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In this work, the effects of finite size on the determination of the three-phase coexistence temperature (T3) of the carbon dioxide (CO2) hydrate have been studied by molecular dynamic simulations and using the direct coexistence technique. According to this technique, the three phases involved (hydrate–aqueous solution–liquid CO2) are placed together in the same simulation box. By varying the number of molecules of each phase, it is possible to analyze the effect of simulation size and stoichiometry on the T3 determination. In this work, we have determined the T3 value at 8 different pressures (from 100 to 6000 bar) and using 6 different simulation boxes with different numbers of molecules and sizes. In two of these configurations, the ratio of the number of water and CO2 molecules in the aqueous solution and the liquid CO2 phase is the same as in the hydrate (stoichiometric configuration). In both stoichiometric configurations, the formation of a liquid drop of CO2 in the aqueous phase is observed. This drop, which has a cylindrical geometry, increases the amount of CO2 available in the aqueous solution and can in some cases lead to the crystallization of the hydrate at temperatures above T3, overestimating the T3 value obtained from direct coexistence simulations. The simulation results obtained for the CO2 hydrate confirm the sensitivity of T3 depending on the size and composition of the system, explaining the discrepancies observed in the original work by Míguez et al. [J. Chem Phys. 142, 124505 (2015)]. Non-stoichiometric configurations with larger unit cells show a convergence of T3 values, suggesting that finite-size effects for these system sizes, regardless of drop formation, can be safely neglected. The results obtained in this work highlight that the choice of a correct initial configuration is essential to accurately estimate the three-phase coexistence temperature of hydrates by direct coexistence simulations. [ABSTRACT FROM AUTHOR]

We determine the surface tension of aqueous electrolyte solutions in contact with non-polar dielectric media using a thermomechanical approach, which involves deriving the stress tensor from the thermodynamic potential of an inhomogeneous fluid. To obtain the surface tension, we calculate both the normal and tangential pressures using the components of the stress tensor, recently derived by us [Y. A. Budkov and P. E. Brandyshev, J. Chem. Phys. 159, 174103 (2023)] within the framework of Wang's variational field theory. Using this approach, we derive an analytical expression for the surface tension in the linear approximation. At low ionic concentrations, this expression represents the classical Onsager–Samaras limiting law. By utilizing only one fitting parameter, which is related to the affinity of anions to the dielectric boundary, we successfully approximated experimental data on the surface tension of several aqueous electrolyte solutions. This approximation applies to both the solution–air and solution–dodecane interfaces, covering a wide range of electrolyte concentrations. [ABSTRACT FROM AUTHOR]

Developing highly efficient methane (CH4) hydrate storage methods and understanding the hydrate dissociation kinetics can contribute to advancing CH4 gas storage and transport. The effects of tetrabutylammonium bromide (TBAB) (a thermodynamic promoter) addition on the kinetics of CH4 hydrate were evaluated on the microscopic scale using synchrotron x-ray computed tomography (CT) and powder x-ray diffraction. Microscopic observations showed that a 5 wt. % TBAB solution facilitated the nucleation of CH4 hydrate owing to the initial growth of TBAB semi-clathrate hydrate particles. The CH4 hydrate crystals in the CH4 + TBAB hydrate sample were sponge-like with many internal pores and exhibited slightly enhanced self-preservation compared to the pure CH4 hydrate, both in the bulk and after pulverization to a fine powder. This study demonstrates the feasibility of controlling the rate of CH4 hydrate formation and preservation by using aqueous TBAB solutions in CH4 hydrate formation. [ABSTRACT FROM AUTHOR]

Semiconductor nanocrystals (NCs) can function as efficient gain materials with chemical versatility because of their surface ligands. Because the properties of NCs in solution are sensitive to ligand–environment interactions, local chemical changes can result in changes in the optical response. However, amplification of the optical response is technically challenging because of colloidal instability at NC concentrations needed for sufficient gain to overcome losses. This paper demonstrates liquid lasing from plasmonic lattice cavities integrated with ligand-engineered CdZnS/ZnS NCs dispersed in toluene and water. By taking advantage of calcium ion-induced aggregation of NCs in aqueous solutions, we show how lasing threshold can be used as a transduction signal for ion detection. Our work highlights how NC solutions and plasmonic lattices with open cavity architectures can serve as a biosensing platform for lab-on-chip devices. [ABSTRACT FROM AUTHOR]

The nucleation of ice from aqueous solutions is a process essential to myriad environmental and industrial processes, but the physical factors affecting the capacity of different solutes to depress the homogeneous nucleation temperature of ice are yet poorly understood. In this work, we demonstrate that for many binary aqueous solutions of non-ionic solutes, this depression is dominated by the entropy of the liquid phase. Employing the classic Turnbull interpretation of the interfacial free energy γ ∼ T S l i q u i d − S s o l i d and estimating solution entropies with a Flory-style modification of the ideal entropy of mixing that accounts for solute size effects, we demonstrate that mixing entropy alone predicts experimental homogeneous nucleation temperatures across a wide variety of non-ionic solutions. We anticipate that this physical insight will not only enhance a fundamental understanding of homogeneous nucleation processes across fields but also open new avenues to the rational design of aqueous solutions for desired nucleation behaviors. [ABSTRACT FROM AUTHOR]

Experimental and theoretical advances for understanding the temperature of maximum density (TMD) of aqueous solutions are outlined. The main equations that relate the TMD behavior to key thermodynamic properties are stated. The experimental TMD data are classified as a function of the nature of the solute (inorganic electrolytes, non-electrolytes, organic salts and ionic liquids, and amino acids and proteins). In addition, the experimental results that explore the effect of pressure are detailed. These experimental data are rationalized by making use of qualitative and semi-quantitative arguments based on the thermodynamics of aqueous systems. The main theoretical and simulation advances in TMD for aqueous solutions are also shown—including new calculations in the context of the scaled particle theory—and their ability to reproduce the experimental data is evaluated. Finally, new experiments and theoretical and simulation developments, which could give important insights into the problem of TMD for aqueous solutions, are proposed. [ABSTRACT FROM AUTHOR]

In this work, we determine the dissociation line of the nitrogen (N2) hydrate by computer simulation using the TIP4P/Ice model for water and the TraPPE force field for N2. We use the solubility method proposed recently by some of us to evaluate the dissociation temperature of the hydrate at different pressures, from 500 to 1500 bar. Particularly, we calculate the solubility of N2 in the aqueous solution when it is in contact with a N2-rich liquid phase and when in contact with the hydrate phase via planar interfaces as functions of temperature. Since the solubility of N2 decreases with temperature in the first case and increases with temperature in the second case, both curves intersect at a certain temperature that determines the dissociation temperature at a given pressure. We find a good agreement between the predictions obtained in this work and the experimental data taken from the literature in the range of pressures considered in this work. From our knowledge of the solubility curves of N2 in the aqueous solution, we also determine the driving force for nucleation of the hydrate, as a function of temperature, at different pressures. In particular, we use two different thermodynamic routes to evaluate the change in chemical potential for hydrate formation. Although the driving force for nucleation slightly decreases (in absolute value) when the pressure is increased, our results indicate that the effect of pressure can be considered negligible in the range of pressures studied in this work. To the best of our knowledge, this is the first time the driving force for nucleation of a hydrate that exhibits crystallographic structure sII, along its dissociation line, is studied from computer simulation. [ABSTRACT FROM AUTHOR]

