Emerging opportunities for nanotechnology to enhance water security

Asymmetrically Coordinated Mn-S1N3 Configuration Induces Localized Electric Field-Driven Peroxymonosulfate Activation for Remarkably Efficient Generation of 1O2

Singlet oxygen (1O2) species generated in peroxymonosulfate (PMS)-based advanced oxidation processes offer opportunities to overcome the low efficiency and secondary pollution limitations of existing AOPs, but efficient production of 1O2 via tuning the coordination environment of metal active sites remains challenging due to insufficient understanding of their catalytic mechanisms. Herein, an asymmetrical configuration characterized by a manganese single atom coordinated is established with one S atom and three N atoms (denoted as Mn-S1N3), which offer a strong local electric field to promote the cleavage of O─H and S─O bonds, serving as the crucial driver of its high 1O2 production. Strikingly, an enhanced the local electric field caused by the dynamic inter-transformation of the Mn coordination structure (Mn-S1N3 ↔ Mn-N3) can further downshift the 1O2 production energy barrier. Mn-S1N3 demonstrates 100% selective product 1O2 by activation of PMS at unprecedented utilization efficiency, and efficiently oxidize electron-rich pollutants. This work provides an atomic-level understanding of the catalytic selectivity and is expected to guide the design of smart 1O2-AOPs catalysts for more selective and efficient decontamination applications.

Novel three-dimensional fibrous covalent organic frameworks constructed via silver amalgam bridging for efficient organic dye adsorption and removal

The construction of covalent organic frameworks (COFs) with unique structures has great significance in exploring the structure-function relationship and extending their potential applications. Fibrous COFs have demonstrated superior performance in specific application scenarios owing to the distinctive three-dimensional (3D) structure. Herein, we report a facile strategy for the fabrication of 3D COF nanofiber by exploiting silver amalgam as a bridging agent to assemble one-dimensional-extended PA-COF modules into a tubular structure. Dimensions of the obtained 3D COF nanofiber were predicted by DFT calculations, and the nanofiber was endowed with the merits of favorable uniformity and high stability. Due to the enhanced exposure of conjugatable binding sites for dye retention offered by the novel 3D architecture, the PA-COF nanofiber exhibits fast adsorption (within 5 min) and superior adsorption capacity to various organic dyes, e.g., 1717 mg g-1 for methylene blue (MB) and 978.3 mg g-1 for methyl orange (MO). Moreover, the PA-COF nanofiber shows excellent reusability in dye adsorption, which makes it a potential medium for removing dye pollutants from wastewater. This work presents an effective strategy to construct COF materials with unique architecture and potential prospects in the fields of separation and wastewater treatment.

Microplastic detection and remediation through efficient interfacial solar evaporation for immaculate water production

Freshwater scarcity and microplastics (MPs) pollution are two concerning and intertwined global challenges. In this work, we propose a "one stone kills two birds" strategy by employing an interfacial solar evaporation platform (ISEP) combined with a MPs adsorbent. This strategy aims to produce clean water and simultaneously enhance MPs removal. Unlike traditional predecessors, our ISEP generates condensed water free from MPs contamination. Additionally, the photothermally driven interfacial separation process significantly improves the MPs removal performance. We observed a removal ratio increase of up to 5.5 times compared to previously reported MPs adsorbents. Thus, our rationally-designed ISEP holds promising potential to not only mitigate the existing water scarcity issue but also remediate MPs pollution in natural water environments.

Ultrafast 2D Nanosheet Assembly via Spontaneous Spreading Phenomenon

In 2D materials, a key engineering challenge is the mass production of large-area thin films without sacrificing their uniform 2D nature and unique properties. Here, it is demonstrated that a simple fluid phenomenon of water/alcohol solvents can become a sophisticated tool for self-assembly and designing organized structures of 2D nanosheets on a water surface. In situ, surface characterizations show that water/alcohol droplets of 2D nanosheets with cationic surfactants exhibit spontaneous spreading of large uniform monolayers within 10 s. Facile transfer of the monolayers onto solid or flexible substrates results in high-quality mono- and multilayer films with high coverages (>95%) and homogeneous electronic/optical properties. This spontaneous spreading is quite general and can be applied to various 2D nanosheets, including metal oxides, graphene oxide, h-BN, MoS2, and transition metal carbides, enabling on-demand smart manufacture of large-size (>4 inchϕ) 2D nanofilms and free-standing membranes.

Cost Effective Photothermal Materials Selection for Direct Solar-Driven Evaporation

The cornerstone of eco-friendly and affordable freshwater generation lies in harnessing solar energy for water evaporation. This process involves extracting vapor from liquid water using solar energy. Numerous innovative, low-cost materials have been proposed for this purpose. These materials aim to enable highly controllable and efficient conversion of solar energy into thermal energy while maintaining high cost-effectiveness. Here, in this review paper, we outline the advancements in solar-driven evaporation technology with a focus on optimizing synthesis methods and materials cost. It prioritizes refining evaporation efficiency and affordability using inventive manufacturing methods. By utilizing innovative reasonably priced materials, this process not only ensures efficient resource utilization but also fosters technological advancements in renewable energy applications. Moreover, the affordability of these materials makes solar-powered water evaporation accessible to a wider range of communities, empowering them to address water scarcity challenges.

Constructing Two-Dimensional (2D) Heterostructure Channels with Engineered Biomembrane and Graphene for Precise Scandium Sieving

The special properties of rare earth elements (REE) have effectively broadened their application fields. How to accurately recognize and efficiently separate target rare earth ions with similar radii and chemical properties remains a formidable challenge. Here, precise two-dimensional (2D) heterogeneous channels are constructed using engineered E. coli membranes between graphene oxide (GO) layers. The difference in binding ability and corresponding conformational change between Lanmodulin (LanM) and rare earth ions in the heterogeneous channel allows for precisely recognizing and sieving of scandium ions (Sc3+). The engineered E. coli membranes not only can protect the integrity of structure and functionality of LanM, the rich lipids and sugars, but also help the Escherichia coli (E. coli) membranes closely tile on the GO nanosheets through interaction, preventing swelling and controlling interlayer spacing accurately down to the sub-nanometer. Apparently, the 2D heterogeneous channels showcase excellent selectivity for trivalent ions (SFFe /Sc≈3), especially for Sc3+ ions in REE with high selectivity (SFCe/Sc≈167, SFLa/Sc≈103). The long-term stability and tensile strain tests verify the membrane's outstanding stability. Thus, this simple, efficient, and cost-effective work provides a suggestion for constructing 2D interlayer heterogeneous channels for precise sieving, and this valuable strategy is proposed for the efficient extraction of Sc.

Sustainable chitosan-based materials as heterogeneous catalyst for application in wastewater treatment and water purification: An up-to-date review

Water pollution is one of serious environmental issues due to the rapid development of industrial and agricultural sectors, and clean water resources have been receiving increasing attention. Recently, more and more studies have witnessed significant development of catalysts (metal oxides, metal sulfides, metal-organic frameworks, zero-valent metal, etc.) for wastewater treatment and water purification. Sustainable and clean catalysts immobilized into chitosan-based materials (Cat@CSbMs) are considered one of the most appealing subclasses of functional materials due to their high catalytic activity, high adsorption capacities, non-toxicity and relative stability. This review provides a summary of various upgrading renewable Cat@CSbMs (such as cocatalyst, photocatalyst, and Fenton-like reagent, etc.). As for engineering applications, further researches of Cat@CSbMs should focus on treating complex wastewater containing both heavy metals and organic pollutants, as well as developing continuous flow treatment methods for industrial wastewater using Cat@CSbMs. In conclusion, this review abridges the gap between different approaches for upgrading renewable and clean Cat@CSbMs and their future applications. This will contribute to the development of cleaner and sustainable Cat@CSbMs for wastewater treatment and water purification.

