3D Multiscale Superhydrophilic Sponges with Delicately Designed Pore Size for Ultrafast Oil/Water Separation

Abstract

Developing novel filtering materials with both high permeation flux and rejection rate presents an enticing prospect for oil/water separation. In this paper, robust porous poly(melamine formaldehyde) (PMF) sponges with superwettability and controlled pore sizes through introducing layered double hydroxides (LDH) and SiO 2 electrospun nanofibers are reported. The LDH nanoscrolls endow the sponge with inherent superhydrophilicity and the SiO 2 nanofibers act as pore size regulators by overlapping the PMF mainframe. This approach allows the intrinsic large pores in the pristine sponge to decrease quickly from 109.50 to 23.35 µm, while maintaining porosity above 97.8%. The resulting modified sponges with varied pore sizes can effectively separate a wide range of oil/water mixtures, including the surfactant-stabilized emulsions, solely by gravity, with ultrahigh permeation flux (maximum of 3 × 10 5 L m −2 h −1 bar −1 ) and satisfactory oil rejection (above 99.46%). Moreover, separation of emulsions stabilized by different surfactants, such as anionic, nonionic, and cationic surfactants has been investigated for further practical evaluation. It is expected that such a pore size tuning technology can provide a low cost and easily scaled-up method to construct a series of filtering materials for high-efficient separation of target oil/water mixtures.

Nonflammable and Magnetic Sponge Decorated with Polydimethylsiloxane Brush for Multitasking and Highly Efficient Oil–Water Separation

“…The separation mechanism of W/O emulsions through PDMS‐Fe 3 O 4 @MF was further investigated. To overcome the size mismatch between substrate macropores and emulsified droplets, pore size tuning technology has been previously utilized, while maintaining the high porosity of the material . Herein, our strategy is to construct PDMS brush decorated channels while preserving the intrinsic macroporous structure of the sponge substrate (Figure b).…”

“…In practice, however, critical challenges still remained for oil‐adsorption sponge materials. For instance, the size mismatch between sponge macropores (100–500 µm) and emulsified droplets ( d < 20 µm) significantly limited the separation efficiency . Furthermore, the poor flame resistance of traditional superhydropobic sponge materials also limited their environment adaptabilities, because oil spills cause not only environment damage but also fire risks.…”

Engineered Nanomaterials for Sustainable Oil Separation and Recovery

“…Yet another sponge‐based nanomaterial was proposed by the Du group, composed of porous poly(melamine formaldehyde) (PMF) substrate instilled with super wettability and controlled pore‐size via coating of layered double hydroxides (LDH) and SiO 2 electro‐spun nanofibers [56] . The obtained sponge could absorb water from oily wastewater owing to the superhydrophilicity, high porosity, and engineered pore size with ultrahigh permeation flux (maximum of 3×10 5 L ⋅ m −2 ⋅ h −1 ⋅ bar −1 ) and satisfactory oil rejection (above 99.46%).…”

Superhydrophobic Hair-Like Nanowire Membrane for the Highly Efficient Separation of Oil/Water Mixtures

“…The oil/water separation as an efficient method has drawn considerable attention [1][2][3][4]. Among various oil/water separation methods, the membrane separation technology is considered as one of most effective methods to separate the oil and water [5,6]. Various materials, such as meshes [7][8][9][10][11][12], polymer film [13][14][15][16], and foams [17][18][19][20], have been developed [21][22][23][24][25].…”