Concentrated ionic aqueous electrolytes possess a diverse array of applications across various fields, particularly in the field of energy storage. Despite extensive examination, the intricate relationships and numerous physical mechanisms underpinning diverse phenomena remain incompletely understood. Molecular dynamics simulations are employed to probe the attributes of aqueous solutions containing LiCl, NaCl, KCl, MgCl2, and CaCl2, spanning various solute fractions. The primary emphasis of the simulations is on unraveling the intricate interplay between these attributes and the underlying physical mechanisms. The configurations of cation-Cl− and Cl−–Cl− pairs within these solutions are disclosed. As the solute fraction increases, consistent trends manifest regardless of solute type: (i) the number of hydrogen bonds formed by the hydration water surrounding ions decreases, primarily attributed to the growing presence of counter ions in proximity to the hydration water; (ii) the hydration number of ions exhibits varying trends influenced by multiple factor; and (iii) the diffusion of ions slows down, attributed to the enhanced confinement and rebound of cations and Cl− ions from the surrounding atoms, concurrently coupled with the changes in ion vibration modes. In our analysis, we have, for the first time, clarified the reasons behind the slowing down of the diffusion of the ions with increasing solute fraction. Our research contributes to a better understanding and manipulation of the attributes of ionic aqueous solutions and may help designing high-performance electrolytes. [ABSTRACT FROM AUTHOR]

We perform molecular dynamics simulations of TIP4P/Ice water in solution with trehalose for 3.65 and 18.57 wt. % concentrations and of bulk TIP4P/Ice water at ambient pressure, to characterize the structure and dynamics of water in a sugar aqueous solution in the supercooled region. We find here that TIP4P/Ice water in solution with trehalose molecules follows the Mode Coupling Theory and undergoes a fragile to strong transition up to the highest concentration investigated, similar to the bulk. Moreover, we perform a Mode Coupling Theory test, showing that the Time Temperature Superposition principle holds for both bulk TIP4P/Ice water and for TIP4P/Ice water in the solutions and we calculate the exponents of the theory. The direct comparison of the dynamical results for bulk water and water in the solutions shows upon cooling along the isobar a fastening of water dynamics for lower temperatures, T < 240 K. We found that the counter-intuitive behavior for the low temperature solutions can be explained with the diffusion anomaly of water leading us to the conclusion that the fastening observed below T = 240 K in water dynamics is only fictitious, due to the fact that the density of water molecules in the solutions is higher than the density of the bulk at the same temperature and pressure. This result should be taken into account in experimental investigations which are often carried out at constant pressure. [ABSTRACT FROM AUTHOR]

CO2 and CH4 hydrates are of great importance both from an energetic and from an environmental point of view. It is therefore highly relevant to quantify and understand the rate with which they grow. We use molecular dynamics simulations to shed light on the growth rate of these hydrates. We put the solid hydrate phase in contact with a guest aqueous solution in equilibrium with the pure guest phase and study the growth of both hydrates at 400 bars with temperature. We compare our results with previous calculations of the ice growth rate. We find a growth rate maximum as a function of the supercooling in all cases. The incorporation of guest molecules into the solid structure strongly decelerates hydrate growth. Consistently, ice grows faster than either hydrate and the CO2 hydrate grows faster than the CH4 one because of the higher solubility of CO2. We also quantify the molecular motion required to build the solids under study and find that the distance traveled by liquid molecules exceeds by orders of magnitude that advanced by any solid. Less molecular motion is needed in order for ice to grow as compared to the hydrates. Moreover, when temperature increases, more motion is needed for solid growth. Finally, we find a good agreement between our growth rate calculations and experiments of hydrate growth along the guest–solution interface. However, more work is needed to reconcile experiments of hydrate growth toward the solution among each other and with simulations. [ABSTRACT FROM AUTHOR]

Nucleotides are organic compounds consisting of a phosphate group, a nitrogenous base, namely adenine (A), thymine (T), cytosine (C), or guanine (G), and a sugar, here deoxyribose. The magnitude of the first hyperpolarizability β of these four DNA nucleotides was determined in aqueous solution with the nonlinear optical technique of hyper rayleigh scattering under non resonant conditions at a fundamental wavelength of 800 nm. The smallest value is found to be 1.67 ± 0.15 × 10−30 esu for thymidine-5′-monophosphate and the highest is 1.76 ± 0.16 × 10−30 esu for 2′-guanosine-5′-monophosphate. Polarization resolved studies were also performed to question the symmetry of the first hyperpolarizability tensor and access the ratio of some elements of the first hyperpolarizability tensor. These experimental results were then compared to the theoretical values of these first hyperpolarizabilities obtained with the density functional theory at the level of the PCM-B3LYP/6-31G+(d) basis and taking into account the solvent. [ABSTRACT FROM AUTHOR]

