Increase In Water Permeability Research Articles

Cu-TCPP Metal-Organic Nanosheets Embedded Thin-Film Composite Membranes for Enhanced Cyanide Detection and Removal: A Multifunctional Approach to Water Treatment and Environmental Safety.

Cyanide is highly toxic, with widespread industrial use posing serious environmental risks. Effective materials for detecting and filtering cyanide from water are urgently needed. This study introduces a novel approach utilizing Cu-TCPP (TCPP = o-tetra(4-carboxyphenyl)porphine) metal-organic nanosheets (MONS) embedded in thin-film composite membranes, offering a multifunctional solution for cyanide detection and filtration. Ultrathin Cu-TCPP MONs were synthesized using a surfactant-assisted method featuring highly accessible metal centers that enhance cyanide interaction and detection. The membranes, developed by modifying cellulose acetate (CA) with Cu-TCPP MONs, demonstrated exceptional performance for cyanide removal. The 6% Cu-TCPP/CA membrane exhibited a 2.3-fold increase in pure water permeability and achieved a cyanide removal efficiency of 94.68%, significantly outperforming the pristine 0% Cu-TCPP/CA membrane (Pure Water Permeability (PWP) = 380.83 L m-2 h-1 bar-1; CN- removal = 5.01%). This is the first report describing the detection and removal of CN- in water using the membrane technique in literature. In addition to its removal efficiency, the Cu-TCPP MONs showed remarkable detection capabilities, with a calculated limit of detection of 1.76 × 10-7 M, surpassing World Health Organization (WHO) and United States Environmental Protection Agency (EPA) safety standards for cyanide levels in water. Additionally, Cu-TCPP MONs, a bioimaging agent with excellent cell viability, were deployed to detect CN- in MiaPaCa-2 cells, detecting concentrations as low as 0.1 ppm.

Highly Permselective Contorted Polyamide Desalination Membranes with Enhanced Free Volume Fabricated by mLbL Assembly.

The permeability-selectivity trade-off in polymeric desalination membranes limits the efficiency and increases the costs of reverse osmosis and nanofiltration systems. Ultrathin contorted polyamide films with enhanced free volume demonstrate an impressive 8-fold increase in water permeance while maintaining equivalent salt rejection compared to conventional polyamide membranes made with m-phenylenediamine and trimesoyl chloride monomers. The solution-based molecular layer-by-layer (mLbL) deposition technique employed for membrane fabrication sequentially reacts a shape-persistent contorted diamine monomer with a trimesoyl chloride monomer, forming highly cross-linked, dense polyamide networks while avoiding the kinetic and mass transfer limitations of traditional interfacial polymerization. The mLbL process allows precise nanoscale control over polyamide selective layer thickness, network structure, and surface roughness. The resulting controlled film thicknesses enable direct measurements of water and NaCl permeabilities. The permselectivities of contorted polyamide membranes surpass those of commercial desalination membranes and approach the reported polyamide upper bound. Solution-diffusion transport modeling indicates that this high permselectivity may be attributed to enhanced water transport pathways in the contorted polyamides that increase water diffusivity-permeability while maintaining high solute rejection through solubility-selectivity.

Development and Characterization of Potato Starch-Pectin-Based Active Films Enriched With Juniper Berry Essential Oil for Food Packaging Applications.

The increasing demand for sustainable food packaging has driven the development of films based on biopolymers. However, enhancing their functional properties remains a challenge. In the current study, potato starch-pectin (PSP) composite films were fabricated and enriched with juniper berry essential oil (JBEO) to improve their physicochemical properties. The effects of incorporating different concentrations of JBEO (0.1%-1% v/v) on various properties of PSP-based films were evaluated, including surface color, transparency, barrier properties, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA and DTA), antioxidant activity, and antimicrobial effectiveness. Increasing the level of JBEO led to a significant decrease in the moisture content, film transparency, and mechanical attributes, while an increase in thickness, water permeability, and film elongation was observed. SEM analysis also revealed morphological properties such as some spherical, bubble-like configuration and cracks on the surface due to an increase in JBEO concentration. TGA and DTA revealed lower weight loss in the initial cycles due to the addition of JBEO, and the thermal stability of the films improved. The antioxidant assays revealed a concentration-dependent increase in the radical scavenging capacity of the films from 11.31% to 17.28% for DPPH and from 3.06% to 25.53% for ABTS. Moreover, significant antibacterial and antifungal activity of the bioactive films was observed against P. aeruginosa, S. aureus, and C. albicans. These findings suggest that JBEO enhances the functional properties of PSP films, making them suitable for active food packaging applications.

