Effect of Ring-Size Variation within Dibenzocrown Ether Resins upon Ion-Pair Sorption of Alkali-Metal Cations from Aqueous and Aqueous Methanol Solutions

Abstract

A batch analysis method has been developed for evaluation of metal salt sorption by crown ether polymers. Selectivity in competitive alkali-metal chloride sorption by a series of formaldehyde condensation polymers of dibenzocrown ethers is influenced by the relationship between the crown ether cavity size and metal ion diameter, as well as the degree of hydration of the metal salt. Effective and selective sorption of KCl from the other alkali-metal chlorides was obtained with a dibenzo-18-crown-6 resin. Excellent sorption selectivity for the monovalent metal chlorides was noted for competitive ion-pair sorption of NaCl, KCl, MgCl₂, and CaCl₂ by this resin. This resin was examined as a stationary phase for selective column separation of KCl from alkali-metal chlorides and of KCl and NaCl from alkali-metal and alkaline-earth chloride mixtures in 80% methanol—20% water.     

Kinetics of HCl emission from inorganic chlorides in simulated municipal wastes incineration conditions

Sulfation of inorganic chlorides (KCl, CaCl₂ and NaCl) of mean particles size 75-125 μm was done in a lab-scale tubular reactor. The reactor was supplied with a mixed gas consisting of SO₂:0.3-1.3 vol%, O₂:2.5-15 vol% and H₂O:5-20 vol% in the temperature range 623-1123 K. The rates of HCl emission from the particles samples were measured and compared.It was found that at 1023 K, an HCl of about 8000 ppm was emitted from CaCl₂ and this emission concentration was more than 3 times as high as those from NaCl and KCl. The reaction kinetic parameters such as rate constants and reaction orders with respect to SO₂, O₂ and H₂O partial pressures were determined for the sulfation of NaCl, KCl and CaCl₂. The rate of HCl emission from KCl, CaCl₂ and NaCl became increasingly high when the temperature was raised above 923 K and depend on SO₂, O₂, and H₂O partial pressures. It was considered that an increase in the rate of HCl emission from the inorganic chlorides at temperatures above 923 K was caused by a change in the reaction mode from a gas-solid to a gas-liquid and/or a gas phase reaction, owing to a partial melting and/or volatilization of the inorganic chlorides.     

Thermodynamic modeling of the dissociation conditions of hydrogen sulfide clathrate hydrate in the presence of aqueous solution of inhibitor (alcohol,salt or ethylene glycol)

Hydrate dissociation conditions of hydrogen sulfide in the presence of aqueous solution of thermodynamic inhibitor (methanol, ethanol, ethylene glycol, NaCl, KCl and CaCl₂) is modeled in this communication. A thermodynamic model is developed to correlate the hydrate dissociation conditions for the systems of H₂S + water + salt (single and mixed salts of NaCl, KCl and CaCl₂), H₂S + water + alcohol (methanol or ethanol), H₂S + water + ethylene glycol and H₂S + water + mixed salt, and methanol/ethylene glycol. Extended-UNIQUAC (e-UNIQUAC) approach is used for modeling of the activity coefficient of water in aqueous phase. The structural parameters of e-UNIQUAC model are extracted from literature but interaction parameters of this model are obtained by fitting the model with experimental data. The results of the present model are in satisfactory agreement with experimental data.     

Reverse osmosis applied to the recovery of water from aqueous salt solutions

A cellulose acetate membrane was applied to the study of reverse osmosis on aqueous solutions of LiCl, NaCl, KCl, CaCl₂, SrCl₂ and BaCl₂. This membrane, 71 microns thick and having an effective diameter of 1 1/2 in. was mounted within a specially constructed cell, made of stainless steel and designed to withstand pressures up to 1500 psi. The cell consisted of two chambers, which were separated by the membrane, and a porous plate supporting it. Solutions of 0·05 N, for all of these salts, were used to establish the osmotic pressure of each solution, the water fluxes through the membrane, and the extent of salt rejection. These variables were also determined for NaCl normalities of 0·2 and 0·6. On a single pass basis, the salt rejections ranged from 76% for KCl up to 95% for CaCl₂. The results are discussed in terms of the size of the hydrated cation. The water fluxes for all these solutions were found to be essentially the same and were independent of the type of salt. For solutions of 0·05 N, the water fluxes ranged from zero at the osmotic pressure up to about 44 × 10^?5 g sec^?1cm^?2 (8·8 gal day^?1ft^?2) at 800 psi and 77°F. Also, for the 0·05 N-NaCl solution, the temperature was varied from 77°F to 120°F. The results of this temperature study show that the extent of salt rejection remains essentially fixed, while the water flux at any given pressure at 120°F becomes nearly double that of 77°F.     

