High Water Stability Research Articles

Chiral Layered Zinc Phosphonates: Exfoliation and Chiroptical Properties

Chiral layered coordination polymers have attracted considerable attention not only because of their intriguing physicochemical properties but also because of their ability to exfoliate into chiral nanosheets. Chiral metal phosphonates with layered structures are of particular interest due to their relatively high thermal and water stabilities, but their corresponding nanosheets are rarely reported on. Herein, we report on a pair of enantiopure zinc phosphonates with the formula S- and R-Zn8(cyampH)8Cl8 (S-Zn, R-Zn), where S- and R-cyampH2 represent S- and R-(1-cyclohexylamino)methylphosphonic acids. They have layered structures in which the {ZnO3Cl} tetrahedra are connected by {PO3C} tetrahedra via corner-sharing. By doping analogous chromophore ligands S- and R-(1-naphthalenethylamino)methylphosphonic acid (S-, R-nempH2), we obtained compounds S- and R-Zn8(cyampH)8-n(nempH)nCl8 (S-, R-Zn-x%, x = 2, 4, 6), which exhibited obvious circular dichroism (CD) and circularly polarized luminescence (CPL) properties. The bulk samples of S-Zn and S-Zn-4% were further subjected to exfoliation in acetone, resulting in chiral nanosheets of one–three-layer thicknesses.

Heterostructured Lanthanide Perovskite Nanoparticles with High Quantum Yield and Water Stability for Optical Information Storage

AbstractIn this study, heterostructured nanoparticles based on lanthanide double perovskite halide are innovatively proposed, which dramatically improved quantum yield and color purity, but the problem of water stability of perovskite materials has also been solved. The nanoparticles without surface ligands have excellent stability and optical properties when dispersed in water, and have higher color purity than those dispersed in organic solvents. Besides, the application potential is demonstrated and the practical performance is verified by preparing luminescent ink. This study provides a new strategy for the performance enhancement and application prospect of lanthanide double perovskite.

Removal of phenol from water using fenchol-menthol hydrophobic deep eutectic solvent

Hydrophobic deep eutectic solvents (HDESs) are regarded as a potential green alternative to conventional organic solvents in separation processes such as liquid-liquid extraction, due to their favourable properties, such as lower vapour pressure and tunable properties. The present work investigated the application of HDES which is synthesised from fenchol and menthol, in the removal of phenol from water. The HDES was synthesised experimentally at a fenchol mole fraction range of 0.1 to 0.9. The experimental results showed that stable liquidus HDES was successfully formed when the fenchol mole fraction in the HDES was 0.2 – 0.9. Further investigation showed that HDES with a fenchol mole fraction of 0.2, which had a low viscosity and high stability in water, had the highest phenol removal efficiency. The phenol removal process was highly sensitive to solution pH and solution-to-HDES ratio. In contrast, phenol removal was less affected by initial concentration and temperature. A high phenol removal efficiency of up to 95.9% was achieved in this study, which further showed the positive feasibility of HDES to serve as an alternative to conventional organic solvents in the liquid-liquid extraction of phenol from water.

Dual-linker Ir-Zr-MOF shows improved porosity to enhance aqueous sulfide photooxidation.

The hetero photooxidation of sulfide under aqueous conditions is of great importance in the green synthesis of sulfoxide. This process requires a type of solid photocatalyst with the properties of high porosity and water stability, as well as photosensitivity. Herein, a stable Ir-Zr-MOF material (compound 1) with high porosity is assembled from two linear linkers of a 2-phenylquinoline-4-carboxylic acid-Ir(III) complex (Irphen) and 4,4'-stilbenedicarboxylic acid (H2SDC), and a Zr6 cluster. 1 is isostructural to JLU-Liu34 with a composition of [Zr6O4.78(OH)3.22(SDC)3.82(Irphen)0.78TFA2.8]·2.8MeOH and permanent porosity with a BET surface area of 1507 m2 g-1. 1 exhibits improved activity for the photocatalytic aerobic oxidation of sulfide to sulfoxide via blue light irradiation under aqueous conditions. Mechanism studies demonstrate that a superoxide radical is the reactive oxygen species in the sulfide photooxidation. 1 can be readily recycled and reused at least 5 times without loss of catalytic activity. This work not only provides a good strategy for the assembly of an Ir(III) complex into MOFs but also an efficient method for the green synthesis of sulfoxide.

