Sodium Chloride Crystals Research Articles

Higher-voltage asymmetric-electrolyte metal-air batteries

Higher-voltage asymmetric-electrolyte metal-air batteries

Radiolysis-Induced Crystallization of Sodium Chloride in Acetone by Electron Beam Irradiation.

In situ liquid cell transmission electron microscopy (LC-TEM) is an innovative method for studying the processes involved in the formation of crystals in liquids. However, it is difficult to capture early stages of crystallization because of the small field of view and the unfavorable changes in sample composition resulting from electron-beam radiolysis. Nevertheless, if the radiolysis required to induce the crystallization of a sample could be controlled in LC-TEM, this would be advantageous for observing the crystallization process. Here, we examined this possibility by using a mixture of sodium chlorate (NaClO3) and acetone in the LC-TEM. The electron beam induced the formation of dendritic crystals in a saturated acetone solution of NaClO3; moreover, these crystals consisted of sodium chloride (NaCl), rather than NaClO3, suggesting that chloride ions (Cl−), which were not present in the initial solution, were generated by radiolysis of chlorate ions ${\rm \lpar ClO}_3^- \rpar$. As a result, the solution then supersaturated with NaCl because its solubility in acetone is much lower than that of NaClO3. The combination of radiolysis and a solvent in which a solute is much less soluble is potentially useful for establishing crystallization conditions for materials that are difficult to crystallize directly in LC-TEM experiments.

Quasi-two-dimensional NaCl crystals encapsulated between graphene sheets and their decomposition under an electron beam.

Quasi-two-dimensional (2D) sodium chloride (NaCl) crystals of various lateral sizes between graphene sheets were manufactured via supersaturation from a saline solution. Aberration-corrected transmission electron microscopy was used for systematic in situ investigations of the crystals and their decomposition under an 80 kV electron beam. Counterintuitively, bigger clusters were found to disintegrate faster under electron irradiation, but in general no correlation between crystal sizes and electron doses at which the crystals decompose was found. As for the destruction process, an abrupt decomposition of the crystals was observed, which can be described by a logistic decay function. Density-functional theory molecular dynamics simulations provide insights into the destruction mechanism, and indicate that even without account for ionization and electron excitations, free-standing NaCl crystals must quickly disintegrate due to the ballistic displacement of atoms from their surface and edges during imaging. However, graphene sheets mitigate damage development by stopping the displaced atoms and enable the immediate recombination of defects at the surface of the crystal. At the same time, once a hole in graphene appears, the displaced atoms escape, giving rise to the quick destruction of the crystal. Our results provide quantitative data on the stability of encapsulated quasi 2D NaCl crystals under electron irradiation and allow the conclusion that only high-quality graphene is suitable for protecting ionic crystals from beam damage in electron microscopy studies.

Optical properties of alkali halide crystals

The results of measuring the transparency bands in a wide wavelength range - from UV to 3000 μm for crystals of sodium chloride (NaCl), potassium chloride (KCl), iodine bromide (KBr) and rubidium iodide (RbI) are presented. It was shown that, along with well-known data on the transparency of these crystals in the UV and IR ranges, they have a transmission zone in the THz range in the region of 1000 μm.

Photothermoelectric SnTe Photodetector with Broad Spectral Response and High On/Off Ratio.

A broadband photodetector with high performance is highly desirable for the optoelectric and sensing application. Herein, we report a "photo-thermo-electric" (PTE) detector based on an ultrathin SnTe film. The (001)-oriented SnTe films with the wafer size scale are epitaxially grown on the surface of sodium chloride crystals by a scalable sputtering method. Due to the giant PTE effect under laser spot excitation on the asymmetric position between two terminals, a built-in electrical field is produced to drive bulk carriers for a self-powered photodetector, leading to a broad spectral response in the wavelength range from 404 nm to 10.6 μm far beyond the limitation of the energy band gap. Significantly, the photodetector displays a high on/off photoswitching ratio of over 105 with a suppressed dark current, which is 4-5 orders of magnitude higher than that of other reported SnTe-based detectors. Under zero external bias, the device yields the highest detectivity of ∼1.3 × 1010 cm Hz1/2 W-1 with a corresponding responsivity of ∼3.9 mA W-1 and short rising/falling times of ∼78/84 ms. Furthermore, the photodetector transferred onto the flexible template exhibits excellent mechanical flexibility over 300 bending cycles. These findings offer feasible strategies toward designing and developing low-power-consumption wearable optoelectronics with competitive performance.