Sunlight-triggered prebiotic nanomotors for inhibition and elimination of pathogen and biofilm in aquatic environment

Pathogen contamination in drinking water sources causes waterborne infectious diseases, seriously threatening human health. Nowadays, stimuli-responsive self-propelled nanomotors are appealing therapeutic agents for antibacterial therapy in vivo. However, achieving water disinfection using these nanobots is still a great challenge. Herein, we report on prebiotic galactooligosaccharide-based nanomotors for sunlight-regulated water disinfection. The nanomotors can utilize galactooligosaccharide-based N-nitrosamines as sunlight-responsive fuels for the spontaneous production of antibacterial nitric oxide. Such a solar-to-chemical energy conversion would power the nanomotors for self-diffusiophoresis, which could promote the diffusion of the nanomotors in water and their penetration in the biofilm, significantly enhancing the inhibition and elimination of the pathogens and their biofilms in aquatic environments. After water treatments, the prebiotic-based residual disinfectants can be selectively utilized by beneficial bacteria to effectively relieve safety risks to the environment and human health. The low-energy-cost, green and potent antibacterial nanobots show promising potential in water disinfection.

Construction of Hydrogels with Highly Salt-Resistant Honeycomb Porous Structures for Solar Desalination and Steam Generation

Interfacial solar desalination is a method for desalinating seawater using solar energy, and the long-term use of this technology requires a stable evaporation rate and some ability to prevent salt crystallization. To address these issues, carbonized polydopamine-coated bentonite (C@PBT), poly(vinyl alcohol), and cellulose nanofibers were used to construct a three-dimensional oriented hydrogel evaporator with a multilayered honeycomb porous structure for long-term desalination. Carbon nanoparticles transferred between the layers of the bentonite, which increases the spacing of the layers and confers a more effective solar light trapping ability. The evaporation rate was 2.26 kg m-2 h-1 in 20 wt % NaCl solution, and no salt crystals were precipitated from the surface of the evaporator in 12 h of continuous operation. This phenomenon occurs due to the wide distribution of pore sizes and the large size of the pores within the evaporator, which create ample space for salt ions to move freely. Furthermore, after undergoing 300 cycles of compression, its internal pore structure remains intact, and the rate of evaporation remains stable. It ensures the evaporator stability during outdoor cycles. The research work provides an effective method to solve the salt accumulation problem and shows its great potential for application.

High-Entropy Photothermal Materials

High-entropy (HE) materials, celebrated for their extraordinary chemical and physical properties, have garnered increasing attention for their broad applications across diverse disciplines. The expansive compositional range of these materials allows for nuanced tuning of their properties and innovative structural designs. Recent advances have been centered on their versatile photothermal conversion capabilities, effective across the full solar spectrum (300-2500 nm). The HE effect, coupled with hysteresis diffusion, imparts these materials with desirable thermal and chemical stability. These attributes position HE materials as a revolutionary alternative to traditional photothermal materials, signifying a transformative shift in photothermal technology. This review delivers a comprehensive summary of the current state of knowledge regarding HE photothermal materials, emphasizing the intricate relationship between their compositions, structures, light-absorbing mechanisms, and optical properties. Furthermore, the review outlines the notable advances in HE photothermal materials, emphasizing their contributions to areas, such as solar water evaporation, personal thermal management, solar thermoelectric generation, catalysis, and biomedical applications. The review culminates in presenting a roadmap that outlines prospective directions for future research in this burgeoning field, and also outlines fruitful ways to develop advanced HE photothermal materials and to expand their promising applications.

Activated nanosulfur for broad-spectrum heavy metals capture

Current problems of existing heavy metal-removing technologies, especially for nanomaterials-based ones, are typically single metal ion-specific, high-cost and collected difficult. Herein, facile modification of commercial sulfur creates a versatile adsorbent platform to address challenges. The versatile adsorbent can be easily prepared through solvothermal treatment of a saturated commercial sulfur solution, followed by water precipitation on a commercial foam that eliminates the need for separation. Interestingly, the solvothermal treatment endows the resulting nanosulfur with sulfate acid groups (hard Lewis base), sulfur anions (soft base), and sulfite groups (borderline base), promising the coordination of all types of heavy metal ions (Lewis acids). As such, this versatile adsorbent with well-distributed adsorption sites exhibits highly effective heavy metal adsorption capacity towards diverse heavy metal ions for both single-component and multi-component adsorption, including soft, hard, borderline Lewis metal ions, with ultra-high adsorption ability (e.g., 903.79 mg g-1 for Cu2+). These findings highlighted the potential of this low-cost sulfur-based adsorbent to address the arising challenges in ensuring clean water.

Efficient removal of environmental pollutants by green synthesized metal nanoparticles of Clitoriaternatea

Prevention and management of water pollution are becoming a great challenge in the present scenario. Different conventional methods like carbon adsorption, ion exchange, chemical precipitation, evaporation, and biological treatments remove water pollutants. Nowadays, the requirement for effective, non-toxic and safe waste management strategies is very high. Nanomaterials have been explored in various fields due to their unique characteristics. Green synthesis of nanomaterial is becoming more popular due to their safety, non-toxicity, and ease of scale-up technology. Metal nanoparticles can be synthesized using a green synthesis method using biological sources provided by eco-friendly, non-hazardous nanomaterials with superior properties to bulk metals. Hence, this study has designed a green synthesis of magnetic (cobalt oxide) and noble (gold) nanoparticles from the fresh flowers of Clitoria ternatea. The flavonoids and polyphenols in the extract decreased the energy band gap of cobalt oxide and gold nanoparticles; hence, the capping of the natural constituents in Clitoria ternatea helped form stable metal nanoparticles. The cobalt oxide and gold nanoparticles are evaluated for their potential for eliminating organic pollutants from industrial effluent. The novelty of this present work represents the application of cobalt oxide nanoparticles in the removal of organic pollutants and a comparative study of the catalytic behaviour of both metal nanoparticles. The degradation of bromophenol blue, bromocresol green, and 4-nitrophenol in the presence of gold nanoparticles was completed in 120, 45, and 20 min with rate constants of 3.7 × 10-3/min, 6.9 × 10-3/min, and 16.5 × 10-3/min, respectively. Similarly, the photocatalysis of bromophenol blue, bromocresol green, and 4-nitrophenol in the presence of cobalt oxide nanoparticles was achieved in 60, 90, and 40 min with rate constants of 2.3 × 10-3/min, 1.8 × 10-3/min, and 1.7 × 10-3/min, respectively. The coefficient of correlation (R2) values justify that the degradation of organic pollutants follows first-order kinetics. The significance of the study is to develop green nanomaterials that can be used efficiently to remove organic pollutants in wastewater using a cost-effective method with minimal toxicity to aquatic animals. It has proved to be useful in environmental pollution management.

Prediction of Nanoparticle Photoreactivity in Mixtures of Surface Foulants Requires Kinetic (Non-equilibrium) Adsorption Considerations

The adsorption of foulants on photocatalytic nanoparticles can suppress their reactivity in water treatment applications by scavenging reactive species at the photocatalyst surface, screening light, or competing for surface sites. These inhibitory effects are commonly modeled using the Langmuir-Hinshelwood model, assuming that adsorbed layer compositions follow Langmuirian (equilibrium) competitive adsorption. However, this assumption has not been evaluated in complex mixtures of foulants. This study evaluates the photoreactivity of titanium dioxide (TiO2) nanoparticles toward a target compound, phenol, in the presence of two classes of foulants ─ natural organic matter (NOM) and a protein, bovine serum albumin (BSA) ─ and mixtures of the two. Langmuir adsorption models predict that BSA should strongly influence the nanoparticle photoreactivity because of its higher adsorption affinity relative to phenol and NOM. However, model evaluation of the experimental phenol decay rates suggested that neither the phenol nor foulant surface coverages are governed by Langmuirian competitive adsorption. Rather, a reactivity model incorporating kinetic predictions of adsorbed layer compositions (favoring NOM adsorption) outperformed Langmuirian models in providing accurate, unbiased predictions of phenol degradation rates. This research emphasizes the importance of using first-principles models that account for adsorption kinetics when assumptions of equilibrium adsorption do not apply.

