Magnesium Chloride Solution Research Articles

Hongurin as hydraulic additive to magnesian-binding substance

Materials on the basis of the magnesian binding substances possess a number of positive characteristics that increases interest in them. Their main shortcoming is low water resistance. Due to input of natural mineral additive of hongurin, the water resistance of a magnesian stone increases. The influence of this additive on the main properties magnesian binding and a stone on its basis is considered in this article. Optimum concentration of a grouting fluid – magnesium chloride solution is also defined. It is defined that input of a natural hongurin to structure of magnesian binding promotes formation of a dense, strong and waterproof magnesian stone.

Experimental Analysis of MOC Composite with a Waste-Expanded Polypropylene-Based Aggregate.

Polypropylene (PP) is one of the most widely produced types of plastic worldwide, but its recycling is limited. This work presents a study of the utilization of expanded polypropylene (EPP) waste in a magnesium oxychloride cement (MOC) composite usable in the building industry. MOC is formed by mixing magnesium oxide powder and a concentrated solution of magnesium chloride and is characterized by excellent bonding ability to large quantities of different types of aggregates. A developed air-cured MOC composite, where an EPP-based aggregate was used for the full replacement of natural aggregate, was investigated in terms of its basic physical, mechanical, thermal and water resistance properties. The results demonstrate that incorporation of EPP waste greatly improved the thermal insulation properties, while the mechanical resistance was reduced to an acceptable level. The developed MOC composite containing EPP waste can be considered as an alternative thermal insulation material applicable for the construction of floor or envelope construction systems.

Investigation of amorphous calcium carbonate’s formation under high concentration of magnesium: The prenucleation cluster pathway

This paper investigates the formation of amorphous calcium carbonate under high magnesium concentration (Mg/Ca = 6) via several novel methods. While feeding calcium chloride solution into the mixed solution of magnesium chloride and sodium carbonate, a large amount of calcium ions (>0.13 mol/L) stably coexisted with the amorphous calcium carbonate in the solution. The calcium concentration detected by the calcium ion selective electrode was proportional to the calcium concentration added. Surprisingly, the ratio of magnesium to calcium in the amorphous calcium carbonate was just 0.07, and the concentration of calcium continued to increase in the solution after the formation of the amorphous calcium carbonate. We propose that stable prenucleation cluster formed in the solution, which stably coexisted with the amorphous calcium carbonate because of the incorporation of hydrated magnesium ions. The high dehydration free energy barrier of magnesium ions led to its slow dehydration. Also, the hydroxide ion helped to bypass the high dehydration free energy barrier. This research indicates the possible significant role of prenucleation cluster pathway in the calcium carbonate crystallization.

Experimental study on properties of magnesium oxychloride cement

Magnesium oxychloride cement is an air-hardening cementitious material formed by the reaction of magnesium oxide and magnesium chloride solution. This kind of cement has high strength and high folding pressure ratio, which is the unmatched performance of ordinary cement concrete. This article tests the modification status of magnesium oxychloride cement after adding organic solution, and provides reference for the processing and design of magnesium oxychloride cement components in the future.

Development of a technology for absorbing screening of command posts with electronic equipment

