Temperature-modulated formation of polyamide layer for enhanced organic solvent reverse osmosis (OSRO) performance

Organic solvent reverse osmosis (OSRO) has gained extensive attention for chemical separation because of its distinct advantages. Polyamide thin-film composite (PA-TFC) OSRO membranes have recently emerged as promising alternatives for this purpose. However, the development of PA-TFC membranes for OSRO remains in its early stages. It is highly desirable to improve the membrane performance to achieve high permeance and selectivity. Herein, we proposed a temperature-assisted method of modulating the performance of a PA-TFC membrane supported by an organic solvent-resistant polyketone substrate for OSRO. For the first time, we investigated the combined effect of an aqueous solution and the reaction circumstance temperature on the formation of the PA layer. These conditions were correlated with the resultant membrane morphology and structure. With increasing temperature, the synergistic effect of the increased reaction kinetics and enhanced IP instabilities induced changes in the structural parameters of the PA layer. By analyzing the evolution of these parameters, including the density of the leaf-like nanostructure and size on the membrane surface, thickness of the PA film (wall of surface nanostructures) and layer, surface roughness, and crosslinking, we proposed a mechanism for modulating the PA-TFC membrane by tuning the temperature. Structural modulation of PA also led to a change in the OSRO performance. In methanol/toluene (90/10, wt) separation, the membranes fabricated at temperatures of 70 and 90 °C displayed competitive performance compared to the results of peer research. This study advances the evolution of PA-TFC membranes in terms of OSRO performance.