Modification of Supramolecular Membranes with 3D Hydrophilic Slide-Rings for the Improvement of Antifouling Properties and Effective Separation

Abstract

A three-dimensional (3D) strategy for the fabrication of ethylene vinyl alcohol (EVAL) membranes with a dynamic surface was developed based on sliding supramolecular polymer brushes (SSPBs). The SSPBs with a 3D hydrophilic structure were introduced into the alkyne–EVAL membrane matrix via an azide–alkyne click coupling reaction. The self-mobile hydrophilic slide-rings in the SSPB provided a proactive exclusion system. This resulted in reduced direct contact of the membrane surface with multiple pollutants such as bovine serum albumin (BSA) and oil droplets. The EVAL-SSPB membrane demonstrated increased surface hydrophilicity, underwater oleophobicity, and antifouling properties. More importantly, the abundant hydrophilic rings in the membrane matrix result in supramolecular assembly and efficient hydrophilic sliding channels. This resulted in a dramatic increase in the water flux [2000 L/(m2 h)] while retaining a 96% rejection of BSA and oil/water emulsions. The results of the study indicate that three effects of the cyclodextrins rings, i.e., the hydrophilic effect, the exclusion effect, and the sliding effect, enabled the improved membrane performance. The demonstrated 3D fabrication strategy is versatile, facile, and scalable, which allows for its application to various other membranes. The fabricated materials possess excellent permeability and separation efficiencies, which make them attractive candidates for use as separation membranes with novel functions.

Fabrication of pH-Sensitive Superhydrophilic/Underwater Superoleophobic Poly(vinylidene fluoride)-graft-(SiO2 Nanoparticles and PAMAM Dendrimers) Membranes for Oil–Water Separation

“…For example, n -dodecane/SDS/water emulsion, n -hexadecane/SDS/water emulsion, soybean/SDS/water emulsion, and rapeseed/SDS/water emulsion demonstrated fluxes of 3100 ± 200, 2500 ± 200, 1000 ± 100, and 500 ± 50 L/(m 2 ·h), respectively. The different fluxes of the oil-in-water emulsions can be attributed to the different densities of oils (Table S1), , and these values are superior to those of universal membranes. ,, …”

“…The different fluxes of the oil-in-water emulsions can be attributed to the different densities of oils (Table S1), 49,50 and these values are superior to those of universal membranes. 19,51,52 Parts c and d of Figure 8 show the TOC values, which reflect the oil concentration, in the feed and permeate solutions. In comparison, high-water-purity filtrates could be obtained under both neutral and acidic conditions.…”

A Review on Oil/Water Mixture Separation Material

“…Then the superhydrophilic membrane was obtained successfully after the sulfonation process, which exhibited excellent antifouling properties and a water-permeation flux recovery achieving 98%. Ma et al 178 fabricated hydrophilic ethylene vinyl alcohol membrane via the azide−alkyne click coupling reaction, which showed underwater oleophobicity and antifouling properties. The water flux reached 2000 L/(m 2 •h) and the oil−water separation efficiency was greater than 95% even after 15 cycles of use.…”

Superwetting Oil/Water Separation Membrane Constructed from In Situ Assembled Metal–Phenolic Networks and Metal–Organic Frameworks

“…During emulsion separation, oil droplets were forced to approach and accumulate near the membrane surface by transmembrane pressure. Owing to the hydration layer and water micropockets captured by the TTN–ZIF–TTN hybrid layer, the contact and adhesion between oil droplets and membrane surface were greatly limited by forming an oil-repulsive barrier , and the composite oil/water/membrane interface. , Thus, the oil droplets were not prone to deposit on the membrane surface and could be easily driven away from the membrane surface by water rinsing flow. At the same time, the underwater superoleophobicity of the TTN–ZIF–TTN hybrid layer also prevented oil droplets from infiltrating into the pores and restricted pore blocking.…”