The problem of creation of a technology for effective protection of rooms of control points with electronic equipment against powerful intentional and industrial interferences was studied. Development of ray weapons is a new challenge to electronic equipment safety by the use of modern powerful electromagnetic weaponry. Absence of theoretical recommendations in the conditions of growing practical needs causes the relevance of this problem solution. As a result of theoretical and experimental studies, rational ways for solution of the problem related to the necessity of absorption of the field energy in a wide frequency range at the level of 40...50 dB were substantiated while the level of absorption known from publications is 10...20 dB. The basis for solving this problem is a significant improvement of the technology for preparation of a filler with necessary electromagnetic properties. This is an electrically conductive ferrite-ferrite compound with a structure of spinel of inverse type which has the commensurate levels of relative dielectric and magnetic permeability and electrical conductivity of (103...104) S/m. These properties of the filler will contribute to the satisfaction of generally contradictory requirements. Such are the requirements for reducing the field energy reflection from the surface of the radiation absorbing coating of the room and the requirements for increasing linear energy absorption by coating (12...15 dB/mm). Therefore, the proposed 4 mm thick absorbing Sorel cement tiles with the proposed filler provide absorption of field energy in a wide frequency band at a level of 40...50 dB due to their polymerization filling. The choice of the aforementioned binder base for the filler is justified because significant levels of thermal stability of the base are required. In principle, it is also necessary to improve the technology of highly concentrated filling of the solid, heat-resistant polymer base for the radiation absorbing coating, which effectively protects hardware of the command post from contemporary ray weapons. Existing organic polymer bases for the required coating have a limited ecological purity and working temperature not exceeding 250...300 o C. Therefore, it is expedient to use an environmentally friendly inorganic polymer in a form of Sorel cement with significantly higher thermal stability. That is why the technology of screening rooms by covering their inner surface with absorbing Sorel cement tiles was proposed. Once the filler is prepared, pre-filling of the aqueous solution of cement ingredients with dispersed filler as a field energy converter is made. After solidification of the Sorel cement tiles and covering the surface of the room, energy of interfering electromagnetic fields falling on the coating converts into heat energy. The necessary hardware screening at a level of 40...50 dB is provided by the following technology stages. First, thermochemical synthesis of conductive ferrite oxide of transition metals with a structure of spinel of inverse type is carried out at a temperature above 600 o C. Secondly, vibrational polymerization concentrated filling of the base mixture of the magnesium oxide and saturated aqueous solution of magnesium chloride is realized without the loss of strength of the tiles after their solidification. The tiles are solidified at room temperature for 15 to 17 hours

Vacuum membrane distillation of liquid desiccants utilizing hollow fiber membranes

Abstract This paper documents the testing of a vacuum membrane distillation system intended for use with liquid desiccants. Liquid desiccants offer the possibility for low-energy, ambient temperature dehumidification. Effective desalination and purification of diluted desiccants outputs two important products: a concentrated desiccant for reuse in dehumidification and fresh water. In this study, vacuum membrane distillation was used in the laboratory to purify diluted liquid desiccants. Calcium chloride and magnesium chloride were the desiccants selected for testing. Desiccant solutions were pumped through the lumens of poly(vinylidene fluoride) (PVDF) hollow fiber membranes at varying feed inlet temperatures, solution velocity rates and vacuum set points during membrane distillation. An average flux of 8 kg m−2 h−1 was obtained using 30 wt% magnesium chloride solution at a temperature of 50 °C while applying vacuum to achieve 25 mbar absolute pressure on the air side of the membrane. The results are promising for the development of a full-scale vacuum membrane distillation process for desiccant solution regeneration and fresh water recovery. In addition, the recovered condensate was of sufficient quality for use in agricultural irrigation or drinking water.

Measurement and modeling of water sorption isotherm for salt‐laden autoclaved aerated concrete

AbstractThe authors reported on the measurement of water sorption isotherms for autoclaved aerated concrete, commonly called “autoclaved lightweight concrete” in Japan, containing aqueous salt (sodium chloride or magnesium chloride) solutions in concentrations ranging from low to saturated with precipitated salt in the material. The important parameters of the salt‐laden porous materials were clearly defined. The measurement results confirmed the significant impacts of salt on the sorption isotherms, particularly at high salt concentrations. The measured sorption isotherms were modeled with the existing model that considers the vapor pressure depression and the density of the salt solution. The results showed that the differences between the measurements and the model increased with increasing amount of precipitated salt in the material. Therefore, a modified model for predicting the water sorption isotherm for a porous material containing not only a salt solution but also precipitated salt was proposed and discussed. The modified model showed better agreement with the measurements.

The Behaviour of Self Compacting Concrete With Waste Plastic Fibers When Subjected To Chloride Attack.

