Ceramic supported composite nanofiltration membrane via a PDA interlayer induced mineralization of TiO2

Inorganic membrane has good stability, which acts as a significant role in water treatment. However, the effective preparation of stable and defect-free nanofiltration membranes on inorganic substrate remains challenge. In this paper, ceramic supported composite nanofiltration membrane (CNM) was prepared by mineralization of TiO2 polymeric sol induced by a polydopamine (PDA) interlayer on ceramic ultrafiltration substrate at low temperature. FESEM analysis shows that a PDA interlayer with a thickness of ∼44 nm and a smooth and dense top layer with a thickness of ∼88 nm are formed. And the construction and chemical changes of the membrane layer are confirmed by XPS and FTIR analyses. The water contact angle and zeta potential characterizations show that the CNM has a hydrophilic surface and a positive charge property. The obtained CNM has a polyethylene glycol (PEG) molecular weight cut-off (MWCO) of 800 Da. The CNM prepared with polymeric sol size less than 10 nm has a higher rejection to divalent salt. At 0.6 MPa, the CaCl2 rejection is 91.5% and the permeation flux is 22.8 L m−2 h−1. In 50 h continuous filtration, the rejection rate changes little. This paper describes a facile and efficient approach for producing stable ceramic supported composite nanofiltration membranes, which has potential applications in water treatment.