Figure - available from: RSC Advances
This content is subject to copyright. Terms and conditions apply.
Superhydrophobicity of lotus leaf and underwater superoleophobicity of fish scale. (a) Lotus leaves. (b and c) Surface microstructure of a lotus leaf. (d) Water droplet on the lotus leaf in air. (e) Photography of fish scales. The inset shows a fish in water. (f and g) Surface microstructure of fish scale. (h) Oil droplet on a fish scale in water. (a–d) Reproduced from ref. 84 with permission from ACS, copyright 2017. (e–h) Reproduced from ref. 100 with permission from Wiley, copyright 2009
Source publication
Oil/water separation (OWS) technology has become an increasingly crucial tool to protect the environment and reduce the economic losses caused by the discharge of oily wastewater and oil spills. Recently, porous materials with superwettability have been applied in effective OWS and have achieved tremendous success. Herein, we review recent advancem...
Similar publications
Oil spills and the emission of oily wastewater have triggered serious water pollution and environment problems. Effectively separating oil and water is a world-wide challenge and extensive efforts have been made to solve this issue. Interfacial super-wetting separation materials e.g., sponge, foams, and aerogels with high porosity tunable pore stru...
Citations
... The second approach is a two-step approach in which the production of superhydrophobic surfaces is performed using creating surface-roughness on high-surface energy material followed by post/pre-treatment with low-surface energy materials [5,6]. Anyway, huge efforts have been devoted to the production of these surfaces for diverse applications, including self-cleaning [7,8], self-healing [9,10], oil-water separations [11,12], anti-icing [13,14], anti-biofouling [15,16], and anti-fogging [17,18]. ...
In this study, a new approach based on dielectric barrier discharge (DBD) plasma was used to fabricate super-buoyant dielectric materials for drag-reduction. We used a glass slide as a high-density substrate for buoyancy tests and a model boat made from Polymethyl methacrylate (PMMA) for drag-reduction experiments. In the first step, an atmospheric pressure DBD plasma was used for the deposition of the hydrogenated amorphous carbon (a-C:H) film using argon working gas and toluene precursors. The layer characterizations were performed versus the plasma deposition time by FE-SEM, AFM, FTIR, and Raman analysis. The morphological characterizations showed the formation of some micro and nanostructures on the surface followed by an increase in surface roughness. Moreover, the chemical characterizations suggested the successful formation of a-C:H film. In the next step, the effect of the deposited layer was assessed on the buoyance and drag reduction. Based on the results, the plasma coating produced a super-buoyant glass slide with remarkable load-bearing capacity, high durability, and robustness. In addition, the drag force was reduced noticeably after the plasma treatment. The results of this study promise the use of atmospheric pressure plasma for the fabrication of super-buoyant surfaces for buoyancy applications.
Graphical abstract
... Therefore, the preparation of periodic and patterned arrays of CuO-Cu 2 O-ZnO heterojunction on 3D micro-/nano-structured copper substrates remains a great challenge. In recent years, laser processing technology has attracted a lot of attention in the preparation of water treatment materials due to its unique advantages such as high energy density and short processing time [39][40][41], including processing various superhydrophobic surfaces with self-cleaning functions and preparing graphene materials with anti-fouling and anti-bacterial functions [42,43]. Our group also reported the fabrication of copper mesh with an oil-water separation function using laser processing technology for oil spill treatment in the environment, along with other uses [44,45]. ...
In this work, 3D periodic “grid-type” CuO/Cu2O layers were fabricated on a copper sheet using laser processing techniques, and the laser processing parameters were optimized for favorable ZnO nanowire growth. It was found that ZnO nanowires could be successfully prepared to form a CuO-Cu2O-ZnO heterojunction structure without an extra catalyst or seed layer coating, which could be attributed to the copper oxide active sites induced via laser texturing. ZnO nanowires on laser textured “grid-type” copper substrates demonstrated an effective piezocatalytic performance with different morphologies and the generation of abundant reactive oxygen species in the CuO-Cu2O-ZnO catalytic system, providing a fundamental mechanism for the degradation of organic dye in water. This simple and low-cost method could provide a useful guide for the large-scale efficient and versatile synthesis of immobilized piezoelectric catalysts.
