Effect of Reaction Interface Structure on the Morphology and Performance of Thin-Film Composite Membrane

Abstract

Thin-film composite (TFC) membrane has been extensively utilized and investigated for its excellent properties. Herein, we have constructed an active layer (AL) containing cave-like structures utilizing large meniscus interface. Furthermore, the impact of interface structure on the growth process, morphology, and effective surface area of AL has been fully explored with the assistance of sodium dodecyl benzenesulfonate (SDBS). The SDBS-induced nanobubbles continuously facilitated the migration of the top layer of AL toward the upper space. During this process, the surface area of sunken AL in the cave-like structures initially exhibited an increase and then a decrease. Additionally, the larger interface significantly enhanced the surface area and delayed the rise in the top layer of AL in the cave-like structures. Therefore, the TFC membrane, utilizing a substrate with a pore size of 1.00 μm and assisted by 0.30 mM SDBS, exhibited remarkable flux enhancement (>63%) and reduced reverse sodium salt flux (>35%) in a forward osmosis system. Moreover, the roughness factor was introduced to directly quantify the effective surface area, which had a good correlation with the water flux. Our findings demonstrated the significant potential of utilizing substrates with a large pore size to overcome the inherent limitations of the TFC membrane.