Analysis of natural and technological factors of changes in exogeodynamic conditions of mine No. 2 of the Stebnytsky potassium deposit as a consequence of self-rehabilitation flooding

The Stebnytsy deposit of potash salts is located in the foothills of the Ukrainian Carpathians. The engineering-geological and hydrogeological conditions of the field’s operation due to the development of a thick layers of loose and water-soluble rocks are difficult of loose and water-soluble rocks are complex and therefore sensitive to mining-technological influences, extraction of rocks, deformation of the surface, hydrographic network, activation of the interaction of surface and groundwater. The most threatening situation was at mine No. 2, where in 1978, due to too intensive blasting, violation of waterproof layers, loosening and increase of water permeability, reduction of rock strength, an emergency breakthrough of super-saline waters occurred in the spent chambers of the first horizon. The total inflow of brines during the years of existence of the flow here constantly increased and reached up to 1700 m³/day, in 2002, the outflow of suprasaline waters developed in 22 points and acquired an irreversibly negative character, suffusion-diffusion processes began to develop actively. During the operation of the mine, ore extraction was carried out for a long time without laying out spent cavities, as a result of which more than 15 million m³ of unlined cavities were formed at the mine, the deformations of which disturbed the geodynamic regime of the salt-bearing massif with the subsequent development of sedimentary and karst-failure processes. In 2004, a comprehensive project for the conservation of mine No. 2 and the reclamation of disturbed lands was approved in order to restore the ecological balance in this area. Mine conservation works were carried out behind the design schedule, which led to the failure of the main provisions of the project and increased the danger due to the expansion of existing karst cavities and the formation of new ones. It can be argued that the works on the conservation of mine No. 2, including: preparation of brines, feeding them to underground mine workings, laying of chambers, etc., were carried out in a timely and incomplete manner, which does not ensure the cessation of negative consequences for the natural environment and ecological safety. The results of our research can be used in the future in the development of projects for the conservation or liquidation of salt mines.

Selective-layer polysulfone membranes based on unfunctionalized and functionalized MoS2/polyamide nanocomposite for water desalination.

Recently, reverse osmosis (RO) has become the most widely used process in membrane technology. It has aroused great interest in water desalination through membranes. According to recent studies, the surface properties of support layers in thin film membranes are crucial for improving reverse osmosis performance. Surface polymerization was used to produce the membranes in this work, with the polyamide acting as a selective layer on the polysulfone support film. Three membranes were produced with different proportions of molybdenum sulfide (MoS2) nanopowder. The effectiveness of the membranes was improved by increasing water permeability while maintaining excellent salt retention. All membranes produced were tested using various characterization methods including scanning electron microscope, Brunauer-Emmett plate, and zeta potential. The water permeability of the polyamide membrane with PA-MoS2 (0.015% w/v) was 29.79 L/m2 h bar, more than the PA-MoS2 membranes (0.005% w/v, 19.36 L/m2 h) and PA-MoS2 (0.01% w/v, 3.63 L/m2 h bar). Under the same conditions, salt rejection of more than 96.0% for NaCl and 97.0% for MgSO4 was also observed. According to the SEM, the 0.015% PA-MoS2 membrane exhibited lower surface roughness, greater hydrophobicity, and a higher water contact angle. Due to the hydrophobic nature of MoS2, these properties resulted in the lowest salt rejection.

Partitioning / Self-assembly of Artificial Water Channels - Toward Controlled Permselectivity through Bilayer Membrane.