This paper outlines laboratory study on chloride resistance of waste plastic fibre reinforced self compacting concrete. Self compacting concrete mixes with varying percentages of waste plastic fibers like 0.0%,0.25%,0.5%,0.75%,1.00%,1.1%,1.2%,1.3% and 1.4% were developed for M40 grade of concrete. The mix proportion was done by NANSU method. The result of fresh property test satisfies the limits specified by EFNARC. The cubes and cylinders were immersed in 5% magnesium chloride solution for a period of 30 days, 60days and 90 days. The degree of chloride attack is determined by evaluating the reduction in compressive strength split tensile strength and percentage loss of weight of specimen. From the test results it is observed that maximum compressive strength and split tensile strength were achieved for 1% of plastic fibre. The chloride content is determined by Argentometric titration method. Percentage loss of weight, loss in compressive strength and chloride penetration have decreased as the percentage of fibre increased.

Adsorption of CO2 onto Activated Carbons Prepared by Chemical Activation with Metallic Salts

Abstract This article has been retracted due to honest error by the author. For further information, please see https://doi.org/10.1515/ijcre-2017-9198. Activated carbons are obtained by chemical activation of African Palm shells (Elaeis guineensis) with different impregnating agents, i. e. magnesium chloride (MgCl2) and calcium chloride (CaCl2) aqueous solutions at different concentrations (3, 5 and 7 % w/v) and temperatures (between 773 and 1073 K), in order to assess their influence on the development of the porosity. The activated carbons prepared are characterized in terms of both textural and chemical properties. The activated carbons have a surface area and a pore volume ranging between 19–501 m2.g−1 and 0.03–0.29 cm3.g−1, respectively. Based on the obtained results, the samples with higher surface area and pore volume (i. e. those impregnated with MgCl2 and CaCl2 solutions and thermally treated at 1073 K) are selected to evaluate the adsorption capacity and affinity for CO2. CO2 adsorption capacity varies between 1.78 and 2.95 mmolCO2.g−1 at 273 K and low pressure, and the activated carbon impregnated with the solution of MgCl2 3 % and activated at 1073 K (i. e. ACMg3-1073) showed the best performances. Finally, the kinetic results show that adsorption rate for sample ACMg3-1073 is enhanced by its micro-mesoporous nature, being the access routes to the micropores larger.

Adsorption of CO2 onto Activated Carbons Prepared by Chemical Activation with Metallic Salts

Abstract Activated carbons are obtained by chemical activation of African Palm shells (Elaeis guineensis) with different impregnating agents, i. e. magnesium chloride (MgCl2) and calcium chloride (CaCl2) aqueous solutions at different concentrations (3, 5 and 7 % w/v) and temperatures (between 773 and 1073 K), in order to assess their influence on the development of the porosity. The activated carbons prepared are characterized in terms of both textural and chemical properties. The activated carbons have a surface area and a pore volume ranging between 19 and 501 m2.g−1 and 0.03–0.29 cm3.g−1, respectively. Based on the obtained results, the samples with higher surface area and pore volume (i. e. those impregnated with MgCl2 and CaCl2 solutions and thermally treated at 1073 K) are selected to evaluate the adsorption capacity and affinity for CO2. CO2 adsorption capacity varies between 1.78 and 2.95 mmolCO2.g−1 at 273 K and low pressure, and the activated carbon impregnated with the solution of MgCl2 3% and activated at 1073 K (i. e. ACMg3-1073) showed the best performances. Finally, the kinetic results show that adsorption rate for sample ACMg3-1073 is enhanced by its micro-mesoporous nature, being the access routes to the micropores larger.

Effect of machining on the stress corrosion cracking behavior in boiling magnesium chloride solution of austenitic stainless steel

The stress corrosion cracking (SCC) behaviors of Z3CN20.09M, 304L, and 316L austenitic stainless steels (SSs) after milling operation in boiling magnesium chloride solution were investigated by scanning electron microscopy (SEM), X‐ray diffraction, and 3D profilometer. The experimental results indicated that the roughness and residual stress increased with increasing feed rate of all specimens. The depth of deformation layer after milling operation reached about 150 µm shown as persistent slip bands (PSBs) were formed, leading to hardness enhanced obviously. After SCC tests in boiling magnesium chloride solution, the crack densities increased with increasing feed rate of the Z3CN20.09M SS specimens. However, the crack densities decreased as well as the intergranular (IG) cracking percentages increased with increasing feed rate of the 304L and 316L SS.

