Self-cleaning Characteristics Research Articles

Environmental Impact and Life Cycle Cost Analysis of Superhydrophobic Coatings for Anti-Icing Applications

Superhydrophobic coatings have great potential to mitigate ice accumulation and ice adhesion issues due to their outstanding water-repellent and self-cleaning characteristics. In the present study, polyurethane elastomer (PUE) is considered a superhydrophobic coating material for anti-icing applications. The life cycle assessment (LCA) of bare aluminum and PUE-coated systems is performed using the Centrum voor Milieukunde Leiden methodology. The cradle-to-gate LCA scope is implemented to evaluate and compare the total environmental impact. This study revealed that the PUE-coated system exhibited a significant reduction in total environmental impact compared to bare aluminum. The levelized cost of coating analysis demonstrates that the PUE coating system is more economical than bare aluminum surfaces. There is scope to reduce the environmental impact associated with PUE-coated systems using bio-based and less toxic chemicals/solvents.

Rational Design and Fine Fabrication of Passive Daytime Radiative Cooling Textiles Integrate Antibacterial, UV-Shielding, and Self-Cleaning Characteristics.

Passive daytime radiative cooling (PDRC) textiles hold substantial potential for localized outdoor cooling of the human body without additional energy consumption, but their limited multifunctional integration severely hinders their practical application. Herein, aluminum-doped zinc oxide (AZO) nanoparticles were purposefully introduced into poly(vinylidene fluoride) (PVDF) nanofibers via a facile electrospinning process, forming a large-scale and flexible PDRC textile with the desired antibacterial, UV-shielding, and self-cleaning capabilities. These prepared PDRC textiles present a weighted sunlight reflection rate of 92.3% and a weighted emissivity of 89.5% in the mid-infrared region. Furthermore, outdoor tests with an average solar intensity of ∼715 W/m2 demonstrated that a skin simulator temperature could be cooled by ∼16.1 °C below the ambient temperature, outperforming cotton fabric by ∼6.3 °C. Owing to the outstanding photocatalytic properties of the AZO nanoparticles, these prepared PVDF textiles exhibit antibacterial properties (Escherichia coli: 99.99%), UV-shielding performance (UPF > 50+), and superior self-cleaning capabilities, providing a cost-effective and eco-friendly avenue for daytime personal thermal management.

Synthesis of novel PdO@Al2O3 nanocomposite for energy storage devices, photodegradation, and other applications

The process for developing PdO@Al2O3 nanocomposites for wastewater treatment involves improving their ability to resist corrosion and their self-cleaning capabilities. To achieve this, it is necessary to carefully combine and analyze different elements to optimize the effectiveness of the catalyst. The objective is to deliver effective and long-lasting solutions for environmental remediation. The PdO@Al2O3 nanocomposite was characterized using FTIR, XRD, SEM, EDS, TEM, UV–Vis, PL, and TGA techniques. The nanocomposites were examined for their photocatalytic activity. The nanocomposite showed significant corrosion resistance and possessed self-cleaning characteristics. The photodegradation of Congo red dye in the aqueous solution was done by using the composite of palladium-aluminum oxides as a catalyst and it revealed excellent photodegradation performance. The photocatalyst degraded the Congo red dye to 98.79 % with a rate constant of 1.5 × 10−2 in a short time of 30 minutes under the irradiation of UV–visible light. The significant band gap in conduction and structure of the core electrostatic field within the p-n heterojunction produces a powerful stimulus for the photogenerated electrons to migrate from PdO to Al2O3 when exposed to visible light. The superior photodegradation of Congo red showed that the heterostructure of the nanocomposite (PdO@Al2O3) exhibited more charge separation with excellent photodegradation proficiency compared to the purely Al2O3 when exposed to visible light. This work represents a significant advancement by providing efficient remedies for wastewater treatment, while also improving the ability to resist corrosion and self-cleaning applications.

