Hierarchical nanoparticle-induced superhydrophilic and under-water superoleophobic Cu foam with ultrahigh water permeability for effective oil/water separation

Abstract

In recent years, Cu foam has attracted intensive attention owing to its remarkable performance for oil/water separation. Most research mainly focused on Cu foam with surfactant decoration, which results in superhydrophobic or even stimuliresponsed membranes. Fabricating Cu foam with intrinsic superhydrophilicity via simple operations still remains as a challenge. Herein, we synthesized superhydrophilic and under-water superoleophobic Cu foam that consists of oxychloridized hierarchical nanoparticles with metal Cu core and polar Cu2O/CuO1-x/2Clx shell via the combination of anodization, HCl etching and calcination. This material shows ultrahigh water permeability (5 μl water-droplet permeating within 9 ms). And the oil/water separation efficiency of superhydrophilic Cu foam (SCuF) is above 99% with the oil content in separated water lower than 3 ppm. Moreover, the oil/water separation performance of SCuF for repeated use and anticorrosion are also excellent. To the best of our knowledge, it is the first attempt to synthesize intrinsic superhydrophilic Cu foam for effective oil/water separation. Due to the greatly enhanced specific surface area and active sites, it has potential applications in catalysis, hydrogen evolution process, electrode materials and many other environmental protection and energy fields.

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

“…However, this approach has some disadvantages, such as high cost, complicated modification, and the bonding strength between the nanofibers and the SiO 2 nanoparticles cannot be guaranteed during the operation. The other strategy is the direct use of commercial sponges and metal foams with 3D structures (most of them with pore size from 100 to 500 µm) as the substrates, followed by the postmodification to achieve the required pore structure and wettability. In this case, the mainframe of the filters is fixed so that the pore size cannot be drastically tuned, which renders these materials unfavorable in separating emulsions with droplet sizes less than 20 µm despite their high flux.…”

A glucose modified filter paper for effective oil/water separation

“…22,23 By utilization of macromolecular layers, nano or micro-particles, nano bres, and etc., a large number of superhydrophilic and underwater superoleophobic materials have been described and drawn extensive attentions due to their highly efficient ltrations and broad application prospects on oil/water separation. 17,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Filter paper, with its porous structure constructed by cotton microbers, is widely used in solid-liquid separation. Natural cotton bres consist of numerous brils of b-glucose with cuticle covered by 55% cellulose and the other non-cellulosic compounds like pectin, protein, and wax, 39 which makes primary lter paper impractical for liquid-liquid separation.…”

Underwater superoleophobic polyurethane-coated mesh with excellent stability for oil/water separation

“…The superhydrophilic and underwater superoleophobic material is usually prepared, then covering the hydrophilic material on the surface of the porous material by physical coating or chemical graing. To achieve the superhydrophilicity and underwater superoleophobicity, many materials have been used as membrane substrates of ltration, including metal meshes, fabrics, [33][34][35] foams, 13,36 nylon meshes, 37 aerogel, 38 sponges [39][40][41] and etcetera. Among them, metal meshes, such as stainless-steel mesh and copper mesh, exhibit superior mechanical properties and feasibility.…”