... When stacking different treatments for removing hydrophobic/hydrophilic pollutants, these methods must be compatible with each other usually resulting in high operational costs. For example, the increasing discharge of produced water (PW) containing oil residuals and additive chemicals from oil and gas (O&G) production facilities and transportation systems has imposed irrecoverable damage to the marine ecosystem [1]. The commonly used hydrocyclone [2] and air flotation [3] techniques can effectively separate oil suspensions, but more thorough treatment technologies are required to remove the dissolved oils and hazardous chemical components, thus achieving the goal of zero-harmful discharge and possible water reuse. ...
... It is known [16,17] that ablation of a metal surface by femtosecond laser pulses is the least destructive method due to the short interaction time. This makes it possible to reproduce not only micron but also submicron patterns [18,19] formed by laser-induced periodic surface structures (LIPSS). The successful formation of such patterns on steel to control wetting was demonstrated in [20], and the dependence of water repellency on microstructure parameters (line-to-line spacing) was studied in [21]. ...
The loss of spontaneous liquid repellency on the surface of AISI 304 stainless steel under UV irradiation has been investigated depending on the textures formed by femtosecond laser pulses using Owens–Wendt plot analysis. Laser-induced periodic surface structures (LIPSS) have shown less liquid repellency compared to microgrooves. The polarity of the super-hydrophobic non-polar layer increased under UV irradiation to a super-hydrophilic state. The rate of this transition is determined by the surface topography and was faster for LIPSS compared to the bihierarchical textures formed by LIPSS in combination with microgrooves. The applicability of the Owens–Wendt approach for the numerical comparison of the achievable liquid repellency of textured surfaces in the Cassie state and the degree of polarity reversal of the hydrophobic layer was shown.
... According to Young's model (Fig. 1a), the CA of a liquid droplet on a smooth solid surface can be expressed by Young's Eq. (1). The CA is an essential parameter in Young's equation to measure the wettability of a solid surface and depends on the solid-vapor, solid-liquid, and liquid-vapor surface tensions (Yong et al. 2019): where θ Y is the CA of a liquid droplet on a smooth solid surface; γ SV, γ SL , and γ LV represent the surface (1) cos Y = SV − SL LV tension of solid-vapor, solid-liquid, and liquid-vapor, respectively. Young's model described above failed to evaluate the wetting property on a solid rough surface (Xiang et al. 2022). ...
The industrial revolution has led to a frequent leakage of crude oil into marine waters and the contamination of wastewater with various oils and organic liquids. Therefore, the development of multifunctional materials for oil/ water separation is a fast-growing research area for the remediation of oil-polluted water. Separation processes based on advanced superwetting materials have been proposed as a novel and smart nonconventional technology for oily wastewater treatment. This review focuses on the fabrication of superwetting cotton textile materials for water/oil separation. The principles of selective water/oil separation including the wettability models, separation mechanism, and separation modes are highlighted. Two types of superwetting materials are presented including superhydrophobic and superhydrophilic/underwater superoleophobic cotton fabrics for the separation of various immiscible and emulsified oil/water mixtures. The discussion of this review focuses on the fabrication process in terms of (a) modification of surface roughness, and (b) surface energy to achieve the superwetting performance. The performance of the modified superwetting cotton textiles was highlighted in terms of their wetting behaviour, durability, separation efficiency, intrusion pressure, and recyclability. Smart cotton fabrics with controllable and switchable wettability are presented including the pH-responsive, thermo-responsive, photo-responsive, dual-responsive, and Janus membranes. The current assessment methods for the evaluation of mechanical and chemical durability are highlighted. Future studies shall focus on the fabrication of cotton textiles with smart, switchable, and controllable wettability as well as the Janus cotton textiles to maximize the utilization of the amphiphilic nature of cotton fabrics and textiles.