Self-Healing 2D Anion-Organic Frameworks for Low-Temperature Water Release.

Molecular frameworks have recently shown a great potential in atmospheric water harvesting, in which the water release at low temperatures is challenging. Anion-organic frameworks based on anion-coordination chemistry are presented herein to meet this challenge. These frameworks are prepared as tubular single crystals in pure water from the in-situ protonation and crystallization of pyridine-terminated triphenylamine derivatives with hydrochloric or hydrobromic acid. They possess a 2D honeycombed porous structure and carry halogen anions confined within 1D hexagonal nanochannels with a modular size of 1.7~2.3 nm. They exhibit a high water uptake of up to 0.87 g g-1 and a water release onset temperature as low as -90 oC. The water uptake and release induce significant changes in the crystal morphology and absorption and emission properties of these framework crystals, providing a visual indication of their hydration states over a wide temperature range. The kinetics of dehydration at subglacial temperatures is successfully determined by emission spectral shifts. These framework crystals show a high water-stability and can be used for repeated water capture and release thanks to a rapid and robust self-healing capability. This discovery opens opportunities for the design and synthesis of flexible and self-healing frameworks for porosity-related applications.

Low Evaporation Enthalpy Ionic Covalent Organic Frameworks for Efficient Atmospheric Water Harvesting at Low Humidity.

Herein, we introduce a series of ionic covalent organic frameworks (iCOFs) with a focus on addressing the challenge of water collection at low relative humidity levels below 25%. These iCOFs are characterized by numerous hydrophilic sites and high water stability, enabling efficient water vapor adsorption even at relatively low humidity levels. Through the use of various hygroscopic salt cations and precise control of ion concentration within the pores, the water state within the iCOFs pores can be effectively managed. Among the iCOFs, TB-COF-Li stands out with an impressive adsorption capacity of 0.24 g g-1 from 0 to 22% RH. Notably, due to its ionic porous structure, TB-COF-Li exhibits a significantly lower enthalpy of evaporation, measured at 967.04 J g-1, compared to bulk water with an enthalpy of 2387.4 J g-1. Moreover, under simulated conditions of 1.5 solar intensity at 60 °C, the majority of the adsorbed water can be rapidly desorbed without the need for additional energy input. This efficient desorption process contributes to a high water collection rate of 0.092 g g-1 h-1 in the final atmospheric water harvesting device. The development of these iCOFs offers a promising and cost-effective solution for obtaining fresh water in arid regions.

Low Evaporation Enthalpy Ionic Covalent Organic Frameworks for Efficient Atmospheric Water Harvesting at Low Humidity

Herein, we introduce a series of ionic covalent organic frameworks (iCOFs) with a focus on addressing the challenge of water collection at low relative humidity levels below 25%. These iCOFs are characterized by numerous hydrophilic sites and high water stability, enabling efficient water vapor adsorption even at relatively low humidity levels. Through the use of various hygroscopic salt cations and precise control of ion concentration within the pores, the water state within the iCOFs pores can be effectively managed. Among the iCOFs, TB‐COF‐Li stands out with an impressive adsorption capacity of 0.24 g g‐1 from 0 to 22% RH. Notably, due to its ionic porous structure, TB‐COF‐Li exhibits a significantly lower enthalpy of evaporation, measured at 967.04 J g‐1, compared to bulk water with an enthalpy of 2387.4 J g‐1. Moreover, under simulated conditions of 1.5 solar intensity at 60 °C, the majority of the adsorbed water can be rapidly desorbed without the need for additional energy input. This efficient desorption process contributes to a high water collection rate of 0.092 g g‐1 h‐1 in the final atmospheric water harvesting device. The development of these iCOFs offers a promising and cost‐effective solution for obtaining fresh water in arid regions.

Lignin-Furanic Rigid Foams: Enhanced Methylene Blue Removal Capacity, Recyclability, and Flame Retardancy.