We demonstrate liquid-jet photoelectron spectroscopy from a flatjet formed by the impingement of two micron-sized cylindrical jets of different aqueous solutions. Flatjets provide flexible experimental templates enabling unique liquid-phase experiments that would not be possible using single cylindrical liquid jets. One such possibility is to generate two co-flowing liquid-jet sheets with a common interface in vacuum, with each surface facing the vacuum being representative of one of the solutions, allowing face-sensitive detection by photoelectron spectroscopy. The impingement of two cylindrical jets also enables the application of different bias potentials to each jet with the principal possibility to generate a potential gradient between the two solution phases. This is shown for the case of a flatjet composed of a sodium iodide aqueous solution and neat liquid water. The implications of asymmetric biasing for flatjet photoelectron spectroscopy are discussed. The first photoemission spectra for a sandwich-type flatjet comprised of a water layer encapsulated by two outer layers of an organic solvent (toluene) are also shown. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) photolysis of nitrite ions (NO2−) in aqueous solutions produces a suite of radicals, viz., NO·, O−, ·OH, and ·NO2. The O− and NO· radicals are initially formed from the dissociation of photoexcited NO2−. The O− radical undergoes reversible proton transfer with water to generate ·OH. Both ·OH and O− oxidize the NO2− to ·NO2 radicals. The reactions of ·OH occur at solution diffusion limits, which are influenced by the nature of the dissolved cations and anions. Here, we systematically varied the alkali metal cation, spanning the range from strongly to weakly hydrating ions, and measured the production of NO·, ·OH, and ·NO2 radicals during UV photolysis of alkaline nitrite solutions using electron paramagnetic resonance spectroscopy with nitromethane spin trapping. Comparing the data for the different alkali cations revealed that the nature of the cation had a significant effect on production of all three radical species. Radical production was inhibited in solutions with high charge density cations, e.g., lithium, and promoted in solutions containing low charge density cations, e.g., cesium. Through complementary investigations with multinuclear single pulse direct excitation nuclear magnetic resonance (NMR) spectroscopy and pulsed field gradient NMR diffusometry, cation-controlled solution structures and extent of NO2− solvation were determined to alter the initial yields of ·NO and ·OH radicals as well as alter the reactivity of NO2− toward ·OH, impacting the production of ·NO2. The implications of these results for the retrieval and processing of low-water, highly alkaline solutions that comprise legacy radioactive waste are discussed. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown and subsequent plasma are produced in ambient air in the proximity of an aqueous surface using a Nd:YAG Q-switched laser at 1064 nm with a pulse width of 9 ns and a delivered focused input energy of 170 mJ. The distance between the focal point of a 10 cm convex lens and the aqueous surface is 4 mm with laser propagation perpendicular to the surface. Using an intensified CCD camera attached to a 1-m spectrometer, spatial and wavelength-resolved plasma emission data are obtained for delay times after breakdown ranging from 50 ns to 10 μs with a gate window typically 5 ns. Plasma electron density is determined by applying Lorentzian fitting and FWHM extraction to three Stark-broadened spectral lines: N II 3P-3Do multiplet (593.85 nm), Hα (656.27 nm), and the Na D doublet (589.00 and 589.59 nm). One-dimensional spatially resolved measurements of the total emission intensity and electron density are obtained by binning the camera image along the laser axis in intervals of 250 μm and are reported as a function of time from 50 ns to 10 μs. Two plasmas are ignited from a single laser pulse; one from laser breakdown at the water surface and the other a few nanoseconds later from laser-induced air breakdown at the focal point of 4 mm above the water surface. Comparisons between the evolution of the air plasma near and far from the water surface are presented along with data for the water surface plasma itself. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) has ice binding and ice nucleating properties. Here, we explore the dependence of the molecular size of PVA on its ice nucleation activity. For this purpose, we studied ice nucleation in aqueous solutions of PVA samples with molar masses ranging from 370 to 145 000 g mol−1, with a particular focus on oligomer samples with low molar mass. The experiments employed a novel microfluidic setup that is a follow-up on the previous WeIzmann Supercooled Droplets Observation on a Microarray (WISDOM) design by Reicher et al. The modified setup introduced and characterized here, termed nanoliter Bielefeld Ice Nucleation ARraY (nanoBINARY), uses droplet microfluidics with droplets (96 ± 4) µm in diameter and a fluorinated continuous oil phase and surfactant. A comparison of homogeneous and heterogeneous ice nucleation data obtained with nanoBINARY to those obtained with WISDOM shows very good agreement, underpinning its ability to study low-temperature ice nucleators as well as homogeneous ice nucleation due to the low background of impurities. The experiments on aqueous PVA solutions revealed that the ice nucleation activity of shorter PVA chains strongly decreases with a decrease in molar mass. While the cumulative number of ice nucleating sites per mass nm of polymers with different molar masses is the same, it becomes smaller for oligomers and completely vanishes for dimer and monomer representatives such as 1,3-butanediol, propan-2-ol, and ethanol, most likely because these molecules become too small to effectively stabilize the critical ice embryo. Overall, our results are consistent with PVA polymers and oligomers acting as heterogeneous ice nucleators. [ABSTRACT FROM AUTHOR]

A set of molecular models for the alkali nitrates (LiNO3, NaNO3, KNO3, RbNO3, and CsNO3) in aqueous solutions is presented and used for predicting the thermophysical properties of these solutions with molecular dynamics simulations. The set of models is obtained from a combination of a model for the nitrate anion from the literature with a set of models for the alkali cations developed in previous works of our group. The water model is SPC/E and the Lorentz–Berthelot combining rules are used for describing the unlike interactions. This combination is shown to yield fair predictions of thermophysical and structural properties of the studied aqueous solutions, namely the density, the water activity and the mean ionic activity coefficient, the self-diffusion coefficients of the ions, and radial distribution functions, which were studied at 298 K and 1 bar; except for the density of the solutions of all five nitrates and the activity properties of solutions of NaNO3, which were also studied at 333 K. For calculating the water the activity and the mean ionic activity coefficient, the OPAS (osmotic pressure for the activity of selvents) method was applied. The new models extend an ion model family for the alkali halides developed in previous works of our group in a consistent way. [ABSTRACT FROM AUTHOR]

The chief source of water pollution is industrial wastewater containing dyes. In current study, the optimum conditions for removal of Red-XGRL dye by green metal oxide polymeric nanocomposites were determined via batch and column study. The synthesized materials were characterized via SEM, FTIR and thermal analysis. The optimum pH for attaining maximum adsorption capacity of WD, WD-ZnO-PTh, WD-ZnO-PAN and WD-ZnO-PPY was found to be 8 (12.9 mg/g), 10 (30.2 mg/g), 11 (35.8 mg/g) and 11 (40 mg/g), respectively, and optimum dose was found to be 0.05 g/50 mL. The highest adsorption potential for all composite materials was attained within 90 min and maximum adsorption potential for WD (40.8 mg/g), WD-ZnO-PTh (60.7 mg/g), WD-ZnO-PAN (70.4 mg/g) and WD-ZnO-PPY (86.3 mg/g) was obtained using 200 mg/L dye concentration at 30 °C. The adsorption data showed better fitness to pseudo-second-order kinetics and Langmuir sorption isotherm giving significant R2 values of 0.95–0.99 and 0.97–0.99, respectively. Thermodynamic study showed exothermic nature of sorption. During column study, optimum adsorbent bed height, dye flow rate and inlet initial dye concentration to attain highest adsorption (35 mgg−1) were determined to be 3 cm, 1.8 mL min−1 and 70 mg/L, respectively. Hence, the present study aimed to remove Red-XGRL dye proved that these green metal oxide polymeric nanocomposites could efficiently be synthesized and utilized for efficient removal of Red-XGRL dye from aqueous solution both in batch and in column mode. [ABSTRACT FROM AUTHOR]

In this work, CuO nanoparticles (CuO-NPs) were synthesized at 400 °C using a modification of the polymer complex-Pechini method. Considering the procedure used, a mechanism was proposed to explain the formation of CuO-NPs. The synthesized nanoparticles were characterized using IR, Raman and UV–Vis spectroscopies, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the sample synthesized contained CuO as the only crystalline phase, with a crystallite size between 9.17 and 14.95 nm, depending on the crystallographic direction and gap energy values of ∼4 eV and ∼5.86 eV. The CuO powder had agglomerates, in the order of microns, and primary particles smaller than 100 nm, with irregular morphology. The CuO synthetized was not stoichiometric and that it had an excess of oxygen, indicating the presence of cation vacancies and/or interstitial oxygen. The study of the capacity of CuO-NPs to remove methylene blue (MB), without irradiating the system with UV–Vis and without the presence of H 2 O 2 , showed that these promoted a percent removal of ∼39% in a basic medium (pH ∼9.7). [ABSTRACT FROM AUTHOR]