Artificial water channels (AWCs) have been extensively explored to mimic natural proteins, which enables to effectively transport water while blocking ions. As one of the first AWCs, self-assembled I-quartets (HCx) have showcased high water-permselectivity that can be enhanced by improving their distribution and stability within membrane. The use of long alkyl chains (n>8) is constrained by their low solubility and aggregation. Herein, we considered cycloalkyl moieties, explored for the increase of the solubility favoring enhanced partition and/ for their self-assembly behaviors resulting the formation of effective stable water-channels with increased water permeability in bilayer membranes. This class of cycloalkyl-ureido-ethyl-imidazole amphiphilic (CxUH) channel could serve as a new reference for the effective design of self-assembled artificial water channels, it may give rise to the applications in desalination or in water treatment.

Partitioning / Self‐assembly of Artificial Water Channels – Toward Controlled Permselectivity through Bilayer Membrane

AbstractArtificial water channels (AWCs) have been extensively explored to mimic natural proteins, which enables to effectively transport water while blocking ions. As one of the first AWCs, self‐assembled I‐quartets (HCx) have showcased high water‐permselectivity that can be enhanced by improving their distribution and stability within membrane. The use of long alkyl chains (n>8) is constrained by their low solubility and aggregation. Herein, we considered cycloalkyl moieties, explored for the increase of the solubility favoring enhanced partition and/ for their self‐assembly behaviors resulting the formation of effective stable water‐channels with increased water permeability in bilayer membranes. This class of cycloalkyl‐ureido‐ethyl‐imidazole amphiphilic (CxUH) channel could serve as a new reference for the effective design of self‐assembled artificial water channels, it may give rise to the applications in desalination or in water treatment.

Impact of membrane surface and module damage on virus removal and integrity in RO membranes

RO membrane modules are very effective in removing viruses and salts, but concerns remain regarding their long-term integrity in full-scale RO spiral wound systems. Membrane defects can arise from delamination, chlorine, or abrasive particle exposure, and module defects can arise from permeate tube, O-ring, and glue line damage. These issues compromise the membrane and module's performance, allowing viruses to pass that are not detected by conductivity monitoring. This paper assesses the impact of damage on virus removal using biological indicators (natural virus markers (NV)) and non-biological surrogates (salt, sulfate, rhodamine WT, pyranine). Three categories of module damage were studied and characterized using different autopsy techniques: membrane module component damage (permeate tube damage, O-ring damage, and membrane delamination), oxidative membrane damage (by hypochlorite exposure dose), and membrane surface damage (by abrasive particle exposure). Module component damage resulted in increased water permeability and decreased natural virus rejection. The conductivity remained similar to that of an intact module except in the case of permeate tube damage. Chlorine exposure (9000 ppm.h) didn't result in detectable NV markers in the permeate, indicating an intact support layer despite active layer damage. Abrasive particle exposure by suspended silicon carbide in the feed resulted in scratches, observed by SEM images, and a decline in the rejection of fluorescent marker, which indicates membrane surface damage. Results demonstrate that NV markers most consistently determine virus removal capacity in modules compromised by component damage. However, for assessing active layer damage, solutes like rhodamine-WT and pyranine prove more effective. This underscores the necessity of employing multiple indicators for a comprehensive evaluation of membrane integrity.

7227 Acute Hyponatremia Following Initiation of Antidepressant in Patient on Desmopressin Treatment for AVP Deficiency

Abstract Disclosure: M.E. Horowitz: None. Y. Gao: None. S.B. Abraham: None. P. Kishore: None. Introduction: Intranasal desmopressin (DDAVP) is indicated as antidiuretic replacement therapy in arginine vasopressin (AVP) deficiency. It increases water permeability in the distal nephron, reducing urine output, increasing urine osmolality, and decreasing serum osmolality. Treatment is titrated to normalize serum sodium and urine output (UOP). Initiation of medications affecting sodium balance or fluid status may lead to abnormalities in these markers. One of these is escitalopram, an antidepressant which can cause hyponatremia attributed to inappropriate AVP secretion. We report a case of acute hyponatremia in a patient with previously stable sodium on chronic DDAVP who was started on escitalopram. Clinical Case: A 44-year-old female with history of a craniopharyngioma resection in 2007 complicated by AVP deficiency on chronic DDAVP, bipolar disorder, and depression presented with nausea, vomiting, and dizziness for two days. Patient was found to be hyponatremic to 118 mEq/L (135-145 mEq/L). Sodium checked one month prior was 135 mEq/L, and historically was never less than 130 mEq/L since 2008. DDAVP was prescribed since resection with few dose changes, at this time four 10mcg sprays in each nostril three times daily since 2020. Escitalopram 5mg daily was initiated two months prior. Desmopressin was held in the setting of hyponatremia, which resolved appropriately to 135 mEq/L over the first five days. During this time, the patient complained of large volume diuresis at ∼three liters daily. On day six, sodium acutely increased to 146 mEq/L; subcutaneous (SC) DDAVP was given and sodium normalized. UOP decreased significantly over the next 24 hours, but large volume diuresis resumed thereafter. On day 10, DDAVP SC was given, again decreasing UOP for 24 hours. Psychiatry recommended continuing escitalopram given improvement in psychiatric symptoms since initiation. Upon discharge, the patient was prescribed DDAVP two 10mcg sprays in each nostril nightly, a significant reduction compared to her prior dose. Sodium rechecked one week later remained within normal limits. Clinical Lessons: This effect of combination DDAVP and escitalopram has not been reported previously. Prescribers should be aware of the potential for hyponatremia and the need to adjust DDAVP dose in combined use. To avoid these risks in patients on chronic DDAVP, the side effects of antidepressants and antipsychotics should be reviewed prior to initiation. Presentation: 6/2/2024

