Superelastic Polyimide Nanofiber-Based Aerogels Modified with Silicone Nanofilaments for Ultrafast Oil/Water Separation

Abstract

Nanofiber membranes via electrospinning with layered structures are frequently used for oil/water separation, thanks to their unique properties. However, challenges that involve nanofibrous membranes still remain, such as high energy consumption and unfavorable transport properties because of the densely compact structure. In this study, superelastic and robust nanofiber-based aerogels (NFAs) with a three-dimensional (3D) structure as well as tunable porosity were prepared using polyimide (PI) nanofibers via a freeze-drying process followed by the solvent–vapor treatment. The porous NFAs were further modified using trichloromethylsilane (TCMS) to generate silicone nanofilaments (SiNFs) on the surface of the PI nanofibers, which could enhance the hydrophobicity (water contact angle 151.7°) of the NFAs. The corresponding superhydrophobic NFAs exhibited ultralow density (<10.0 mg m–3), high porosity (>99.0%), and rapid recovery under 80% compression strain. SiNFs-coated NFAs (SiNFs/NFAs) could also collect a wide range of oily solvents with high absorption capacities up to 159 times to their own weight. Moreover, surfactant-stabilized water-in-oil emulsions could also be efficiently separated (up to 100%) under the driving force of gravity, making it a promising energy-efficient technology. Additionally, SiNFs/NFAs maintained high separation efficiency throughout five separation–recovery cycles, indicating the potential of SiNFs/NFAs in the field of oil/water separation, sewage treatment, as well as oily fume purification.

Robust graphene/poly(vinyl alcohol) aerogel for high‐flux and high‐purity separation of water‐in‐oil emulsion and its computational fluid dynamic simulation

“…This material was employed for gravity separation of oil–water mixture with high separation purity and reusability. Shen et al 24 prepared superelastic nanofiber aerogels (NFAs) with 3D structure using polyimide (PI) nanofibers as raw materials and adjusted the porosity through freeze‐drying and solvent steam treatment. The as‐prepared aerogel could collect a variety of oily solvents up to 159 times its own weight with 100% purity.…”

Facile Fabrication of Electrospun Nanofibrous Aerogels for Efficient Oil Absorption and Emulsified Oil–Water Separation

“… 25 Recently, Deng et al demonstrated a simple method to design superelastic and robust SiNFs/PI-NFAs with excellent absorption capacity (70–159 g g –1 ) and effectively separate water-in-oil emulsions. 26 In a previous study, our group successfully prepared polydimethylsiloxane (PDMS)-functionalized PAN@PDMS NFAs using coaxial electrospinning and solution immersion methods, respectively. The resulting aerogels showed excellent absorption performance (55.43–127.37 g g –1 ), superior chemical stability, excellent recyclability, and outstanding separation efficiency (above 99.47 wt %).…”

Superhydrophobic PDMS-pCA@CNWF Composite with UV-Resistant and Self-Cleaning Properties for Oil/Water Separation

“…With the development of industrialization, the problem of water pollution has become a major challenge. As one of the three major types of industrial wastewater, oily wastewater is viewed as a serious environmental issue, threatening human life and the global ecosystem [ 1 , 2 , 3 , 4 , 5 ]. Oil/water separation is a green technology that separates oil/water mixtures to achieve waste oil recycling and sewage purification.…”