Aminal-Linked Covalent Organic Framework Membranes Achieve Superior Ion Selectivity

High-salinity wastewater treatment is perceived as a global water resource recycling challenge that must be addressed to achieve zero discharge. Monovalent/divalent salt separation using membrane technology provides a promising strategy for sulfate removal from chlor-alkali brine. However, existing desalination membranes often show low water permeance and insufficient ion selectivity. Herein, an aminal-linked covalent organic framework (COF) membrane featuring a regular long-range pore size of 7 Å and achieving superior ion selectivity is reported, in which a uniform COF layer with subnanosized channels is assembled by the chemical splicing of 1,4-phthalaldehyde (TPA)-piperazine (PZ) COF through an amidation reaction with trimesoyl chloride (TMC). The chemically spliced TPA-PZ (sTPA-PZ) membrane maintains an inherent pore structure and exhibits a water permeance of 13.1 L m-2 h-1 bar-1, a Na2SO4 rejection of 99.1%, and a Cl-/SO4 2- separation factor of 66 for mixed-salt separation, which outperforms all state-of-the-art COF-based membranes reported. Furthermore, the single-stage treatment of NaCl/Na2SO4 mixed-salt separation achieves a high NaCl purity of above 95% and a recovery rate of ≈60%, offering great potential for industrial application in monovalent/divalent salt separation and wastewater resource utilization. Therefore, the aminal-linked COF membrane developed in this work provides a new research avenue for designing smart/advanced membrane materials for angstrom-scale separations.

Surface Bio-engineered Polymeric Nanoparticles

Surface bio-engineering of polymeric nanoparticles (PNPs) has emerged as a cornerstone in contemporary biomedical research, presenting a transformative avenue that can revolutionize diagnostics, therapies, and drug delivery systems. The approach involves integrating bioactive elements on the surfaces of PNPs, aiming to provide them with functionalities to enable precise, targeted, and favorable interactions with biological components within cellular environments. However, the full potential of surface bio-engineered PNPs in biomedicine is hampered by obstacles, including precise control over surface modifications, stability in biological environments, and lasting targeted interactions with cells or tissues. Concerns like scalability, reproducibility, and long-term safety also impede translation to clinical practice. In this review, these challenges in the context of recent breakthroughs in developing surface-biofunctionalized PNPs for various applications, from biosensing and bioimaging to targeted delivery of therapeutics are discussed. Particular attention is given to bonding mechanisms that underlie the attachment of bioactive moieties to PNP surfaces. The stability and efficacy of surface-bioengineered PNPs are critically reviewed in disease detection, diagnostics, and treatment, both in vitro and in vivo settings. Insights into existing challenges and limitations impeding progress are provided, and a forward-looking discussion on the field's future is presented. The paper concludes with recommendations to accelerate the clinical translation of surface bio-engineered PNPs.

Enhanced water treatment performance of ceramic-based forward osmosis membranes via MOF interlayer

Forward osmosis (FO) membrane processes could operate without hydraulic pressures, enabling the efficient treatment of wastewaters with mitigated membrane fouling and enhanced efficiency. Designing a high-performance polyamide (PA) layer on ceramic substrates remains a challenge for FO desalination applications. Herein, we report the enhanced water treatment performance of thin-film nanocomposite ceramic-based FO membranes via an in situ grown Zr-MOF (UiO-66-NH2) interlayer. With the Zr-MOF interlayer, the ceramic-based FO membranes exhibit lower thickness, higher cross-linking degree, and increased surface roughness, leading to higher water flux of 27.38 L m-2 h-1 and lower reverse salt flux of 3.45 g m-2 h-1. The ceramic-based FO membranes with Zr-MOF interlayer not only have an application potential in harsh environments such as acidic solution (pH 3) and alkaline solution (pH 11), but also exhibit promising water and reverse salt transport properties, which are better than most MOF-incorporated PA membranes. Furthermore, the membranes could reject major species (ions, oil and organics) with rejections ＞94 % and water flux of 22.62-14.35 L m-2 h-1 in the treatment of actual alkaline industrial wastewater (pH 8.6). This rational design proposed in this study is not only applicable for the development of a high-quality ceramic-based FO membrane with enhanced performance but also can be potentially extended to more challenging water treatment applications.

Dealloying-Derived Self-Supporting Nanoporous Zinc Film with Optimized Macro/Microstructure for High-Performance Solar Steam Generation

Solar steam generation (SSG) is a promising technology for the production of freshwater that can help alleviate global water scarcity. Nanostructured metals, known for their localized surface plasmon resonance effect, have generated significant interest, but low-cost metal films with excellent water evaporation properties are challenging. In this work, we present a one-step dealloying route for fabricating self-supporting black nanoporous zinc (NP-Zn) films with a bicontinuous ligament/channel structure, using Al-Zn solid solution alloys as the precursors. The influence of alloy composition on the formation and macro/microstructure of NP-Zn was investigated, and an optimal Al98Zn2 was selected. Additionally, in situ and ex situ characterizations were conducted to unveil the dealloying mechanism of Al98Zn2 and phase/microstructure evolution of NP-Zn during dealloying, including the phase transition of Al(Zn) → Zn, significant volume shrinkage (89.8%), and the development of high porosity (81.3%). The nanoscale ligament/channel structure and high porosity endow the NP-Zn films with good broadband absorption and superior hydrophilicity and, more importantly, give them excellent SSG performance. The NP-Zn2 film displays high evaporation efficiency, superior stability, and good seawater desalination performance. The efficient SSG performance, material abundance, and low cost suggest that NP-Zn films have promising applications in metal-based photothermal materials for SSG.

Silver Nanoparticles: Multifunctional Tool in Environmental Water Remediation

Water pollution is a worldwide environmental and health problem that requires the development of sustainable, efficient, and accessible technologies. Nanotechnology is a very attractive alternative in environmental remediation processes due to the multiple properties that are conferred on a material when it is at the nanometric scale. This present review focuses on the understanding of the structure-physicochemical properties-performance relationships of silver nanoparticles, with the objective of guiding the selection of physicochemical properties that promote greater performance and are key factors in their use as antibacterial agents, surface modifiers, colorimetric sensors, signal amplifiers, and plasmonic photocatalysts. Silver nanoparticles with a size of less than 10 nm, morphology with a high percentage of reactive facets {111}, and positive surface charge improve the interaction of the nanoparticles with bacterial cells and induce a greater antibacterial effect. Adsorbent materials functionalized with an optimal concentration of silver nanoparticles increase their contact area and enhance adsorbent capacity. The use of stabilizing agents in silver nanoparticles promotes selective adsorption of contaminants by modifying the surface charge and type of active sites in an adsorbent material, in addition to inducing selective complexation and providing stability in their use as colorimetric sensors. Silver nanoparticles with complex morphologies allow the formation of hot spots or chemical or electromagnetic bonds between substrate and analyte, promoting a greater amplification factor. Controlled doping with nanoparticles in photocatalytic materials produces improvements in their electronic structural properties, promotes changes in charge transfer and bandgap, and improves and expands their photocatalytic properties. Silver nanoparticles have potential use as a tool in water remediation, where by selecting appropriate physicochemical properties for each application, their performance and efficiency are improved.

Harnessing Synchronous Photothermal and Photocatalytic Effects of Substoichiometric MoO3-x Nanoparticle-Decorated Membranes for Clean Water Generation

Solar-driven interfacial evaporation provides a promising pathway for sustainable freshwater and energy generation. However, developing highly efficient photothermal and photocatalytic nanomaterials is challenging. Herein, substoichiometric molybdenum oxide (MoO3-x) nanoparticles are synthesized via step-by-step reduction treatment of l-cysteine under mild conditions for simultaneous photothermal conversion and photocatalytic reactions. The MoO3-x nanoparticles of low reduction degree are decorated on hydrophilic cotton cloth to prepare a MCML evaporator toward rapid water production, pollutant degradation, as well as electricity generation. The obtained MCML evaporator has a strong local light-to-heat effect, which can be attributed to excellent photothermal conversion via the local surface plasmon resonance effect in MoO3-x nanoparticles and the low heat loss of the evaporator. Meanwhile, the rich surface area of MoO3-x nanoparticles and the localized photothermal effect together effectively accelerate the photocatalytic degradation reaction of the antibiotic tetracycline. With the benefit of these advantages, the MCML evaporator attains a superior evaporation rate of 4.14 kg m-2 h-1, admirable conversion efficiency of 90.7%, and adequate degradation efficiency of 96.2% under 1 sun irradiation. Furthermore, after being rationally assembled with a thermoelectric module, the hybrid device can be employed to generate 1.0 W m-2 of electric power density. This work presents an effective complementary strategy for freshwater production and sewage treatment as well as electricity generation in remote and off-grid regions.

