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In this study, silica thin film pH=6 (precursor TEOS:tetraethyl ortosilicate) developed from sol gel process and deposited (2 layers) directly onto alumina substrate(tubular support with 100 nm pore size) without depositing interlayer (interlayer-free).Then, the desalination process via pervaporation was applied to test the membranesperformanceusing artificial saline water and wetland saline water. Results show the decrease of water flux (1.9 to 1.43 kg m-2 h-1) and salt rejection(97 to 95%) when using artificial salty water (0-7.5 wt%) and the long-term stability of silica membrane was stable at 1.7 kg m-2 h-1 for over 100 hours when using wetland saline water as a feed.

Global population growth and climate change are causing freshwater scarcity, which necessitates creative solutions like solar‐driven desalination. This technology's widespread adoption is hampered by cost and efficiency issues. Intrinsic photothermal conversion efficiency has gotten less attention than light trapping and thermal management, which have been the main focuses of efforts to increase photo‐to‐vapor efficiencies. Here, a commercial padding and vapor polymerization method are used to develop scalable nylon fabrics that act as solar absorbers. This is achieved by anchoring iron catalysts with hydrolyzed perfluorooctyltriethoxysilane chains, which cause confined polymerization of pyrrole to generate polypyrrole. By narrowing the bandgap and generating bioinspired light‐trapping nanostructures, this technique achieves a superior intrinsic photothermal conversion efficiency of 84.6%, which is 4.94 times higher than that of unconfined polymerization. These fabrics are used to create a Janus evaporator, which operates steadily in prolonged seawater testing and shows an evaporation rate of 3.84 kg m−2 h−1. The low manufacturing cost of ≈28 RMB m−2 emphasizes its scalability and economic potential. This work offers insights into the design of high‐performance, scalable, and cost‐effective solar absorbers by prioritizing increases in light absorption and intrinsic photothermal conversion efficiencies for developing solar desalination technology. Scalable nylon fabrics with bioinspired light‐trapping nanostructures and 84.6% intrinsic photothermal conversion efficiency are developed for solar desalination. The Janus evaporator shows high evaporation rate of 3.84 kg m−2 h−1 and long‐term stability in seawater, offering a cost‐effective solution for solar desalination. This material also emphasizes scalability and economic feasibility, making it suitable for widespread application.

Water scarcity has emerged as an intense global threat to humanity and needs prompt attention from the scientific community. Solar-driven interfacial evaporation and seawater desalination are promising strategies to resolve the primitive water shortage issue using renewable resources. However, the fragile solar thermal devices, complex fabricating techniques, and high cost greatly hinder extensive solar energy utilization in remote locations. Herein, we report the facile fabrication of a cost-effective solar-driven interfacial evaporator and seawater desalination system composed of carbon cloth (CC)-wrapped polyurethane foam (CC@PU). The developed solar evaporator had outstanding photo-thermal conversion efficiency (90%) with a high evaporation rate (1.71 kg m−2 h−1). The interfacial layer of black CC induced multiple incident rays on the surface allowing the excellent solar absorption (92%) and intensifying heat localization (67.37 °C) under 1 kW m−2 with spatially defined hydrophilicity to facilitate the easy vapor escape and validate the efficacious evaporation structure using extensive solar energy exploitation for practical application. More importantly, the long-term evaporation experiments with minimum discrepancy under seawater conditions endowed excellent mass change (15.24 kg m−2 in consecutive 8 h under 1 kW m−2 solar irradiations) and promoted its operational sustainability for multi-media rejection and self-dissolving potential (3.5 g NaCl rejected from CC@PU surface in 210 min). Hence, the low-cost and facile fabrication of CC@PU-based interfacial evaporation structure showcases the potential for enhanced solar-driven interfacial heat accumulation for freshwater production with simultaneous salt rejection.

