Mitigation of fouling of polyethersulfone membranes using an aqueous suspension of cellulose nanocrystals as a nonsolvent

An aqueous suspension of cellulose nanocrystals (CNCs) was prepared by acidic hydrolysis of microcrystalline cellulose to be used as a nonsolvent in the fabrication of polyethersulfone (PES) membranes via the phase inversion method. The effect of CNC concentration on the membrane permeability, surface morphology and antifouling capability was probed. Also, the efficiency of adding nanocrystals to the nonsolvent for two different concentrations of PES dope solution was examined. The coagulation of PES in the presence of CNCs led to a more hydrophilic and smoother surface as well as higher bulk porosity. The thin skin layer and more porous membrane suggested higher water flux for CNC-treated membranes. Due to the hydrophilic nature of CNCs trapped in the membrane top layer, a superior antifouling ability was found for membranes precipitated in 0.1 wt% CNCs aqueous suspension. The concentration of the CNC suspension had a more significant influence on the permeability of membranes prepared by the dope solution with a low content of PES rather than highly concentrated one.