Reversible pH-Gated MXene Membranes with Ultrahigh Mono-/Divalent-Ion Selectivity

Artificial ion channel membranes hold high promise in water treatment, nanofluidics, and energy conversion, but it remains a great challenge to construct such smart membranes with both reversible ion-gating capability and desirable ion selectivity. Herein, we constructed a smart MXene-based membrane via p-phenylenediamine functionalization (MLM-PPD) with highly stable and aligned two-dimensional subnanochannels, which exhibits reversible ion-gating capability and ultrahigh metal ion selectivity similar to biological ion channels. The pH-sensitive groups within the MLM-PPD channel confers excellent reversible Mg2+-gating capability with a pH-switching ratio of up to 100. The mono/divalent metal-ion selectivity up to 1243.8 and 400.9 for K+/Mg2+ and Li+/Mg2+, respectively, outperforms other reported membranes. Theoretical calculations combined with experimental results reveal that the steric hindrance and stronger PPD-ion interactions substantially enhance the energy barrier for divalent metal ions passing through the MLM-PPD, and thus leading to ultrahigh mono/divalent metal-ion selectivity. This work provides a new strategy for developing artificial-ion channel membranes with both reversible ion-gating functionality and high-ion selectivity for various applications.

Separation and reutilization of heavy metal ions in wastewater assisted by p-BN adsorbent

Extracting heavy metal ions from wastewater has significant implications for both environmental remediation and resource preservation. However, the conventional adsorbents still suffer from incomplete ion removal and low utilization efficiency of the recovered metals. Herein, we present an extraction and reutilization method assisted by porous boron nitride (p-BN) containing high-density N atoms for metal recovery with simultaneous catalyst formation. The p-BN exhibits stable and efficient metal adsorption performance, particularly for ultra-trace-level water purification. The distribution coefficients towards Pb2+, Cd2+, Co2+ and Fe3+ can exceed 106 mL g-1 and the residual concentrations that reduced from 1 mg L-1 to 0.8-1.3 μg L-1 are much lower than the acceptable limits in drinking water standards of World Health Organization. Meanwhile, the used p-BN after Co ion adsorption can be directly adopted as a high-efficiency catalyst for activating peroxymonosulfate (PMS) in organic pollutant degradation without additional post-treatment, avoiding the secondary metal pollution and the problems of neglected manpower and energy consumption. Moreover, a flow-through multistage utilization system assisted by p-BN/polyvinylidene fluoride (PVDF) membrane is constructed for achieving both metal ion separation and reutilization in the removal of organic pollutants, providing a new avenue for sustainable wastewater remediation.

Regulating ion affinity and dehydration of metal-organic framework sub-nanochannels for high-precision ion separation

Membrane consisting of ordered sub-nanochannels has been pursued in ion separation technology to achieve applications including desalination, environment management, and energy conversion. However, high-precision ion separation has not yet been achieved owing to the lack of deep understanding of ion transport mechanism in confined environments. Biological ion channels can conduct ions with ultrahigh permeability and selectivity, which is inseparable from the important role of channel size and "ion-channel" interaction. Here, inspired by the biological systems, we report the high-precision separation of monovalent and divalent cations in functionalized metal-organic framework (MOF) membranes (UiO-66-(X)2, X = NH2, SH, OH and OCH3). We find that the functional group (X) and size of the MOF sub-nanochannel synergistically regulate the ion binding affinity and dehydration process, which is the key in enlarging the transport activation energy difference between target and interference ions to improve the separation performance. The K+/Mg2+ selectivity of the UiO-66-(OCH3)2 membrane reaches as high as 1567.8. This work provides a gateway to the understanding of ion transport mechanism and development of high-precision ion separation membranes.

Wood-inspired metamaterial catalyst for robust and high-throughput water purification

Continuous industrialization and other human activities have led to severe water quality deterioration by harmful pollutants. Achieving robust and high-throughput water purification is challenging due to the coupling between mechanical strength, mass transportation and catalytic efficiency. Here, a structure-function integrated system is developed by Douglas fir wood-inspired metamaterial catalysts featuring overlapping microlattices with bimodal pores to decouple the mechanical, transport and catalytic performances. The metamaterial catalyst is prepared by metal 3D printing (316 L stainless steel, mainly Fe) and electrochemically decorated with Co to further boost catalytic functionality. Combining the flexibility of 3D printing and theoretical simulation, the metamaterial catalyst demonstrates a wide range of mechanical-transport-catalysis capabilities while a 70% overlap rate has 3X more strength and surface area per unit volume, and 4X normalized reaction kinetics than those of traditional microlattices. This work demonstrates the rational and harmonious integration of structural and functional design in robust and high throughput water purification, and can inspire the development of various flow catalysts, flow batteries, and functional 3D-printed materials.

Plastic wastes-derived N-doped carbon nanotubes for efficient removal of sulfamethoxazole in high salinity wastewater via nonradical peroxymonosulfate activation

Peroxymonosulfate (PMS) catalytic activation is effective to eliminate organic pollutants from water, thus the development of low-cost and efficient catalysts is significant in applications. The resource conversion of plastic wastes (PWs) into carbon nanotubes (CNTs) is a promising candidate for PMS-based advanced oxidation processes (AOPs), and also a sustainable strategy to realize plastic management and reutilization. Herein, cost-effective PWs-derived N-doped CNTs (N-pCNTs) were synthesized, which displayed efficient activity for PMS activation through an electron transfer pathway (ETP) for sulfamethoxazole (SMX) degradation in high salinity water. The pyrrolic N induced the positively charged surface of N-pCNTs, favoring the electrostatic adsorption of PMS and subsequent generation of active PMS* . A galvanic oxidation process was developed to prove the electron-shuttle dominated ETP for SMX oxidation. Combined with theoretical calculations, the efficiency of ETP was determined by the potential difference between HOMO of SMX and LUMO of N-pCNTs. Such oxidation produced low-toxicity intermediates and resulted in selective degradation of specific sulfonamide antibiotics. This work reveals the feasibility of low-cost N-pCNTs catalysts from PWs serving as an appealing candidate for PMS-AOPs in water remediation, providing a new solution to alleviate environmental issues caused by PWs and also advances the understanding of ETP during PMS activation.

Recent Advances in Layered-Double-Hydroxide-Based Separation Membranes

The use of two-dimensional materials shows great promise for the development of next-generation membrane materials, thanks to their atomic thinness and the ease with which precise nanochannels can be constructed. Among these materials, layered double hydroxides (LDHs) stand out as an important class, possessing many features that make them ideal for constructing high-performance membranes. LDHs offer many advantages, such as their abundant and tunable interlayer anions, which enable the preparation of membranes with adjustable sub-nanometer pore sizes. Additionally, their hydrophilicity and positive charge characteristics afford them unique benefits. LDHs have been found to be effective in gas separation, ion sieving, and nanofiltration. This review provides a summary of the latest progress in using LDHs for membrane separation. It begins by introducing the basic properties of LDHs, followed by the assembly strategy for LDH membranes. Furthermore, the review presents the research status of LDHs membranes in various fields in a systematic manner. Lastly, the paper highlights some challenges and future prospects for preparing and applying LDHs membranes.