Mechanically robust and self-cleaning antireflective coatings for photovoltaic modules

As the conversion efficiency of solar cells approaches its theoretical upper limit, the importance of photon management in enhancing photovoltaic modules performance becomes paramount. One promising approach involves the application of antireflective coatings to the surface of the photovoltaic glass to improve its transmittance. However, balancing mechanical durability, self-cleaning characteristics, and optical performance for photovoltaic applications remains challenging. This study focuses on synthesizing a composite coating through the sol-gel method, aiming to achieve high optical transmittance and superior mechanical properties. Hollow silica nanoparticles (HSN) are employed to achieve a reduced refractive index, while a composite sol of zirconium dioxide (ZrO2) and titania (TiO2) is utilized to enhance mechanical strength and hydrophilicity. The prepared composite coatings demonstrate notable improvements, with the photovoltaic transmittance (TPV) increasing from 88.31 % to 94.03 % in the 300–1100 nm wavelength range, with peak transmittance reaching 98.01 %. Additionally, the coatings exhibited a pencil hardness rating of 3H alongside exceptional abrasion resistance, affirming their potential for enduring practical deployment. When compared to uncoated glass, modules integrated with these composite coatings showed a significant increase in short-circuit current density (JSC) by 1.28 mA cm-2 and in photoelectric conversion efficiency (PCE) by 0.70 %. These results highlight the composite coatings' capacity to enhance the conversion efficiency of photovoltaic modules significantly. By attempting to prepare anti reflective coatings with high mechanical strength and self-cleaning properties, this study is expected to make a valuable contribution to the advancement of sustainable and durable solar cell technology.

Facile fabrication of super-slippery and transparent glass with anti-fogging and self-cleaning characteristics

The present work reports a facile and effective approach for developing slippery liquid-infused porous surface (SLIPS) nanoporous glass. Glass was chemically etched using KOH solution followed by silanization and silicone oil coating using vapour deposition at different temperatures. SLIPS glass showed high contact angle ∼ 115⁰ compared to nascent glass (∼40⁰), low hysteresis (<5°). The sample showed sliding angle < 5⁰ against wide range of liquids with surface tension as low as 28 mN/m. The super-slippery behaviour was coupled with uncompromised transparency (>90 %) and enhanced oil retention owing to the presence of nanopores acting as reservoirs. The SLIPS glass maintained slippery nature (SA < 5⁰) during exposure to ultrasonic vibrations, multiple cloth wiping cycles and multiple high-velocity droplet impacts. The slippery glass showed exquisite combination of properties involving anti-fogging, self-cleaning and anti-staining, with widespread applications.

Holistic approach for fabrication of superhydrophobic MXene-based membrane for enhanced membrane distillation

There is growing interest in membrane distillation (MD) as a means of desalinating seawater with 100 % theoretical salt rejection which has the capacity to address freshwater scarcity. MD has huge potential for commercial applications owing to its low operating temperature and pressure requirements. However, wetting polymeric membranes inhibits water permeance and lowers salt rejection. MXene nanosheet-incorporated polyvinylidene (PVDF) membranes have been constructed for enhanced vapor transport with high water repellence and antiwetting properties. MXene nanosheets in PVDF polymeric matrices are responsible for their high super-hydrophobicity, which can mitigate membrane fouling and wetting during the MD process. As far as experimental outcomes are concerned, the pristine PVDF membrane exhibited severe wetting with salt leakage. Ti3C2Tx MXene nanosheets allow the formation of hierarchical polymeric micro/nanostructures, changing the intrinsic hydrophilicity to super-hydrophobicity. Surface engineering of a PVDF membrane with MXene nanosheets enables efficient saline desalination during the MD process. The surface-engineered MXene/PVDF membrane demonstrated a high-water contact angle of 143° with extremely high self-cleaning characteristics as compared to that of pristine PVDF membrane. As far as the performance of the membrane is concerned, the water flux of the pristine PVDF membrane decreased from 6.5 LMH to 6 LMH after the 14th hour which can be attributed to partial pores wetting during MD operation. Eventually, the pristine PVDF membrane exhibited a continuous salt flux (SF) increase. However, MXene/PVDF membrane showed stable water flux (8 LMH) and negligible SF. The study therefore demonstrates a facile and holistic approach for constructing MXene-based PVDF membranes that exhibit superior antiwetting performance during MD operation.

