Fabrication and characterization of temperature and pH resistant thin film nanocomposite membranes embedded with halloysite nanotubes for dye rejection

In this study, nanofiltration (NF) membranes with high pH and temperature resistance were fabricated by introducing halloysite nanotubes (HNTs) into the organic phase during the interfacial polymerization step. HNTs were dispersed in cyclohexane with the concentration 0% (TFN0), 0.02% (TFN0.02), 0.04% (TFN0.04) and 0.06% (TFN0.06) as w/v (%). Fabricated membranes were characterized by FT-IR spectroscopy, SEM and AFM analyses, optical profilometry, contact angle and zeta potential measurements. Filtration performance tests were conducted with 2000 ppm MgSO₄ and NaCl solutions and 100 ppm of synthetic dye solutions (Setazol Red Reactive and Reactive Orange dyes), respectively. For pH-resistance tests, synthetic dyes were filtrated in acidic, neutral and base conditions (pH = 4–7–11) to measure changes in flux and rejection. The effect of the temperature of the feed stream on membranes were determined by the filtration of pure water and dye solutions at 15 °C, 25 °C and 40 °C. Among different membranes fabricated with varying HNTs content, TFN0.04 membrane showed increased water flux without considerable salt and dye rejection loss.