Worldwide, populations face issues related to water and energy consumption. Water scarcity has intensified globally, particularly in arid and semiarid regions. Projections indicate that by 2030, global water demand will rise by 50%, leading to critical shortages, further intensified by the impacts of climate change. Moreover, wastewater treatment needs further development, given the presence of persistent organic pollutants, such as dyes and pharmaceuticals. In addition, the continuous increase in energy demand and rising prices directly impact households and businesses, highlighting the importance of energy savings through effective building insulation. In this regard, tannin-furanic foams are recognized as promising sustainable foams due to their fire resistance, low thermal conductivity, and high water and chemical stability. In this study, tannin and lignin rigid foams were explored not only for their traditional applications but also as versatile materials suitable for wastewater treatment. Furthermore, a systematic approach demonstrates the complete replacement of the tannin-furan foam phenol source with two lignins that mainly differ in molecular weight and pH, as well as how these parameters affect the rigid foam structure and methylene blue (MB) removal capacity. Alkali-lignin-based foams exhibited notable MB adsorption capacity (220 mg g-1), with kinetic and equilibrium data analysis suggesting a multilayer adsorption process. The prepared foams demonstrated the ability to be recycled for at least five adsorption-desorption cycles and exhibited effective flame retardant properties. When exposed to a butane flame for 5 min, the foams did not release smoke or ignite, nor did they contribute to flame propagation, with the red glow dissipating only 20 s after flame exposure.

Study on performance deterioration of asphalt and asphalt mixtures containing Mafilon under internal salt freeze–thaw cycles

The purpose of this work is to determine the implications of internal salt freeze–thaw cycles (F–TCs) on performance deterioration to asphalt and asphalt mixtures containing Mafilon (MFL). The deterioration to different numbers of F–TCs and different MFL contents on asphalt properties and mechanism were investigated by physical properties tests and microcosmic tests. Then the damages of road performance indexes of asphalt mixtures containing different MFL contents were studied by road performance tests. The experimental results show that asphalt containing MFL after F–TCs has a remarkable decline in ductility and penetration, while growth in softening point. Internal salt F–TCs are most damaging to the cryogenic properties of asphalt. Chemical reactions and salt aging effects occur in salt F–TCs, raising the glass transition temperature of asphalt. Road performance tests indicate the deterioration of internal salt F–TCs to high temperature stability and water stability is the most pronounced, with 29.18% and 21.78% reduction, respectively.

Adsorption behavior of zirconium metal–organic frameworks in multicomponent metal-ion solutions

Abstract In this study, the adsorptive behavior of zirconium metal–organic frameworks (Zr-MOFs) was investigated for the adsorption of alkali and alkaline earth metal ions from multi-element aqueous solutions. Zr-MOFs exhibit high water stability, notable surface area, and a significant pore volume, all of which contribute to their enhanced adsorption capacity. Three Zr-MOFs, namely bare UiO-66, amine-functionalized NH2-UiO-66, and carboxyl-functionalized UiO-66-(COOH)2, were tested for the adsorption of alkali and alkaline earth metal ions. Among the 3 MOFs that were tested, only the carboxyl group-functionalized Zr-MOF showed significant adsorption capacity toward divalent metal ions. Further, a thorough investigation was conducted to understand how the pH, initial concentration of the solution, and Zr-MOF dosage impact the adsorption properties of UiO-66-(COOH)2. At the natural pH (6.5) of the solution, UiO-66-(COOH)2 exhibited a superior adsorption capacity toward Sr2+ (15.3 mg g−1) and Ca2+ (7.9 mg g−1), which was attributable to the stronger electrostatic attraction of these ions relative to monovalent ions. The kinetic study results indicated that the preferred mechanism of adsorption was chemisorption for divalent metal ions. Additionally, the adsorption behavior of UiO-66-(COOH)2 for 24 elements was evaluated and the MOF showed significant adsorption of Sr2+ and Ca2+ alongside other divalent and trivalent metal ions. The experimental findings of the present study suggest that carboxylic-functionalized Zr-MOF holds significant potential toward the preparation of suitable sorbents for the extraction of higher-valence metal ions.

Computational Analysis of Amine Functionalization in Zwitterionized Polyether Sulfone Dialysis Membranes.