Effects of particle size and modifier amount on hydrophobicity of as-synthesized and modified nano-silica spheres

Superhydrophobic coatings possess dust-proof and self-cleaning characteristics. Reducing surface energy and improving nanoscale roughness is considered to be crucial for the development and design of superhydrophobic coatings as they can result in significant reduction in the adhesion between solid surfaces and water droplets. In this work, silica spheres were synthesized and hydrophobically modified using the Stober process. Surface morphology and particle size as well as grafting modification effect, grafting quality, hydrophobic properties, and chemical hydrophobic modification mechanism of synthesized silica spheres were analyzed. Results show that the size of synthesized particles is significantly correlated with the concentration of ammonia catalyst, and their hydrophobic properties are significantly correlated with the amount of dichlorodimethylsilane (DCDMS) modifier. Superhydrophobic behavior is obtained for modified silica sphere (MSS) samples with particle sizes of 850, 400, 320, and 120 nm by varying the molar ratio (MR) of DCDMS to silica spheres (MR = 4, 8, and 16). The optimal amount of modifier is closely related to the size of spheres with fixed mass of silica spheres. In addition, large MSS arrays can provide rougher surfaces and thus trap more air within the voids, which resulting in stable hydrophobic properties. This work can provide guidance for the design of superhydrophobic coatings.

Design of superhydrophobic coatings fabricated by spraying for anti-icing

The icing of transmission lines has a serious impact on people’s lives and disrupts the secure and steady functioning of the power grid, causing huge economic losses. To retard the icing of transmission line glass insulators, we prepared coatings on a glass slide by spraying using epoxy resin, fluorosilicone resin, and hydrophobic silicon dioxide (SiO2). The study examined the microscopical morphology, wetting behaviour, and anti-icing and self-cleaning characteristics of coatings containing various SiO2 mass fractions. The findings indicated that the SiO2 mass fraction notably impacted the micro-nanostructure, anti-wettability, and anti-icing performance of coatings. In addition, the largest contact angle (168.2°), the smallest sliding angle (2.6°), and the longest freezing time (181.7 s) were measured for the superhydrophobic coating with SiO2 mass fraction of 34%, which was attributed to the most uniform microstructure. The superhydrophobic coatings fabricated through spraying exhibited good anti-icing and self-cleaning properties. This facilitates the anti-icing and anti-fouling of transmission line glass insulators.

Superoleophilic cotton fabric decorated with hydrophobic Zn/Zr MOF nanoflowers for efficient self-cleaning, UV-blocking, and oil–water separation

Oil spills significantly threaten aquatic life, human health and the environment, necessitating oil–water separation methods. To address these environmental concerns, a hydrophobic Zn/Zr bimetallic metal–organic framework nanoflowers (H-Zn/Zr MOF-NF) functionalized superhydrophobic cotton fabric is developed for oil–water separation. Hydrophilic amine-terminated bimetallic Zn/Zr MOF with distinctive flower-like morphology is hydrothermally synthesized and functionalized with myristic acid. Finally, cotton fabric is coated with a hydrophobic emulsion of H-Zn/Zr MOF-NF and polydimethylsiloxane (PDMS) via dip-coating,enhancing surface roughness and lowering surface energy. The developed superhydrophobic cotton fabric shows exceptional water-repellency with a water contact angle (WCA) and water slidingangle (WSA) of 161° and 4°, respectively. The Zn/Zr MOF-NF coated superhydrophobic cotton fabric with a porous structure efficiently separates diesel oil, n-hexane, toluene, and chloroform from water mixtures with over 98% separation efficiency and high flux. The coated cotton fabric demonstrates remarkable reusability, upholding superior separation efficiency over 95% and retaining WCA at 156° after 12 cycles with excellent physical and chemical stability. The modified cotton fabric also exhibits enhanced UV-blocking properties and self-cleaning characteristics. The designed emulsion is also applied to other surfaces, such as sponge, wood, and filter paper, demonstrating promising superhydrophobicity. This study opens new possibilities for manufacturing multifunctional superhydrophobic surfaces for oil–water separation applications using bimetallic hydrophobic MOFs.