... Texturing is an effective way to achieve liquid-repellent surfaces bioinspired by lotus leaves, reeds, and rose petals [1]. A high throughput of metal surface micro-texturing is provided by femtosecond laser ablation [2,3]. It also allows the formation of nanotextures, including highly ordered laser-induced periodic surface structures (LIPSS). ...
The eligibility of applying the Owens–Wendt approach to determining the free surface energy of liquid-repellent aluminum surfaces, with micro- and nanotextures formed by a femtosecond laser, was considered. This approach has been shown to be applicable using two essential parameters that can be derived from the graphs. The first is related to the fraction of the contact area between the liquid and the solid surface in the Cassie state. The second is related to the degree of intrinsic
polarity of the surface material or the applied organic modifier. The presented interpretation was used to compare the liquid repellency of the obtained textures. A microtexture with a period of 60um and a groove width of 45um has been shown to be the most liquid repellent. Among the modifiers, 1H,1H,2H,2H-perfluoroctyltriethoxysilane was the most effective, and stearic acid was
only slightly inferior, but promising in terms of cost and environmental friendliness. It was shown that spontaneous hydrophobization provided a contact angle with water up to 159deg, but the stability of such textures was inferior to the considered modifiers.
... Therefore, very high temperatures and pressures are produced at a very shallow depth in the range of microns. Herein, contrary to the irradiation with a pulsed laser, the material ablation happens without producing a recast layer on the ablated area and thus results in a smooth ablated region as compared to the irradiation with a pulsed laser [ Fig. 5(a-d)] [33]. ...
... SEM image of the substrates after nanosecond and femtosecond laser ablation respectively. Reproduced from Ref.[33] with permission from the Royal Society of Chemistry. ...
In recent years, the application of lasers for modifying the surface topography of dental biomaterials has received increased attention. This review paper aims to provide an overview of the current status on the utilization of lasers as a potential tool for surface modification of dental biomaterials such as implants, ceramics, and other materials used for restorative purposes. A literature search was done for articles related to the use of lasers for surface modification of dental biomaterials in English language published between October 2000 and March 2023 in Scopus, Pubmed and web of science, and relevant articles were reviewed.
Lasers have been mainly used for surface modification of implant materials (71%), especially titanium and its alloys, to promote osseointegration. In recent years, laser texturing has also emerged as a promising technique to reduce bacterial adhesion on titanium implant surfaces. Currently, lasers are being widely used for surface modifications to improve osseointegration and reduce peri-implant inflammation of ceramic implants and to enhance the retention of ceramic restorations to the tooth. The studies considered in this review seem to suggest laser texturing to be more proficient than the conventional methods of surface modification. Lasers can alter the surface characteristics of dental biomaterials by creating innovative surface patterns without significantly affecting their bulk properties. With advances in laser technology and availability of newer wavelengths and modes, laser as a tool for surface modification of dental biomaterials is a promising field, with excellent potential for future research.
... The prepared surface showed robust superhydrophobicity under thermal aging, thermal cycling, and UV exposure. In all, the laser ablation technique can accurately control the structural parameters (spacing, size, depth, etc.) of micro-nano structures, which helps the comprehensive analysis of the anti-icing mechanism and improves the optimization of superhydrophobic surfaces [154]. Nevertheless, the technical difficulty of applying on curved and geometrically complex surfaces still needs further study and overcoming. ...
The icing on overhead transmission lines is one of the largest threats to the safe operation of electric power systems. Compared with other security accidents in the electric industry, a sudden ice disaster could cause the most serious losses to electric power grids. Among the numerous de-icing and anti-icing techniques for application, direct current ice-melting and mechanical de-icing schemes require power cuts and other restrictive conditions. Superhydrophobic coating technology has been widely focused for good anti-icing properties, low cost and wide application range. However, the special structure of curved transmission lines, complicated service environments, and variated electric performance could significantly limit the application of superhydrophobic anti-icing coatings on overhead transmission lines. In particular, superhydrophobic surfaces can be achieved by combining the rough micro-nano structure and modification agents with low surface energy. Compared with superhydrophobic coatings, superhydrophobic surfaces will not increase the weight of the substrate and have good durability and stability in maintaining the robust structure to repeatedly resist aging, abrasion, corrosion and corona damages, etc. Therefore, this review summarizes the theoretical basis of anti-icing behavior and mechanisms, influencing factors of anti-icing properties, potential techniques of superhydrophobic surfaces on transmission lines, and, finally, presents future development challenges and prospects of superhydrophobic surfaces in the anti-icing protection of overhead transmission lines.