Hydration and Ion Pairing in Aqueous Mg2+ and Zn2+ Solutions: Force-Field Description Aided by Neutron Scattering Experiments and Ab Initio Molecular Dynamics Simulations.

Magnesium and zinc dications possess the same charge and have an almost identical size, yet they behave very differently in aqueous solutions and play distinct biological roles. It is thus crucial to identify the origins of such different behaviors and to assess to what extent they can be captured by force-field molecular dynamics simulations. In this work, we combine neutron scattering experiments in a specific mixture of H2O and D2O (the so-called null water) with ab initio molecular dynamics simulations to probe the difference in the hydration structure and ion-pairing properties of chloride solutions of the two cations. The obtained data are used as a benchmark to develop a scaled-charge force field for Mg2+ that includes electronic polarization in a mean field way. We show that using this electronic continuum correction we can describe aqueous magnesium chloride solutions well. However, in aqueous zinc chloride specific interaction terms between the ions need to be introduced to capture ion pairing quantitatively.

Wavelength and concentration-dependent optical constants of NaCl, KCl, MgCl2, CaCl2, and Na2SO4 multi-component mixed-salt solutions.

The optical constants of sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl2), calcium chloride (CaCl2) and sodium sulfate (Na2SO4) solutions at weight fractions ranging from 0 to 16.6667% are measured by the combined ellipsometry-transmission method in the spectral range 0.3-1.0μm. In the combined method, a modified ellipsometry method is used to measure the refractive indices of liquids, and then the transmission method is conducted to obtain the extinction coefficients using the refractive indices obtained by the ellipsometry method. The experimental refractive indices of these binary solutions are utilized to obtain a mole-fraction weighted mixing rule, which relates the refractive index of multi-component mixed-salt solutions to the wavelength and concentration of each component. The effects of wavelength and concentration are taken into account by empirical expressions of the Lorentz-Lorenz formulized molar refraction. A mole-fraction weighted linear combined mixing rule is proposed to study the wavelength and concentration-dependent extinction coefficients of mixed-salt solutions. The optical constants of NaCl-KCl and NaCl-Na2SO4 ternary solutions, NaCl-KCl-CaCl2 quaternary solutions, and NaCl-KCl-MgCl2-CaCl2-Na2SO4 multi-component solutions are measured to verify the mixing rules. The results show that the optical constants calculated based on the mixing rules are in good agreement with experimental data, which demonstrate the feasibility of the proposed mixing rules. As the experimental analysis indicates, both the refractive indices and the extinction coefficients of the saline solutions increase with solute concentrations in the spectral range 0.3-1.0μm.

Charge‐assisted ultrafiltration membranes for monovalent ions separation in electrodialysis

ABSTRACTSelectivity for monovalent ions is a very important feature of ion exchange membranes in view of a further expansion of the scope of electrodialysis (ED). An efficient one‐step chemical process to graft a thin polyaniline (PANI) layer on the surface and pores of an ultrafiltration (UF) membrane is reported. The existence of a PANI layer on such modified UF membrane was confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy images. These membranes were extensively characterized by studying their properties such as water uptake, ion‐exchange capacity, contact angle, and performance in diffusion dialysis. ED experiments were conducted by comparing desalting of sodium chloride and magnesium chloride solutions. During the desalting procedure, the driving force has two contributions, the electrical field and the salinity‐gradient. Initially, transport of ions by the electrical field is dominant, while at the end of the experiment, diffusion dialysis by the salinity gradient plays a larger role in ion transport. The presence of PANI can hinder Mg2+ transport from the concentrate to the diluate compartment because of the electrostatic effect, while there is no obvious effect on Na+ ions. The ability of such a surface modification layer to improve the membrane selectivity for Na+/Mg2+ was confirmed by means of ED in a mixed solution. The flux of Na+ was slightly increased to 13.21 × 10−8 mol/L/min while the flux of Mg2+ was reduced to 3.32 × 10−8 mol/L/min, so that the permselectivity is almost doubled. The protonation reaction of the PANI layer creates positive charges, thus leading to an electrical repulsion barrier, which may reduce the penetration of divalent cations with respect to monovalent ions. Polyacrylonitrile‐based UF membranes with different molecular cutoff was used to determine the influence of the permselectivity. Results showed that the membrane permselectivity of smaller molecular cutoff UF membranes is higher. It can be concluded that this method is suitable for preparing membranes based on UF membranes for efficient separation of monovalent ions by electro‐driven separation techniques. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45692.

