Improvement of filtration and antifouling performance of cellulose acetate membrane reinforced by dopamine modified cellulose nanocrystals

Abstract

A thin layer of polydopamine (PDA) was coated on the surface of cellulose nanocrystals (CNCs) by the self-polymerization of dopamine (DA) in water to improve the hydrophilicity and lipophilicity of CNCs. Then, the CNCs coated with PDA (PDA@CNCs) were blended with pore forming agent and cellulose acetate (CA), and the CA composite membrane reinforced by PDA@CNCs (PDA@CNCs/CA) was prepared by solution phase transformation method. The effects of PDA@CNCs content on the filtration performance, antifouling ability and mechanical properties of the composite membrane were studied. The results show that adding a small amount of PDA@CNCs can significantly improve the filtration capacity, antifouling performance and tensile strength of CA membrane. When the content of PDA@CNCs was 4 wt%, the hydraulic permeability, flux recovery ratio and tensile strength of PDA@CNCs/CA composite membrane increased by 33%, 15% and 76%, respectively. Simple DA modification improves the lipophilicity and dispersion of CNCs, enhances the binding force between CNCs filler and CA matrix, and improves the performance of CA composite membrane, thus widen the industrial application of CA materials, and shows a broad application prospect in the field of biological separation membrane and water treatment membrane.