Characterization methods of thin film composite nanofiltration membranes

This review provides a comprehensive survey on the characterization methods used to study the properties and performances of thin film composite nanofiltration (NF) membranes in water separation processes. In general, the intrinsic properties of NF membranes are characterized with respect to chemical properties and physical properties using various analytical instruments. For instance, FTIR spectroscope, zeta potential analyzer, XPS, XRD, and NMR spectroscope are some of the widely used instruments to evaluate the membrane chemical properties while SEM, FESEM, TEM, AFM, contact angle goniometer, and positron annihilation spectroscopy are those that have been commonly employed to study the membrane structural properties. With respect to permeability and selectivity, NF membranes are generally characterized through filtration experiments using appropriate feed properties under specific testing conditions. Furthermore, this review also covers the characterization techniques used to study the resistance of NF membranes against chlorination, solvent, thermal, and fouling. These resistance tests can be individually conducted, depending on the practical applications of the membranes. Overall, this review attempts to give readers insights into the experimental planning and subsequent interpretation of the above-mentioned characterization techniques. It is also expected to help new researchers in the field of NF to quickly learn various NF characterization methods.