Facile fabrication of superhydrophobic copper mesh for oil/water separation and theoretical principle for separation design

In-situ oil-spill remediation by an electrodeposited superhydrophobic copper mesh

The present study aims to combat the problem of oil in water pollution via its separation using a superhydrophobic copper mesh. An ecofriendly superhydrophobic copper mesh with a water contact angle of 166 ± 2° is developed by a facile two-step process (electrodeposition followed by coating). The coated mesh with mechanical robustness, chemical endurance and thermal stability is a promising choice for real-world conditions. Additionally, its resistance to corrosion in harsh chemical environments ensures its long-term durability. With a separation efficiency of 99.9 %, the coated mesh serves as an efficient medium for oil-water separation. It can be used as a reusable filtering medium with high separation efficiency in alkali and neutral environments. Besides, it is also competent for continuous oil-water separation and collection of oil from wastewater. Thus, the above study clearly manifests that the coated mesh holds tremendous potential for large-scale oil spill cleanup.

Micropatterned superhydrophobic meshes coated with low-cost carbon nanoparticles for efficient oil/water separation

Superhydrophobic and superoleophilic meshes have gained considerable attention in oil/water separation in recent years. To fabricate such meshes, surface roughness features can be introduced, and the surface free energy can be lowered, preferably, by utilizing low cost, safe, and readily available materials. Herein, we report a novel approach for fabricating a superhydrophobic copper mesh using low-cost carbon nanoparticles embedded within surface micropatterns. To create the micropatterns, a femtosecond laser was employed. The fabricated mesh exhibited a water contact angle of 168.9° and a roll-off angle of only 5.9°. Additionally, the mesh was highly durable and effectively retained its superhydrophobicity during water jet impact and tape-peeling tests. After 50 cycles of the water jet impact test and 5 cycles of the tape-peeling test, the water contact angle reduced by only 0.3° and 2.3°, respectively. When tested for separating n-hexane/water mixtures, the mesh exhibited a separation efficiency of up to 98%. The separation efficiency remained essentially constant after 10 cycles of n-hexane/water separation. It was observed that the surface micropatterns played a significant role in achieving superhydrophobicity and imparting high durability to the mesh. Meshes lacking these laser-induced micropatterns showed higher wettability, lower durability, and decreased separation performance with repeated use.

Robust and stable superhydrophilic MIL-101 (Cr)-coated copper mesh for highly efficient oil/water emulsion separation

In this study, dip coating method was investigated to prepare superhydrophilic MIL-101 (Cr)-coated copper mesh for highly efficient oil/water emulsion separation. To increase the surface area of synthesized MIL-101 (Cr), a purification procedure was developed to remove unreacted H2BDC crystals present in the channel of the initial MIL-101 (Cr) sample synthesized. After that, a dispersing solution of MIL-101 (Cr) was needed to coat on the copper mesh. Thermoplastic polyurethane (TPU) was used as a binder in this procedure. The prepared membranes of M1 (once coated mesh) to M6 (six times coated mesh) were performed to separate oil/water emulsion effectively. Contact angle tests showed the superhydrophilic/underwater superoleophobic wettability behavior of MIL-101 (Cr)-coated copper meshes. The wetting mechanism of the prepared membranes is mostly relevant to the surface functional groups of purified MIL-101 (Cr). Also, the roughness of the nanostructured coated membranes was improved because of the uniform coating of MIL-101 (Cr) which is integrated into hydrophilic TPU. Oil/water separation results showed that M2 (twice coated mesh) showed the maximum amount of water flux (83076 L m-2 h-1) in oil/water separation and M3 (three times coated mesh) had the best performance of oil/water emulsion with 99.99% separation efficiency.

Fabrication of Superhydrophobic Porous Brass by Chemical Dealloying for Efficient Emulsion Separation

By taking advantage of typical dealloying and subsequent aging methods, a novel homogeneous porous brass with a micro/nano hierarchical structure was prepared without any chemical modification. The treatment of commercial brass with hot concentrated HCl solution caused preferential etching of Zn from Cu62Zn38 alloy foil, leaving a microporous skeleton with an average tortuous channel size of 1.6 μm for liquid transfer. After storage in the atmosphere for 7 days, the wettability of the dealloyed brass changed from superhydrophilic to superhydrophobic with a contact angle > 156° and sliding angle < 7°. The aging treatment enhanced the hydrophobicity of the brass by the formation of Cu2O on the surface. By virtue of the opposite wettability to water and oil, the aged brass separated surfactant-stabilized water-in-oil emulsions with separation efficiency of over 99.4% and permeate flux of about 851 L·m-2·h-1 even after recycling for 60 times. After 10 times of tape peeling or sandpaper abrasion, the aged brass maintained its superhydrophobicity, indicating its excellent mechanical stability. Moreover, the aged brass still retained its superhydrophobicity after exposure to high temperatures or corrosive solutions, displaying high resistance to extreme environments. The reason may be that the bicontinuous porous structure throughout the whole foil endows stable mechanical properties to tolerate extreme environments. This method should have a promising future in expanding the applications of alloys.

A Facile Route to Fabricate Superhydrophobic Cu2O Surface for Efficient Oil–Water Separation

The mixture of insoluble organics and water seriously affects human health and environmental safety. Therefore, it is important to develop an efficient material to remove oil from water. In this work, we report a superhydrophobic Cu2O mesh that can effectively separate oil and water. The superhydrophobic Cu2O surface was fabricated by a facile chemical reaction between copper mesh and hydrogen peroxide solution without any low surface reagents treatment. With the advantages of simple operation, short reaction time, and low cost, the as-synthesized superhydrophobic Cu2O mesh has excellent oil–water selectivity for many insoluble organic solvents. In addition, it could be reused for oil–water separation with a high separation ability of above 95%, which demonstrated excellent durability and reusability. We expect that this fabrication technique will have great application prospects in the application of oil–water separation.

Environmental perspectives of interfacially active and magnetically recoverable composite materials - A review

Aquatic ecosystem contaminated with toxic pollutants and heavy metals due to the rapid growth of industrialization has become a top-priority global concern exhibiting highly adverse effects on human health and the environment. Many treatment techniques have been envisioned for the removal of these toxic contaminants from the aqueous environment. Among these techniques, magnetic separation has attracted burgeoning research attention owing to its simplicity, eco-friendly nature, large surface area, electron mobility, and excellent performance for removing water contaminants. In particular, interfacial active nanoparticles and nanocomposites with unique structures and magnetic properties are considered as ideal provides candidates in material science for next-generation water treatment. This review gives an insight into current research activities associated with the synthesis strategies and applications of interfacially active and magnetically responsive nanomaterials and nanocomposites for sustainable purification processes. In the first half, various synthesis routes for magnetic iron oxide nanoparticles development and the corresponding formation mechanism are summarized. In the second half, we reviewed the magnetic and wettability properties of interfacially active and magnetically responsive nanocomposites and their environmental applications including oil-water separation, removal of hazardous dye-based pollutants and potentially toxic heavy metals. Finally, the review is wrapped up with major concluding remarks and future perspectives of these magnetic nanoscale composite materials for sustainable wastewater remediation.