High throughput polyamide-hydrazide reverse osmosis membrane mediated by dynamic covalent interlayer

Abstract

Reverse osmosis (RO) is the preferred technology for seawater and brackish water desalination. The ongoing pursuit of scientific research and industrial innovation aims to develop high-performance RO membranes. An effective approach to enhancing the performance of composite RO membranes is the use of interlayers. To simplify the construction process of the interlayer and improve its regulation effect on the interfacial polymerization process, we propose a construction scheme for an in-situ dynamic covalent interlayer. By adding glutaraldehyde (GA) to the aqueous solution containing cyclobutane tetraformylhydrazide (CBTH), we successfully synthesized a crosslinked acylhydrazone interlayer onto a polysulfone (PSF) substrate during the aqueous coating stage to optimize the interfacial polymerization process. In the early stage of interfacial polymerization, the crosslinked acylhydrazone interlayer can bind the amine monomer, preventing the initial polyamide layer from becoming too dense and creating a self-regulating mechanism. In the later stages, it continuously supplies amine monomers to the reaction zone, compensating for defects in the polyamide layer and establishing a self-perfection mechanism. The in-situ simultaneous dynamic covalent interlayer increased the permeation flux of the CBTH-TMC membrane by 3 times (4.0 L m⁻² h⁻¹⋅bar⁻¹) with NaCl rejection of 99.14 % by effectively controlling the membrane formation process. This approach demonstrates advantages in simplicity and operability, successfully overcoming the "trade-off" limitation of original polyamide-hydrazide membranes.