Self-Cleaning Highly Porous TiO2 Coating Designed by Swelling-Assisted Sequential Infiltration Synthesis (SIS) of a Block Copolymer Template.

Photocatalytic self-cleaning coatings with a high surface area are important for a wide range of applications, including optical coatings, solar panels, mirrors, etc. Here, we designed a highly porous TiO2 coating with photoinduced self-cleaning characteristics and very high hydrophilicity. This was achieved using the swelling-assisted sequential infiltration synthesis (SIS) of a block copolymer (BCP) template, which was followed by polymer removal via oxidative thermal annealing. The quartz crystal microbalance (QCM) was employed to optimize the infiltration process by estimating the mass of material infiltrated into the polymer template as a function of the number of SIS cycles. This adopted swelling-assisted SIS approach resulted in a smooth uniform TiO2 film with an interconnected network of pores. The synthesized film exhibited good crystallinity in the anatase phase. The resulting nanoporous TiO2 coatings were tested for their functional characteristics. Exposure to UV irradiation for 1 h induced an improvement in the hydrophilicity of coatings with wetting angle reducing to unmeasurable values upon contact with water droplets. Furthermore, their self-cleaning characteristics were tested by measuring the photocatalytic degradation of methylene blue (MB). The synthesized porous TiO2 nanostructures displayed promising photocatalytic activity, demonstrating the degradation of approximately 92% of MB after 180 min under ultraviolet (UV) light irradiation. Thus, the level of performance was comparable to the photoactivity of commercial anatase TiO2 nanoparticles of the same quantity. Our results highlight a new robust approach for designing hydrophilic self-cleaning coatings with controlled porosity and composition.

Self-Cleaning and Charge Transport Properties of Foils Coated with Acrylic Paint Containing TiO2 Nanoparticles

The study comprehensively investigates the design and performance of self-cleaning surfaces fabricated by coating aluminum foil with an acrylic paint matrix enriched with different content of titanium dioxide (TiO2) nanoparticles. The main goal was to assess the self-cleaning characteristics of the surfaces obtained. This study employs scanning electron microscopy (SEM) to analyze the morphology of TiO2-modified acrylic surfaces, revealing spherical particles. Raman spectroscopy elucidates signatures characterizing TiO2 incorporation within the acrylic matrix, providing comprehensive insights into structural and compositional changes for advanced surface engineering. Alternating current (AC) impedance spectroscopy was used to assess selected charge transport properties of produced self-cleaning surfaces, allowing us to gain valuable insights into the material’s conductivity and its potential impact on photocatalytic performance. The self-cleaning properties of these tiles were tested against three frequently used textile dyes, which are considered to pose a serious environmental threat. Subsequently, improving self-cleaning properties was achieved by plasma treatment, utilizing a continuous plasma arc. The plasma treatment led to enhanced charge separation and surface reactivity, crucial factors in the self-cleaning mechanism. To deepen our comprehension of the reactive properties of dye molecules and their degradation dynamics, we employed a combination of density functional tight binding (DFTB) and density functional theory (DFT) calculations. This investigation lays the foundation for advancing self-cleaning materials with extensive applications, from architectural coatings to environmental remediation technologies.

Facile-Solution-Processed Silicon Nanofibers Formed on Recycled Cotton Nonwovens as Multifunctional Porous Sustainable Materials.

Limited efficiency, lower durability, moisture absorbance, and pest/fungal/bacterial interaction/growth are the major issues relating to porous nonwovens used for acoustic and thermal insulation in buildings. This research investigated porous nonwoven textiles composed of recycled cotton waste (CW) fibers, with a specific emphasis on the above-mentioned problems using the treatment of silicon coating and formation of nanofibers via facile-solution processing. The findings revealed that the use of an economic and eco-friendly superhydrophobic (contact angle higher than 150°) modification of porous nonwovens with silicon nanofibers significantly enhanced their intrinsic characteristics. Notable improvements in their compactness/density and a substantial change in micro porosity were observed after a nanofiber network was formed on the nonwoven material. This optimized sample exhibited a superior performance in terms of stiffness, surpassing the untreated samples by 25-60%. Additionally, an significant enhancement in tear strength was observed, surpassing the untreated samples with an impressive margin of 70-90%. Moreover, the nanofibrous network of silicon fibers on cotton waste (CW) showed significant augmentation in heat resistance ranging from 7% to 24% and remarkable sound absorption capabilities. In terms of sound absorption, the samples exhibited a performance comparable to the commercial standard material and outperformed the untreated samples by 20% to 35%. Enhancing the micro-roughness of fabric via silicon nanofibers induced an efficient resistance to water absorption and led to the development of inherent self-cleaning characteristics. The antibacterial capabilities observed in the optimized sample were due to its superhydrophobic nature. These characteristics suggest that the proposed nano fiber-treated nonwoven fabric is ideal for multifunctional applications, having features like enhanced moisture resistance, pest resistance, thermal insulation, and sound absorption which are essential for wall covers in housing.

