Construction of thin-film nanocomposite membranes by incorporating acyl chloride@MoS2 for enhanced nanofiltration performance

Abstract

Incorporating suitable-sized nanoparticles into the organic phase of interfacial polymerization to form a nanomaterial-polyamide (PA) selective layer is a promising approach to enhancing membrane performance. In this work, we prepared novel thin-film nanocomposite (TFN) membranes by modifying the PA layer with acyl chloride@MoS2 nanoparticles. The nanoparticles added in the organic phase could obviously restrict the diffusion of piperazine monomers to the reaction zone during the interfacial polymerization process, demonstrated by both experiment results and molecular dynamics simulation. Compared to the thin-film composite (TFC) control membrane, the TFN membranes possessed a looser PA layer as well as a rougher and more hydrophilic surface with more negative charges, confirming the significant effects of the incorporated acyl chloride@MoS2 nanoparticles on the PA layer formation. The optimal TFN membrane achieved a high Na2SO4 rejection of 98.6% and a satisfying water permeance of 27.1 L m−2h−1 bar−1, over 2.9 times higher than that of the TFC membrane (9.3 L m−2h−1 bar−1). Moreover, attributed to the chemical affinities (including covalent connection, hydrogen bonds, and electrostatic attraction) between acyl chloride groups of the nanoparticles and the PA matrix, the TFN membranes exhibited excellent long-term operation stability. The beneficial effect of grafting acyl chloride groups on the surface of MoS2 nanoparticles was verified by the more superior membrane performance enabled by acyl chloride@MoS2 than that achieved by original MoS2. This study offers a feasible strategy to improve the performance of TFN nanofiltration membranes by utilizing proper nanoparticles as organic phase additives.