Atmospheric Pressure Plasma Functionalized Polymer Mesh: An Environmentally Friendly and Efficient Tool for Oil/Water Separation

Abstract

Oil/water separation has been addressed by various materials characterized with superwettability, but most of the methods involve corrosive or toxic chemicals which will cause environmental concerns. Proposed herein is an environmentally friendly method to realize oil/water separation. Nylon mesh is exposed to atmospheric pressure plasma for surface modification, by which micro-/nanostructures and oxygen-containing groups are created on nylon fibers. Consequently, the functionalized mesh possesses superhydrophilicity in air and thus superoleophobicity underwater. The water prewetted mesh is then used to separate oil/water mixtures with the separation efficiency above 97.5% for various oil/water mixtures. Results also demonstrate that the functionalized nylon mesh has excellent recyclability and durability in terms of oil/water separation. Additionally, polyurethane sponge slice and polyester fabric are also functionalized and employed to separate oil/water mixtures efficiently, demonstrating the wide suitability of this method. This simple, green, and highly efficient method overcomes a nontrivial hurdle for environmentally safe separation of oil/water mixtures and offers insights into the design of advanced materials for practical oil/water separation.

Table Salt as a Template to Prepare Reusable Porous PVDF–MWCNT Foam for Separation of Immiscible Oils/Organic Solvents and Corrosive Aqueous Solutions

“…Then the adsorbed oil/organic solvent blocked the air channels in the porous foam, which allowed the vacuum pump system to provide a force to suck the oil/organic solvent into the “tank,” and when the oil/organic solvent was completely removed, the air channels in the porous foam regenerated and thus avoided the suction of aqueous solution into the porous foam. [6,13b] With the assistance of a pump, oil/organic solvent removal ability of the adsorbents can be independent of its original adsorption capacity, which greatly improves the separation efficiency and decreases the amount of adsorbents required. Therefore, pump‐assisted continuous oil/organic solvent collection by porous adsorbents could be desirable for large scale oil/organic solvent and aqueous solution separations.…”

“…Therefore, pump‐assisted continuous oil/organic solvent collection by porous adsorbents could be desirable for large scale oil/organic solvent and aqueous solution separations. [6,13b] Figure c and Video S8 (Supporting Information) depict the vacuum‐assisted continuous collection of toluene (dyed with oil blue) from strongly acidic solution (HCl, 2 m ) surface. By applying a vacuum pressure of ≈2.2 kPa for about 1 min, the toluene was totally separated from the mixture.…”

“…Finally, we also compared the performance of the foam presented herein against those from the recent literatures (Table S3, Supporting Information). Among those reported, carbon‐based ultralight adsorbents, such as carbon nanotube (CNT) sponge,[4a] pyrolyzed melamine/lignin sponge, carbon aerogel, and cellulose aerogel,[13c] are characterized with ultrahigh oil/organic solvent adsorption capacity (up to ≈30 000%), but their preparation processes are either complex/inefficient or harmful to the environment/operator, and their oil/organic solvent removal stability in highly acidic, alkaline, and salty environments have rarely been considered. Functionalized commercial sponges, such as polyurethane sponge coated with Ag,[4b] CNT,[7a] nanodiamonds,[7b] straw soot,[7c] and iron oxide/polytetrafluoroethylene particles[4f] and melamine sponge coated by polydopamine particles,[4d] are the most explored materials for oil/organic solvent selective adsorption due to their inherently 3D porous structures and low density.…”

“…However, owing to the poor solubility of PVDF, the all hitherto reported PVDF‐based materials with superwettability involved the use of toxic organic solvents, such as N,N ‐dimethylformamide (DMF), N ‐methyl‐2‐pyrrolidone (NMP), triethyl phosphate (TEP), and N,N ‐dimethylacetamide (DMAC); these solvents are harmful to the operators and the environment and naturally result in volatile organics components (VOC) release, which is highly undesirable. As green chemistry and sustainable engineering have recently witnessed a significant growth of interest for water cleaning, developing environmentally friendly methods to fabricate PVDF‐based materials with superhydrophobicity for oil/organic solvent and water separation is of great importance.…”

Smart Cotton Fabric with CO2-Responsive Wettability for Controlled Oil/Water Separation

“…Effective separation of oil/water mixtures is regarded as a potential solution to resolve environmental pollution for oil spillages, industrial discharge of oils/organic solvents, and environmental protection [1][2][3][4][5]. In recent years, the oil/water separation materials with special surface wettability have been widely studied, and there are many approaches have been developed to construct the special materials, including adsorption, biological treatment, gravity separation membrane filtration, centrifugation, and ultrasonic separation [6][7][8]. However, these methods are limited in practical applications due to their low efficiency, complicated instrument setup, second pollutants, and high energy usage.…”