Superhydrophilic Fluorinated Heterogeneous Membranes with Boosting Antifouling Property and High Stable Permeance for Efficient Emulsion Separation

Abstract

It is yet a query that whether chemically heterogeneous superwetting surface is able to enhance the permeability and anti-fouling capability of membrane contemporaneously, heretofore which is lacking and well worth creating. Here, we propose a bio-adhesion coupled with self-assembly strategy, to construct superhydrophilic fluorinated heterogeneous membranes, through in-situ biomimetic adhesion of the hydrophilic polyphenol-silane coating (TAT) on the porous PVDF membrane, as a secondary reaction platform, and subsequently self-assembly of amphoteric fluorocarbon surfactant (FS-50). Unsurprisingly, we find that introducing FS-50 not only significantly strengthens the permeability, but also improves the anti-fouling self-cleaning, thanks to the formation of robust hydration layer and slippery micro-domains with low friction, to realize the dual anti-fouling effects of pollution resistance and pollution release. The champion PVDF/TAT/FS-2% composite membrane exhibits superhydrophilic and underwater superoleophobic (oil contact angle above 162°) property with very low oil-adhesion. This composite membrane possesses an ultrahigh water permeance of 29214.6 L m-2 h-1 bar-1, which is 2.8 times larger than that of pristine PVDF membrane. The PVDF/TAT/FS-2% composite membrane presents the high separation efficiencies (above 99.5%) for various surfactant-stabilized oil-in-water emulsions and high permeances of 3193.2-4212.3 L m-2 h-1 bar-1. Especially, the membrane at continuous operation for 1.0 h can reach a high stable permeance of 2505 L m-2 h-1 bar-1. Moreover, this composite membrane shows strong chemical stability and robustness. This research answers the initial question, and provides the insight for further design and production of chemically heterogeneous superwetting membranes with high permeability, selectivity and antifouling ability.

Keywords: Chemically heterogeneous surface, Superwetting membrane, Improved permeance, Anti-fouling self-cleaning, Emulsion separation