Fusibility study of the magnesium cell electrolyte containing MgCl2, CaCl2, NaCl and KCl

The four-component magnesium cell electrolyte containing MgCl₂, CaCl₂, NaCl and KCl has been converted to a quasi-ternary system by keeping the proportion of NaCl and KCl in the mixture equimolecular. The triangular phase diagram has been drawn depicting the fusibility isotherms of the system. It has been possible to obtain complete liquid mixtures at temperatures as low as 400° C by suitably adjusting the proportions of the four components of the molten salt mixture.     

Stability of a boron-doped diamond electrode in molten chloride systems

Stability of a boron-doped diamond as an oxygen evolution electrode material was evaluated at 773 K in molten LiCl–KCl (58.5:41.5 mol%), LiCl–KCl (75:25 mol%), LiCl–CaCl₂ (64:36 mol%), LiCl–NaCl–CaCl₂ (52.3:13.5:34.2 mol%). In molten LiCl–KCl systems, the BDD is stable at 773 K regardless of the concentration of oxide ion and the composition of the melt. In molten LiCl–CaCl₂ and LiCl–NaCl–CaCl₂, the BDD electrode is less stable than in molten LiCl–KCl systems.     

Solubility of CO2 in aqueous solutions of NaCl, KCl, CaCl2 and their mixed salts at different temperatures and pressures

The solubility of CO₂ in water and aqueous solutions of NaCl, KCl, CaCl₂, NaCl + KCl (weight ratio = 1:1), NaCl + CaCl₂ (weight ratio = 1:1), KCl + CaCl₂ (weight ratio = 1:1), and NaCl + KCl + CaCl₂ (weight ratio = 1:1:1) was determined at 35.0, 45.0 and 55.0 °C up to 16 MPa, and the concentration of the salt was up to 14.3 wt%. It was demonstrated that solubility increased with increase in pressure, and decreased with increasing temperature. Addition of a salt or salt mixture resulted in reduction in the solubility due to the salting-out effect. At the same salt concentration (wt%), the salting-out effect of KCl was considerably smaller than those of NaCl and CaCl₂. The salting-out effect of a salt mixture is between those of its components.     

Selective transport of inorganic ions along CA membranes

Transport of inorganic ions along asymmetric cellulose acetate (CA) membrane from aqueous binary systems with a common ion: KCl–NaCl, Na₂SO₄–CuSO₄, K₂CrO₄–KNO₃, KCl–CaCl₂, and NaCl–LiCl was studied. The transport proceeds via the support matrix of the membrane and can be measured by the growth of whiskers on its exposed surface and the change of composition of the solution. Differences in the growth rates resulted from differences in transport rates of the various ions. The selectivity of the membrane is attributed to the interaction support matrix–water–ion.     

Prediction of the viscosity of mixed electrolyte solutions from single-salt data

The viscosities of sonic mixed electrolyte solutions (NaCl + KCl, NaCl, + Nll₄NO₃, NaCl + CaCl₂, NaCl + Ca(NO₃)₂, NaCl + MgSO₄) have been measured to high concentration at 298 K. Existint: viscosity data for the single-salt solutions have been fitted, as required, to Goldsack's two-parameter equation. Mixed electrolyte data have been used to test the predictive accuracy of five simple methods of estimation. The usefulness and relative accuracies of the methods have been discussed briefly.     

