Inorganic Salt Solutions Research Articles

Indoor relative humidity as a fire risk indicator

A low cost weather station has been tested for monitoring relative humidity (RH) in sitting rooms as a dry wood fast fire development risk indicator. Ten Norwegian wooden homes/flats, built between 1843 and 2012, were selected for testing during the winter 2015/2016. Linear calibration curves for each in- and outdoor sensor, based on saturated inorganic salt solution controlled air, were needed to ensure ±3% RH accuracy. Recorded average moisture supply to the indoor air during the winter varied from 0.30 to 2.64 g/m3, with mean 1.29 ± 0.75 g/m3. The oldest buildings and the modern balanced ventilation buildings were generally driest. A near step change to drier weather in January resulted in a 6–7 days decay period for recorded indoor RH of the older buildings with wood panel wall linings. This was within reasonable proximity (30%) of theoretically expected step change diffusion controlled wood panel drying. The decay period was shorter for a modern building with plasterboard wall linings. A similarly long decay period was not observed for subsequent rising RH values two weeks later. This discrepancy may be explained by wood desorption adsorption hysteresis. The calibrated weather stations gave reliable results throughout the winter season. They served, and may very well also in the future serve, as detectors for warning local fire brigades about emerging dry wood fire risk situations. Due to hysteresis, more research is, however, needed to know when to call off a dry indoor climate high fire risk condition as the conditions gets less dry.

Synthesis, microstructure, and electric properties of CaZr0.9Y0.1O3 – δ films obtained on porous SrTi0.8Fe0.2O3 – δ supports

Compact CaZr0.9Y0.1O3–δ (CZY) film on a porous SrTi0.8Fe0.2O3–δ (STF) support is obtained using the technique of deposition from solutions of inorganic salts in ethanol. According to the data of scanning electron microscopy (SEM), the film has a nanoporous granular structure with the grain size of 0.2 to 1 μm. The thickness of the CZY film on the STF support is about 3 μm after 15-fold solution application. The results of studying the elemental composition showed that elements of the support diffuse into the film in the course of synthesis. Analysis of the data of impedance spectroscopy shows that conductivity of the CZY film is limited the grain bulk. It is assumed that the comparatively low conductivity activation energy of the film (50.3 kJ/mol) is due to diffusion of elements of the STF support that results in variation of the film composition and properties.

Species dependent iodine extractions in polymer based aqueous biphasic systems: Emerging relations with aggregation number of polymeric micelles

A simple, rapid and sensitive spectrophotometric method has been developed for the extraction and speciation of iodine species; periodate (IO4−), iodide (I−) and povidone-iodine. The proposed method is based on aqueous biphasic system (ABS), obtained by mixing 50% aqueous solution of polyethylene glycol (PEG) of molecular weight 6000 with aqueous solution of inorganic salts (1.5M Na2SO4, 1.5M Na3C6H5O7·5H2O and 1M Na2HPO4) respectively at 300K. Haematoxylin (5mM in 50% PEG), was used as sensing agent for periodate (IO4−). The absorption spectra of iodide and povidone-iodine were measured directly in the PEG solution. The molar absorptivity and sandal sensitivity for IO4−, I− and I2 were 45,562L/mol/cm, 288.88L/mol/cm, 27,736L/mol/cm and 4.69μg/cm2, 3.46μg/cm2, 9.1μg/cm2 respectively. The optimum pH of the salt rich phases were evaluated for extraction of iodine species in aqueous biphasic systems. The extraction of iodine species were preferred at neutral (pH=7) or in basic conditions (pH=9–11). The aggregation numbers of the pure PEG solution as well as that after aqueous biphasic extraction at optimum pH of different salt rich phases were monitored by fluorescence quenching method. This work is the first report on the interdependence between percentage of extraction of iodine species in polymer rich phase and its corresponding aggregation number.