On the Transparency of Alkali-Halide Crystal in the Terahertz Spectral Range

The transmission of THz (to 3000 μm) radiation by alkali halide single crystals of sodium chloride (NaCl), potassium chloride (KCl), potassium bromide (KBr), and rubidium iodide (RbI), which are widely used in the IR spectral region, is studied. The spectral dependences of the absorption coefficients of these materials in the range of 0.9–3000 μm are determined. These materials are transparent in the range of 1000‒3000 μm, which makes it possible to use them in terahertz (millimeter) devices.

Temperature-Dependent Phase Transitions of Aqueous Aerosol Droplet Systems in Microfluidic Traps

Well-mixed atmospheric aqueous aerosol droplets containing multiple chemical species can undergo processes such as liquid–liquid phase separation (LLPS) and crystallization depending on the ambient temperature and relative humidity (RH). So far, only a handful of single droplet studies have examined the effect of temperature in conjunction with the organic to inorganic ratio (OIR) on the separation RH for LLPS. In this work, we present a temperature-controlled microfluidic static trap approach to study the LLPS and efflorescence phenomenon in multiple ternary systems in a quasi-equilibrium manner. Ammonium sulfate or sodium chloride is used as the inorganic phase and 3-methylglutaric acid (3-MGA), poly­(ethylene glycol), poly­(propylene glycol), or poly­(ethylene glycol) diacrylate is used as the organic phase. Results show a clear trend in droplets containing 3-MGA with either salt of the initial LLPS and efflorescence events occurring at higher RH at lower temperatures, while this trend is less obvious for the other organics. The organic to inorganic ratio (OIR) of the system also affected the type of first phase transition, which can be either LLPS or efflorescence. Finally, the rate of RH change also had an impact on the temperature dependence of the formation of either anhydrous or dihydrous crystals of sodium chloride upon efflorescence. These results help inform the effects of temperature, OIR, and rate of RH change on the phase state of aqueous aerosol droplets containing multiple species.

Real-time observation of dynamic structure of liquid-vapor interface at nanometer resolution in electron irradiated sodium chloride crystals

The dynamics and structure of the liquid and vapor interface has remained elusive for decades due to the lack of an effective tool for directly visualization beyond micrometer resolution. Here, we designed a simple liquid-cell for encapsulating the liquid state of sodium for transmission electron microscopic (TEM) observation. The real-time dynamic structure of the liquid-vapor interface was imaged and videoed by TEM on the sample of electron irradiated sodium chloride (NaCl) crystals, a well-studied sample with low melting temperature and quantum super-shells of clusters. The nanometer resolution images exhibit the fine structures of the capillary waves, composed of first-time observed three zones of structures and features, i.e. flexible nanoscale fibers, nanoparticles/clusters, and a low-pressure area that sucks the nanoparticles from the liquid to the interface. Although the phenomenons were observed based on irradiated NaCl crystals, the similarities of the phenomenons to predictions suggest our real-time ovserved dynamic structure might be useful in validating long-debated theoretical models of the liquid-vapor interface, and enhancing our knowledge in understanding the non-equilibrium thermodynamics of the liquid-vapor interface to benefit future engineering designs in microfluidics.

Artificial wetland planted with Limonium Perezzi, for the treatment of wastewater from tanning

The wastewater from leather tanning contains different types of pollutants depending on the internal process that is carried out, in particular, the riparian and tanning stages provide the greatest contaminant load within the process, in terms of organic matter, grease and oils, chlorides, chromium, sulfides among other substances. This study analyzed the efficiency of a biological treatment system, consisting of artificial wetlands of horizontal subsurface flow, in order to evaluate the removal of salinity and organic load present in the water produced during the process of soaking leathers. Two prototypes were tested, one planted with Limonium perezzi and the other unplanted as a control parameter, the wetlands were operated for 32 days. The results show that the planted wetland removes 49.2% of the initial chloride present (44,414.8 mgCl-/L) in the water and 86.2% of the total organic carbon (755.9 mgC/L). It was demonstrated that artificial wetlands are still a viable and efficient alternative in terms of organic load removal, on the other hand, the selected plant showed a very good performance in the treatment of wastewater because of its high tolerance to high concentrations of salt dissolved in the water, reaching perspiration of sodium chloride crystals through the leaves and stem.