Effect of low-temperature surface carburization on stress corrosion cracking of AISI 304 austenitic stainless steel

The effect of low-temperature surface carburization on the stress corrosion cracking (SCC) behavior of AISI 304 austenitic stainless steel in boiling magnesium chloride (MgCl2) solution at 155±1°C was investigated. The SCC tests were carried out for untreated and carburized AISI 304 with varying four-point bend loading. In order to elucidate the influence of low-temperature surface carburization on SCC resistance, optical microscope (OM), scanning electron microscope (SEM), X-ray diffractometry (XRD) and residual stress analyzer were used. The results show that the tensile stress on the surface of untreated four-point bend loaded AISI 304 and the occurrence of pits during SCC tests had bad influence on the SCC resistance. The surface of carburized four-point bend loaded AISI 304 was in a state of compressive stress over the whole loading range due to the presence of carburization-induced huge compressive residual stress. The chloride-induced SCC resistance of AISI 304 can be obviously improved by low-temperature surface carburization due the carburization-induced compressive residual stress and the improved pitting corrosion resistance. The carburization-induced compressive residual stress was the dominant reason for the improvement of SCC resistance. No relaxation happened in carburization-induced compressive residual stress and the phase of the expanded austenite was stable during SCC tests.

Solvent-Shared Ion Pairs at the Air–Solution Interface of Magnesium Chloride and Sulfate Solutions Revealed by Sum Frequency Spectroscopy and Molecular Dynamics Simulations

The ion distribution and ion pairing properties of Mg2+, SO42-, NO3-, and Cl- in the interfacial region of MgSO4, Mg(NO3)2, and MgCl2 solutions were investigated using vibrational sum frequency generation (VSFG) spectroscopy and molecular dynamics (MD) simulations. An electric field reversal relative to Mg(NO3)2 and MgCl2 solutions is observed at the interface of a MgSO4 solution. We show that, although magnesium cations are expected to have preference for bulk solvation, solvent-shared ion pairs (SIPs) exist in the interfacial region in which Mg2+ cations are closer to the solution surface than sulfate anions. While interfacial SIPs are few, they dominate the electric field effect observed. Thus, SIPs play a significant role in determining the electric field direction and magnitude at the air-aqueous interface. In addition to impact on the fundamental understanding of aqueous surfaces and interfacial ion-ion interactions, these findings have implications for atmospheric aerosol chemistry and thundercloud electrification.

A Coarse-Grained Force Field Parameterized for MgCl2 and CaCl2 Aqueous Solutions.

Calcium and magnesium ions play important roles in many physicochemical processes. To facilitate the investigation of phenomena related to these ions that occur over large length and time scales, a coarse-grained force field (CGFF) is developed for MgCl2 and CaCl2 aqueous solutions. The ions are modeled by CG beads with characteristics of hydration shells. To accurately describe the nonideal behavior of the solutions, osmotic coefficients in a wide range of concentrations were used as guidance for parametrization. The osmotic coefficients were obtained from the chemical potential increments of water calculated using the Bennett acceptance ratio (BAR) method. The result CGFF accurately reproduces experimental osmotic coefficients, densities, surface tensions, and cation-anion separations of calcium chloride and magnesium chloride solutions at molalities up to 3.0 mol/kg. As a preliminary application, the force field is applied to simulate aggregations of sodium dodecyl sulfate (SDS) in calcium chloride solution, and the simulation results are consistent with experimental observations.