Hemodialysis is a critical treatment for patients with end-stage renal disease (ESRD) who lack kidney transplant options. The compatibility of hemodialysis membranes is vital, as incompatibility can trigger inflammation, coagulation, and immune responses, potentially increasing morbidity and mortality among patients with ESRD. This study employed molecular dynamics simulation (MDS) and molecular docking to assess the hemocompatible properties of Polyether Sulfone (PES) membranes modified via two distinct amine functionalization techniques. The molecular docking results demonstrated that side amine functionalization exhibited a lower affinity energy (-7.6) for fibrinogen compared to the middle amine functionalization (-8.2), suggesting enhanced antifouling properties and superior hemocompatibility. Additionally, side amine functionalization formed hydrogen bonds with four amino acids, enhancing its resistance to protein adhesion compared to three amino acids in the middle amine structure. Furthermore, the molecular dynamics simulations revealed differences in water mobility, with the side amine functionalized membranes showing a lower mobility value (9.74 × 10-7) than those treated with the middle amine method (9.85 × 10-7), indicating higher water stability and potentially better patient outcomes. This study's findings contribute to the design of more efficient and safer hemodialysis treatments by optimizing membrane materials.

High-Sensitivity Refractive Index Sensing Based on an SNPNS Composite Structure

In this paper, we design and demonstrate an all-fiber-sensitive refractive index (RI) sensor based on the Mach–Zehnder interferometer (MZI). It is constructed by splicing two no-core fibers (NCFs) and a photonic crystal fiber (PCF) between two single-mode fibers (SMFs) to obtain an SMF–NCF–PCF–NCF–SMF composite structure (SNPNS). A study of the effect of varying PCF lengths on the RI reveals that the shorter the length, the higher the sensitivity. The maximum RI sensitivity of 176.9 nm/RIU is attained within the RI range of 1.3365–1.3767 when the PCF length in the SNPNS structure is 3 cm. Meanwhile, the sensor exhibits a high stability in water, with an RSD of only 0.0019% for the interference trough over a duration of two hours. This proposed sensing structure offers the advantages of a large extinction ratio, small size, low temperature sensitivity, and simple fabrication, exhibiting a great potential in RI measurements.

Reconstructed wood with high water stability from bark cellulose and corncob lignin

Natural wood has been highly valued for thousands of years due to its excellent strength, low density, and ease of processing. However, its poor water stability, which leads to swelling and deformation, limits its competitiveness. In response, we designed a reconstructed wood through a process involving pretreatment, TEMPO oxidation, lignin self-assembly, lignin melting, and densification. In this material, cellulose serves as the skeleton, while lignin with a phenylpropyl structure acts as both a filler and binder. The resulting wood exhibits outstanding water stability, with no changes after 60 days of water immersion and a water absorption rate as low as 8.32 %. This stability is achieved through the densification of lignin, which is enhanced by lignin melting and pressure during self-assembly. The reconstructed wood not only offers excellent water stability but also boasts superior UV resistance and thermal stability. Additionally, it can be hot-pressed into straws within a mold, providing better water stability and tensile strength compared to paper straws. This reconstructed wood, made from natural wood and corncob, is biodegradable and environmentally friendly, offering a new approach to wood water stability strategies.

Reaction Time Induced a Two-Step Dissolution and Recrystallization Structural Transformation with Three Eu Metal-Organic Frameworks: Crystal Structures and Multiresponsive Fluorescence Detection.

Under solvothermal conditions, three 3D lanthanide metal-organic frameworks (Ln-MOFs): [Eu(H2DHTA)1.5(DMF)2]·DMF (1), [Eu(H2DHTA)0.5(DHTA)0.5(DMF)(H2O)]·2H2O (2), and Eu(HCOO)3 (3) (H4DHTA = 2,5-dihydroxyterephthalic acid) have been synthesized by different reaction times. Interestingly, induced by reaction time, compounds 1-3 underwent a two-step dissolution and recrystallization structural transformation (DRST) reaction. Investigations on the DRST processes were carried out, and the transformation pathway was deduced, which was verified by XRD analyses. Notably, compound 2 demonstrates pronounced luminescence as well as high stability in water and other organic solvents. The fluorescent detection of furan antibiotics can serve as turn-off effects, and glutamic acid (Glu), aspartic acid (Asp), and riboflavin (VB2) can serve as the turn-on effect. To explain the enhancing and quenching mechanisms, XRD, UV-visible absorption spectroscopy, electrochemistry, IR spectra, theoretical calculation, fluorescence lifetimes, and XPS were discussed. Additionally, MOF-coated test strips were utilized to detect these analytes, exhibiting excellent agreement with fluorescence spectroscopy. This work provides an example for more effective designs to employ Ln-MOFs as multiresponsive fluorescent sensors for detection of environmental pollutants in aqueous solution.