2D-Like Catalyst with a Micro-nanolinked Functional Surface for Water Purification

In water purification, the performance of heterogeneous advanced oxidation processes significantly relies upon the utilization of the catalyst's specific surface area (SSA). However, the presence of the structural "dead volume" and pore-size-induced diffusion-reaction trade-off limitation restricts the functioning of the SSA. Here, we reported an effective approach to make the best SSA by changing the traditional 3D spherule catalyst into a 2D-like form and creating an in situ micro-nanolinked structure. Thus, a 2D-like catalyst was obtained which was characterized by a mini "paddy field" surface, and it exhibited a sharply decreased dead volume, a highly available SSA and oriented flexibility. Given its paddy-field-like mass-transfer routine, the organic capture capability was 7.5-fold higher than that of the catalyst with mesopores only. Moreover, such a catalyst exhibited a record-high O3-to-·OH transition rate of 2.86 × 10-8 compared with reported millimetric catalysts (metal base), which contributed to a 6.12-fold higher total organic removal per catalyst mass than traditional 3D catalysts. The facile scale preparation, performance stability, and significant material savings with the 2D-like catalyst were also beneficial for practical applications. Our findings provide a unique and general approach for designing potential catalysts with excellent performance in water purification.

Mesoporous Magnetic/Polymer Hybrid Nanoabsorbent for Rapid and Efficient Removal of Heavy Metal Ions from Wastewater

As an advanced water purification technology, magnetic nanoabsorbents are highly attractive for their sustainability, robustness, and energy efficiency. However, magnetic responsiveness and high adsorptive capacity are irreconcilable during the design and synthesis of a high-performance magnetic nanoabsorbent. Here, we address this issue by designing a kind of mesoporous magnetic polymer hybrid microspheres, where functional polymers such as polyrhodanine and polypyrrole were attached to the pore walls in the interior of mesoporous Fe3O4 microspheres through in situ polymerization. Due to the integrated large saturation magnetic moment, porous structure, and dense polymer layer, the mesoporous magnetic polymer hybrid microspheres demonstrated fast magnetic responsiveness, excellent recycling performance, and high adsorption capacities toward Pb(II) ions (189 mg g-1) for polyrhodanine and Cr(VI) ions (199 mg g-1) for polypyrrole. Furthermore, their potential application in wastewater treatment was verified by a self-made magnetic separation column, where the designed magnetic nanoabsorbent exhibits significant advantages including rapid separation of heavy metal ions and high outflow. This study provided a promising magnetic polymer hybrid nanoabsorbent for realizing efficient removal of heavy metal ions from wastewater.

Enhanced Photothermal Property of NDI-Based Conjugated Polymers by Copolymerization with a Thiadiazolobenzotriazole Unit

Solar steam generation (SSG) is a promising photothermal technology to solve the global water storage issue. The potential of π-conjugated polymers as photothermal materials is significant, because their absorption range can be customized through molecular design. In this study, naphthalenediimide (NDI) and thiadiazolobenzotriazole (TBZ) were employed as bifunctional monomers to produce conjugated polymers. There are two types of polymers, P1 and P2. P1 is based on NDI, while P2 is a copolymer of NDI and TBZ in a ratio of 9:1. Both polymers had high molecular weights and sufficient thermal stability. UV-vis-near-infrared (NIR) absorption spectra revealed that both polymers have large extinction coefficients ascribed to the NDI and TBZ chromophores. Notably, the absorption spectrum of P2 exhibited a significant red shift compared to P1, resulting in a narrow optical bandgap and absorption in the NIR range. This result suggested that P2 has a higher light absorption than P1. Photoluminescence (PL) spectra were measured to elucidate the conversion of the absorbed light into thermal energy. It was found that P2 has a reduced fluorescence quantum yield as a result of the TBZ unit, signifying a proficient conversion of the photothermal energy. Based on the results, it appears that the P2 film has a greater photothermal property compared to that of the P1 film. The surface temperature of the P2 film reached approximately 50 °C under the investigated conditions. In addition, copolymer P2 exhibited an impressive SSG efficiency of 72.4% under 1 sun (1000 W/m2) irradiation. All the results suggested that narrow bandgap conjugated polymers containing the TBZ unit are highly effective materials for achieving optimal performance in SSGs.

Contact-Electro-Catalysis-Assisted Separation via a Dancing PTFE Membrane for Fouling Control

Advanced oxidization processes (AOPs) offer promising solutions for addressing the fouling issues in membrane separation systems. However, the high energy requirements for electrical or light power in the AOPs can be a drawback. In this study, we present a contact-electro-catalysis (CEC)-based approach for controlling membrane fouling, which is stimulated by mild ultrasonic irradiation. During this process, electrons are transferred between a dancing polytetrafluoroethylene membrane and water or oxygen molecules, resulting in the formation of free radicals •OH and •O2-. These free radicals are capable of degrading or inactivating foulants, eliminating the need for additional chemical cleaners, secondary waste disposal, or external stimuli. Furthermore, the time-dependent voltage spikes/oscillations (peak, +7.8/-8.2 V) generate a nonuniform electric field that drives dielectrophoresis, effectively keeping contaminants away from the membrane surface and further enhancing the antifouling performance of the dancing membrane. Therefore, the CEC-assisted membrane separation system offers a green and effective strategy for controlling membrane fouling through mild mechanical stimulation.

Advancement in nanomaterials for environmental pollutants remediation: a systematic review on bibliometrics analysis, material types, synthesis pathways, and related mechanisms

Environmental pollution is a major issue that requires effective solutions. Nanomaterials (NMs) have emerged as promising candidates for pollution remediation due to their unique properties. This review paper provides a systematic analysis of the potential of NMs for environmental pollution remediation compared to conventional techniques. It elaborates on several aspects, including conventional and advanced techniques for removing pollutants, classification of NMs (organic, inorganic, and composite base). The efficiency of NMs in remediation of pollutants depends on their dispersion and retention, with each type of NM having different advantages and disadvantages. Various synthesis pathways for NMs, including traditional synthesis (chemical and physical) and biological synthesis pathways, mechanisms of reaction for pollutants removal using NMs, such as adsorption, filtration, disinfection, photocatalysis, and oxidation, also are evaluated. Additionally, this review presents suggestions for future investigation strategies to improve the efficacy of NMs in environmental remediation. The research so far provides strong evidence that NMs could effectively remove contaminants and may be valuable assets for various industrial purposes. However, further research and development are necessary to fully realize this potential, such as exploring new synthesis pathways and improving the dispersion and retention of NMs in the environment. Furthermore, there is a need to compare the efficacy of different types of NMs for remediating specific pollutants. Overall, this review highlights the immense potential of NMs for mitigating environmental pollutants and calls for more research in this direction.

Structure Evolution of Iron (Hydr)oxides under Nanoconfinement and Its Implication for Water Treatment

In the development of nanoenabled technologies for large-scale water treatment, immobilizing nanosized functional materials into the confined space of suitable substrates is one of the most effective strategies. However, the intrinsic effects of nanoconfinement on the decontamination performance of nanomaterials, particularly in terms of structural modulation, are rarely unveiled. Herein, we investigate the structure evolution and decontamination performance of iron (hydr)oxide nanoparticles, a widely used material for water treatment, when confined in track-etched (TE) membranes with channel sizes varying from 200 to 20 nm. Nanoconfinement drives phase transformation from ferrihydrite to goethite, rather than to hematite occurring in bulk systems, and the increase in the nanoconfinement degree from 200 to 20 nm leads to a significant drop in the fraction of the goethite phase within the aged products (from 41% to 0%). The nanoconfinement configuration is believed to greatly slow down the phase transformation kinetics, thereby preserving the specific adsorption of ferrihydrite toward As(V) even after 20-day aging at 343 K. This study unravels the structure evolution of confined iron hydroxide nanoparticles and provides new insights into the temporospatial effects of nanoconfinement on improving the water decontamination performance.