The structure of water

Images of water clusters have been reported recently. In this paper, the dynamics of water clusters when dissolving crystals of sodium chloride is studied under a microscope. Images of water clusters have two different colours, a dark outer layer and a shallow inner layer as a water cluster is composed of two phases. Since the experiments were conducted at room temperature there should be no solid phase (ice) in water clusters. Therefore, it is proposed that individual water clusters are composite of two phases, an outer liquid phase and an inner gas phase. Obviously, there will be water clusters everywhere in bulk water and they maintain a certain distance among them; there are spaces among water clusters which are filed with gases and named free volume. At a molecular level, hydrogen atom in a water cluster are pointing outward while oxygen atoms are pointing inward. In this configuration, the cluster is more stable. A formula for calculating the forces inside a water cluster is developed. In this study the structure of water is presented in a new light. The study has opened a door for further understanding of water and its mysterious properties.

NaCl‐Templated and Polyvinylpyrrolidone‐Assisted Fabrication of a MnO/C‐rGO Composite as a High‐Capacity Anode Material for Li‐Ion Batteries

A 3D hierarchically‐heterostructured manganese oxide/pyrolytic carbon and reduced graphene oxide composite material (MnO/PC‐rGO) is synthesized by the in situ redox reaction between a PC‐rGO carbon aerogel framework and KMnO4 solution, followed by heat treatment in an inert atmosphere. Herein, the 3D porous PC‐rGO carbon aerogel is prepared via crystal sodium chloride (NaCl)‐templated and polyvinylpyrrolidone (PVP)‐assisted freeze drying in the presence of graphene oxide (GO) and high‐temperature pyrolysis. As an anode material for lithium‐ion batteries, this composite exhibits a high charge capacity of ≈1030 mAh g−1 at 100 mA g−1 and 515 mAh g−1 at 2000 mA g−1. After cycling at 500 mA g−1 for 200 cycles, the capacity retention is ≈70%, demonstrating much superior lithium storage performance over the MnO/PC composite prepared under similar conditions. The superior electrochemical performance is ascribed to its good electrode kinetics behavior and the supernumerary capacity contribution of the PC‐rGO carbon framework due to the presence of rGO in the composite. As a synergic carbon support, the rGO can not only increase the specific capacity and rate capability but also improve the cyclability due to the enhanced electrical conductivity and the buffering effect of the flexible PC‐rGO against a large volume change during cycling.

Crystal growth, optical bandgap, thermal, mechanical, dielectric studies on NLO active semiorganic 4-dimethylaminopyridine sodium chloride crystal for frequency conversion

4-Dimethylaminopyridine sodium chloride crystal (4-DMAPNC) was synthesized by slow evaporation solution growth technique. Grown as- 4-DMAPNC crystal was subjected to various studies in order to understand its physiochemical properties. The crystalline nature and orthorhombic crystal system and cell parameters values a = 6. 852, b = 7.290, c = 11.073 with volume V = 553 A3 were identified from powder and single crystal XRD studies. FTIR spectroscopy study confirms the presence of various modes vibrations available in the 4-DMAPNC sample. Linear optical studies show the lower cutoff wavelength of 194 nm with optical bandgap value (Eg) of 6.22 eV. Extinction coefficients (K), reflectance (R) and refractive index (n0 = 1.44) are calculated in addition for better understanding the optical behavior of the 4-DMAPNC crystal. TGA and DTA curve shows that the material thermally stable up to 128 °C. The electrical behavior of the 4-DMAPNC crystal was studied using dielectric studies. The Vickers hardness study shows the reveres indentation size effect (RISH) and belongs to soft category one. EDAX analysis was carried out and confirms the presence of metal sodium in the title compound. The second nonlinear optical (NLO) behavior of 4-DMAPNC crystal was measured using Kurtz-Perry powder techniques and found to be 0.5 than that of reference KDP.

