Effect of Low Concentrations of Lithium Chloride Additive on Cellulose-Rich Ultrafiltration Membrane Performance

Various water treatment processes make extensive use of porous polymeric membranes. A key objective in membrane fabrication is to improve membrane selectivity without sacrificing other properties such as permeability. Herein, LiCl (0-2 wt.%) was utilised as a preforming agent in fabricating biomass-derived cellulosic membranes. The fabricated membranes were characterised by dope solution viscosity, surface and cross-sectional morphology, pure water flux, relative molecular mass cut-off (MWCO, 35 kDa), membrane chemistry, and hydrophilicity. The results demonstrated that at the optimum LiCl concentration (0.4 wt.%), there is an interplay of thermodynamic instability and kinetic effects during membrane formation, wherein the membrane morphology and hydrophilicity can be preferably altered and thus lead to the formation of the membrane with better rejection at no detriment to its permeability.

Automated summary

Porous polymeric membranes used in various water treatment processes can be improved in selectivity without sacrificing permeability by utilizing LiCl (0-2 wt.%) as a preforming agent in fabricating biomass-derived cellulosic membranes. The membranes fabricated at the optimum LiCl concentration (0.4 wt.%) showed improved rejection without detriment to permeability, attributed to the interplay of thermodynamic instability and kinetic effects during membrane formation.