Mechanisms determining water permeability and ion selectivity of multilayered glycine-functionalized graphene oxide membranes in saline water reverse osmosis processes: A computational investigation

Non-Equilibrium Molecular Dynamics simulations were performed to examine in detail the mechanisms involved in a reverse osmosis process for the removal of monovalent (Na+, Cl−) and divalent (Mg2+) ions from saline water, using multilayered glycine-functionalized graphene oxide (GO) membranes. We varied parameters such as the degree of functionalization of the GO flakes and the structural flexibility of the membranes and examined their performance in a wide range of applied pressure gradients. In all models examined, water permeability was found to be almost 2 orders of magnitude larger compared to that in conventional reverse osmosis (RO) membranes. High structural flexibility of the membranes was found to increase water permeability due to the formation of additional nanochannels that favor faster water transport. Functionalization of the GO flakes by the glycinate groups resulted in a decrease in water permeability due to the formation of a denser hydrogen-bonding network within the membranes. Three main mechanisms were identified regarding ion selectivity. Due to the overall negative charge of the membranes, the strong adsorption of the Mg2+ ions onto the GO flakes resulted in their full rejection. Weaker adsorption of the Na+ ions led only to their partial rejection. At the same time, the electrostatic repulsion of the Cl− ions by the membranes was found to result in almost full removal levels at high pressure gradients. The rejection of the monovalent ions was found to decrease with the structural flexibility of the membranes and increase with the functionalization of the GO flakes, in response to the changes observed in water permeability on these membrane modifications. The pressure-dependent deformability of the structurally flexible membranes combined with charge accumulation close to the membrane's entrance, resulted in a non-monotonic dependence of the monovalent ion rejection on the applied pressure difference.

The Effect of Water on Gas-Containing Coal with Cyclic Loading: An Experimental Study

In deep mining engineering, coal often is subjected to the influence of cyclic loading and water. In order to study the effect of water on gas-containing coal with cyclic loading, the pore evolution, permeability and energy dissipation of gas-containing coal under the effects of water and cyclic axial stress were analyzed in depth. The results showed that with the increase of water content, dissipation energy and permeability of coal samples decreased gradually. The presence of water weakened the increase in micropores and mesopores and promoted the increase in macropores during the cyclic loading process. Compared to dry coal samples, the ratio of micropores and mesopores in saturated coal samples decreased by 0.8872%, while the proportion of macropores increased by 0.0341%. On the basis of the above, a new formula for calculating the dissipation energy of gas-containing coal under the effects of water was proposed. A new damage variable based on energy dissipation was proposed. Finally, a theoretical model was derived to describe the permeability of gas-containing coal under the effects of water and cyclic axial stress.

High-Performance Nanofiltration Membrane with Dual Resistance to Gypsum Scaling and Biofouling for Enhanced Water Purification.