Recent advances in thermally localized solar evaporation hold significant promise for vapor generation, seawater desalination, wastewater treatment, and medical sterilization. However, salt accumulation is one of the key bottlenecks for reliable adoption. Here, we demonstrate highly efficient (>80% solar-to-vapor conversion efficiency) and salt rejecting (20 weight % salinity) solar evaporation by engineering the fluidic flow in a wick-free confined water layer. With mechanistic modeling and experimental characterization of salt transport, we show that natural convection can be triggered in the confined water. More notably, there exists a regime enabling simultaneous thermal localization and salt rejection, i.e., natural convection significantly accelerates salt rejection while inducing negligible additional heat loss. Furthermore, we show the broad applicability by integrating this confined water layer with a recently developed contactless solar evaporator and report an improved efficiency. This work elucidates the fundamentals of salt transport and offers a low-cost strategy for high-performance solar evaporation. Solar evaporation is promising for sustainable freshwater production but typically limited by salt accumulation. Here, by manipulating natural convection, authors develop a wick-free confined water layer that enables highly efficient and salt rejecting solar evaporation.

Tailor-made structure and morphology are critical to the highly permeable and selective polyamide membranes used for water purification. Here we report an asymmetric polyamide nanofilm having a two-layer structure, in which the lower is a spherical polyamide dendrimer porous layer, and the upper is a polyamide dense layer with highly ordered nanovoids structure. The dendrimer porous layer was covalently assembled in situ on the surface of the polysulfone (PSF) support by a diazotization-coupling reaction, and then the asymmetric polyamide nanofilm with highly ordered hollow nanostrips structure was formed by interfacial polymerization (IP) thereon. Tuning the number of the spherical dendrimer porous layers and IP time enabled control of the nanostrips morphology in the polyamide nanofilm. The asymmetric polyamide membrane exhibits a water flux of 3.7−4.3 times that of the traditional monolayer polyamide membrane, showing an improved divalent salt rejection rate (more than 99%), which thus surpasses the upper bound line of the permeability−selectivity performance of the existing various structural polyamide membranes. We estimate that this work might inspire the preparation of highly permeable and selective reverse osmosis (RO), organic solvent nanofiltration (OSNF) and pervaporation (PV) membranes. Structure and morphology are critical to the performance of permeable and selective polyamide membranes in water purification. Here, the authors report a two layer asymmetric polyamide nanofilm in which a spherical polyamide dendrimer porous lower and a polyamide dense upper layer form hierarchical nanovoids.

Direct solar desalination exhibits considerable potential for alleviating the global freshwater crisis. However, the prevention of salt accumulation while maintaining high water production remains an important challenge that limits its practical applications because the methods currently employed for achieving rapid salt backflow usually result in considerable heat loss. Herein, we fabricate a solar evaporator featuring vertically aligned mass transfer bridges for water transport and salt backflow. The 3D open architecture constructed using mass transfer bridges enables the evaporator to efficiently utilize the conductive heat that would otherwise be lost, significantly improving the water evaporation efficiency without compromising on salt rejection. The fabricated evaporator can treat salt water with more than 10% salinity. Moreover, it can continuously and steadily work in a real environment under natural sunlight with a practical solar-to-water collection efficiency of >40%. Using the discharged water from reverse osmosis plants and sea water from the Red Sea, the evaporator demonstrates a daily freshwater generation rate of ~5 L/m 2 , which is sufficient to satisfy individual drinking water requirements. With strong salt rejection, high energy efficiency, and simple scalability, the 3D evaporator has considerable promise for freshwater supply for water-stressed and off-grid communities. Conventional salt-rejection evaporators typically exhibit low evaporation rate due to large heat loss. Here, authors demonstrate a solar evaporator featuring vertically aligned mass transfer bridges that takes advantage of the conductive heat to enable optimized water transport and salt backflow.