Nowadays, water pollution by herbicides is known as a global concern. Paraquat (PQ) (1-1-methyl-4,4-bi-pyridinium-dichloride) is a chip with high performance, which is being widely used herbicide to remove weeds from agricultural and natural ecosystems. PQ can contaminate water sources due to its high solubility in water. Human death by poisoning effects of PQ has been reported in several countries. Therefore, the side effects of PQ are a global challenge. This study aimed to investigate the bioremediation of PQ by plant extracts, as a low-cost, nontoxic, and natural absorbent to remove PQ from aqueous solutions in different conditions. In this regard, the extracts of common purslane (portulaca oleracea), florist kalanchoe (kalanchoe blossfeldiana), and jade plant (crassula portulaca) were used as adsorbents. For this purpose, the effect of various parameters such as contact time, initial concentration of PQ solution, temperature, pH, and amount of extract was investigated. The results of present study showed that P. oleracea extract and C. portulaca extracts have higher adsorption efficiency than k. blossfeldiana extract. The highest PQ removal was obtained by P. oleracea extract (79.04%) and C. portulaca extract (78.72%) at pH = 11, the adsorbent content of 0.2 mg L−1, and the lowest absorption of PQ (50.6%) was obtained by K. blossfeldiana extract. The highest PQ removal by plant extract was observed at 30 min for P. oleracea and C. portulaca, and at 15 min for k. blossfeldiana extract. Moreover, surface absorption capacity increased with increasing plant extract concentration, decreasing PQ concentration and decreased with increasing temperature. Finally, it can be concluded that plant extract can help to remove PQ from the aqueous solution. Contamination of raw water with herbicides such as paraquat (PQ) is recognized as a problem in many countries. PQ is known as a chemical contaminant that is highly toxic with high water solubilities (620 g/l) among herbicides. Despite the ban on the use of PQ in some countries, due to its low price, high efficiency at low concentrations, and high speed of paraquat in suppressing weeds, today this herbicide is used to control a wide range of weeds in the world. In recent years, various approaches to removing PQ from the environment have been studied. Some of these methods are relatively time-consuming and expensive, with large amounts of sludge and hazardous by-products. Among the mentioned methods, the adsorption process shows the simplicity of operation, low-cost process, and high efficiency in removing PQ from water. Recently, many adsorbents have been developed to remove PQ from aqueous solutions, including biochar, activated carbon, chitosan and alginate, clay, rice husk, and bentonite. Plant extracts may be known as new adsorbent materials for removing PQ from water as an eco-friendly and economical process. Therefore, in this study we investigate the plant extracts performance as adsorbents in PQ removal from water. [ABSTRACT FROM AUTHOR]

In this study, CaMg 0.5 Co x Ni 0.5-x Si 2 O 6 (0.0 ≤ x ≤ 0.5) solid solutions with a diopside structure were prepared to reduce the cobalt and nickel amounts compared to M 2 SiO 4 or MgMSiO 4 (M = Co, Ni) compounds or CaCo x Ni 1-x Si 2 O 6 solid solutions. Colloidal gels were obtained by adding an ammonia aqueous solution to the suspensions of precursors in aqua until pH = 10. Diopside structure began to develop at 800 °C and at 1000–1200 °C crystallinity and pink colour of materials (x ≠ 0) are optimal. In both CaMg 0.5 Co x Ni 0.5-x Si 2 O 6 (0.0 ≤ x ≤ 0.5) and MgCo x Ni 1-x SiO 4 (0.0 ≤ x ≤ 1.0) solid solutions with diopside and olivine structures the position of the third transition of octahedral Co(II), 4T 1 → 4T 1 (P), is centred into the green absorption range and the observed colour is pink. A higher red amount in diopside than in olivine structure can be explained by the minor width of band of this third transition (minor distortion of octahedral M1 site) and shorter mean M1-O distances (M = Ni, Co). [Display omitted] [ABSTRACT FROM AUTHOR]

The present study draws attention to arsenic (V) (As(V)), chromium (III) (Cr(III)), and chromium (VI) (Cr(VI)) heavy metal pollutants, which have negative effects on aquatic ecosystems and indirectly pose a serious threat to the health of living things in the environment. Homopolymer and copolymer hydrogels were synthesized by the UV polymerization technique using 2-acrylamido-2-methyl-1-propansulfonic acid sodium salt (AMPS) and 3-acrlylamidopropil-trimethyl ammonium chloride monomers, and a crosslinker aimed to improve the swelling properties and metal sorption of the prepared hydrogels. The swelling balance values of hydrogels were determined by the gravimetric method in deionized water and different pH values, and their structural characterizations were carried out by Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA) techniques. Sorption efficiencies and sorption capacities of the synthesized hydrogels were determined using aqueous solutions containing As(V), Cr(III), and Cr(VI) heavy metal ions at 25 °C. It was determined that there was a significant increase in p(AMPS) (AM1)-based hydrogel's balance swelling value in deionized water compared to p(AP1) and p(AMPS-co-APTMACl) (AMAP1)-based hydrogels. The lowest equilibrium swelling value was reached in the AMAP1 hydrogel, and the main reason for this result was thought to be due to the closure of the active functional groups of the increased cross-links between AMPS and APTMACl monomer. When sorption results were examined, it was observed that the highest heavy metal ion removal for AM1, AP1, and AMAP1 was in As(V) metal. The highest metal ion holding capacity of AM1, AP1, and AMAP1 was found to be 494 mg/g, 2336 mg/g, and 1439 mg/g for As(V), 323 mg/g, 111 mg/g, and 276 mg/g for Cr(III), and 303 mg/g, 723 mg/g, and 554 mg/g for Cr(VI), respectively. Considering the swelling and sorption results, it is thought that the synthesized hydrogels will provide a significant advantage in the removal of heavy metal ions, which have negative effects on environmental pollution and live health. [ABSTRACT FROM AUTHOR]

Heavy metals and humic acid (HA) are often found together in aquatic ecosystems. HA has been shown to make nanoparticles (NPs) more stable because of its strong repulsion between particles and high charge density. In this study, soil-based HA nanoparticles coated with nano-TiO2 (HA-TiO2 nanocomposite) are used to remove Cd(II) and Cr(VI) ions from aqueous solutions. These particles are stable for 90 days. The zeta potential of HA-TiO2 (28 ± 2.4 nm) at pH 6.5 was 30.4 mV, and this is significant for environmental remediation because the surface charge can be either negatively or positively charged. The three-factorial Box–Behnken design; BBD with the response surface methodology was utilized for sorption system optimization. At optimal process variables, the highest sorption capacities of HA-TiO2 for Cd(II) and Cr(VI) ions were 358.4 ± 0.2 and 243.5 ± 0.1 mg.g−1 (169.7 and 127.6 mg.g−1 for native HA), respectively, at pH 6.5 after 30 minutes. To fit the kinetic data, the normalized standard deviation was preferable to the pseudo-second-order model. Thermodynamic parameters revealed endothermicity (ΔHo = 6.52–4.89 kJ mol−1) and spontaneity (ΔGo = −6.3–9.5 kJ K−1 mol−1) of the sorption processes at (20–40 °C). The ion-exchange sorption mechanism was suggested to take part in the Langmuir model fit. The application of the fabricated nanocomposite for the removal of Cd(II) and Cr(VI) from different environmental water samples was conducted with 98.5 − 99.7% efficiency. All results suggest that HA-TiO2 can be used as an effective and ecofriendly sorbent for the removal of heavy metal ions in an aqueous environment. [ABSTRACT FROM AUTHOR]

Using fluorescence spectroscopy, the two-photon absorption cross sections of aqueous solutions of the styryl dye trans-4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide (DASPI) and its inclusion complexes with cucurbit[n]urils (CB[n] n = 6–8) have been measured. A nonmonotonic dependence of the cross section on the excitation wavelength and on the cavitand cavity size has been revealed. Compared to the free dye, a sevenfold increase in the two-photon absorption cross section has been observed in DASPI inclusion complexes with CB[8] at an excitation wavelength of 980 nm. [ABSTRACT FROM AUTHOR]