Nanofiltration (NF) technology is pivotal for ensuring a sustainable and reliable supply of clean water. To address the critical need for advanced thin-film composite (TFC) polyamide (PA) membranes with exceptional permselectivity and fouling resistance for emerging contaminant purification, we introduce a novel high-performance NF membrane. This membrane features a selective polypiperazine (PIP) layer functionalized with amino-containing quaternary ammonium compounds (QACs) through an in situ interfacial polycondensation reaction. Our investigation demonstrated that precise QAC functionalization enabled the construction of the selective PA layer with increased surface area, enhanced microporosity, stronger electronegativity, and reduced thickness compared to the control PIP membrane. As a result, the QAC NF membrane exhibited an approximately 51% increase in water permeance compared to the control PIP membrane, while achieving superior retention capabilities for divalent salts (>99%) and emerging organic contaminants (>90%). Furthermore, the incorporation of QACs into the PIP selective layer was proved to be effective in mitigating mineral scaling by allowing selective passage of scale-forming cations, while simultaneously exhibiting strong antimicrobial properties to combat biofouling. The in situ QAC incorporation strategy presented in this study provides valuable guidelines for the fit-for-purpose design of the selective PA layer, which is crucial for the development of high-performance NF membranes for efficient water purification.

Fabrication of ultra-permeable membranes with antibiofouling capability by incorporating bifunctionalized zeolite

Poor water permeance and biofouling significantly limit the application of nanofiltration (NF) membranes in wastewater treatment and seawater desalination. Herein, bifunctionalized FAU-Ag-OH zeolites, featuring abundant hydroxyl groups and silver ions on their surface, were designed and incorporated into polyamide (PA) layer of a thin-film nanocomposite (TFN) membrane, effectively enhancing the antibiofouling properties and water permeance of membrane. The plentiful hydroxyl groups and well-dispersed silver ions on the bifunctionalized FAU-Ag-OH zeolites impart the membrane with more negative surface charge, increased hydrophilicity, and superior antibiofouling property. Additionally, the doped FAU-Ag-OH zeolites can retard the diffusion of piperazine during interfacial polymerization (IP) process and have improved chemical compatibility with polymers, which results in desirable membrane structure. Consequently, the optimal M–0.05 membrane containing FAU-Ag-OH zeolites exhibited a 2.3-fold increase in water permeance (18.8 ± 2.0 L m−2 h−1 bar−1) and enhanced antibiofouling ability (with antibacterial efficiency up to 95.4 % and flux recovery ratio up to 85 %) compared with the TFC membrane. The successful fabrication of such membrane with enhanced antibiofouling properties and improved water permeance is expected to promote the application of NF membranes in water treatment.

Molecular Dynamics Simulations of the Eye Lens Water Channel Aquaporin 0 from Fish.

Aquaporin 0 (AQP0) plays a key role in water circulation in the eye lens through a variety of functions. In contrast to mammalian genomes, zebrafish contains two aqp0 genes leading to a separation of AQP0 multiple functions between the two gene products, Aqp0a and Aqp0b. A notable feature of the zebrafish AQP0 paralogs is the increased water permeability of Aqp0b relative to Aqp0a as well as a severa lfold increase relative to mammalian AQP0. Here, we report equilibrium molecular dynamics (MD) simulations on the microsecond timescale to identify the structural basis underlying the differences in water permeability between zebrafish AQP0 paralogs and between AQP0 mammalian and fish orthologs. Our simulations are able to reproduce the experimental trends in water permeability. Our results suggest that a substitution of a key Y23 residue in mammalian AQP0 for F23 in fish AQP0 orthologs introduces significant changes in the conformational dynamics of the CS-I structural motif, which, in conjunction with different levels of hydration of the channel vestibule, can account for the differences in permeabilities between fish and mammalian AQP0 orthologs and between zebrafish AQP0 paralogs.

