Simple method for preparing thin film composite polyamide nanofiltration membrane based on hydrophobic polyvinylidene fluoride support membrane

This study attempts to prepare thin film composite (TFC) polyamide (PA) membrane using polyvinylidene fluoride (PVDF) as support membrane. PVDF has superior physical characteristics but is difficult to be used as TFC PA support membrane because of its strong hydrophobicity. However, in this study TFC PA membrane was prepared using a simple method of flowing trimesoyl chloride (TMC) organic solution at a specific velocity after putting specific quantity of m-phenylenediamine (MPD) aqueous solution on hydrophobic PVDF support membrane. The presence of polyamide formed by the interfacial polymerization of MPD and TMC were verified with X-ray photoelectron spectroscopy and attenuated total reflectance-fourier transform infra-red spectrophotometer, and field emission scanning electron microscopy and atomic force microscopy were used to observe the TFC PA membrane's surface and structural characteristics. The prepared TFC PA membrane showed maximum performance at TMC organic solution flow velocity of 1.21 m/s and TMC concentration of 0.3% (w/v). The TFC PA membrane prepared under these optimal conditions showed rejection rates of 68.14, 88.80, and 96.06% against NaCl, CaCl₂ Na₂SO₄ 5000 ppm, respectively. This proved that the TFC PA membrane prepared in this study had nanofiltration performance. - Highlights: • Thin polyamide (PA) layer was coated on hydrophobic surface by simple method. • PA composite membrane displayed peak performance at 1.21 m/s (organic phase). • PA composite membrane showed maximum 96.06% rejection rate against Na₂SO₄ 5000 ppm.