Two-stage thiol-ene click reaction for fluorine-free superhydrophobic fabrics with buoyancy boost and drag reduction

Superhydrophobic fabrics suggest tremendous potential in some emerging fields such as electronic skin, bioelectronic sensors and special clothing due to their excellent liquid repellency and self-cleaning properties. However, currently reported superhydrophobic materials are usually prepared using biologically toxic fluorinated compounds, which severely restricts their practical applications. Herein, we propose a two-step thiol-ene click reaction strategy to fabricate fluorine-free superhydrophobic cotton fibers (Fabric-SH-PB-SiO2). The 1,2-polybutadiene (1,2-PB) with flexible rubber molecular chains and low surface energy was coated by cotton fiber through thiol-ene click reaction. Subsequently, based on this reaction, the coated cotton fiber was used to establish chemical bonds with hydrophobic silica. The Fabric-SH-PB-SiO2 possesses a rich multi-level micro-nano structure that can form stable air layer on the surface of the fabric, which showed a high hydrophobic angle of 156° and exhibited some distinct advantages such as anti-fouling and self-cleaning characteristics, high buoyancy, and reduced drag. More remarkably, the Fabric-SH-PB-SiO2 could float on the water surface after carrying 34 times its weight. Compared with unmodified fabrics, the Fabric-SH-PB-SiO2 demonstrated a high drag reduction rate of up to 102 %, among the highest values for the reported hydrophobic materials. The strategy developed here provides insights towards fabricating high-buoyancy fluorine-free superhydrophobic cotton fibers.

Superhydrophobic bilayer coating for passive daytime radiative cooling

Abstract Passive radiative cooling is an energy-free cooling method by exchanging thermal radiation with the cold universe through the transparent atmospheric window. Spectrum tailoring of the radiative cooler is the key to daytime radiative cooling in previously reported works. In addition, radiative coolers with large-scale fabrication and self-cleaning characteristics should be further developed to improve their industrial applicability. Herein, we propose a bilayer radiative cooling coating with the superhydrophobic property and a scalable process, by covering TiO2/acrylic resin paint with a silica/poly(vinylidene fluoride-co-hexafluoropropylene) (SiO2/P(VdF-HFP)) composite masking layer. The strong Mie scattering in TiO2/acrylic resin paint contributes to high solar reflection, while the SiO2/P(VdF-HFP) masking layer is responsible for superhydrophobicity and synergetic solar reflection in the ultraviolet band, resulting in an effective solar reflectivity of 94.0 % with an average emissivity of 97.1 % and superhydrophobicity with a water contact angle of 158.9°. Moreover, the as-fabricated coating can be cooled to nearly 5.8 °C below the temperature of commercial white paint and 2.7 °C below the local ambient temperature under average solar irradiance of over 700 W m−2. In addition, yearly energy saving of 29.0 %–55.9 % can be achieved after the coating is applied to buildings in Phoenix, Hong Kong, Singapore, Guangzhou, and Riyadh.

