Showing papers on "Sodium sulfate published in 2023"
TL;DR: In this paper , the long-term degradation of nano-SiO2 (NS) modified cement mortar exposed to sodium sulfate (Na2SO4) attack was investigated in joint with the mineralogical and microstructural changes.
4 citations
TL;DR: In this article , the corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate (SDS) was investigated by hydrogen analysis, scanning electron microscopy (SEM), electrochemical test, scanning Kelvin probe force microscopy, and computational methods.
4 citations
TL;DR: An ion chromatography technique with conductivity detection was selected as an analytical tool for the simultaneous indirect determination of sodium sulfate, potassium sulfate and magnesium sulfate via their respective cations as discussed by the authors .
Abstract: An ion chromatography technique with conductivity detection was selected as an analytical tool for the simultaneous indirect determination of sodium sulfate, potassium sulfate, and magnesium sulfate via their respective cations. The method was developed and validated for the quantitative assay of the inorganic salts under study in oral pharmaceutical dosage forms. Chromatographic separation was achieved on a Dionex®IonPac® CS16 column (250 × 5 mm) column using the gradient elution method. A mobile phase-A consisting of methane sulfonic acid (6.7%, v/v) in Milli-Q water, which is used together with Milli-Q water, was used as a mobile Phase-B. The flow rate was 1.2 mL/min. The retention times of sodium, potassium, and magnesium as sulfates were 7.8, 12.8, and 16.2 min, respectively. The method was validated according to ICH guidelines and showed good linearity and accuracy results within concentration ranges of 80.0–240.0, 20.0–60.0, and 4.5–13.5 ppm for sodium, potassium, and magnesium as sulfates, respectively. The relative standard deviation results for intra- and inter-day precision were less than 1.0%. The method was applied successfully for determination of the analytes under study in their mixed pharmaceutical oral solution and found suitable for their routine and stability analysis.
3 citations
TL;DR: In this article , nano magnesia (nM) was used to accelerate the early hydration rate of sodium sulfate (Na2SO4) activated slag via nano-nM, resulting in a marked enhancement of the early compressive strength of the hardened SS3 mixture.
3 citations
TL;DR: In this article , the effects of sodium chloride (NaCl) and gypsum on the mechanical properties and resistance to sulfate attack of slag-based geopolymer concrete activated by quicklime as well as the mechanism of action were studied.
Abstract: Based on compressive strength, sulfate resistance, mass change, and relative dynamic elastic modulus tests, and XRD and SEM analysis, the effects of sodium chloride (NaCl) and gypsum on the mechanical properties and resistance to sulfate attack of slag-based geopolymer concrete activated by quicklime as well as the mechanism of action were studied. The results indicate that: (1) with appropriate dosages of NaCl or gypsum, the compressive strength of geopolymer concrete can be increased by 55.8% or 245.3% at 3 days and 23.9% or 82.3% at 28 days, respectively. When NaCl and gypsum are combined, Friedel’s salt, Kuzel’s salt, and NaOH are generated, and the strength is increased by 90.8% at 3 days, and 180.3% at 28 days. (2) With 2% NaCl alone, the mass loss is reduced from 5.29% to 2.44%, and the relative dynamic elastic modulus is increased from 0.37 to 0.41. When compounded with 7.5% gypsum, the mass is increased by 0.26%, and the relative dynamic elastic modulus is increased to 1.04. With a further increase of NaCl to 4%, the mass is increased by 0.27%, and the relative dynamic elastic modulus is increased to 1.09. The sulfate corrosion resistance coefficient of geopolymer concrete is increased from 0.64 to 1.02 when it is immersed with 7.5% gypsum alone for 90 days, and it can be further increased to 1.11 when compounded with 4% NaCl. (3) The geopolymer prepared with sodium chloride: gypsum: quicklime: slag = 4:7.5:13.5:75 can be used to replace 32.5 slag Portland cement in plain concrete. The cost and carbon emissions are reduced by 25% and 48%, respectively, and the sulfate corrosion resistance coefficient is higher by 38.8% than with slag Portland cement.