Icing of seawater droplets is capable of causing catastrophic damage to vessels, buildings, and human life, yet it also holds great potential for enhancing applications such as droplet-based freeze desalination and anti-icing of sea sprays. While large-scale sea ice growth has been investigated for decades, the icing features of small salty droplets remain poorly understood. Here, we demonstrate that salty droplet icing is governed by salt rejection-accompanied ice crystal growth, resulting in freezing dynamics different from pure water. Aided by the observation of brine films emerging on top of frozen salty droplets, we propose a universal definition of freezing duration to quantify the icing rate of droplets having varying salt concentrations. Furthermore, we show that the morphology of frozen salty droplets is governed by ice crystals that sprout from the bottom of the brine film. These crystals grow until they pierce the free interface, which we term ice sprouting. We reveal that ice sprouting is controlled by condensation at the brine film free interface, a mechanism validated through molecular dynamics simulations. Our findings shed light on the distinct physics that govern salty droplet icing, knowledge that is essential for the development of related technologies. The understanding of salty water droplet freezing is limited. The authors examine the formation of brine film on top of frozen salty droplets and discover a new ice crystal growth pattern sprouting from the bottom of the brine film.

Covalent organic frameworks (COFs) hold great promise in molecular separations owing to their robust, ordered and tunable porous network structures. Currently, the pore size of COFs is usually much larger than most small molecules. Meanwhile, the weak interlamellar interaction between COF nanosheets impedes the preparation of defect-free membranes. Herein, we report a series of COF membranes through a mixed-dimensional assembly of 2D COF nanosheets and 1D cellulose nanofibers (CNFs). The pore size of 0.45–1.0 nm is acquired from the sheltering effect of CNFs, rendering membranes precise molecular sieving ability, besides the multiple interactions between COFs and CNFs elevate membrane stability. Accordingly, the membranes exhibit a flux of 8.53 kg m −2 h −1 with a separation factor of 3876 for n-butanol dehydration, and high permeance of 42.8 L m −2 h −1 bar −1 with a rejection of 96.8% for Na 2 SO 4 removal. Our mixed-dimensional design may inspire the fabrication and application of COF membranes. The fabrication of defect-free covalent organic framework (COF) membranes for the separation of small molecules is challenging. Here, the authors report robust COF membranes with precise molecular sieving through a mixed-dimensional assembly, exhibiting high performance for alcohol dehydration and salt rejection.

Rational design of high-performance stable metal–organic framework (MOF) membranes is challenging, especially for the sustainable treatment of hypersaline waters to address critical global environmental issues. Herein, a molecular-level intra-crystalline defect strategy combined with a selective layer thinning protocol is proposed to fabricate robust ultrathin missing-linker UiO-66 (ML-UiO-66) membrane to enable fast water permeation. Besides almost complete salt rejection, high and stable water flux is achieved even under long-term pervaporation operation in hash environments, which effectively addresses challenging stability issues. Then, detailed structural characterizations are employed to identify the type, chemical functionality, and density of intra-crystalline missing-linker defects. Moreover, molecular dynamics simulations shed light on the positive atomistic role of these defects, which are responsible for substantially enhancing structural hydrophilicity and enlarging pore window, consequently allowing ultra-fast water transport via a lower-energy-barrier pathway across three-dimensional sub-nanochannels during pervaporation. Unlike common unfavorable defect effects, the present positive intra-crystalline defect engineering concept at the molecular level is expected to pave a promising way toward not only rational design of next-generation MOF membranes with enhanced permeation performance, but additional water treatment applications. The development of highly water-permeable membranes is key for the treatment of high salinity waters. Here the authors enhance the water permeability of a metal-organic framework nanoporous membrane via an intra-crystalline defect engineering strategy.

Carbon nanomaterials are robust and possess fascinating properties useful for separation technology applications, but their scalability and high salt rejection when in a strong cross flow for long periods of time remain challenging. Here, we present a graphene-based membrane that is prepared using a simple and environmentally friendly method by spray coating an aqueous dispersion of graphene oxide/few-layered graphene/deoxycholate. The membranes were robust enough to withstand strong cross-flow shear for a prolonged period (120 h) while maintaining NaCl rejection near 85% and 96% for an anionic dye. Experimental results and molecular dynamic simulations revealed that the presence of deoxycholate enhances NaCl rejection in these graphene-based membranes. In addition, these novel hybrid-layered membranes exhibit better chlorine resistance than pure graphene oxide membranes. The desalination performance and aggressive shear and chlorine resistance of these scalable graphene-based membranes are promising for use in practical water separation applications. Scalable graphene-based membranes reject more than 80% NaCl under aggressive shear for more than 20 h and exhibit chlorine resistance.