Fabrication of next-generation multifunctional LBG-s-AgNPs@ g-C3N4 NS hybrid nanostructures for environmental applications

Toxic industrial wastes and microbial pathogens in water pose a continuous threat to aquatic life as well as alarming situations for humans. Developing advanced materials with an environmentally friendly approach is always preferable for heterogeneous visible light photocatalysis. As a green reducing tool, LBG-s-AgNPs@ g-C3N4 NS hybrid nanostructures were anchored onto graphitic carbon nitride (g-C3N4) using an environmentally friendly approach of anchoring/decorating AgNPs onto g-C3N4. With the help of advanced techniques, the fabricated hybrid nanostructures were characterized. Using a sheet like matrix of g-C3N4, nanosized and well-defined uniform AgNPs displayed good antibacterial activity as well as superior photodegradation of hazardous dyes, including methylene blue (MB) and Rhodamine B (RhB). Based on the disc diffusion method, three pathogenic microorganisms of clinical significance can be identified by showing the magnitude of their susceptibility. As a result, the following antimicrobial potency was obtained: E. coli ≥ M. luteus ≥ S. aureus. In this study, green synthesized (biogenic) AgNPs decorated with g-C3N4 were found to be more potent antimicrobials than traditional AgNPs. Under visible light irradiation, LBG-s-AgNPs@g-C3N4 NS (0.01 M) demonstrated superior photocatalytic performance: ∼100% RhB degradation and ∼99% of MB degradation in 160 min. LBG-s-AgNPs@g-C3N4 NS showed the highest kinetic rate, 3.44 × 10-2 min-1, which is 27.74 times for the control activity in case of MB dye. While in case of RhB dye LBG-s-AgNPs@g-C3N4 NS showed the highest kinetic rate, 2.26 × 10-2 min-1, which is 17.51 times for the control activity. Due to the surface plasmon resonance (SPR) and reduction in recombination of the electrons and holes generated during photocatalysis, anchoring AgNPs to g-C3N4 further enhanced the photocatalytic degradation of dyes. Using this photocatalyst, hazardous dyes can be efficiently and rapidly degraded, allowing it to be applied for wastewater treatment contaminated with dyes. It also showed remarkable antimicrobial activity towards Gram-ve/Gram + ve pathogens.

Porphyrin/phthalocyanine-based porous organic polymers for pollutant removal and detection: Synthesis, mechanisms, and challenges

The growing global concern about environmental threats due to environmental pollution requires the development of environmentally friendly and efficient removal/detection materials and methods. Porphyrin/phthalocyanine (Por/Pc) based porous organic polymers (POPs) as a newly emerging porous material are prepared through polymerizing building blocks with different structures. Benefiting from the high porosity, adjustable pore structure, and enzyme-like activities, the Por/Pc-POPs can be the ideal platform to study the removal and detection of pollutants. However, a systematic summary of their application in environmental treatment is still lacking to date. In this review, the development of various Por/Pc-POPs for pollutant removal and detection applications over the past decade was systematically addressed for the first time to offer valuable guidance on environmental remediation through the utilization of Por/Pc-POPs. This review is divided into two sections (pollutants removal and detection) focusing on Por/Pc-POPs for organic, inorganic, and gaseous pollutants adsorption, photodegradation, and chemosensing, respectively. The related removal and sensing mechanisms are also discussed, and the methods to improve removal and detection efficiency and selectivity are also summarized. For the future practical application of Por/Pc-POPs, this review provides the emerging research directions and their application possibility and challenges in the removal and detection of pollutants.

Hierarchical nanofibrous and recyclable membrane with unidirectional water-transport effect for efficient solar-driven interfacial evaporation

Solar-driven interfacial evaporation technology has attracted significant attention for water purification. However, design and fabrication of solar-driven evaporator with cost-effective, excellent capability and large-scale production remains challenging. In this study, inspired by plant transpiration, a tri-layered hierarchical nanofibrous photothermal membrane (HNPM) with a unidirectional water transport effect was designed and prepared via electrospinning for efficient solar-driven interfacial evaporation. The synergistic effect of the hierarchical hydrophilic-hydrophobic structure and the self-pumping effect endowed the HNPM with unidirectional water transport properties. The HNPM could unidirectionally drive water from the hydrophobic layer to the hydrophilic layer within 2.5 s and prevent reverse water penetration. With this unique property, the HNPM was coupled with a water supply component and thermal insulator to assemble a self-floating evaporator for water desalination. Under 1 sun illumination, the water evaporation rates of the designed evaporator with HNPM in pure water and dyed wastewater reached 1.44 and 1.78 kg·m-2·h-1, respectively. The evaporator could achieve evaporation of 11.04 kg·m-2 in 10 h under outdoor solar conditions. Moreover, the tri-layered HNPM exhibited outstanding flexibility and recyclability. Our bionic hydrophobic-to-hydrophilic structure endowed the solar-driven evaporator with capillary wicking and transpiration effects, which provides a rational design and optimization for efficient solar-driven applications.

A scalable and anti-fouling silver-nickel/cellulose paper with synergy photothermal effect for efficient solar distillation

Solar interfacial evaporation is one of the most efficient and environmentally-friendly clean freshwater production technologies. Plasma metal nanoparticles are excellent optical absorption materials, but their high cost and inherent resonance narrow bandwidth absorption limit their application. In this work, commercial cellulose papers are used as substrates to synthesize Ag-Ni/cellulose paper by the seed-mediated method. The Ag-Ni/cellulose paper exhibits high light absorption at the full wavelength (200-2500 nm) resulting from the synergistic effect of localized surface plasmon resonance (LSPR) of Ag NPs and the interband transitions (IBTs) of Ni. Under one-sun irradiation (1 kW m-2), the energy utilization efficiency of Ag-Ni/cellulose paper is as high as 93.8%, and the water evaporation rate is 1.87 kg m-2 h-1. Diffusion inhibition experiment results show that the Ag-Ni/cellulose paper exhibits excellent antibacterial performance, and the antibacterial performance is highly related with Ag NPs content. These provide new opportunities for commercial production of competitive cost, green, and portable solar evaporators for different application sceneries.

Salinity-mediated water self-purification via bond network distorting of H2O molecules on DRC-surface

High salinity has plagued wastewater treatment for a long time by hindering pollutant removal, thereby becoming a global challenge for water pollution control that is difficult to overcome even with massive energy consumption. Herein, we propose a novel process for rapid salinity-mediated water self-purification in a dual-reaction-centers (DRC) system with cation-π structures. In this process, local hydrogen bond networks of H2O molecules can be distorted through the mediation of salinity, thereby opening the channels for the preferential contact of pollutants on the DRC interface. As the result, the elimination rate of pollutants increased approximately 32-fold at high salinity (100 mM) without any external energy consumption. Our findings provide a novel technology for high-efficiency and low-consumption water self-purification, which is of great significance in environmental remediation and even fine chemical industry.

Non-Lignin Constructing the Gas-Solid Interface for Enhancing the Photothermal Catalytic Water Vapor Splitting

The progress of solar-driven water-splitting technology has been impeded by the limited light response capability of semiconductor materials. Despite attempts to leverage nearly 50% of infrared radiation for photothermal synergy and catalytic reaction enhancement, heat loss during liquid phase reactions results in low energy conversion efficiency. Here, the photothermally driven catalytic water-splitting system, which designs K-SrTiO3 -loaded TiN silica wool at the water-air interface. Photocatalytic tests and density functional theory calculations demonstrate that the thermal effect transforms liquid water into water vapor, thereby reducing the reaction free energy of catalysts and improving the transmission rate of catalytic products. Hence, the hydrogen evolution rate reaches 275.46 mmol m-2  h-1 , and the solar-to-hydrogen (STH) efficiency is 1.81% under 1 sun irradiation in this gas-solid system, which is more than twice that of liquid water splitting. This novel photothermal catalytic pathway, which involves a coupled reaction of water evaporation and water splitting, is anticipated to broaden the utilization range of the solar spectrum and significantly enhance the conversion efficiency of STH.