Non-aromatic fluorescent and multi-responsive materials, exhibiting inherent fluorescence emission and controlled phase change, have garnered significant attention in recent years. However, the underlying interaction between their fluorescent properties and phase transition remains unclear. In this study, we synthesized a series of catalyst-free aza-Michael addition-based polyethyleneimine (RFPEI) materials by reacting polyethyleneimine (PEI) with N-isopropyl acrylamide (NIPAM). The resulting RFPEI was comprehensively characterized, and demonstrated dual-phase transition behavior (LCST and UCST) in water, which could be finely tuned by adjusting its composition or external factors such as pH. Notably, upon UV irradiation (365 nm), RFPEI exhibited strong fluorescence emission. We further investigated the effects of NIPAM grafting percentage to PEI, polymer concentration, and pH on the LCST/UCST and fluorescent properties of RFPEI aqueous solutions. Moreover, we showcased the great potential of RFPEI as a versatile tool for physiological cell imaging, trace detection, and controlled release of doxorubicin. Our study presents a novel class of stimuli-responsive fluorescent materials with promising applications in the field of biomedicine. [ABSTRACT FROM AUTHOR]

A selective, facile, and highly efficient spectrophotometric approach was established for the determination of 1,4-dioxane in drinking water quantitatively. This approach depends on the reaction selectively of 1,4-dioxane with 1-Amino-2-naphthol-4-sulphonic acid (AHSA) to give an instantly complex measured at 340 nm. The maximum spectra development with high intensity of dioxane-AHSA complex was obtained at 15 min. Variable parameters that affecting the dioxane-AHSA efficacy were estimated and optimised. Under optimal conditions, the dioxane-AHSA complex obeyed Beer's law within the range of 0.5–15 mg/L of 1,4-dioxane with a regression factor of 0.996 (n = 5) and a detection limit of 16 µg/L. The results of precision and accuracy within-day were ≤2.0% in terms of relative standard deviation (RSD%), which confirmed the reproducibility of the analytical performance. The proposed method was applied successfully in the simultaneous assessment of 1,4-dioxane in an aqueous solution. The accuracy and reliability of the developed approach recommended being applied in all quality control of water companies without the use of sophisticated instrumentation and procedure. [ABSTRACT FROM AUTHOR]

A new ternary coordination polymer (CP), {[Cd(L)(nip)(H2O)]·H2O}n (1) (L = 1,6-bis(benzimidazol-2-yl)hexane, H2nip = 5-nitroisophthalic acid), was hydrothermally synthesized and characterized. 1 is a two-dimensional sheet and extends into three-dimensional supramolecular networks through O-H···O hydrogen bonding interactions, which displays high thermal and pH stabilities. 1 demonstrated notable selectivity, sensitivity, and reusability for the luminescent sensing of chlortetracycline (CTC) and Fe3+ ions. Density functional theory calculations and UV−Vis absorption spectroscopy were employed to investigate the possible sensing mechanisms. A new Cd(II) metal coordination polymer, namely {[Cd(L)(nip)(H2O)]·H2O}n can act as a sensitive luminescent probe for chlortetracycline (CTC) and Fe3+ ions in water with excellent selectivity and recyclability. [ABSTRACT FROM AUTHOR]

Pesticide contamination to water bodies is considered as a global concern. This study involves the use of activated carbon synthesized from the shells of Thevetia peruviana shell (TPS) for the removal of the potential pollutant, Methoxychlor (MXC) from water. The TPS was activated using potassium hydroxide and was characterized by pH point zero charge (pHpzc), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET). The activated material shows a high BET of 394.97 m2/g with a pHpzc of 2. Batch experiments were conducted to investigate the influence of operating conditions such as pH, temperature, adsorbent dosage, initial concentration, and contact time. Under optimum conditions, adsorption of MXC onto TPS had a removal efficiency of 94.90%. The sorption experiment data best fits the pseudo-second-order (PSO) kinetic model (R2 = 0.999) and also correlated with Langmuir isotherm model (maximum sorption capacity of 197.2 mg/g). The results reveal that TPS can be considered as an excellent adsorbent material for the removal of pesticides and applicable for real waste water treatment. [ABSTRACT FROM AUTHOR]

• High iron recovery efficiency. • Low recovery cost. • The performance of regenerated LFP battery is better. The recovery of valuable metals from used lithium batteries is essential from an environmental and resource management standpoint. However, the most widely used acid leaching method causes significant ecological harm. Here, we proposed a method of recovering Li and Fe selectively from used lithium iron phosphate batteries by using low-concentration organic acid and completing the closed-loop regeneration. Low-concentration oxalic acid is used to carry out PO 4 3− , which is significantly less soluble in aqueous solution than Li, two-stage selective leaching Li, where the leaching rate of Li reaches 99 %, and the leaching rate of Fe is only 2.4 %. The leach solution is then decontaminated. The solubility of Li 3 PO 4 in aqueous solution is much smaller than that of Li 2 C 2 O 4 , which was required to recover Li to change the pH and Li can be recovered as Li 3 PO 4 ; Fe can be retrieved as FeC 2 O 4 ·2H 2 O, and re-prepared into lithium iron phosphate. [ABSTRACT FROM AUTHOR]

PEGylated 2-(2-(6-(dimethylamino)benzooxazol-2-yl)vinyl)quinolin-8-ol (BQ-mPEG) was synthesized, which exhibited strong fluorescence at 610 nm (φf = 0.11) and a large Stoke's shift (Δλ = 202 nm) in the aqueous solution. The fluorophore displayed a two-photon absorption characteristic and a strong red emission (λem = 625 nm) was observed with NIR (950 nm) irradiation. The feasibility of using BQ-mPEG as a fluorescent imaging reagent suggested that the fluorophore targets mitochondria, and with 950 nm excitation, bright fluorescence images in HeLa live cells were observed. Furthermore, the fluorophore exhibited some advantages of high photostability and pH stability, as well as low cytotoxicity. [ABSTRACT FROM AUTHOR]

We have demonstrated a green aqueous synthesis of rod-shaped MoO3 material, [MoVI3O9{K(H2O)4}(CH3COO)]·H2O (2) intercalating potassium–aqua-complex acetate into its lamellar space, simply by ion-exchange of Co(II)–aqua-complex in compound [MoVI4O12(CH3COO)2{CoII(H2O)6}]·2H2O (1) by {K(H2O)4}+ in an aqueous solution of 1 and KCl. Compound 2 acts as a potential storage system of alkali metal ions. [ABSTRACT FROM AUTHOR]

In this paper, the adsorption behavior of intrinsic black phosphorus (BP) and BP doped with five atoms of O, Si, S, Cu and Zn on Pb 2 + in aqueous solution was investigated by using the first principle of nature. The formation energy was calculated to be the smallest for Si-doped BP at 2.608 eV, indicating the best structural stability. The adsorption energy was calculated and showed that the doped BP is more capable of adsorbing Pb 2 + than the intrinsic BP, with the S-doped BP having the strongest adsorption capacity of 0.151 eV. The density of states was calculated and showed that the bandgaps of the doped BP are all smaller than the 1.3 eV of the intrinsic BP, indicating that the doping can improve electrical conductivity of the adsorption system. The charge transfer was calculated and showed that S doping, O doping, Cu doping and Zn doping enhanced the ionic bonding between BP surface atoms and Pb 2 + , while Si doping weakened the ionic bonding. The charge transfer of S doping was the largest at 1.371 e, indicating that S-doped BP had the strongest ability to adsorb Pb 2 + . [ABSTRACT FROM AUTHOR]