PRODUCT CHARACTERISTICS IN SIMULTANEOUS CRYSTALLIZATION OF NaCl AND CaSO4 FROM AQUEOUS SOLUTION WITH SEEDING

Zero liquid discharge strategies for industrial wastewater treatment have become prominent in recent years. When evaporative simultaneous crystallization is applied, knowledge about the particle crystallization mechanisms and morphology are important to ease solids downstream handling and for recovery of their valuable components. In this work, batch simultaneous crystallization of sodium chloride (NaCl) and calcium sulphate hemihydrate (CaSO4.0.5H2O) from aqueous solution was studied. It was found that CaSO4.0.5H2O is not an effective substrate for NaCl heterogeneous nucleation, but agglomerates with NaCl particles instead. CaSO4.0.5H2O particles on the surface of NaCl crystals sterically hamper agglomeration of NaCl particles with each other and, for a sufficiently high CaSO4.0.5H2O seed load, cover the NaCl crystals so that NaCl supersaturation rises, inducing NaCl primary nucleation. Simultaneous crystallization of CaSO4.0.5H2O and NaCl yields a satisfactory product for downstream handling even for high CaSO4.0.5H2O content in the crystallizer. However, seeding with CaSO4.0.5H2O is not recommended as it reduces the mean size and increases product size dispersion. NaCl seeding may be considered if it is desirable to separate CaSO4.0.5H2O from NaCl downstream the crystallizer by size classification, as it favors CaSO4.0.5H2O to build up in product sizes of 200 μm and below.

Coupling of Contact Nucleation Kinetics with Breakage Model for Crystallization of Sodium Chloride Crystal in Fluidized Bed Crystallizer

There are many nucleation theory-based different mechanisms. These theories mainly focused on production parameters in the crystallization and less on physical properties of crystals. In this research, a new model of contact nucleation theory coupled with the breakage mechanism of crystals is applied to describe the collision process in sodium chloride crystallization. This coupling nucleation model is presented here which relates the number of contact-collision site in nucleation owing to collision rate and the interfacial energy. F2 in the expression of the classic contact nucleation rate is redefined as a power function with the physical properties of crystals and breakage propensity. The experiment results indicate that crystal breakage propensity has a significant influence on the nucleation rate. Finally, analysis of the contact nucleation kinetic model and comparison with experiments reveal that the new nucleation model results are in better agreement with experiments. This new nucleation model is confirmed to represent the time-dependent collision behavior. The parameters of model are strongly related to the physical properties of crystal and fluidization conditions.

Effect of pore architecture on the mesenchymal stem cell responses to graphene/polycaprolactone scaffolds prepared by solvent casting and robocasting

In the study graphene-containing porous, three dimensional polycaprolactone (PCL) scaffolds were prepared by solvent casting-salt leaching and robocasting methods for tissue engineering applications. Graphene nanopowders in the form of nanoflakes were incorporated into the polymer matrix at different concentrations namely 1, 3, 5 and 10 wt%. The dichloromethane was used as the solvent and sodium chloride crystals were utilized as the water-soluble porogen for the formation of an interconnected porous network (with non-oriented pores) inside the composite scaffolds in solvent casting-salt leaching method. On the other hand, acetone was utilized as solvent and PCL solutions were prepared at 20 wt% in robocasting method to construct scaffolds (with oriented pores) having a grid-like structure. The biological response of bone marrow mesenchymal stem cells seeded on these composite constructs having different architecture were tested using MTT method, live-dead cell viability assay and Alcian blue stanining. Cytotoxicity experiments revealed that mesenchymal stem cells did not show toxic response to composite robocast scaffolds. Cells proliferate and differentiate well on the surface of the robocast scaffolds compared to solvent-cast scaffolds under the same conditions. Results showed that scaffolds prepared in the study have potential to be used in cartilage tissue engineering in the presence of electric stimulation.

Effect of particle breakage conditions on child particle aspect ratio

In particulate processes, the goal is often to control the particle size and aspect ratio distributions. One common unit operation is solution crystallization in agitated vessels, where a rotating impeller can break newly formed crystals. This study used sodium chloride crystals in three sets of laboratory scale experiments to investigate the effects of agitation rate, parent particle size, and solids concentration on crystal breakage. The first set used agitation rates of 1000, 1250, 1750, and 2000 rpm; the second set used average parent particle lengths of 569, 656, 3350, and 4690 μm; and the third set used solids concentrations of 1, 5, 7, and 10 g crystals/100 ml liquid. As expected, increasing the agitation rate produced a higher number fraction of particles smaller than 50 μm. The resulting child particle aspect ratios were primarily a function of the child particle size under the conditions studied.