Design of Mixed-Metal MOF-74-MgNi for Water Adsorption-Driven Solar Thermal Energy Storage and Heat Transformation Applications.

Adsorption solar thermal energy storage and heat transformation are ecologically benign and energy-efficient technologies. Efficient adsorbents are the key to this technology. In this paper, two metal ions, Mg2+ and Ni2+, were introduced into the metal-organic framework MOF-74. The synthesis conditions were adjusted to obtain MOF-74 with a high water adsorption capacity and stability. The results show that MOF-74-MgNi-2 has the maximum water adsorption capacity. At a low moisture pressure P/P0 = 0.1, its water adsorption capacity is 0.44 g/g, 0.12 g/g, and 0.10 g/g greater than that of MOF-74-Mg and MOF-74-Ni, respectively. Its saturated water adsorption capacity at P/P0 = 0.9 is as high as 0.62 g/g, which is 1.3 times that of MOF-74-Ni and 1.1 times that of MOF-74-Mg, respectively. Its superior water adsorption capacity is explained by the combination of experiment and molecular simulation, which takes into account the pore structure and electrostatic potential energy distribution. Its thermal breakdown temperature is greater than 250 °C. Its water adsorption capacity decreases by only 9.0% in the 10th cycle. Under conventional refrigeration conditions, its refrigeration coefficient and working capacity are 0.75 and 0.43 cm3/cm3, respectively, which are greater than those of the majority of the regularly used adsorbents. In addition, it satisfies the primary technological goals of adsorption-based thermal batteries with a heat storage capacity of up to 1394 kJ/kg. The mixed-metal method is shown to be useful in the design of high-performance MOF-74 for solar thermal energy storage and heat transformation.

8-Hydroxyquinoline incorporated ZIF-8 nanocomposites for efficient decomposition and detection of manganese ions in aquatic environments

The presence of potassium permanganate in aquatic environment poses a significant issue that requires resolution. In response, zeolitic imidazolate framework nanoparticles with large pore sizes, extensive surface areas, and high chemical stability in water were synthesized. Subsequently, 8-hydroxyquinoline was incorporated into ZIF-8 (named 8-HQ@ZIF-8) to enhance its capability to decompose potassium permanganate in aquatic environment. The synthesized material underwent thorough characterization using powder X-ray diffraction, Fourier-transform infrared spectroscopy, nitrogen isothermal adsorption-desorption at 77 K, thermogravimetric analysis, and scanning electron microscopy. Electrical conductivity tests revealed that the 8-HQ@ZIF-8 material can decompose potassium permanganate within 5 min and be recycled over five runs. Furthermore, the nanocomposite of 8-HQ and ZIF-8 exhibited greater stability than the original ZIF-8 under strong oxidizing conditions. This suggests that functionalizing with organic ligands can enhance the durability and performance of the material. In addition to its degradability, the 8-HQ@ZIF-8 material, which carries manganese oxide, also displays variable fluorescence properties, making it a potential sensor for detecting residual potassium permanganate in drinking water treatment systems. Therefore, the 8-HQ@ZIF-8 material shows considerable promise for both the treatment and detection of pollutants in aquatic environments.

The influence of acid rain on asphalt and its mixture performance, simulation and micro-mechanism exploration