Superhydrophilic ZnO nano-needle decorated over nanofibrous PAN membrane and its application towards oil/water separation

Oil spills in the marine environment as well as release of industrial effluent and oily wastewater can pose serious threats to ecosystems and human health. Therefore, designing a filtrating material for treatment of wastewater has been a focus of research. Herein, we employed a simple and low temperature hydrothermal technique to effectively adorn the surface of the electrospun nanofibrous PAN membrane with micro-nano structure of ZnO nano-needles. The proposed membrane integrates a membrane filtration and photodegradation process and has demonstrated improvement in permeability, pollutant eradication, anti-fouling and self-cleaning capabilities. The in-air superhydrophilic NPAN-ZnO nano-needle membrane with micro-nano hierarchal needle architectures captures water and conveys it with underwater superoleophobicity. The substantial amount of pure water flux (7349 ± 200 Lm−2h−1) and separation efficacy (98 ± 1%) justify the membrane's effectiveness in the separation process. The membrane also demonstrated antifouling and self-cleaning characteristics upon UV irradiation after being fouled by BSA and octadecanoic acid, restoring the original flux performance. Furthermore, the membrane has the capability of disintegrating organic and pharmaceutical contaminants found in oily effluent. Given the NPAN-ZnO nano-needle membrane's particular superiority, the technology may inspire the general engineering of multipurpose superwetting polymers materials with intriguing application for complicated oily wastewater treatment.

Design and performance optimization of self-cleaning coating on decorative UHPC surface

After long-term use, decorative UHPC may adhere to pollutants due to its hydrophilicity, which affects its aesthetics. Due to the smooth and dense exposed surface of UHPC, ordinary self-cleaning coatings have poor adhesion on its surface and are prone to peeling off due to rain wash in the environment, which cannot maintain the self-cleaning performance of UHPC for a long time. In this paper, a modified self-cleaning coating with a double layer structure was designed. The bottom layer is an epoxy resin (ER) adhesive layer to improve the adhesion performance of the coating to UHPC. The surface layer is a polymethylhydrosiloxane (PMHS) modified nano-SiO2 superhydrophobic layer, which satisfies the self-cleaning characteristics while constructing a regular rough superhydrophobic surface on the UHPC surface. The prepared superhydrophobic UHPC showed good self-cleaning performance, with a static water contact angle of 156.5and a sliding angle of only about 2.2. The performance test results show that the double-layer structure design makes the superhydrophobic coating have good wear resistance, water erosion resistance and excellent chemical stability. The surface functional groups, micro-area morphology and roughness were characterized by Fourier transform infrared spectrometer, scanning electron microscopy, optical profiler and atomic force microscopy, respectively. The reasons for the excellent self-cleaning performance and long-term stability of the coating were explained.

Sedimentation efficiency evaluation of an aquaculture tank through experimental floc characterization and CFD simulation

One of the most important parameters for the proper functioning of an aquaculture tank is water quality. The survival and healthy growth of fish depends on it. The main factors affecting water quality are the remains of food and feces of fish which form cohesive particles called flocs that are kept within the tank or in the modules of the recirculating aquaculture system (RAS). Through the application of non-invasive optical techniques such as particle tracking velocimetry (PTV) it was possible to experimentally characterize the particles from aquaculture tanks obtaining diameters and settling velocity distribution, which allowed estimating the effective density of the flocs. With these parameters, the discrete phase model (DPM) was applied using computational fluid dynamics (CFD) to estimate the position and velocity of the particles within a prototype tank with geometry that promotes hydrodynamics suitable for particles sedimentation while maintaining the conditions for fish growth. Through an experimental validation it was verified that by having a tank with circular geometry, central settler made of concentric cylinders, perimeter gratings and outlet spillway cone, it is possible to achieve an efficiency of 77.91–90% of particles sedimentation not exceeding 1 h in the process. Thus, through computer simulation coupled with experimental validation, it was possible to establish geometric parameters for the design of aquaculture tanks with self-cleaning characteristics under the sustainable scheme of water recirculation and reuse.

Synergetic Role of Nano-/Microscale Structures of the Trifolium Leaf Surface for Self-Cleaning Properties.

