Interfacial assembly of micro/nanoscale nanotube/silica achieves superhydrophobic melamine sponge for water/oil separation

Robust mussel-inspired superhydrophobic sponge with eco-friendly photothermal effect for crude oil/seawater separation

Frequent oil spills have significant implications for the preservation of ecological balance. However, conventional superhydrophobic materials are limited to organic solvent separation, lacking the ability to undergo thermal conversion. In response to these challenges, photothermal materials have emerged as a promising, environmentally friendly, and cost-effective solution. These materials utilize solar energy as a constant power source to effectively reduce the viscosity of crude oil without the need for additional energy input. This work presents the self-assembly of titanium nitride/polydopamine (TiN/PDA) nanoparticles using hydrolytic methyltrimethoxysilane (MTMS) on the polyurethane (PU) sponge and subsequently dip-coats this sponge with polydimethylsiloxane (PDMS). The TiN nanoparticles act as a photothermal medium, while the PDA coating exhibits a photothermal synergistic effect on TiN nanoparticles. Additionally, the PDA coating demonstrates strong adhesion on the PU sponge through chemical bonding with MTMS, as confirmed by density functional theory (DFT). Furthermore, the superhydrophobic sponges process exceptional mechanical or chemical stability in harsh environments, thanks to the dual protective mechanisms provided by MTMS and PDMS. Particularly important, the excellent photothermal conversion efficiency of this material results in a maximum temperature of 99.4 °C being achieved within 3 min and a stable heating performance of over 99.0 °C across 10 cycles under a standard sunlight intensity. These superhydrophobic sponges can be effectively utilized for continuous vacuum-assisted separation of crude oil/seawater, enabling rapid adsorption and purification in oceanic environments.

Durable superhydrophobic/superoleophilic melamine foam based on biomass-derived porous carbon and multi-walled carbon nanotube for oil/water separation

In the present study, fabrications of two eco-friendly superhydrophobic/superoleophilic recyclable foamy-based adsorbents for oil/water mixture separation were developed. Hierarchically biomass (celery)-derived porous carbon (PC) and multi-walled carbon nanotube (MWCNT) were firstly synthesized and loaded on pristine melamine foam (MF) by the simple dip-coating approach by combining silicone adhesive to create superhydrophobic/superoleophilic, recyclable, and reusable three-dimensional porous structure. The prepared samples have a large specific surface area of 240 m²/g (MWCNT), 1126 m²/g (PC), and good micro-mesoporous frameworks. The water contact angle (WCA) values of the as-prepared foams, PC/MF and MWCNT/MF, not only were 159.34° ± 1.9° and 156.42° ± 1.6°, respectively but also had oil contact angle (OCA) of equal to 0° for a wide range of oils and organic solvents. Therefore, PC/MF and MWCNT/MF exhibited superhydrophobicity and superoleophilicity properties, which can be considered effective adsorbents in oil/water mixture separations. In this context, superhydrophobic/superoleophilic prepared foams for kind of different oils and organic solvents were shown to have superior separation performance ranges of 54-143 g/g and 46-137 g/g for PC/MF and MWCNT/MF, respectively, suggesting a new effective porous material for separating oil spills. Also, outstanding recyclability and reusability of these structures in the ten adsorption-squeezing cycles indicated that the WCA and sorption capacity has not appreciably changed after soaking into acidic (pH = 2) and alkaline (pH = 12) as well as saline (3.5% NaCl) solutions. More importantly, the reusability and chemical durability of the superhydrophobic samples made them good opportunities for use in different harsh conditions for oil-spill cleanup.

Separation of Oil from an Oil/Water Mixed Drop under a Lamb Wave Field: A Review

Oil separation from oil/water mixed drop under a Lamb wave field is one of the emerging acoustofluidic technologies that integrate acoustics and microfluidics. In recent years, this technology has attracted significant attention due to its effective, fast, contactless, and pollution-free. It has been validated in the separation of oil/water mixture on different non-piezoelectric substrates and shows great potential in incompatible liquids applications. Here, we summarize our recent progress in this exciting field and show great potential in different applications. This review introduces the theories and mechanisms of oil/water mixed drop separation induced by Lamb waves, the applications of this technology in the separation of oil/water mixed drop, and discusses the challenges and prospects of this field.

Exploring maleimide-anchored halloysites as nanophotoinitiators for surface-initiated photografting strategies

Maleimide-functionalized HNTs (HNTs-I) were prepared and explored as a nanophotoinitiator. Vinyl monomers can be grafted onto the nanotubes following a spatially controllable, metal-free and non-contact photoinitiated approach. The obtained HNTs-I were further used in a 3D printing system to fabricate hydrogels with designed configurations.

Superhydrophobic polyurethane sponge based on sepiolite for efficient oil/water separation

Massive oil leakage accidents and illegal discharge of oily wastewater have not just destroyed the sustainability of the ecological environment but caused permanent damage to marine ecosystems, which makes it urgent to handle it. In this paper, by means of sol-gel, micro-nan silica that grew from the surface of fibrous sepiolite was organically modified with 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane (PFDS). The superhydrophobic sepiolite/silica firmly attached to the surface of polyurethane sponge under the action of oily epoxy resin with strong adhesion. The sponge exhibited superhydrophobicity and excellent selective oil adsorption capacity (19.98-40 times of their own weight). More importantly, besides the effective separation of immiscible oil-water mixtures (the separation rate reached 98.72%), it could also efficiently separate oil with water and oil with salt solution emulsions. In addition, the sponges kept hydrophobic even after floating in extremely corrosive liquids for 20 h, showing a strong resistance to strong acidic as well as alkaline liquids. After 100 times of mechanical compression, the three-dimensional structure of sponge held still and the water contact angle was greater than 144°, demonstrating an excellent mechanical stability, which provided a reference for its practical application in oil-water separation.

Facile one-step fabrication of superhydrophobic melamine sponges by poly(phenol-amine) modification method for effective oil-water separation

Although polydopamine (PDA)-related modification is widely studied in the fabrication of superhydrophobic sponges, the high cost of dopamine limits its widespread application. To imitate PDA modification, a low-cost and facile one-step poly(phenol-amine) modification was performed on melamine sponges in this study. Low-cost catechol and diethylenetriamine (DETA) were used as the monomers, and n-dodecanethiol was used as an additive in the one-step modification. The results confirmed that the poly(phenol-amine) aggregations were successfully anchored on the sponge skeleton surface and that the aggregations were formed via the Schiff base reaction and the Michael addition reaction. Furthermore, the as-prepared sponges still showed excellent mechanical properties after modification. Additionally, the optimally modified sponge (MS-0.5) exhibited superhydrophobic properties with a contact angle value above 150° under various environments, high oil-absorption capacity for various oils and organic solvents, high continuous oil-water separation performance with efficiency greater than 98.8% in 30 cycles, outstanding demulsification performance with 99.52% toward oil-in-water emulsion, and excellent recoverability and long-term stability. Thus, this work provides a feasible facile one-step modification method that can be used in place of PDA-related modification.