Acid rain will destroy asphalt roads and affect human production and life. Therefore, this study has designed a new indoor simulated acid rain erosion test, and explored the effects of acid rain on the properties of 70# petroleum asphalt, SBS asphalt and their mixtures and the acid rain erosion mechanism from the micro and macro perspectives. In this paper, the influence of acid rain erosion on the microscopic properties of asphalt has been revealed through microscopic experiments. Through the combination with the basic performance test of asphalt, the effect of acid rain erosion on the conventional properties of asphalt was studied. The effects of acid rain on the properties of road asphalt mixtures were studied by Marshall immersion and high-temperature rutting tests. The results show that there is no obvious chemical reaction between the two kinds of asphalt after acid rain erosion, but the surface structure and morphology have changed significantly. There was a mass loss, the decreases of the softening point and ductility, and an increase of the penetration; the residual stability and high temperature resistance of both asphalt mixtures were reduced. In the worst case, the quality of petroleum asphalt was lost by 82.2%, the softening point and ductility decreased by 9.6% and 16.9% respectively, the penetration degree increased by 3.1% and the residual stability and dynamic stability of petroleum asphalt mixture decreased by 8.82% and 27.9% respectively. The mass loss of SBS asphalt was 82.5%, the softening point and ductility decreased by 5% and 3.3% respectively, the penetration increased by 2.6%, and the residual stability and dynamic stability of SBS asphalt mixture decreased by 4.82% and 25.4% respectively. In general, under the action of acid rain, the performance of 70# oil asphalt, SBS asphalt and their mixtures are affected to varying degrees. The specific performance is to destroy the original shape of asphalt, resulting in the loss of quality of asphalt, the reduction of deformation resistance, high temperature stability and low temperature stability of asphalt, weakening the high temperature stability and water stability of asphalt mixture, and leading to the decline of road performance.

Chemical-free fabrication of silk fibroin microspheres with silk I structure

Silk fibroin (SF) microspheres show bright prospects for biomedical applications, such as microcarriers, drug delivery, tumor embolization agents, and microscaffolds. However, the chemistry-independent preparation of SF microspheres, which is critical to biomedical applications, has been challenging. In this study, the SF microspheres with silk I crystal type were generated by using electrostatic spraying and freezing-induced assembly. The SF solution was sprayed into liquid nitrogen to form frozen microspheres with tunable size. Annealing can crystallize frozen SF to form silk I crystal type, providing a green approach to harvest water-insoluble microspheres. The SF microspheres can retain a monolithic shape in water for up to 30 days, while having a 77 % degradation ratio in PBS in 14 days, showing high stability in water and rapid degradation under physiological conditions. The biomedical application prospects of the silk I microspheres were demonstrated by cell culture and small molecule drugs (doxorubicin). The microspheres can support the growth and expansion of mammalian cells, and provide a sustainable release for DOX with 10 days. This strategy offers a green approach that avoids the use of organic solvents and cross-linkers for designing SF microsphere biomaterials.

Antihepatoma activity of Marsdenia tenacissima polysaccharide-decorated selenium nanoparticles by regulating the Bax/Bcl-2/caspases and p21/Akt/cyclin A2 signaling pathways

Combining selenium nanoparticles (SeNPs) with bioactive polysaccharides is one of the effective ways to overcome the shortcomings of SeNPs and polysaccharides and obtain novel antitumor drug candidates. In this study, a heteropolysaccharide (MTP70) with moderate antihepatoma activity was isolated from the stems of Marsdenia tenacissima (Roxb.) Wight et Arn. To further improve the antihepatoma activity of MTP70 and the application of SeNPs, a novel stable nanoparticle (MTP-SeNP) was designed and fabricated. MTP-SeNPs (Se content of 8.25 %) were characterized as monodisperse spherical nanoparticles (50 nm) with MTP70 wrapped on the surface of the SeNPs by the formation of CO⋯Se bonds and possessed high stability and good dispersion in water for almost a month. In addition, MTP-SeNPs showed higher inhibitory effect compared with MTP70. MTP-SeNPs could effectively inhibit the proliferation, invasion, and metastasis of HepG2 cells by inducing apoptosis and arresting the cell cycle at the S phase, which were closely related to the activation of the Bax/Bcl-2/Caspases and p21/Akt/Cyclin A2 signaling pathways. Our results provide a theoretical basis for further development and application of M. tenacissima polysaccharide, and show that MTP-SeNPs could be explored as a promising anti-hepatoma agent in the pharmaceutical and biomedical industries.

Supramolecular Ionic Nanomaterials via Ionic Self-Assembly with High Thermal and Water Stability for the Detection of Trinitrophenol

Supramolecular Ionic Nanomaterials via Ionic Self-Assembly with High Thermal and Water Stability for the Detection of Trinitrophenol