Significant Enhancement in the Thermoelectric Properties of PEDOT:PSS Films through a Treatment with Organic Solutions of Inorganic Salts.

PSS) films through a treatment with organic solutions of inorganic salts. N,N-Dimethylformamide (DMF) and a common inorganic salt like zinc chloride (ZnCl2) are used as the solvent and solute of the solutions, respectively. The treatments can significantly increase both the Seebeck coefficient and electrical conductivity of the PSS films. The thermoelectric properties of the PSS films are sensitive to the experimental conditions, such as the salt concentration, treatment temperature, and the cation of the salts. After treatment at the optimal experimental conditions, the PSS films can exhibit a Seebeck coefficient of 26.1 μV/K and an electrical conductivity of over 1400 S/cm at room temperature. The corresponding power factor is 98.2 μW/(m·K(2)). The mechanism for the enhancement in the thermoelectric properties is attributed to the segregation of some PSSH chains from PSS and the conformation change of PEDOT chains as a result of the synergetic effects of inorganic salts and DMF.

Interplay of Electrostatic Interactions and Hydrophobic Hydration at the Surface of Tetra-n-alkylammonium Bromide Solutions

We use intensity and heterodyne-detected vibrational sum-frequency generation (VSFG and HD-VSFG) to study the structure of water at the surface of aqueous tetra-n-alkylammonium bromide (TAABr) solutions. We compare the water structure for four different n-alkyl chains (n = 1, 2, 3, 4). For solutions of tetra-n-alkylammonium bromides with short n-alkyl chains (n = 1, 2), we observe the structure of the surface water to be similar to the structure observed for simple inorganic salt solutions. For these solutions, the presence of Br– at the interface is observed to lead to a small decrease in the average strength of the hydrogen bonds. For solutions of tetra-n-alkylammonium bromides with long n-alkyl chains (n = 3, 4), we observe a strong ordering of the water molecules at the solution surface. The water molecules show a net orientation of their O–H group toward the bulk, which can be explained from the high surface propensity of positively charged tetra-n-alkylammonium ions with long alkyl chains (n = 3, 4)...

Poly(ethylene glycol) crosslinked sulfonated polysulfone composite membranes for forward osmosis

ABSTRACTForward osmosis (FO) membranes were prepared by a coating method with poly(ethylene glycol) crosslinked sulfonated polysulfone (SPSf) as a selective layer. The poly(ether sulfone)/SPSf substrate was prepared by phase inversion. The composite membranes were characterized with respect to membrane chemistry (by attenuated total reflectance/Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy), hydrophilicity (by static contact angle measurement), and surface morphology (by scanning electron microscopy and atomic force microscopy). The FO performance was also characterized. The effects of the crosslinker concentration on the hydrophilicity and FO performance were investigated. The crosslinked membrane exhibited a high hydrophilicity with a lowest contact angle of 15.5°. Under FO tests, the membranes achieved a higher water flux of 15.2 L m−2 h−1 when used against deionized water as the feed solution and a 2 mol/L sodium chloride (NaCl) solution as the the draw solution. The membranes achieved a magnesium sulfate rejection of 96% and an NaCl rejection of 55% when used against a 1 g/L inorganic salt solution as the feed solution and a 2 mol/L glucose solution as the draw solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43941.

Why physicochemical properties of aqueous solutions of various compounds are linearly interrelated