In this work, biopolymer chitosan and natural clay were used to obtain composite materials. The overall aim of this study was to improve the properties (porosity, thermal stability and density) of pure chitosan beads by the addition of clay and to obtain a chitosan-based composite material for the adsorption of heavy metals from an aqueous solution, using Mongolian resources, and to study the adsorption mechanism. The natural clay was pre-treated with acid and heat to remove the impurities. The chitosan and pre-treated clay were mixed in different ratios (8:1, 8:2 and 8:3) for chemical processing to obtain a composite bead for the adsorption of chromium ions. The adsorption of Cr(III) and Cr(VI) was studied as a function of the solution pH, time, temperature, initial concentration of the chromium solution and mass of the composite bead. It was found that the composite bead obtained from the mixture of chitosan and treated clay with a mass ratio of 8:1 and 8:2 had the highest adsorption capacity (23.5 and 17.31 mg·g−1) for Cr(III) and Cr(VI), respectively, in the optimum conditions. The properties of the composite materials, prepared by mixing chitosan and clay with a ratio of 8:1 and 8:2, were investigated using XRD, SEM–EDS, BET and TG analysis. The adsorption mechanism was discussed based on the XPS analysis results. It was confirmed that the chromium ions were adsorbed in their original form, such as Cr(III) and Cr(VI), without undergoing oxidation or reduction reactions. Furthermore, Cr(III) and Cr(VI) were associated with the hydroxyl and amino groups of the composite beads during adsorption. The kinetic, thermodynamic and isothermal analysis of the adsorption process revealed that the interaction between the chitosan/clay composite bead and Cr(III) and Cr(VI) ions can be considered as a second-order endothermic reaction, as such the adsorption can be assessed using the Langmuir isotherm model. It was concluded that the composite bead could be used as an adsorbent for the removal of chromium ions. [ABSTRACT FROM AUTHOR]

The dilational modulus (E) of polymer films has been commonly measured using the oscillating ring/bubble/drop methods with an external force, and often without specifying the state of the adsorbed film. This study explores an approach where E was determined from the relaxations of surface tension (ST) and surface area (SA) of natural perturbations, in which ST and SA were monitored using a pendant bubble tensiometer. The E of the adsorbed film of PAA (polyacrylic acid) was evaluated for aqueous solutions at CPAA = 5 × 10−4 g/cm3, [MW = 5, 25, and 250 (kDa)]. The E (=dγ/dlnA) was estimated from the surface dilational rate (dlnA/dt) and the rate of ST change (dγ/dt) of the bubble surface from the natural perturbation caused by minute variations in ambient temperature. The data revealed that (i) a considerable time is required to reach the equilibrium-ST (γeq) and to attain the saturated dilational modulus (Esat) of the adsorbed PAA film, (ii) both γeq and Esat of PAA solutions increase with MW of PAA, (iii) a lower MW solution requires a longer time to reach its γeq and Esat, and (iv) this approach is workable for evaluating the E of adsorbed polymer films. [ABSTRACT FROM AUTHOR]

This study investigates the unique morphology and mechanical properties of multi-jet electrospun cashew gum (CG) when combined with high-molecular-weight polyethylene oxide (PEO) and glycerol. Cashew gum (CG) is a low-cost, non-toxic heteropolysaccharide derived from Anacardium occidentale trees. Initially, the electrospinnability of aqueous solutions of cashew gum alone or in combination with PEO was evaluated. It was found that cashew gum alone was not suitable for electrospinning; thus, adding a small quantity of PEO was needed to create the necessary molecular entanglements for fiber formation. By using a single emitter with a CG:PEO ratio of 85:15, straight and smooth fibers with some defects were obtained. However, additional purification of the cashew gum solution was needed to produce more stable and defect-free straight and smooth fibers. Additionally, the inclusion of glycerol as a plasticizer was required to overcome material fragility. Interestingly, when the optimized formulation was electrospun using multiple simultaneous emitters, thicker aligned fiber bundles were achieved. Furthermore, the resulting oriented fiber mats exhibited unexpectedly high elongation at break under ambient conditions. These findings underscore the potential of this bio-polysaccharide-based formulation for non-direct water contact applications that demand elastic properties. [ABSTRACT FROM AUTHOR]

The influence of bovine serum albumin (BSA) on collapsing poly(N-isopropylacrylamide) (PNIPAM) chains was studied with turbidimetry and spin probe and spin label electron paramagnetic resonance spectroscopy. An increased ratio of collapsed chains in aqueous solutions in the narrow temperature region near the LCST appeared in the presence of 2.5–10 wt% BSA. The spin probe EPR data indicate that the inner cavities of the BSA dimers are probably responsive to the capture of small hydrophobic or amphiphilic molecules, such as TEMPO nitroxyl radical. The observed features of the structure and dynamics of inhomogeneities of aqueous PNIPAM-BSA solutions, including their mutual influence on the behavior of the polymer and protein below the LCST, should be considered when developing and investigating PNIPAM-based drug delivery systems. [ABSTRACT FROM AUTHOR]

Accurately predicting the phase behavior and physical properties of carbon dioxide (CO2) in pure water/NaCl mixtures is crucial for the design and implementation of carbon capture, utilization, and storage (CCUS) technology. However, the prediction task is complicated by CO2 liquefaction, CO2 hydrate formation, multicomponent and multiphase coexistence, etc. In this study, an improved method that combines Benedict–Webb–Rubin–Starling equation of state (BWRS EOS) + hydrate thermodynamic theories was proposed to predict CO2 solubility and phase equilibrium conditions for a mixed system across various temperature and pressure conditions. By modifying the interaction coefficients in BWRS EOS and the Van der Waals–Platteeuw model, this new method is applicable to complex systems containing two liquid phases and a CO2 hydrate phase, and its high prediction accuracy was verified through a comparative evaluation with a large number of reported experimental data. Furthermore, based on the calculation results, the characteristics of CO2 solubility and the variation of phase equilibrium conditions of the mixture system were discussed. These findings highlight the influence of hydrates and NaCl on CO2 solubility characteristics and clearly demonstrate the hindrance of NaCl to the formation of CO2 hydrates. This study provides valuable insights and fundamental data for designing and implementing CCUS technology that contribute to addressing global climate change and environmental challenges. [ABSTRACT FROM AUTHOR]

This research explores the adsorption (AD) of diclofenac sodium (DS) onto a Hydrothermally produced activated carbon impregnated with ZnO (HTC-AC/ZnO) surface, considering various factors such as initial concentration (IC), adsorbent dose, contact time, and pH. The characterization of HTC-AC/ZnO was performed using X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and nitrogen physisorption spectroscopy (BET). Tests were conducted with different adsorbent doses (0.5–4 g/L) at 303 K and various initial diclofenac concentrations (ranging from 50 mg/L to 250 mg/L) to observe their effects. Additionally, pH values were altered from 2 to 12 to study their influence on AD. Kinetic studies, thermodynamic studies, and AD isotherm models were examined. The Temkin isotherm model (TIM) was found to be the most accurate for DS-AD on HTC-AC/ZnO. For DS-AD on HTC-AC/ZnO, pseudo-first-order models (PFOM), intraparticle diffusion model (IPDM), and pseudo-second-order models (PSOM) were applied, with a correlation coefficient of 0.945, indicating a good fit for PFOM. The kinetics suggested rapid adsorption. Notably, the HTC-AC/ZnO composite exhibited consistent AD characteristics across four consecutive cycles, with a removal efficiency exceeding 99.38%. This suggests that HTC-AC/ZnO is an appropriate and economically viable adsorbent for the elimination of DS from water-based solutions. The investigation provides compelling evidence that HTC-AC/ZnO is a viable adsorbent for the effective elimination of DS from water sources. [ABSTRACT FROM AUTHOR]

