitosan demonstrated optimum desalination properties that is 75% salt rejection and water flux of 1.52 kg/h.m2. It has been found that maximum salt rejection was achieved with 2 wt.% chitosan blend membrane and maximum permeate flux was achieved with 4 wt.% chitosan blend membrane.