Application of a New Gibbs Energy Equation to Model a Distillation Tower for Production of Pure Ethanol

A steady‐state equilibrium‐stage model based on MESH equations was proposed to simulate saline extractive distillation columns. The interaction parameters between each component of water‐CaCl₂ and ethanol‐water were obtained from mean ionic activity coefficients and vapor‐liquid equilibrium (VLE) experimental data. Additionally, the interaction coefficients for the ethanol‐CaCl₂ pair were fitted to experimental VLE data which were reported by Nishi for the ethanol‐water‐CaCl₂ system. It should be noted that adjustable parameters between each pair were considered to be temperature dependent. The results confirmed that the proposed model could accurately predict the experimental vapor‐liquid equilibrium data for ethanol‐CaCl₂‐water systems. Finally, the validated model was coded using MATLAB software and was solved using the Wang‐Henke method, including the VLE and enthalpy models.     

Thermosensitive and ampholytic hydrogels for salt solution

A series of N‐isopropylacrylamide/[[3‐(methacryloylamino)propyl]dimethy(3‐sulfopropyl)ammonium hydroxide] (NIPAAm/MPSA) copolymer hydrogels were prepared with various compositions. Swelling of the hydrogels in water, aqueous NaCl, KCl, CaCl₂, and MgCl₂ solutions was studied. NIPAAm/MPSA hydrogels have a higher degree of swelling in water and salt solutions than that of poly(N‐isopropylacrylamide) (PNIPAAm). Also, NIPAAm/MPSA hydrogels are more salt resistant when deswelling in salt solutions. For <7 mol % MPSA, the formed hydrogels retain both temperature reversibility and high swelling. A higher content of MPSA (>11 mol %) leads to better salt resistance but a decrease in thermosensitivity. The swelling of NIPAAm/MPSA hydrogel in 0.05M NaCl is non‐Fickian. In NaCl and KCl aqueous solutions, the zwitterionic hydrogels do not show obvious antipolyelectrolyte swelling behavior, whereas in divalent salt CaCl₂ and MgCl₂ solutions, the swelling ability of NIPAAm/MPSA hydrogels is enhanced at low salt concentration, then decreases with further increase in salt concentration. The lower critical solution temperatures of NIPAAm/MPSA hydrogels are also affected by concentrated salt solution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2032–2037, 2003     

Experimental studies and modeling of CO2 solubility in high temperature aqueous CaCl2, MgCl2, Na2SO4, and KCl solutions

The phase equilibria of CO₂ and aqueous electrolyte solutions are important to various chemical‐, petroleum‐, and environmental‐related technical applications. CO₂ solubility in aqueous CaCl₂, MgCl₂, Na₂SO₄, and KCl solutions at a pressure of 15 MPa, the temperatures from 323 to 423 K, and the ionic strength from 1 to 6 mol kg^?1 were measured. Based on the measured experimental CO₂ solubility, the previous developed fugacity‐activity thermodynamic model for the CO₂‐NaCl‐H₂O system was extended to account for the effects of different salt species on CO₂ solubility in aqueous solutions at temperatures up to 523 K, pressures up to 150 MPa, and salt concentrations up to saturation. Comparisons of different models against literature data reveal a clear improvement of the proposed PSUCO2 model in predicting CO₂ solubility in aqueous salt solutions. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2286–2297, 2015     

Thermal energy storage in inorganic salts

The work involved studying the potential of Na₂SO₄, NaCl, KCl, CaCl₂ and some eutectic mixtures of inorganic salt for storing thermal energy. Heat storage materials have wide application in devices such as “off-peak” space heating furnaces. Data reveal Na₂SO₄ to be a better heat storage material than other salts as well as conventional heat storage materials because of its dimorphic nature and high heat of transition. It is estimated that less than 0.29 m³ of Na₂SO₄ would be required for heating a normal sized house on the Canadian Prairies.     

Cation effect on gel – sol transition of kappa carrageenan

The steady state fluorescence (SSF) technique was employed to study gel – sol transitions of kappa carrageenan in NaCl, KCl and CaCl₂ solutions. Pyranine was used as a fluorescence probe for monitoring these transitions. Scattered light, I_sc and fluorescence intensity, I was monitored against temperature to determine the gel - sol (T_gs) transition temperatures and exponents. It was observed that T_gs values are strongly correlated to the NaCl, KCl and CaCl₂ contents. The weight average degree of polymerization, DP_w and gel fraction G, exponents (γ and β) were measured and found to be in accord with the classical Flory–Stockmayer Model.     