Mathematical Modeling of the Process of Centrifugal Washing of Sludge

In the chemical, food and other industries, in many cases it is necessary to clean crystalline powdery substances to remove surface impurities. For this, at the final stage of the treatment process, they are washed with water or other liquids. In this article, this process is investigated on the example of quantitative analysis of the dissolution of sodium chloride crystals in water by pressure filtration of the solution through the sludge of the processed product on the basis of filtration on centrifugal equipment. To this end, a physico-mathematical problem of the flow of substances in the interstitial capillary gap is formulated in terms of molecular mass by modeling a cylindrical channel. Based on the proposed model and operating parameters of the process of washing NaCl crystals with water from sludge on a centrifugal machine, numerical analysis of the process simulating cleaning the surface of this product to remove impurities was carried out.

Interface porosity in multilayered all‐conducting polymer electrodes

Multilayered films made with at least two different electroactive polymers, in which the least conducting one acts as a dielectric and separates the layers made with the other, behave as efficient electrodes for electrochemical supercapacitors. In this work, we present a simple strategy to develop improved multilayered electrodes with structured interfaces by enhancing the porosity of the dielectric. This has been achieved by growing sodium chloride crystals onto a conducting polymer layer and, after generation of all required layers using the layer‐by‐layer electrodeposition technique, salt crystals have been eliminated by water etching. Results from morphological and topographical studies on single‐layered poly(3,4‐ethylenedioxythiophene) (PEDOT), poly(N‐methylpyrrole) (PNMPy), and poly(3,4‐ethylenedioxythiophene‐co‐N‐methylpyrrole) (COP), as well as electrochemical investigations on bi‐layered films with enhanced porosity at the interface between the two layers, have been used to design new four‐layered electrodes. These consist in two layers of PEDOT separated by two layers of nanosegregated COP with a porous interface in the middle. Although the properties of the new four‐layered electrodes improve due to the porous interface, the highest specific capacitance corresponds to the two‐layered electrode in which two PEDOT layers are separated by an ultra‐porous interface. POLYM. ENG. SCI., 59:1624–1635 2019. © 2019 Society of Plastics Engineers

DETERIORATION MECHANISMS AFFECTING THE BRICKS USED IN THE BUILDING OF THE WATER WELLS AT KARNAK TEMPLES, LUXOR, EGYPT

The water wells at Karnak temples made of red brick and belonging to different eras, (Graeco-Roman and Byzantine periods). These water wells suffer from several deterioration aspects such as exfoliation, hard crusts, disintegration, spalling, cracks, fractures, salts crystallization, micro-organisms colonization's and vegetation. The aim of this paper is to study the deterioration mechanisms affecting the brick units of these wells to prepare a conservation strategy. Different scientific methods such as Light Optical Microscope (LOM), Polarizing Microscope (PM), Scanning Electron Microscope coupled with an Energy Dispersive X-Ray Spectrometer (SEM-EDX) and X-Ray Powder Diffraction (XRD) have been used to determine the mineralogical composition and the deterioration products. The obtained results have proved that the water wells suffer from salts crystallization of sodium chloride and sodium sulfate (thenardite) due to the severe effects of deterioration factors particularly the dominated environmental conditions, water-soluble salts and mineralogical composition of the brick.

Role of Steam as a Medium for Droplet Crystallization

Mannitol and sodium chloride (NaCl) were spray dried using a counter current superheated spray dryer. Superheated steam was found to induce relatively high nucleation during the solidification of the sprayed droplets when compared to hot air. This allowed the production of spherical mannitol particles with very fine crystals at a lower temperature. In addition, superheated steam led to the formation of unique salt microspheres consisting of hollow hopperlike sodium chloride crystals. These unique particle morphologies were not observed in hot air spray drying. Further analysis revealed that higher droplet temperature during the constant rate drying period, under superheated steam conditions, led to the high nucleation phenomenon. Results from this work illustrate the potential of superheated steam as a useful medium for in situ crystallization control in spray dryers.