Nanocomposite Substrate-Supported Nanofiltration Membrane for the Efficient Treatment of Rare Earth Wastewater

Abstract

Rare earth wastewater is an emerging wastewater featuring high salinity, strong acidity and a complex background with multiple contaminants. A nanofiltration (NF) membrane with better performance is desired to tackle the challenge of rare earth wastewater to reduce its negative impact on the environment. Herein, a novel nanocomposite substrate-supported thin film composite (TFC) NF membrane with good stability and superior separation performance was reported. The inorganic two-dimensional O-MoS2 nanosheets were embedded into the PSf substrate via a nonsolvent-induced phase inversion method. The PSf/O-MoS2 nanocomposite was used as the support for the interfacial polymerization. the pore structure of the substrate shifted from a larger irregular bubble pore structure into a finger-like porous structure when the content of O-MoS2 was 0.06 wt%. As a result, the nanocomposite substrate-supported TFC membrane had a 1.7 times higher water flux and improved salt rejections compared to that of the control membrane. The obtained NF membrane showed excellent separation performance with a high salinity removal efficiency of 95% in treating real rare earth wastewater (diluted 50 times, pH: 2.46). This work also highlights the modification of the substrate by functional nanomaterials could provide versatile ways to improve the separation performance and stability of TFC membranes.