In this paper, we review various novel/modified interfacial polymerization (IP) techniques for the fabrication of polyamide (PA) thin film composite (TFC)/thin film nanocomposite (TFN) membranes in both pressure-driven and osmotically driven separation processes. Although conventional IP technique is the dominant technology for the fabrication of commercial nanofiltration (NF) and reverse osmosis (RO) membranes, it is plagued with issues of low membrane permeability, relatively thick PA layer and susceptibility to fouling, which limit the performance. Over the past decade, we have seen a significant growth in scientific publications related to the novel/modified IP techniques used in fabricating advanced PA-TFC/TFN membranes for various water applications. Novel/modified IP lab-scale studies have consistently, so far, yielded promising results compared to membranes made by conventional IP technique, in terms of better filtration efficiency (increased permeability without compensating solute rejection), improved chemical properties (crosslinking degree), reduced surface roughness and the perfect embedment of nanomaterials within selective layers. Furthermore, several new IP techniques can precisely control the thickness of the PA layer at sub-10 nm and significantly reduce the usage of chemicals. Despite the substantial improvements, these novel IP approaches have downsides that hinder their extensive implementation both at the lab-scale and in manufacturing environments. Herein, this review offers valuable insights into the development of effective IP techniques in the fabrication of TFC/TFN membrane for enhanced water separation.

The conventional interfacial polymerization (CIP) technique used for preparing thin-film composite (TFC) nanofiltration membranes typically requires a large amount of monomers during polyamide (PA) synthesis where most of the monomers are discarded after cross-linking. Thus, a new fabrication concept is proposed in this work to synthesize a PA layer via a mist-based interfacial polymerization (MIP) technique where only a small amount of aqueous solution is dispersed as mist. This approach also eliminates the rubber-rolling step in CIP. In addition to forming a thinner and looser PA structure, the piperazine solution required in the IP reaction is significantly reduced, that is, 17 times lower than that of CIP. The microdroplet dispersion approach in MIP could form a higher cross-linked PA due to the high polymerization interface besides forming a higher free-volume selective layer due to the disruption in the PA repeat structure. Our findings revealed that the newly developed mist-based TFC membrane could achieve 9.08 L/m2·h·bar pure water permeability and 97.2% Na2SO4 rejection coupled with a complete flux recovery rate. As a comparison, the conventional TFC membrane only attained 2.84 L/m2·h·bar and 95.7%, respectively. The MIP technique could also be potentially considered for developing a nanofiller-incorporated TFC membrane due to the absence of the rubber-rolling step.

No abstract

No abstract

No abstract