Enhancing permeability of CA/MoS2 pervaporation membrane via electric field-induced orientation of MoS2 nanosheets

Abstract

The formation of a mixed matrix membrane by incorporating nanofillers into a polymer matrix is a potential strategy to improve the separation performance of polymer membranes. However, agglomeration and random arrangement of nanofillers in the mixed matrix membrane result in lower permeation flux increase than expected. In this work, mixed matrix membranes composed of cellulose acetate polymer and varying amounts of Molybdenum disulfide (MoS₂) nanosheets as nanofillers were prepared, and an electric field was applied to induce the alignment of MoS₂ nanosheets in the membrane thickness direction. The effects of solution parameters including solvent type, MoS₂ content, and polymer concentration as well as electric field parameters i.e., frequency, strength, and action time on MoS₂ orientation were investigated using a stereoscopic microscope. The pervaporation desalination performance of mixed matrix membranes with randomly arranged MoS₂ and orientally arranged MoS₂ was assessed. At 2 wt% MoS₂ content, the mixed matrix membrane with orientally arranged MoS₂ exhibited a flux of 5.44 kg/(m²·h), representing a 25.9 % increase over the mixed matrix membrane with randomly arranged MoS₂, while maintaining a salt rejection rate of over 99.9 %. The mixed matrix membrane demonstrated good long-term stability with consistent water flux and salt rejection during 120 h of operation.