Reversible Thermochromic Superhydrophobic BiVO4 Hybrid Pigments Coatings with Self-Cleaning Performance and Environmental Stability Based on Kaolinite

Surface wettability control and electron transport regulation in zerovalent iron for enhanced removal of emerging polystyrene microplastics-heavy metal contaminants

Emerging microplastics-heavy metal (MPs-HM) contaminants in wastewaters pose an emerging health and environmental risk due to their persistence and increasing ecological risks (e.g., "Trojan horse" effect). Hence, removing MPs in solution and preventing secondary releases of HM has become a key challenge when tackling with MPs pollution. Leveraging the hydrophobic nature of MPs and the electron transfer efficiency from Fe0 to HM, we demonstrate an alkylated and sulfidated nanoscale zerovalent iron (AS-nZVI) featuring a delicate "core-shell-hydrophobic film" nanostructure. Exemplified by polystyrene (PS) MPs-Pb(II) removal, the three nanocomponents offer synergistic functions for the rapid separation of MPs, as well as the reduction and stabilization of Pb(II). The outmost hydrophobic film of AS-nZVI greatly improves the anticorrosion performance of nanoscale zerovalent iron and the enrichment abilities of hydrophobic MPs, achieving a maximum removal capacity of MPs to 2725.87 mgMPs·gFe-1. This MPs enrichment promotes the subsequent reductive removal of Pb(II) through the electron transfer from the iron core of AS-nZVI to Pb(II), a process further strengthened by the introduced sulfur. When considering the inevitable aging of MPs in wastewaters due to mechanical wear or microbial degradation, our study concurrently examines the efficiencies and behaviors of AS-nZVI in removing virgin-MPs-Pb(II) and aged-MPs-Pb(II). The batch results reveal that AS-nZVI has an exceptional ability to remove above 99.6 % Pb(II) for all reaction systems. Overall, this work marks a pioneering effort in highlighting the importance of MPs-toxin combinations in dealing with MPs contamination and in demonstrating the utility of nZVI techniques for MPs-contaminated water purification.

Scalable Fabrication of Superhydrophobic Coating with Rough Coral Reef-Like Structures for Efficient Self-Cleaning and Oil-Water Separation: An Experimental and Molecular Dynamics Simulation Study

Superhydrophobic coating has a great application prospect in self-cleaning and oil-water separation but remains challenging for large-scale preparation of robust and weather-resistant superhydrophobic coatings via facile approaches. Herein, this work reports a scalable fabrication of weather-resistant superhydrophobic coating with multiscale rough coral reef-like structures by spraying the suspension containing superhydrophobic silica nanoparticles and industrial coating varnish on various substrates. The coral reef-like structures effectively improves the surface roughness and abrasion resistance. Rapid aging experiments (3000 h) and the outdoor building project application (3000 m2 ) show that the sprayed superhydrophobic coating exhibits excellent self-cleaning properties, weather resistance, and environmental adaptability. Moreover, the combined silica-coating varnish-polyurethane (CSCP) superhydrophobic sponge exhibits exceptional oil-water separation capabilities, selectively absorbing the oils from water up to 39 times of its own weight. Furthermore, the molecular dynamics (MD) simulation reveals that the combined effect of higher surface roughness, smaller diffusion coefficient of water molecules, and weaker electrostatic interactions between water and the surface jointly determines the superhydrophobicity of the prepared coating. This work deepens the understanding of the anti-wetting mechanism of superhydrophobic surfaces from the perspective of energetic and kinetic properties, thereby paving the way for the rational design of superhydrophobic materials and their large-scale applications.

Superhydrophobicity Mechanism and Nanoscale Profiling of PDMS-Modified Kaolinite Nanolayers via Ab Initio-MD Simulation and Atomic Force Microscopy Study

This study aimed to investigate the superhydrophobic mechanism of kaolinite particles modified with poly(dimethylsiloxane) (PDMS), which has potential as a superior hydrophobic coating. The study employed a combination of density functional theory (DFT) simulation modeling, characterization of the chemical properties and microstructure, contact angle measurements, and chemical force spectroscopy of atomic force microscopy. The results showed successful PDMS grafting onto the kaolinite surface, resulting in micro- and nanoscale roughness and a contact angle of 165°, indicating a successful superhydrophobic effect. The study also identified the mechanism of the hydrophobic interaction through two-dimensional micro- and nanoscale hydrophobicity images, highlighting the potential of this approach for developing new hydrophobic coatings.