Analysis of physicochemical properties, such as water activity, osmotic coefficients, surface tension, viscosity, and relative permittivity, of aqueous solutions of different inorganic salts, organic compounds, and polymers shows that these properties are linearly interrelated and this interrelationship may be described as: Yi1(ci1)=k1+k2Yi2(ci2)+k3Yi3(ci3), where Yi1(ci1), Yi2(ci2), and Yi3(ci3) are properties of aqueous solutions of individual compounds 1, 2, and 3 at the same ith concentration i of each compound (ci1=ci2 = ci3); k1, k2, and k3 are constants. The relationship holds for various concentrations of compounds provided properties of aqueous solutions of the individual compounds are compared at the same concentration of each compound. Similar interrelationships are established also between different properties of aqueous solutions of any given compound. It is suggested that the reason for these relationships is that all physicochemical properties of aqueous solutions of any compound display different aspects and peculiarities of intermolecular water-water interactions affected by the presence of the compound, its nature, and concentration. The different types of water-water interactions in aqueous solutions may be quantified with the solvatochromic dyes. The solvent dipolarity/polarizability, π*, hydrogen bond donor acidity, α, and hydrogen bond acceptor basicity, β of water reported previously for aqueous solutions of organic compounds and polymers as well as those obtained for solutions of inorganic salts are linearly interrelated likely due to the cooperativity of intermolecular interactions in water. It is shown that any physicochemical property of aqueous solution of a given salt, organic compound, or polymer may be described by linear combination of two solvent features, π* and α, or in some cases by a single solvent feature. This fact explains the reason for the existence of the aforementioned linear interrelationships between the physicochemical properties of aqueous solutions of different compounds.

Electrical behaviors of ZnO/graphene/Si and ZnO/graphene/PS composite structures obtained by spraying different volumes of graphene solution

In this paper, a novel ZnO/graphene/porous silicon hybrid device is fabricated and its electrical behaviors are studied along with a ZnO/graphene/silicon device. Graphene (G) is prepared by exfoliation of graphite foil in aqueous solution of inorganic salt. Porous silicon (PS) is fabricated by electrochemical etching of p-type silicon (Si). Graphene is deposited on the surface of Si and PS substrates by thermal spray pyrolysis method. ZnO rods are grown on the samples by using catalyst-free chemical vapor transport and condensation method. The current–voltage relationships of ZnO/G/Si and ZnO/G/PS devices are studied under different volumes of graphene solution. The results reveal the distinctive features of the I–V characteristics of the two devices for different volumes of graphene solution under room light as well as UV illumination.

A facile route to prepare cellulose-based films

Cellulose is the most abundant renewable and biodegradable material available in nature. Its insoluble character in water as well as common organic and inorganic liquids, however, curtails the wholesome utility. The continuous rise for biodegradable products based on cellulose coupled with its intrinsic ability to form a viable substitute for the petroleum-based materials necessitates the critical need for solubilizing the cellulose. Herein, we demonstrate the feasibility of ZnCl2 solutions, especially the 64–72% concentrations, to dissolve cellulose. FTIR results suggest that Zn2+ ions promote Zn⋯O3H interactions, which in-turn weaken the intrinsic O3H⋯O5 hydrogen bonds that are responsible for strengthening the cellulose chains. Interestingly, Ca2+ ions promote interactions among the Zn-cellulose chains leading to the formation of nano fibrils and yield gelling solutions. The tensile strength of the Ca2+ added Zn-cellulose films increases by around 250% compared to the Zn-cellulose films. Overall, utilization of inorganic salt solutions to solubilize and crosslink cellulose is cost-effective, recyclable and certainly stands out tall among the other available systems. More importantly, the proposed protocol is simple and is a “green” process, and thus its large-scale adaptability is quite feasible. We strongly believe that the outcome opens up a new window of opportunities for cellulose in the biomedical, pharmaceutical, food and non-food applications.