... On the other hand, shorter pulse lasers such as femtosecond lasers provide higher precision and minimal thermal effects around the ablation spot. The main disadvantage of shorter lasers is that they tend to be more expensive [120,121,126,127]. Khan et al. [121] investigated the wettability and self-cleaning performance of three laser ablated metals (aluminum, copper and galvanized steel) with femtosecond and picosecond pulse durations with different scanning speeds, followed by storage in air and in a low-pressure environment. ...
Nature has proven to be a valuable resource in inspiring the development of novel technologies. The field of biomimetics emerged centuries ago as scientists sought to understand the fundamental science behind the extraordinary properties of organisms in nature and applied the new science to mimic a desired property using various materials. Through evolution, living organisms have developed specialized surface coatings and chemistries with extraordinary properties such as the superhydrophobicity, which has been exploited to maintain structural integrity and for survival in harsh environments. The Lotus leaf is one of many examples which has inspired the fabrication of superhydrophobic surfaces. In this review, the fundamental science, supported by rigorous derivations from a thermodynamic perspective, is presented to explain the origin of superhydrophobicity. Based on theory, the interplay between surface morphology and chemistry is shown to influence surface wetting properties of materials. Various fabrication techniques to create superhydrophobic surfaces are also presented along with the corresponding advantages and/or disadvantages. Recent advances in the characterization techniques used to quantify the superhydrophobicity of surfaces is presented with respect to accuracy and sensitivity of the measurements. Challenges associated with the fabrication and characterization of superhydrophobic surfaces are also discussed.
... Various methods have been used to manufacture superhydrophobic surfaces such as mechanical, chemical, and physical surface modifications, etc. [33][34][35]. Laser irradiation is one of the promising and state-of-the-art ways to form surfaces with spectacular and controllable wetting properties [36][37][38]. Laser processing is a very fast, one-step, and eco-friendly method to construct micro/nanostructures on the various materials surface for wetting applications [38][39][40]. Indeed, laser parameters and environmental conditions can be changed the chemical compositions and surfaces structures to vary the wetting properties [41,42]. ...
Laser-induced surface structuring is a promising technique for the novel formation of nanostructures that can effectively be used to modify the surface and synthesis of nanostructures. Metallic and semiconductor oxide nanotubes presently have been attracted in an extensive domain of materials that range from optoelectronic, gas sensor, catalyst, and superhydrophobic surface applications. In this work, aluminum oxide nanotubes were successfully fabricated by laser ablation processes of a 40-nm gold nanolayer coated on an aluminum surface plate inside the ethanol. A continuous-wave fiber laser with a power of 40 W was used to create Al2O3 nanotubes. The electron diffraction pattern analysis of these nanotubes demonstrated that the Al2O3 nanotubes had a single crystal and hexagonal crystal structure with the lattice parameter of a = 0.432 nm as well as zone axis of z=12¯13¯. These nanotubes had a highly-crystalline structure with about 50–200 nm diameters, 10–50 nm wall thicknesses, and 5–20 µm length as well as open-ended. In addition, aluminum oxide nanotubes structures indicated a near superhydrophobic behavior with about 155° ± 2° as a contact angle using experimental and simulation approaches. Meanwhile, molecular dynamics simulation was applied to investigate the wetting property of the aluminum surface and the aluminum surface containing Al2O3 nanoparticles and Al2O3 nanotubes. The effect of the Al2O3 nanotubes on wetting properties was considerable compared to the Al2O3 nanoparticles. The growth mechanism of Al2O3 nanotubes was proposed and illustrated in detail. Also, the obtained findings of this work can be applied to superhydrophobic surfaces in industrial production.