Rational construction of positively charged polyamide nanofiltration membranes for precision cation separations

Nanofiltration has gained extensive attention in various energetically efficient separations towards a sustainable water–energy nexus. However, state-of-the-art polyamide nanofiltration membranes are constrained by the inherent trade-off between water permeance and solute selectivity, and a remarkable improvement in membrane permselectivity remains a big challenge. Here we conceived a density functional theory (DFT) assisted surface modification approach using triaminoguanidine hydrochloride (TGH) as the functional modifier to fabricate polyamide membranes with extremely high surface electropositivity and well-defined nanopores to overcome this challenge. Experimental data and DFT simulation results show that TGH surface modification can significantly manipulate surface charges and polarity to facilitate water permeation and enhance Donnan exclusion selectivity. Compared with the pristine benchmark membrane, the TGH-modified membrane exhibited a 4-fold increase in water permeance and a 6-fold increase in salt rejection, which successfully breaks the trade-off, excellent monovalent/divalent cation selectivity, and superior operational stability over a wide range of testing pressure, feed pH, and operation time, outperforming state-of-the-art membranes with similar chemistry. Taken together, this study demonstrates a feasible and reliable method combining DFT and experiments to rationally tailor the membrane characteristics at the molecular level, enabling the successful fabrication of effective polyamide nanofiltration membranes with precisely regulated structural and surface properties for water purification and precision ion separations.

Anionic COF nanosheets construct porous and charged interlayer for the preparation of high-performance desalination membranes

Polyamide (PA) membranes prepared by interfacial polymerization (IP) provide an effective solution for efficient desalination. The IP reaction, as a diffusion-controlled polymerization reaction, regulates the storage and diffusion of monomers in the IP process to achieve effective regulation of the PA membrane structure. Higher initial monomer concentration and slower monomer release rate can effectively reduce the membrane thickness and enhance the permeance of the membrane. Herein, ionic covalent organic framework (iCOF) materials with well-developed and ordered pore channels bearing high-density –SO3H groups are used to construct a porous and charged interlayer to regulate the release process of monomers during the IP process. The well-ordered pore structure of iCOF provides sufficient storage space for amine monomers and uniform monomer distribution, accelerating the closure of the incipient film. Moreover, the electrostatic interactions between the high density of negatively charged anionic groups on iCOF and the positively charged amine monomer can reduce the diffusion coefficient of the amine monomer by a factor of two. The above two effects resulted in a nearly 10-fold reduction in the thickness of the PA separation layer and an increase in water permeance up to 24.8 L m−2 h−1 bar−1, nearly three times improvement compared to unmodified PA membrane.

Modulating interfacial polymerization dynamics in nanostructured thin-film composite membranes: The role of polyvinylpyrrolidone and NaCl

Optimizing the performance of thin-film composite polyamide (TFC-PA) membranes is crucial for enhancing filtration efficiency across diverse applications. This study investigated the role of polyvinylpyrrolidone (PVP) in modulating the diffusion kinetics of piperazine (PIP) during the interfacial polymerization (IP) process, essential for membrane fabrication. By incorporating PVP into the aqueous phase, and combining it with selected inorganic salts such as sodium chloride (NaCl), the formation of a more controlled Turing-like nanostructure within the PA layer was achieved, significantly improving membrane permeability and structural uniformity. Employing molecular simulations alongside diverse characterization techniques, the mechanisms by which PVP and NaCl additives influence the diffusion of PIP monomers at the water-oil interface were elucidated. The optimized membranes demonstrated a substantial increase in water permeability, achieving 16.2 ± 0.9 L m−2 h−1 bar−1, and an impressive sodium sulfate (Na2SO4) rejection rate of 97.5 ± 0.6 %, outperforming untreated nanofiltration (NF) membranes. The findings provide a deeper understanding of the molecular interactions during IP and open avenues for the development of advanced filtration membranes with tailored properties.

Powering the Future Green Buildings: Multifunctional Ultraviolet-Shielding Transparent Wood.