Viscosities of Some Saccharides in Aqueous Solutions of Phosphate-Based Inorganic Salts

The viscosities η of some monosaccharides, their methyl- and deoxy- derivatives, disaccharides, and trisaccharides have been measured in (0.25, 0.5, 1.0, and 1.25) mol·kg–1 aqueous solutions of potassium phosphate (KH2PO4) and (0.5, 1.0, 1.5, and 2.0) mol·kg–1 aqueous solutions of sodium phosphate (NaH2PO4) and ammonium phosphate (NH4H2PO4) monobasic salts, and potassium phosphate (K3PO4) tribasic salt over the temperature range (288.15 to 318.15) K and at atmospheric pressure, P = 0.1 MPa. The viscosity data have been utilized to calculate the Jones–Dole viscosity B-coefficients and their corresponding coefficients of transfer, ΔtB. The ΔtB values were found to be positive and their magnitudes vary depending on the nature of solutes and cosolutes. The dB/dT coefficients and pair ηAB and triplet ηABB interaction coefficients have also been calculated and discussed in terms of solute–solvent/cosolute interactions. The results have been compared in phosphate-based salts on the basis of the nature of the cat...

Discrimination for inorganic and organic mercury species by cloud point extraction of polyethylene glycol

Speciation and extraction of mercury has been studied using cloud point extraction of polyethylene glycol (PEG). A solution of PEG itself is reported to form cloud at a considerably high temperature which is unfavorable for the extraction and separation of volatile analytes. Different inorganic salt solutions (Na2SO4, NaH2PO4, NaCl, NaOAc) when used as additives were found to lower the cloud point temperature of PEG (#6000) effectively. The lowest temperature for cloud formation was observed at 35°C with 0.8M Na2SO4. The cloud so formed was found suitable to discriminate between inorganic and organic mercury species. 1-(2-pyridylazo)-2-napthol (PAN) was used for spectrophotometric detection of inorganic and organic mercury. Confocal microscopic images and zeta potential values reveal the actual interactions of the inorganic Hg species with the organized PEG micelles in aqueous medium. Environmental samples were also analyzed using the present method.

Characteristic of the Nanoparticles Formed on the Carbon Steel Surface Contacting with 3d-Metal Water Salt Solutions in the Open-Air System.

The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed layered double hydroxides (LDHs) together with non-stoichiometric spinel ferrite nanoparticles are formed on the steel surface. Mixed LDHs keep stability against further oxidation and complicate the obtaining of spinel ferrite nanoparticles. Thermal treatment of mixed LDHs among other mineral phases formed via the rotation-corrosion dispergation process at certain temperatures permits to obtain homogenous nanoparticles of spinel ferrites as well as maghemite or hematite doped by 3d-metal cations.

Chemical and environmental compatibility of red mud liners for hazardous waste containment

Red mud residue from alumina production has been proposed as an alternative liner material. The chemical and environmental compatibility of red mud upon exposure to representative organic (methanol, heptane, TCE, and acetic acid) and inorganic liquids (CaCl2 and seawater) was studied. Chemical compatibility assays comprised Atterberg limits and sedimentation and hydraulic conductivity tests for red mud interacted with the chemical liquids, whereas the environmental compatibility was assessed through the leaching of metals from red mud as permeated with the liquids. Methanol greatly reduced the plasticity at concentrations ≥80 % by volume, but it did not increase the hydraulic conductivity of compacted red mud. High concentrations (≥60 % v/v) of acetic acid reduced the plasticity and enhanced the sedimentation of red mud. Conversely, acetic acid concentrations ≤40 % caused dispersion, but damaged the hydraulic properties and structure of red mud. The percolation of a pH 2 acetic acid solution did not adversely affect the hydraulic performance of the red mud liner. Neither diluted heptane nor TCE affected the red mud. However, pure organics suppressed the plasticity and induced aggregation of red mud, suggesting a great detrimental effect on red mud liners. The red mud exhibited great resistance to attack by inorganic salt solutions. Some concerning leaching of metals (primarily Al and Cr) occurred as water, acetic acid, and CaCl2 solutions percolated through red mud, but effluent metals concentration quickly dropped to permissible levels. In general, red mud exhibited a high resistance against chemical attack; nevertheless, exposure to low-dielectric-constant organic chemicals should be avoided.

