Layer-by-Layer Assembly of Zeolite/Polyelectrolyte Nanocomposite Membranes with High Zeolite Loading

Incorporation of zeolite nanopartides into nanocomposite membranes is advantageous with respect to enhancing membrane permeability by providing preferential water flow paths through the subnanometer porous structure of zeolite while maintaining excellent separation capability. We present a layer-by-layer assembly approach to effectively incorporate zeolite nanopartides into nanocomposite membranes. Negatively charged Linde type A (LTA) zeolite nanopartides were sandwiched between two different polyelectrolyte layers, negatively charged poly(acrylic acid) (PAA) and positively charged polyethylenimine (PEI), to form a PEI-LTA-PAA trilayer. The zeolite loading in the multitrilayer membranes was between 30 and 60 wt %, which is attributed to the drastically improved compatibility between zeolite and polymers, a direct result of electrostatic interactions. The performance of the trilayer membrane was compared with that of a control PEI-PAA bilayer membrane in a forward osmosis membrane system. The incorporation of zeolite nanoparticles was found to enhance membrane water permeability by >2-fold without compromising the membrane selectivity for tested species.