Extraordinary Superhydrophobic Polycaprolactone-Based Composite Membrane with an Alternated Micro–Nano Hierarchical Structure as an Eco-friendly Oil/Water Separator

Abstract

Extraordinary superhydrophobic polycaprolactone (PCL) composite membranes with an alternated hierarchical micro−nano structure were designed by addition of SiO 2 aerogel. The highest water contact angle (WCA) of 166.8 ± 1.5°was obtained when SiO 2 aerogel content was 0.5% (PCL/SiO 2 -a0.5) in the PCL composite membrane, which was higher than other reported polymer-based membranes. SiO 2 aerogel lowered PCL composite membrane's surface energy. The triple curvature structure composed of microspheres, nanospheres, and nanofibers produced on PCL/SiO 2 -a0.5 membranes endowed the excellent roughness of the surface. Also, the inner structure of the PCL/ SiO 2 -a0.5 composite membrane composed of micro−nano spheres, nanofibers, and microfibers increased the porosity of the separation membrane, which would provide more adsorption space. The PCL/SiO 2 -a0.5 composite membrane as a separator for surfactant-stabilized emulsions of water-in-oil showed ultrahigh separation flux and efficiency. Meanwhile, the PCL/SiO 2 -a0.5 composite membrane had an outstanding chemical resistance, self-cleaning ability, and good reusability. The composite membranes reported in this work as eco-friendly separation materials possessed all these characters in oil/water separation. This research proposed a very simple method to design eco-friendly high-efficiency separators through the construction of the alternated micro− nano hierarchical structure.

Polycaprolactone Blended Cellulose Acetate Thin Film Composite Membrane for Dairy Waste Treatment Using Forward Osmosis

“…Similarly, the characteristic peak observed at 1732 cm -1 which corresponds to C=O, has shifted to a lower value. These results indicated that the PCL has effectively interacted with CA to form a blend (He et al 2021). Similarly, Figure 2c The tensile strength and percentage elongation of the prepared neat and blend membrane are depicted in Figure 2d.…”

Superwetting Polyvinlydene Fluoride Membranes with Micro‐Nano Structure for Oil‐in‐Water Emulsion Separation

“…To describe the permeation pressure of membrane contacting with oil or water, wetting mechanisms of PVDF and PVDF-P/P-ZIF-TA are illustrated in Figure 12. The permeation pressure was calculated according to the Laplace equation, as shown in the following equation: [14,59] Δp = 2𝜎 L ∕r = −4𝜎 L cos 𝜃∕d (1) whereΔp is the intrusion pressure, 𝜎 L is surface tension of a liquid, r is droplet radius, d is the average pore size of membrane, and 𝜃 is contact angle. PVDF membrane contacting with water will prevent water from passing through membrane pores due to 𝜃>90°and Δp>0, while oil droplets will penetrate PVDF membrane due to𝜃<90°and Δp<0.…”

“…Filtration oil-water separation treats oily wastewater through size sieving. [14] Oilwater mixtures, including slick oil, dispersed oil, and emulsified oil, can be separated by selecting filter separation materials with different pore sizes. [15] Membrane technology can process oilwater emulsion with high separation efficiency and user-friendly operation, but there is a problem of membrane fouling in the separation process.…”

Environmentally Friendly Chitosan-Modified Polycaprolactone Nanofiber/Nanonet Membrane for Controllable Oil/Water Separation

“…Various environmentally friendly polymers were used to fabricate fibrous membranes for oil/water separation, such as cellulose, polylactide (PLA), and polycaprolactone (PCL). Among these, PCL is considered the most potential candidate for making membranes for oil/water separation due to its mechanical property and processing advantages. , In previous studies, PCL has been widely used to develop novel superhydrophobic biodegradable separation materials due to its hydrophobic nature. , However, the separation ability of the superhydrophobic membranes made from PCL is limited because these membranes were mainly used for separating heavy oil/water mixtures and water-in-oil emulsions. Therefore, PCL should be modified to create a superamphiphilic membrane, which could be prewetted to control the separation of different oil/water mixtures, including immiscible oil/water mixtures, oil-in-water emulsions, and water-in-oil emulsions.…”