The critical gelation conditions observed in dilute aqueous solutions of multiple nanoscale uranyl peroxide molecular clusters are reported, in the presence of multivalent cations. This gelation is dominantly driven by counterion‐mediated attraction. The gelation areas in the corresponding phase diagrams all appear in similar locations, with a characteristic triangle shape outlining three critical boundary conditions, corresponding to the critical cluster concentration, cation/cluster ratio, and the degree of counterion association with increasing cluster concentration. These interesting phrasal observations reveal general conditions for gelation driven by electrostatic interactions in hydrophilic macroionic solutions. [ABSTRACT FROM AUTHOR]

The present study assessed the effective use of biochar for the adsorption of two potent HAB toxins namely, Microcystin-LR (MCLR) and Saxitoxin (STX) through a combination of dosage, kinetic, equilibrium, initial pH, and competitive adsorption experiments. The adsorption results suggest that biochar has excellent capabilities for removing MCLR and STX, with STX reporting higher adsorption capacities (622.53–3507.46 µg/g). STX removal required a minimal dosage of 0.02 g/L, while MCLR removal needed 0.4 g/L for > 90%. Similarly, a shorter contact time was required for STX removal compared to MCLR for > 90% of toxin removed from water. Initial pH study revealed that for MCLR acidic conditions favored higher uptake while STX favored basic conditions. Kinetic studies revealed that the Elovich model to be most suitable for both toxins, while STX also showed suitable fittings for Pseudo-First Order and Pseudo-Second Order in individual toxin systems. Similarly, for the Elovich model the most suited kinetic model for both toxins in presence of each other. Isotherm studies confirmed the Langmuir–Freundlich model as the best fit for both toxins. These results suggest adsorption mechanisms including pore filling, hydrogen bonding, π–π interactions, hydrophobic interactions, electrostatic attraction, and dispersive interactions. [ABSTRACT FROM AUTHOR]

This research paper focuses on the removal of the nonsteroidal anti-inflammatory drug, ibuprofen, from an aqueous solution using a dissolved air flotation process. The comparison of different types of cationic surface-active agents such as cetyltrimethyl ammonium bromide (CTAB), tetrabutyl ammonium bromide (TBAB), and octyltrimethyl ammonium bromide (OTAB) have been employed to scrutinize the effective removal of the ecotoxic pharmaceutically active compound. The work included the influencing parameters such as pressure, contact time, surfactant dosage, pH, flow rate, and initial concentration owing to the best-optimized conditions. The maximum removal rate of 96.09% was achieved at 15 min for CTAB, TBAB had 62.36% at 45 min, and 89.6% was obtained for OTAB at 30 min, with 50 mg L−1 as the initial concentration and pH = 4. The removal rate was better with the optimized dosage of CTAB at 0.6 g, TBAB at 1.2 g, and OTAB at 1.0 g. It was observed that the geometric shape of the surface-active agents had greater impacts on the contaminants' efficiency. CTAB and OTAB were combined to find out the best possible removal rate of contaminants. The synergistic effect augments surfactant-based occurrence to be better in forming a good foaming effect and tends to have a lower critical micelle concentration (CMC). From the evaluation of kinetic models, pseudo-second-order flotation kinetics fitted the experimental data best. Furthermore, the formed metabolites that had been identified using gas chromatography-mass spectrometry were found to be less toxic than the parenting compounds. [ABSTRACT FROM AUTHOR]

The ability of an octanuclear cubic coordination cage to catalyse a nucleophilic aromatic substitution reaction on a cavity‐bound guest was studied with 2,4‐dinitrofluorobenzene (DNFB) as the guest/substrate. It was found that DNFB undergoes a catalysed reaction with hydroxide ions within the cavity of the cubic cage (in aqueous buffer solution, pH 8.6). The rate enhancement of kcat/kuncat was determined to be 22, with cavity binding of the guest being required for catalysis to occur. The product, 2,4‐dinitrophenolate (DNP), remained bound within the cavity due to electrostatic stabilisation and exerts two apparently contradictory effects: it initially auto‐catalyses the reaction when present at low concentrations, but at higher concentrations inhibits catalysis when a pair of DNP guests block the cavity. When encapsulated, the UV/Vis absorption spectrum of DNP is red‐shifted when compared to the spectrum of free DNP in aqueous solution. Further investigations using other aromatic guests determined that a similar red‐shift on cavity binding also occurred for 4‐nitrophenolate (4NP) at pH 8.6. The red‐shift was used to determine the stoichiometry of guest binding of DNP and 4NP within the cage cavity, which was confirmed by structural analysis with X‐ray crystallography; and was also used to perform catalytic kinetic studies in the solution‐state. [ABSTRACT FROM AUTHOR]

Transition and rare earth metals serve as indispensable raw materials across a broad spectrum of technological applications. However, their utilization is frequently linked to substantial waste production. Consequently, the recycling and recovery of these metals from end-of-life products or metal-contaminated aqueous environments hold significant importance within the framework of a circular economy. In our investigation, we employed synthetic mesoporous silica monoliths, synthesized via the sol–gel method and functionalized with chelating groups, for the efficient recovery of metal ions from aqueous matrices. The monoliths were characterized using a multi-technique approach and were tested in the recovery of paramagnetic Gd3+, Cu2+ and Co2+ ions from aqueous solutions, using 1H-NMR relaxometry to evaluate their uptake performance in real time and under simple conditions. Detailed information on the kinetics of the capture process was also highlighted. Finally, the possibility to regenerate the solid sorbents was evaluated. [ABSTRACT FROM AUTHOR]