Regulating N Species in N-Doped Carbon Electro-Catalysts for High-Efficiency Synthesis of Hydrogen Peroxide in Simulated Seawater

Electrochemical oxygen reduction reaction (ORR) is an attractive and alternative route for the on-site production of hydrogen peroxide (H2 O2 ). The electrochemical synthesis of H2 O2 in neutral electrolyte is in early studying stage and promising in ocean-energy application. Herein, N-doped carbon materials (N-Cx ) with different N types are prepared through the pyrolysis of zeolitic imidazolate frameworks. The N-Cx catalysts, especially N-C800 , exhibit an attracting 2e- ORR catalytic activity, corresponding to a high H2 O2 selectivity (≈95%) and preferable stability in 0.5 m NaCl solution. Additionally, the N-C800 possesses an attractive H2 O2 production amount up to 631.2 mmol g-1  h-1 and high Faraday efficiency (79.8%) in H-type cell. The remarkable 2e- ORR electrocatalytic performance of N-Cx catalysts is associated with the N species and N content in the materials. Density functional theory calculations suggest carbon atoms adjacent to graphitic N are the main catalytic sites and exhibit a smaller activation energy, which are more responsible than those in pyridinic N and pyrrolic N doped carbon materials. Furthermore, the N-C800 catalyst demonstrates an effective antibacterial performance for marine bacteria in simulated seawater. This work provides a new insight for electro-generation of H2 O2 in neutral electrolyte and triggers a great promise in ocean-energy application.

MAD Water: Integrating Modular, Adaptive, and Decentralized Approaches for Water Security in the Climate Change Era

Centralized water infrastructure has, over the last century, brought safe and reliable drinking water to much of the world. But climate change, combined with aging and underfunding, is increasingly testing the limits of-and reversing gains made by-these large-scale water systems. To address these growing strains and gaps, we must assess and advance alternatives to centralized water provision and sanitation. The water literature is rife with examples of systems that are neither centralized nor networked, but still meet water needs of local communities in important ways, including: informal and hybrid water systems, decentralized water provision, community-based water management, small drinking water systems, point-of-use treatment, small-scale water vendors, and packaged water. Our work builds on these literatures by proposing a convergence approach that can integrate and explore the benefits and challenges of modular, adaptive, and decentralized ("MAD") water provision and sanitation, often foregrounding important advances in engineering technology. We further provide frameworks to evaluate justice, economic feasibility, governance, human health, and environmental sustainability as key parameters of MAD water system performance.

3D Tea-Residue Microcrystalline Cellulose Aerogel with Aligned Channels for Solar-Driven Interfacial Evaporation Co-generation

Solar-driven interfacial evaporation co-generation (SIE-CG) technology is of great significance in solving the problem of water and energy shortage. Herein, we report the ionic liquid-assisted alignment of waste biomass tea residue-based microcrystalline cellulose for aerogels (abbreviated as TPPA-5) with aligned channels for solar-driven interfacial evaporation co-generation. In the ionic liquid, strong H-bonding is formed between the pyranoid rings of cellulose combined with the slow freezing technique, resulting in the microcrystalline cellulose being reoriented, which allowed TPPA-5 to form abundant aligned channels after solvent replacement and freeze-drying. These aligned channels enable the brine to form a localized circulating flow, which is conducive to the improvement of the TPPA's evaporation rate and salt resistance. The salinity gradient is naturally formed in the channel of TPPA, which enables TPPA-5 to show excellent power generation performance. The evaporation rate of TPPA-5 can reach 3.39 kg m-2 h-1 under 1 kW m-2. With methanol as a highly polar proton solvent, the maximum output voltage obtained was 67.534 mV due to the overlapping electric double-layer effect formed by hydrogen protons on the TPPA surface, and the energy utilization efficiency is 95.95%. Moreover, TPPA-5 can purify pesticide-containing wastewater, which has the advantages of being recyclable and environmentally friendly, showing potential application value in the field of seawater desalination and steam co-generation.

HVHC-ESD-Induced Oxygen Vacancies: An Insight into the Phenomena of Interfacial Interactions of Nanostructure Oxygen Vacancy Sites with Oxygen Ion-Containing Organic Compounds

The challenging environmental chemical and microbial pollution has always caused issues for human life. This article investigates the detailed mechanism of photodegradation and antimicrobial activity of oxide semiconductors and realizes the interface phenomena of nanostructures with toxins and bacteria. We demonstrate how oxygen vacancies in nanostructures affect photodegradation and antimicrobial behavior. Additionally, a novel method with a simple, tunable, and cost-effective synthesis of nanostructures for such applications is introduced to resolve environmental issues. The high-voltage, high-current electrical switching discharge (HVHC-ESD) system is a novel method that allows on-the-spot sub-second synthesis of nanostructures on top and in the water for wastewater decontamination. Experiments are done on rhodamine B as a common dye in wastewater to understand its photocatalytic degradation mechanism. Moreover, the antimicrobial mechanism of oxide semiconductors synthesized by the HVHC-ESD method with oxygen vacancies is realized on methicillin- and vancomycin-resistant Staphylococcus aureus strains. The results yield new insights into how oxygen ions in dyes and bacterial walls interact with the surface of ZnO with high oxygen vacancy, which results in breaking of the chemical structure of dyes and bacterial walls. This interaction leads to degradation of organic dyes and bacterial inactivation.

Solar-driven strongly coupled plasmonic Au nanoarrays on mesoporous silica nanodisks enable selective fungal and bacterial inactivation in well water

Well water is an important water source in isolated rural areas but easily suffers from microbial contamination. Herein, we anchored periodic Au nanoarrays on mesoporous silica nanodisks (Au-MSN) to fabricate a solar-driven nano-stove for well water disinfection. The solar/Au-MSN process completely inactivated 3.98, 6.55, 7.11 log10 cfu/mL, and 3.37 log10 pfu/mL of Aspergillus niger spores, Escherichia coli, chlorine-resistant Spingopyxis sp. BM1-1, and bacteriophage MS2 within 5 min, respectively. Moreover, the complete inactivation of various microorganisms (even at a viable but nonculturable state) was achieved in the flow-through reactor under natural solar light in real well water matrixes. Thorough characterizations and theoretical simulations verified that the densely anchoring strategy of Au-MSN's nanoarray worked on broadband absorption via the photon confinement effect, and trace amounts of Au can induce strong electromagnetic fields and collective localized heating. The resulting surge of 1O2 and heat synergically destroyed membranes, dysfunction cellular self-defense and metabolic system, induced intracellular oxidative stress, and ultimately inactivated microorganisms. Additionally, the 1O2-dominated oxidation and cell adhesion facilitated the selective disinfection in real well water matrixes. This study provides a cost-effective and practical solution for efficient well water disinfection, which assists isolated rural areas in getting safe drinking water.

Engineering In Situ Catalytic Cleaning Membrane Via Prebiotic-Chemistry-Inspired Mineralization

Pressure-driven membrane separation promises a sustainable energy-water nexus but is hindered by ubiquitous fouling. Natural systems evolved from prebiotic chemistry offer a glimpse of creative solutions. Herein, a prebiotic-chemistry-inspired aminomalononitrile (AMN)/Mn2+ -mediated mineralization method is reported for universally engineering a superhydrophilic hierarchical MnO2 nanocoating to endow hydrophobic polymeric membranes with exceptional catalytic cleaning ability. Green hydrogen peroxide catalytically triggered in-situ cleaning of the mineralized membrane and enabled operando flux recovery to reach 99.8%. The mineralized membrane exhibited a 9-fold higher recovery compared to the unmineralized membrane, which is attributed to active catalytic antifouling coupled with passive hydration antifouling. Electron density differences derived from the precursor interaction during mediated mineralization unveiled an electron-rich bell-like structure with an inner electron-deficient Mn core. This work paves the way to construct multifunctional engineered materials for energy-efficient water treatment as well as for diverse promising applications in catalysis, solar steam generation, biomedicine, and beyond.

