A study on the fabrication and characterization of non-ionic polyether sulfone nanofiltration membrane for dye removal

Nanofiltration (NF) is a membrane liquid-separation technology sharing many characteristics with reverse osmosis (RO). Unlike RO, which has high rejection of virtually all dissolved solutes, NF provides high rejection of multivalent ions, such as calcium, and low rejection of monovalent ions, such as chloride. Today, due to the increase in population and the decrease in fresh water resources, membrane processes are considered to be among the most cost-effective processes for preparing fresh water from salt water. Also, membrane separation is one of the best methods for the final stages of wastewater treatment. The newest membranes are nanofiltration membranes, which have a much higher flux and acceptable retention of salts than reverse osmosis membranes. One of the newest nanofiltration membranes is asymmetric thin film composite (TFC) membranes, the most common method for their preparation is surface polymerization (IP) using two aqueous and organic phases. Recently, dyes are generally used in various industries and release of these dyes into streams will pose a serious threat to the environment. In this research, a nanofiltration membrane was fabricated via phase inversion as it is one of the most convenient methods for membrane fabrication. It is used in removing dyes by using pluronic as a surfactant and chitosan as an additive. By varying the concentration of pluronic as a surfactant at ۱ wt%, ۲ wt%, and ۳ wt%, and a constant amount of chitosan as an additive, three newly dope solutions were formulated. The fabricated membranes were analyzed by evaluating the membrane in terms of pure water permeation (PWP), permeation flux, salts rejection and dyes rejection. The introduction of pluronic as a surfactant and chitosan as an additive to the nanofiltration membrane produced high PWP and presented high salts rejection and dyes removal. Generally, high dyes rejections were achieved by M۳ which contained high weight percentage (wt%) of pluronic as it showed highest percentage rejection for acid red, methyl blue and reactive black ۵. The functional groups of the membranes were characterized and verified by using Fourier transform infrared spectroscopy (FTIR).