In this paper, the precursors of the target product were prepared using a simple solvothermal method. After pyrolysis of the precursors, a three-dimensional Fe/CuFe2O4@C (referred to as FCC) nanomaterial with a relief texture was successfully prepared, which was employed as a novel catalyst material for activated persulfate (referred to as PS) degradation, tetracycline (referred to as TC), in wastewater. X-ray photoelectron spectroscopy (XPS) revealed that Fe(III) and Cu(II) served as the primary active metal ions, while the formation of a surface carbon shell positively influenced electron transfer during catalytic degradation. A comprehensive investigation was conducted to assess the efficiency of FCC nanocatalysts in degrading TC under various conditions. The results demonstrated that the degradation rate of TC in the 100 min range was about 96% at concentrations of 0.2 g L−1 FCC and 1 mmol L−1 persulfate and pH 7. Quenching experiment results and EPR results consistently indicated that both free radical and non-radical pathways involved in TC degradation by FCC nanomaterials, and sulfate radicals, hydroxyl radicals, superoxide radicals and singlet oxygen were identified to be the main active substances. The degradation intermediates were analyzed by liquid mass spectrometry and toxicology. FCC, as a catalyst exhibiting high catalytic activity, demonstrates superior performance in the activated persulfate degradation of TC. The environmental risk associated with the degradation of intermediate products is significantly lower than that of TC itself. FCC holds significant potential for the degradation of antibiotics in wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] Amphiphilic molecules functionalized with photoresponsive motifs have attractive prospects for applications in smart functional bio-material ranging from cell-material interfaces to drug delivery systems owing to the precisely controllable functionality of self-assembled hierarchical supramolecular structures in aqueous media by a non-invasive light stimulation with high temporal- and spatial-resolution. However, most of reported photoresponsive amphiphiles are triggered by bio-damaging UV-light, which greatly limits the potential in bio-related applications. Herein, we present newly designed red-light controlled N,N' -diaryl-substituted indigo amphiphiles (IA), exhibiting excellent photoswitchablity and photostability with dual red-/green-light in organic media. Meanwhile, aqueous solutions of IA assembled into supramolecular structures in both microscopic and macroscopic length-scale, though the photoresponsiveness of IA is slightly compromised in aqueous media. At macroscopic length-scale, morphological changes of IA macroscopic scaffold prepared by a shear-flow method can be fine adjusted upon red-light irradiation. Moreover, the preferential attachment of live h-MSCs to IA macroscopic scaffold surface also indicates a good biocompatibility of IA macroscopic scaffold. These results provide the potential for developing the next generation of red-light controlled soft functional materials with good biocompatibility. [ABSTRACT FROM AUTHOR]

In this study, fiber‐polymer composite films were prepared by adding 0.5 g, 1.0 g, and 1.5 g of modal/cotton (50 : 50) waste to 10 % PVA film, and the properties of the films were revealed by SEM, FTIR analyzes and swelling percentage. It is observed that the strength of the bonds in the FTIR analysis decreases when modal/cotton fibers are added to the PVA film. While a 406 % swelling is achieved in the PVA film, the swelling percentages of the films decrease when modal/cotton fibers are added to the PVA film, and a greater swelling is observed at pH 9 compared to pH 5. The adsorption efficiency of tetracycline and diclofenac sodium on the films was researched at different pH levels and film doses. Tetracycline removal reached its highest value at pH 9, while diclofenac sodium removal reached its highest value at pH 5. Langmuir and Freundlich isotherm models were determined for tetracycline and diclofenac sodium adsorption. Tetracycline removal is better described by the Freundlich isotherm model, whereas diclofenac sodium removal fits the Langmuir isotherm model better. As a result, films prepared with modal/cotton waste not only provide tetracycline and diclofenac sodium removal but also contribute to waste recycling by utilizing waste fiber materials. [ABSTRACT FROM AUTHOR]

Zeolite imidazolate framework-8 (ZIF-8), which is a special subgroup of metal–organic frameworks (MOFs), was synthesized and modified by ethylenediamine (ZIF-8-EDA) to prepare an efficient adsorbent for the high sorption of Cd2+ ions from solution. The synthesized and modified ZIF-8 (ZIF-8-EDA) were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FE-SEM) with energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM) analysis. The optimum conditions for dosage of adsorbent, initial ion concentration, pH, and contact time were 0.05 g/l, 50 mg/l, 6, and 60 min, respectively, for cadmium ion sorption from aqueous solutions with a removal efficiency of 89.7% for ZIF-8 and 93.5% for ZIF-8-EDA. Adsorption kinetics and equilibrium data were analyzed using the Langmuir and Freundlich equations. The Langmuir model fitted the equilibrium data better than the Freundlich model. According to the Langmuir equation, the maximum uptake for the cadmium ions was 294.11(mg/g). The calculated thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicated that the adsorption process was feasible, spontaneous, and endothermic at 20–50 °C. Based on the results, the amino functionalized ZIF-8 had improved adsorption performance due to the replacing of the starting linker with organic ligands that had effective functional groups, leading to chemical coordination due to the interaction of metal ions with the non-bonding pair of electrons on the N atoms of the amino functional group. The selectivity toward metal ion adsorption by ZIF-8-EDA was Cd2+ > Pb2+ > Ni2+‏. [ABSTRACT FROM AUTHOR]

The number of crystal structures of pertechnetates derived from aqueous solutions has been expanded from seven to over 30. We report the conversion of NH4TcO4 to aqueous HtcO4 via acidic cation exchange. This is followed by the synthesis and structural elucidation of pertechnetate salts of alkaline earth (AE), transition metal I and lanthanoids (Ln) elements. Various degrees of hydration and coordination are discussed. Where possible, a comparison with the perrhenate homologues is made. The described syntheses and materials may be used as novel starting materials for extended technetium research. [ABSTRACT FROM AUTHOR]

The artificial microenvironments inside coordination cages have gained significant attention for performing enzyme‐like catalytic reactions by facilitating the formation of labile and complex molecules through a "ship‐in‐a‐bottle" approach. Despite many fascinating examples, this approach remains scarcely explored in the context of synthesizing metallic clusters such as polyoxometalates (POMs). The development of innovative approaches to control and influence the speciation of POMs in aqueous solutions would greatly advance their applicability and could ultimately lead to the formation of elusive clusters that cannot be synthesized by using traditional methods. In this study, we employ host–guest stabilization within a coordination cage to enable a novel cavity‐directed synthesis of labile POMs in aqueous solutions under mild conditions. The elusive Lindqvist [M6O19]2− (M=Mo or W) POMs were successfully synthesized at room temperature via the condensation of molybdate or tungstate building blocks within the confined cavity of a robust and water‐soluble Pt6L4(NO3)12 coordination cage. Importantly, the encapsulation of these POMs enhances their stability in water, rendering them efficient catalysts for environmentally friendly and selective sulfoxidation reactions using H2O2 as a green oxidant in a pure aqueous medium. The approach developed in this paper offers a means to synthesize and stabilize the otherwise unstable metal‐oxo clusters in water, which can broaden the scope of their applications. [ABSTRACT FROM AUTHOR]

The artificial microenvironments inside coordination cages have gained significant attention for performing enzyme‐like catalytic reactions by facilitating the formation of labile and complex molecules through a "ship‐in‐a‐bottle" approach. Despite many fascinating examples, this approach remains scarcely explored in the context of synthesizing metallic clusters such as polyoxometalates (POMs). The development of innovative approaches to control and influence the speciation of POMs in aqueous solutions would greatly advance their applicability and could ultimately lead to the formation of elusive clusters that cannot be synthesized by using traditional methods. In this study, we employ host–guest stabilization within a coordination cage to enable a novel cavity‐directed synthesis of labile POMs in aqueous solutions under mild conditions. The elusive Lindqvist [M6O19]2− (M=Mo or W) POMs were successfully synthesized at room temperature via the condensation of molybdate or tungstate building blocks within the confined cavity of a robust and water‐soluble Pt6L4(NO3)12 coordination cage. Importantly, the encapsulation of these POMs enhances their stability in water, rendering them efficient catalysts for environmentally friendly and selective sulfoxidation reactions using H2O2 as a green oxidant in a pure aqueous medium. The approach developed in this paper offers a means to synthesize and stabilize the otherwise unstable metal‐oxo clusters in water, which can broaden the scope of their applications. [ABSTRACT FROM AUTHOR]