MOF-derived LDH modified flame-retardant polyurethane sponge for high-performance oil-water separation: Interface engineering design based on bioinspiration

Frequent petrochemical spill accidents and secondary fire hazards have threatened the ecological environment and environmental safety. The traditional purification technology has the problems of high energy consumption and secondary pollution, which also brings new challenges to spill disposal. Herein, we demonstrate a biomimetic structure-based flame-retardant polyurethane (PU) sponge (FPUF@MOF-LDH@HDTMS) for continuous oil-water separation. Inspired by desert beetle and lotus leaf, the biomimetic micro-nano composite structure was constructed by in-situ growth of metal-organic framework-derived layered double hydroxide (MOF-LDH) on the surface of the PU sponge. After grafting MOF-LDH with hexadecyltrimethoxysilane, FPUF@MOF-LDH@HDTMS showed excellent superhydrophobic/superoleophilic performance (water contact angle=153° and oil contact angle=0°). FPUF@MOF-LDH@HDTMS can easily and quickly adsorb oily liquids suspended/settled in the water thanks to the unique bionic structure. FPUF@MOF-LDH@HDTMS has excellent oil/organic solvents absorption capacity; even after 20 cycles of use still maintains high adsorption capacity. More importantly, the continuous oil-water separation through FPUF@MOF-LDH@HTMS has achieved a separation efficiency of up to 99.1%. In addition, the bionic superhydrophobic sponge has excellent flame retardancy, which reduces the possibility of secondary fire caused by PU sponges. Thus, the biomimetic micro-nano composite structure provides a new design strategy for the more high-performance oil-water separation sponges.

A Superhydrophobic Alkali Activated Materials Coating by Facile Preparation

Alkali activated materials (AAMs) were considered as economical and environmentally friendly that have attracted incrementally attention as green coating materials. However, alkali activated materials were inclined to be infiltrated and ruined by harmful ions in water due to their hydrophilicity. And the ordinary ways of construct superhydrophobic coatings were costly, complex and need fluorine material. The superhydrophobic surfaces were fragile owing to the super-hydrophobicity of materials were controlled to surface merely. In this work, a facile, convenient and economical strategy to synthesize alkali activated slag materials (AAS) superhydrophobic coatings with excellent water repellence was developed. Herein, the hydrolysis and polymerization of triethoxy (octyl)silane (TTOS) were applied for generating micro/nanostructures to construct a three-dimensional overall superhydrophobic alkali activated slag materials coating. The water contact angle (CA) about surfaces and bottoms of superhydrophobic alkali activated slag materials coatings were 150.2°, 152° and the water rolling angle (SA) of surfaces and bottoms were 5°, 4° respectively. Besides, the superhydrophobic alkali activated slag materials coatings demonstrated excellent mechanical abrasion effect that still maintain super-hydrophobicity after sandpaper abrasion stand. Super-hydrophobicity of coatings could be regenerated by simple sandpaper rubbing when they were attacked chemically. Concisely, the superhydrophobic alkali activated slag materials coatings were show the benefit of affordable and feasibility so that they have the potential for expandable industrial promotion.

Super Pressure-Resistant Superhydrophobic Fabrics with Real Self-Cleaning Performance

Detergents are extensively used for laundry, causing significant negative impacts on water bodies, plants and animals. Superhydrophobic fabrics are promising to reduce detergent consumption but suffer from low pressure resistance. Here, we report super pressure-resistant superhydrophobic fabrics prepared using polysiloxane modified SiO₂ nanoparticles with epoxy groups. The fabrics show real self-cleaning performance, essentially different from the conventional self-cleaning property of solid particles loosely placed on superhydrophobic surfaces. The contaminated fabrics by various stains can be completely cleaned by home machine laundering without using any detergent whereas the traditional superhydrophobic fabrics cannot. This is owing to excellent abrasion and washing durability, low liquid adhesion force, superior pressure-resistance and vapor-resistance of the fabrics, originating from the low surface energy and dense micro-/nanostructure. Moreover, the superhydrophobic fabrics can be scaled up using the conventional fabric finishing line with low cost. The superhydrophobic fabrics will help significantly reduce the global detergent consumption.

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Superhydrophobic fabrics with real self-cleaning performance are prepared

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The fabrics show high durability and pressure-resistance, low liquid adhesion force

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The contaminated fabrics can be cleaned by home machine laundering without detergent

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The fabrics can be scaled up using the conventional fabric finishing line