Synthesis of Submicrometer Calcium Carbonate Particles from Inorganic Salts Using Linear Polymers as Crystallization Modifiers

In this study, we report the synthesis of submicrometer calcium carbonate particles using the simplest approach of mixing solutions of calcium chloride and ammonium carbonate inorganic precursors in the presence of crystallization modifiers. Instead of the typical crystallization of CaCO3 into large calcite crystals with rhombohedral morphology, very small uniform spherical vaterite particles were formed with the addition of small amounts of the anionic homopolymer poly(sodium 4-styrenesulfonate) (PSS). In contrast, large spheres made of a collection of calcite polycrystallite aggregates formed in the presence of poly(acrylic acid) (PAA). Crystal growth in a pre-organized environment created by the selective distribution of CaII ions in the shell of polyestyrene-b-poly(acrylic acid) (PS-b-PAA) core-shell spherical micelles revealed a rather poor control of the size and morphology. Therefore, the PSS anionic homopolymer can be applied to the synthesis of submicrometer CaCO3 particles from solutions of inorganic salts, which is a much cheaper and sustainable method than controlled CO2 gas production and diffusion.

Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance.

Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm(-2) at the current density of 6 mA cm(-2) in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (∼15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ∼88% of the capacitance when the charging rate increased from 6 to 48 mA cm(-2). Moreover, the activated CC electrode exhibited excellent cycling stability with ∼97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm(-2). A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors.

ВНЕДРЕНИЕ ТЕХНОЛОГИИ ЭЛЕКТРОЛИТНО-ПЛАЗМЕННОГО ПОЛИРОВАНИЯ МЕТАЛЛИЧЕСКИХ ИЗДЕЛИЙ

Modern methods of final polishing of complex-surface goods are labor-consuming and unsustainable. Nowadays, the method of electrolytic-plasma polishing is developed intensively. This method is the high-efficiency process of conductive goods treatment in the environmentally safe aqueous solutions of inorganic salts of weak concentration. Commercial application of electrolytic-plasma polishing method is impeded in engineering due to its poor exploration. The authors studied the influence of multistep polishing and electrolyte composition on the process technological parameters and surface roughness of plate specimens of 08H18N10T austenitic stainless steel processed using laboratory machine. The authors carried out the comparing study of surface roughness of specimens processed according to the suggested modes and the specimens processed according to the known modes of polishing in the widely used aqueous solutions of ammonium sulfate-based (4 % (NH4)2SO4) and sodium carbonate-based (12 % Na2CO) electrolytes. The study showed that the introduction of 0,05–0,45 % chlorine hydride to the electrolyte containing 4–5 % of ammonium sulfate reduces twofold the temperature of working electrolyte. It is established that the multistep polishing allows decreasing the stainless steel surface roughness by 20–25 % in comparison with traditional polishing methods. Basing on the results obtained, the authors suggested technological modes of final treatment of austenitic stainless steels with the use of electrolytic-plasma polishing method, developed and produced the machine for electrolytic-plasma polishing of goods (MEPPG-1). This machine is universal and allows carrying out the final polishing of various conductive materials up to 250 cm2 in area used in manufacturing industry (copper, aluminum, steel, titanium and others) by means of the electrolyte composition and processing modes changes.

Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance

Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance

A resolution approach of racemic phenylalanine with aqueous two-phase systems of chiral tropine ionic liquids

Aqueous two-phase systems (ATPS) based on tropine type chiral ionic liquids and inorganic salt solution were designed and prepared for the enantiomeric separation of racemic phenylalanine. The phase behavior of IL-based ATPS was comprehensive investigated, and phase equilibrium data were correlated by Merchuk equation. Various factors were also systematically investigated for their influence on separation efficiency. Under the appropriate conditions (0.13g/g [C8Tropine]pro, 35mg/g Cu(Ac)2, 20mg/g d,l-phenylalanine, 0.51g/g H2O and 0.30g/g K2HPO4), the enantiomeric excess value of phenylalanine in solid phase (mainly containing l-enantiomer) was 65%. Finally, the interaction mechanism was studied via 1D and 2D NMR. The results indicate that d-enantiomer of phenylalanine interacts more strongly with chiral ILs and Cu2+ based on the chiral ion-pairs space coordination mechanism, which makes it tend to remain in the top IL-rich phase. By contrast, l-enantiomer is transferred into the solid phase. Above chiral ionic liquids aqueous two-phase systems have demonstrated obvious resolution to racemic phenylalanine and could be promising alterative resolution approach for racemic amino acids in aqueous circumstance.