Porous organic polymers (POPs) for environmental remediation

Modern global industrialization along with the ever-increasing growth of the population has resulted in continuous enhancement in the discharge and accumulation of various toxic and hazardous chemicals in the environment. These harmful pollutants, including toxic gases, inorganic heavy metal ions, anthropogenic waste, persistent organic pollutants, toxic dyes, pharmaceuticals, volatile organic compounds, etc., are destroying the ecological balance of the environment. Therefore, systematic monitoring and effective remediation of these toxic pollutants either by adsorptive removal or by catalytic degradation are of great significance. From this viewpoint, porous organic polymers (POPs), being two- or three-dimensional polymeric materials, constructed from small organic molecules connected with rigid covalent bonds have come forth as a promising platform toward various leading applications, especially for efficient environmental remediation. Their unique chemical and structural features including high stability, tunable pore functionalization, and large surface area have boosted the transformation of POPs into various macro-physical forms such as thick and thin-film membranes, which led to a new direction in advanced level pollutant removal, separation and catalytic degradation. In this review, our focus is to highlight the recent progress and achievements in the strategic design, synthesis, architectural-engineering and applications of POPs and their composite materials toward environmental remediation. Several strategies to improve the adsorption efficiency and catalytic degradation performance along with the in-depth interaction mechanism of POP-based materials have been systematically summarized. In addition, evolution of POPs from regular powder form application to rapid and more efficient size and chemo-selective, "real-time" applicable membrane-based application has been further highlighted. Finally, we put forward our perspective on the challenges and opportunities of these materials toward real-world implementation and future prospects in next generation remediation technology.

Environmental energy enhanced solar-driven evaporator with spontaneous internal convection for highly efficient water purification

Solar-driven interfacial evaporation for water purification is limited by the structural design of the solar evaporator and, more importantly, by the inability to separate the water from volatile organic compounds (VOCs) present in the water source. Here, we report a three-dimensional (3D) bifunctional evaporator based on N-doped carbon (CoNC/CF), which enables the separation of fresh water from VOCs by activating PMS during the evaporation process with a VOC removal rate of 99%. There is abundant van der Waals interaction between peroxymonosulfate (PMS) and CoNC/CF, and pyrrolic N is confirmed as the active site for binding phenol, thus contributing to the separation of phenol from water. With the advantageous features of sufficient light absorption, adequate water storage capacity, and spontaneous internal convection flow on its top surface, the 3D evaporator achieves a high evaporation rate under one sun (1 kW/m2) at 3.16 kg/m2/h. More notably, through careful structural design, additional energy from the environment and water can be utilized. With such a high evaporation rate and satisfactory purification performance, this work is expected to provide a promising platform for wastewater treatment.

Electrically conductive membrane distillation via an alternating current operation for zero liquid discharge

Membrane distillation (MD) shows promise for achieving high salinity treatment and zero liquid discharge (ZLD) compared to conventional water treatment processes due to its unique characteristics, including low energy consumption and high resulting water quality. However, performance degradation due to fouling and scaling under high recovery conditions remains a challenge, particularly considering the need to control both cations and anions for maximum scaling mitigation. Accordingly, in this study, alternating current (AC) operation for electrically conductive membrane distillation (ECMD) is newly proposed, based on its potential for controlling both cations and anions, in contrast to conventional direct current (DC) operation. Systematic experiments and theoretical analysis show that water recovery in ECMD can be increased by 27% through AC operation. The proposed modification and effective AC operation of ECMD increase the practicality of using MD in desalination for a high recovery rate, perhaps even for ZLD.

Optimized Water Supply in a Solar Evaporator for Simultaneous Freshwater Production and Salt Recycle

Solar desalination has shown great potential in alleviating global water scarcity. However, the trade-off between energy efficiency and salt rejection remains a challenge, restricting its practical applications. In this study, we report a three-dimensional nitrocellulose membrane-based evaporator featuring a high evaporation rate (1.5 kg m-2 h-1) and efficient salt precipitation at the edges. Additionally, the salt is isolated from the photothermal area of the evaporator and falls automatically with a salt recovery rate of 97 g m-2 h-1 in brine with 10 wt % salt content. The distinctive performance is attributed to the precise water supply control, which was adjusted by changing the resistance force and driven force in the evaporator. With a high evaporation rate, stable performance, and specific salt recovery ability, this solar evaporation structure holds great potential in water desalination and resource recovery.

Two-dimensional MXene membranes with biomimetic sub-nanochannels for enhanced cation sieving

Membranes with high ion permeability and selectivity are of considerable interest for sustainable water treatment, resource extraction and energy storage. Herein, inspired by K+ channel of streptomyces A (KcsA K+), we have constructed cation sieving membranes using MXene nanosheets and Ethylenediaminetetraacetic acid (EDTA) molecules as building blocks. Numerous negatively charged oxygen atoms of EDTA molecules and 6.0 Å two-dimensional (2D) sub-nanochannel of MXene nanosheets enable biomimetic channel size, chemical groups and tunable charge density for the resulting membranes. The membranes show the capability to recognize monovalent/divalent cations, achieving excellent K+/Mg2+ selectivity of 121.2 using mixed salt solution as the feed, which outperforms other reported membranes under similar testing conditions and transcends the current upper limit. Characterization and simulations indicate that the cation recognition effect of EDTA and partial dehydration effects play critical roles in cations selective sieving and increasing the local charge density within the sub-nanochannel significantly improves cation selectivity. Our findings provide a theoretical basis for ions transport in sub-nanochannels and an alternative strategy for design ions separation membranes.

Influence of water quality factors on cake layer 3D structures and water channels during ultrafiltration process

The three-dimensional (3D) structure of the cake layer, which could be influenced by water quality factors, plays a significant role in the ultrafiltration (UF) efficiency of water purification. However, it remains challenging to precisely reveal the variation of cake layer 3D structures and water channel characteristics. Herein, we systematically report the variation in the cake layer 3D structure at the nanoscale induced by key water quality factors and reveal its influence on water transport, in particular the abundance of water channels within the cake layer. In comparison with pH and Na+, Ca2+ played more significant role in determining cake layer structures. The sandwich-like cake layer, which was induced by the asynchronous deposition of humic acids and sodium alginate (SA), shifted to an isotropic structure when Ca2+ was present due to the Ca2+ bridging. In comparison with the sandwich-like structure, the isotropic cake layer has higher fractions of free volume (voids) and more water channels, leading to a 147% improvement in the water transport coefficient, 60% reduction in the cake layer resistance, and 21% increase in the final membrane specific flux. Our work elucidates a structure-property relationship where improving the isotropy of the cake layer 3D structure is conducive to the optimization of water channels and water transport within cake layers. This could inspire tailored regulation strategies for cake layers to enhance the UF efficiency of water purification.

A Bilayered Wood-Poly(3,4-ethylenedioxythiophene):Polystyrene Sulfonate Hydrogel Interfacial Evaporator for Sustainable Solar-Driven Sewage Purification and Desalination

Solar-driven interfacial evaporation and purification is a promising solar energy conversion technology to produce clean water or solve water scarcity. Although wood-based photothermal materials have attracted particular interest in solar water purification and desalination due to their rapid water supply and great heat localization, challenges exist given their complicated processing methods and relatively poor stability. Herein, we propose a facile approach for fabricating a bilayered wood-poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (wood-PEDOT:PSS) hydrogel interfacial evaporator by direct drop-casting and dry-annealing. Benefiting from the unique combined merits of the wood-PEDOT:PSS hydrogel evaporator, i.e., excellent light absorption (~99.9%) and efficient photothermal conversion of nanofibrous PEDOT:PSS and the strong hydrophilicity and fast water transport from wood, the as-fabricated bilayered wood-PEDOT:PSS hydrogel evaporator demonstrates a remarkably high evaporation rate (~1.47 kg m-2 h-1) and high energy efficiency (~75.76%) at 1 kW m-2. We further demonstrate the practical applications of such an evaporator for sewage purification and desalination, showing outstanding performance stability and partial salt barrier capability against a continuous 10-day test in simulated seawater and an ultrahigh ion removal rate of 99.9% for metal ion-containing sewage. The design and fabrication of such novel, efficient wood-based interfacial evaporators pave the way for large-scale applications in solar water purification.