Preparation of synthetic carnallite and amorphous silica from chromite beneficiation plant tailings

Abstract In this paper, synthetic carnallite (MgCl2 ∙ KCl ∙ 6H2O) and amorphous silica (SiO2) preparation possibilities were investigated by utilizing chromite beneficiation plant tailings which contain 3.44% chromite (Cr2O3) and 30.55% magnesium oxide (MgO) by weight. Firstly, laboratory scale high intensity wet magnetic separator was applied for removing the magnetic materials such as chromite, iron (II ) and manganese (II ) minerals in the tailings. About 85.75% of chromite, 91.22% of MnO and 64.71% of Fe2O3 were removed by single stage magnetic separation. After the magnetic separation, hydrometallurgical recovery was initiated by leaching of the tailings with hydrochloric acid (HCl). Amorphous silica particles and the other solids were separated from the leach solution by filtration. Impurities were precipitated from the leach solution by elevating the solution pH via magnesium hydroxide (Mg(OH)2) adding. The purified magnesium chloride (MgCl2) solution was mixed with potassium hydroxide (KOH ) at stoichiometric ratio. According to the XRD and chemical analysis, the synthetic carnallite was synthesized by controlled heating of this solution at 90-100°C. Also, the amorphous silica with 96.5% SiO2 content and 84.38% recovery yield was obtained by additional magnetic separation treatment.

Investigations on phosphorus recovery from aqueous solutions by biochars derived from magnesium-pretreated cypress sawdust

The ability of biochars, derived from the pyrolysis at 400 °C; 500 °C and 600 °C of pretreated cypress sawdust with 20 wt% magnesium chloride (MgCl2) solutions, in recovering phosphorus from aqueous solutions was investigated under various experimental conditions in batch mode. The experimental results indicated that cypress sawdust pretreatment with MgCl2 induced important modifications of the physical and chemical biochars' properties favoring phosphorus recovery from the used synthetic solutions. Moreover, phosphorus recovery efficiency increased with the increase of the used pyrolysis temperature. Indeed, for an aqueous pH of 5.2 and a phosphorus concentration of 75 mg L−1, the recovered amounts increased from 19.2 mg g−1 to 33.8 mg g−1 when the used pyrolysis temperature was raised from 400 °C to 600 °C. For all the tested biochars, the phosphorus recovery kinetics data were well fitted by the pseudo-second-order model, and the equilibrium state was obtained after 180 min of contact time. Furthermore, the phosphorus recovery data at equilibrium were well described by the Langmuir model with a maximal recovery capacity of 66.7 mg g−1 for the magnesium pretreated biochar at 600 °C. Phosphorus recovery by the used biochars occurred probably through adsorption onto biochars' active sites as well as precipitation with magnesium ions as magnesium phosphates components. All these results suggested that biochars derived from MgCl2 pretreated cypress sawdust could be considered as promising materials for phosphorus recovery from wastewaters for a possible further subsequent use in agriculture as amendments.

THE CONSTRUCTION OF A COMPOSITION BASED ON MAGNESIA BINDER WITH PEAT

Obtained building material based on magnesia binder with different content of peat (0 to 90 %), on a specially developed technique. As a binder used PMK 87, for mixing mixtures used aqueous solution of magnesium chloride and peat from the Ivanovo region. It were determined such physical and physico-mechanical properties of the investigated material as the compressive strength and the density. The strength characteristics of silicate bricks, ceramic bricks and the investigated material based on magnesia binder and peat was analyzed and compared. It is established that the samples of construction material with content of peat not exceeding 40 wt.% can be attributed to the materials of structural purpose by its compressive strength. Samples of the material with content of the peat 40% have a density 943,75 kg/m3, that provides good heat and sound insulation properties. It is revealed that the solution of the raw material mixture of magnesia binder, peat, the solution of bischofite is optimized to place, and the material gets at least 85% of its strength during 30 days.