Microwave-assisted dehydration of D-xylose into furfural by diluted inexpensive inorganic salts solution in a biphasic system

Production of furfural from biomass using less corrosive acids and minimizing the formation of undesired by-products is great challenge. Dehydration of D-xylose to furfural was carried out under microwave irradiation in biphasic system consisting of CPME and aqueous inorganic salts solution. Best conditions of dehydration of D-xylose using FeCl3 were investigated by varying temperature, reaction time, pentose loading and influence of NaCl. Highest furfural yield of 74% was achieved at 170°C for 20min in presence of 10mol% of iron chloride and 100mol% of sodium chloride in water-CPME, 1:3, v/v. Addition of NaCl was found to increase the catalytic activity of FeCl3 and allowed to reduce the amounts of FeCl3 used from 20mol% to 10mol%. This approach was tested with success starting from L-arabinose and xylan, a pentose-rich polysaccharide.

Micron Scale Cathodically Coated Graphene Impedes Corrosion on Ti, Cube, and Stainless Steel

Graphene has been studied with great interest ever since its unique mechanical and electronic properties were reported a little more than a decade ago. Common experiments involve coating non-carbon surfaces such as paper,1 metal oxide nanoparticles,2 or nickel3in order to either increase their conductivity, or to make them resistant to corrosion. Coating processes often involve mechanical transfer of graphene or chemical reduction of graphene oxide to graphene, but sometimes electrochemical cathodic reduction of the graphene oxide is used in the coating process. Here we report the first instance of cathodically coated Ti metal along with cathodically coated stainless steel and copper-beryllium. We report Raman microscope images to verify complete surface coverage of Ti, and partial coverage of ~2 micron islands of graphene on both stainless steel and CuBe. We also report Tafel plotted voltammograms to show that the presence of graphene on Ti shifts the potential of zero current, normally called the “corrosion potential,” in 3.5% NaCl(aq) to a value positive of the formal potential for the O2/H2O redox couple in sea water. We also present Tafel plots which show that the corrosion potential of graphene coated CuBe has shifted positive by 0.1V and the corrosion current decreased by nearly an order of magnitude, and that the corrosion potential of graphene coated stainless steel has shifted positive by 0.3V. 1. Parvez, Khaled; Wu, Zhong-Shuai; Li, Rongjin; Liu, Xianjie; Graf, Robert; Feng, Xinliang; and Mullen, Klaus. “Exfoliation of Graphite into Graphene in Aqueous Solutions of Inorganic Salts”. Journal of the American Chemical Society (2014) vol 136, iss 16, pp 6083-6091. 2. Nguyen-Phan, Thuy-Duong; Pham, Viet Hung; Shin, Eun Woo; Pham, Hai-Dinh; Kim, Sunwook; Chung, Jin Suk; Kim, Eui Jung; and Hur, Seung Hyun. “The role of graphene oxide content on the adsorption-enhanced photocatalysis of titanium dioxide/graphene oxide composites”. Chemical Engineering Journal (2011) vol 170, iss 1, pp 226-232. 3. Prasai, Dhiraj; Tuberquia, Juan Carlos; Harl, Robert R.; Jennings, G. Kane; and Lolotin, Kirill I. “Graphene: Corrosion-Inhibiting Coating”. ACS Nano (2012) vol 6, iss 2, pp 1102-1108.