A CNT/PVA film supported TFC membranes for improvement of mechanical properties and chemical cleaning stability: A new insight to an alternative to the polymeric support

Abstract

Thin film composite (TFC) nanofiltration (NF) membranes supported by polymeric membranes have suffered from limited mechanical properties and chemical cleaning stability, resulting in an increasing operation cost. Strengthening the support of TFC membranes is expected to provide great stability for membranes. This work provided a TFC membrane constructed on the poly (vinyl alcohol) (PVA) incorporated carbon nanotube film, which was named CNT/PVA-TFC. Characteristics of substrates, including morphology, pore size, and mechanical properties, were investigated by scanning electron microscopy (SEM), intrusion mercury porosimetry and tensile method. The results demonstrated that PVA can improve the mechanical properties and hydrophilicity of the CNT film. The morphology, physicochemical properties and separation performance of CNT/PVA-TFC were also investigated. CNT/PVA-TFC showed great enhancement of mechanical properties with its elastic modulus and hardness approximately 330% and 200% of the control, respectively. Furthermore, CNT/PVA-TFC achieved greater resistance to caustic cleaning than TFC membranes supported by polymeric membranes. In addition, CNT/PVA-TFC exhibited an excellent flux decline of 29.3% and a flux recovery of 97.0%. The mechanism of the support of CNT and enhancement of PVA was systematically studied. This work highlighted the feasibility of fabricating TFC membranes on the CNT/PVA film, providing a new insight to alternate the polymeric substrate of TFC membranes.