Plugging behavior of gellan in porous saline media

In this article, the hydrodynamic behavior of dilute aqueous solutions of a natural polysaccharide—gellan in the porous media under the modeled oilfield conditions is described. The hydrodynamic properties of gellan and poly(acrylamide) solutions in saline porous media are compared. The influence of inorganic salts NaCl, KCl, CaCl₂, MgCl₂, and BaСl₂ on sol–gel and gel–sol transitions of dilute gellan solutions was evaluated. The mechanism of sol–gel transition in the presence of individual alkaline and alkaline‐earth metal salts is described on the basis of literature data. The viscometric measurements revealed that the effectiveness of salts to enhance gelation of gellan changes in the following order: BaСl₂ > CaCl₂ ≈ MgCl₂ > KCl > NaCl. The sol–gel and gel–sol phase transitions of gellan solution were also observed upon addition of oil field water containing 73 g L^?1 of alkaline and alkaline earth metal ions. During the injection of gellan solutions into the porous media saturated by saline water an oscillation of the injection pressure was observed. Such behavior of gellan is explained by either the sol‐to‐gel and the gel‐to‐sol transitions of the polymer taking place in saline water or the step‐by‐step plugging of high permeable channels until all high permeable channels of sand packs are plugged due to gellan invasion. The application of brine‐initiated gelation of gellan for water shutoff operations (WSO) in field conditions was demonstrated. Higher technological effectiveness of gellan injection in comparison with existing gelation systems was shown. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41256.     

Methods of estimating the water activity of supersaturated aqueous solutions

Empirical and semi-empirical methods of estimating the water activity of supersaturated aqueous solutions at up to twice the saturation molality are compared for CaCl₂ and Na₂SO₄ at °0C and K₂SO₄, KH₂PO₄, NaCl, KCl, RbCl, CsCl, KNO₃ and mannitol at 25°. An empirical method, applicable to both electrolytes and non-electrolytes, is described.     

Prediction of carbon dioxide gas hydrate formation conditions in aqueous electrolyte solutions

A methodology for predicting the incipient equilibrium conditions for carbon dioxide gas hydrates in the presence of electrolytes such as NaCl, KCl and CaCl₂ is presented. The method utilizes the statistical thermodynamics model of van der Waals and Platteeuw (1959) to describe the solid hydrate phase. Three different models were examined for the representation of the liquid phase: Chen and Evans (1986), Zuo and Guo (1991), and Aasberg-Petersen et al. (1991). It was found that the model of Zuo and Guo (1991) gave the best results for predicting incipient CO₂ gas hydrate conditions in aqueous single salt solutions. The model was then extended for prediction of CO₂ gas hydrates in mixed salts solutions. The predictions agree very well with experimental data.     

常压水热Ca-Na-Cl溶液中用磷石膏制备α-半水石膏

引言常压水热电解质溶液中,二水石膏(calcium sulfate dihydrate,DH)、α-半水石膏(α-calcium sulfate hemihydrate,α-HH)、无水石膏(calcium sulfate anhydrate,AH)三相之间的转化对于无机     

The saturation vapour pressure and decomposition potential of ThCl4 solutions in molten alkali chlorides

The partial pressures of the components (ThCl₄, MCl and MThCl₅) in the saturated vapours of ThCl₄ solutions in molten LiCl, NaCl, KCl, RbCl and CsCl are determined as a function of temperature (900–1200 K) and ThCl₄ concentration (2–50 mol % ThCl₄) by dynamic method. Thorium tetrachloride volatility is shown to exceed that of alkali from the melts containing less than 98 LiCl or NaCl, 83 KCl, 67 RbCl and 48 mol % CsCl. From experimental observations the decomposition potential of the electrolytes under investigation was estimated in temperature and concentration ranges of our measurements. Under otherwise equal conditions, it increases in the series of alkali chlorides from LiCl to CsCl.