Indoor UV damage is a serious problem that is often ignored. Common glasses cannot filter UV rays well and have fragility and environmental issues. UV-shielding transparent wood (TW) holds promise, yet striking the right balance between blocking UV rays and allowing sufficient visible-light transmission poses a challenge. The pronounced capillary force, fueled by persistent moisture and extractives in wood, alongside the existence of multiphase interfaces, collectively hinder the uniform penetration of polymers and the effective dispersion of nanomaterials within the wood skeleton. Here, we incorporate high-pressure supercritical CO2 fluid-assisted impregnation (HSCFI) into fabricating UV-shielding TW. The supercritical CO2 pretreatment efficiently eliminates moisture and refines wood structure by extracting polar substances, resulting in a prominent 52.4% increase in average water permeability. Subsequently, this HSCFI method facilitates the infiltration of methyl methacrylate (MMA) monomer and Ce-ZnO nanorods (NRDs) into the refined anhydrous wood, leveraging the excellent solvency of supercritical CO2 for MMA. The impregnation rate of PMMA undergoes a substantial increase from 34.5 to 59.1%. With the robust UV-blocking capability of Ce-ZnO NRDs, thanks to dual-valence Ce doping widening the ZnO energy gap via the Burstein-Moss effect and their unique photoactive microstructure featuring a solid prism with a sharp hexahedral pyramidal tip, along with intrinsic physical scattering/reflection actions, Ce-ZnO NRDs@TW achieves an impressive 99.6% UVA radiation blockage (the highest for TW) and maintains high visible-light transmission (83.2%). Furthermore, Ce-ZnO NRDs@TW presents favorable energy-saving, sound absorption, and antifungal abilities, making it a promising candidate for future green buildings.

Engineering shrinkage resistance of nano-structured hydrogels in seawater for fast uranium capture

Synthetic hydrogels, which are 3D networks composed of crosslinked hydrophilic polymer chains, have been created using various crosslinked ways for uranium capture due to full exposure of chelate functional groups. However, the conventional honeycomb-like hydrogels exhibit non-connected micropore structure, which locks abundant water molecules and hence is unfavorable for mass transfer. Herein, we demonstrate a simple synthesis of the nano-structured hydrogel with activated nanogels as nano-crosslinkers (denoted as PGP hydrogel), and probe into the relationship between hydrogel structural parameters and uranium adsorption kinetics. It is found that the PGP hydrogel with a low crosslinking density of ∼0.02 mol/m3 possesses interconnected micropores, thereby facilitating diffusion of uranyl ions (UO22+) in 3D polymeric networks. Furthermore, a freeze-assisted soaking strategy is proposed to endow PGP hydrogel (denoted as target hydrogel) with strong shrinkage resistance in natural seawater, resulting in a ∼40 % increase in water permeance to reach 369 Lm−2h−1MPa−1. Correspondingly, the adsorption equilibrium time is shortened to ∼11 days. Although the uranium uptake capacity of PGP hydrogels with and without freeze-assisted soaking treatment remain basically unchanged (∼9.73 mg-U/g-Ads), a high uranium adsorption rate of 0.88 mg/g/d for the target hydrogel surpasses most currently available polymer adsorbents. The presented strategy is generalizable to a broader range of applications involving the adsorption of economically valuable ions in seawater or brine lake.

On the role of the porous support membrane in seawater reverse osmosis membrane synthesis, properties and performance

In this study, we explore the role of the polysulfone (PSU) support membrane skin-layer and whole-body pore morphology on the physical-chemical properties and separation performance of hand-cast polyamide-PSU (PA-PSU) composite seawater reverse osmosis (SWRO) membranes. We tailor the support membrane pore morphology by varying the PSU concentration and the coagulation bath temperature. In order to isolate the impacts of the PSU support, all of the porous supports are coated using identical m-phenylene diamine (MPD) and trimesoyl chloride (TMC) solution compositions, reaction conditions, and post-treatments. As PSU concentration increases, PSU support membrane pore size, surface and body porosity, water permeability, MPD mass uptake (by the PSU support), and PA-PSU composite membrane water permeability decrease, while MPD and TMC conversion, PA film mass and thickness, crosslinking degree (XD), and PA-PSU composite membrane NaCl rejection increase. As PSU support membrane coagulation bath temperature increases, support membrane pore size, surface and body porosity, MPD uptake, PA film mass, thickness and XD, MPD and TMC conversion, and NaCl rejection increase, while composite PA-PSU membrane water and NaCl permeability decrease. Composite membrane permeabilities were 70–90 percent of the (theoretical) unsupported PA film permeabilities due to the high XD and low PA coating film thickness. Composite PA-PSU membrane water/salt permeabilities both correlate most strongly with PA coating film mass/thickness and XD, which in turn correlate most strongly with TMC conversion. The key to increasing water permeability is lower PA film mass/thickness and XD with higher support membrane surface pore size and porosity. In contrast, the key to increasing NaCl rejection is higher PA film mass/thickness and XD with lower support membrane surface pore size and porosity.