Wetting has an essential pertinence to surface applications. The exemplary water-repelling and self-cleaning surfaces in nature have stimulated considerable scientific exploration, given their practical leverage in cleaning window glasses, painted surfaces, fabrics, and solar cells. Here, we explored the three-tier hierarchical surface structure of the Trifolium leaf with distinguished self-cleaning characteristics. The leaf remains fresh, withstands adverse weather, thrives throughout the year, and self-cleans itself against mud or dust. Self-cleaning features are attributed to a three-tier hierarchical synergetic design. The leaf surface is explicated by an optical microscope, a scanning electron microscope, a three-dimensional profilometer, and a water contact angle measuring device. Hierarchical base roughness (i.e., nano-/microscale) comprises a fascinating arrangement, which imparts a superhydrophobic feature to the surface. As a result, the contaminants present on the leaf surface are washed with rolling water droplets. We noticed that self-cleaning is a function of impacting or rolling droplets, and the rolling mechanism is identified as efficient. The self-cleaning phenomenon is studied for contaminations of variable sizes, shapes, and compositions. The contaminations are supplied in both dry and aqueous mixtures. Furthermore, we examined the self-cleaning effect of the Trifolium leaf surface by atmospheric water harvesting. The captured water drops fuse, roll, descend, and wash away the contaminating particles. The diversity of contaminants investigated makes this study applicable to different environmental conditions. And, along with other parallel technologies, this investigation could be useful for crafting sustainable self-cleaning surfaces for regions with acute water scarcity.

Reactive Ceramic Membrane for Efficient Micropollutant Purification with High Flux by LED Visible-Light Photocatalysis: Device Level Attempts

Micropollutants (MPs) are widely occurring in surface water all over the world with extremely low concentrations, and their treatment requires high energy consumption and efficiency. In this study, a large-sized planar photocatalytic reactive ceramic membrane (PRCM) was prepared using the facile dip-coating method with nitrogen-doped TiO2 (N-TiO2-CM) for the purification of tetracycline hydrochloride (TC) as a model MP. The N-TiO2 nanoparticles and the as-prepared N-TiO2-CM were characterized by SEM/EDS, TEM, XPS, UV–Vis DRS, and FT-IR. A fixed bed reactor integrated N-TiO2-CM, and visible LED light was fabricated for the new PRCM water treatment system for the removal of TC with a comprehensive consideration of the degradation rate and permeate flux. The SEM/EDS results indicated that the N-TiO2 was uniformly and tightly loaded onto the flat CM, and the pure water flux could reach over 2000 L/(m2 × h) under a trans-membrane pressure (TMP) of −92 kPa. The fixed bed PRCM water treatment system is extremely suited for MP purification, and the removal efficiency of TC was as high as 92% with 270 min even though its initial concentration was as low as 20 mg/L. The degradation rate and permeate flux of N-TiO2-CM was 2.57 and 2.30 times as high as that of the CM, indicating its good self-cleaning characteristics. The quenching experiments illustrated that the reactive radicals involved in the PRCM process, •OH and •O2−, were responsible for TC degradation. This research also provides a utilization proposal for a scale-up N-TiO2-CM system for water and wastewater treatment.

Transparent and superhydrophobic room temperature vulcanized (RTV) polysiloxane coatings loaded with different hydrophobic silica nanoparticles with self-cleaning characteristics

Superhydrophobic coatings based on room temperature vulcanized (RTV) polysiloxane matrix loaded with organically modified silica (ORMOSIL) nanoparticles were successfully prepared using the cost-effective and scalable one-step spraying coating approach. ORMOSIL nanoparticles were prepared by sol-gel treatment at ambient conditions through the reaction between the commercial hydrophilic silica (R200) and octyl-triethoxysilane (R200.OTS), (1H,1H,2H,2H-nonafluorohexyl)-triethoxysilane (R200.NFS) and a mixture of both (R200.OTS/NFS). The functionalization of the silica was followed by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). Commercial hydrophobic silica particles functionalized with siloxane (R202) and octyl-silane (R805) were also used for comparison. The presence of 20 % of R202 and R200.NFS resulted in coatings with water contact angle (WCA) higher than 160°, sliding angle <5°, high transparency and an effective self-cleaning behavior. Increasing the amount of nanoparticles increased the superhydrophobic response but the translucence decreased. Coatings containing R200.OTS particles presented high translucence and high WCA, but the sliding angle was also high, which limits their use as self-cleaning material.