3 citations
2 citations
2 citations
TL;DR: In this article , a novel lauric acid/modified boron nitriding nanosheets-sodium sulfate composite phase change material was fabricated by vacuum impregnation.
Abstract: Lauric acid as phase change material is broadly used in thermal energy storage, whereas its poor heat transfer performance and low shape-stability hinder the practical application. In this work, a novel lauric acid/modified boron nitriding nanosheets‑sodium sulfate composite phase change material was fabricated by vacuum impregnation. During the fabrication process, sodium sulfate was introduced to improve the porosity and thermal conductivity of composite phase change material. The results show that the load capacity of lauric acid can reach to 83.5 wt% in lauric acid/modified boron nitride nanosheets‑sodium sulfate composite phase change material under the control of sodium sulfate. Besides, the thermal conductivity of lauric acid/modified boron nitride nanosheets-5 wt% sodium sulfate composite phase change material can reach up to 0.744 W/(m.K), which is 196.4 % higher than that of pure lauric acid, as well as the latent heat was increased by 7.49 % than that of composite phase change material without sodium sulfate. After 200 thermal cycles, lauric acid/modified boron nitride nanosheets‑sodium sulfate composite phase change material still has excellent phase change behavior and thermal stability. These properties show that sodium sulfate as a pore-forming agent has great significance for optimizing the thermal performance of composite phase change material. The excellent performance of lauric acid/modified boron nitride nanosheets‑sodium sulfate composite phase change material has a broad application prospect in the field of thermal energy storage and thermal management, etc.
2 citations
TL;DR: In this paper , SAB-THPS with diameters of about 2-5 mm and super-fast adsorption rate for Cr(VI) removal were successfully prepared by impregnation at 25 °C to crosslink phosphate groups on the surfaces of sodium alginate beads (SAB) using bis[tetrakis(hydroxymethyl)phosphonium] (THPS) as the modifier.
Abstract: Sodium alginate/phosphorus tetramethylmethyl sulfate beads (SAB-THPS) with diameters of about 2–5 mm and super-fast adsorption rate for Cr(VI) removal were successfully prepared by impregnation at 25 °C to crosslink phosphate groups on the surfaces of sodium alginate beads (SAB) using bis[tetrakis(hydroxymethyl)phosphonium] (THPS) as the modifier. The static adsorption of SAB-THPS conforms to the pseudo-second order kinetics and Langmuir model on monolayer chemical absorption; its maximum adsorption capacity fitted from Langmuir model is 145.77 mg/g, which is much higher than that of SAB (21.51 mg/g). Especially, SAB-THPS shows ultra-fast adsorption rate below initial Cr(VI) concentrations of 100 mg/L; it achieved removal efficiencies of more than 99.7 % at 2.5, 6.5 and 20 min, respectively with initial Cr(VI) concentrations of 20, 50 and 100 mg/L, respectively.Its adsorption mechanisms include main chemical reduction of Cr(VI) into Cr(Ⅲ), ions exchange and electrostatic interaction. The environmentally friendly SAB-THPS with the advantages of ultra-fast adsorption rate, high adsorption capacity and easy separation shows good application prospect for rapid remediation of wastewater.
2 citations
TL;DR: In this paper , a new NaCl retention model was developed to predict the NaCl transport resistance for dilute NaCl solutions at very low membrane flux, based on the experimental results generated in this study and obtained from open literature.
1 citations
TL;DR: In this article , the effect of sulfate attack on the change of phase assemblage and desorption of bound chloride for seawater mixed cement paste with different w/b ratios and supplementary cementitious materials (SCMs) is investigated.
Abstract: In this study, the effect of sulfate attack on the change of phase assemblage and desorption of bound chloride for seawater mixed cement paste with different w/b ratios and supplementary cementitious materials (SCMs) is investigated. It is shown that the decrease of w/b ratio from 0.4 to 0.2 and use of SCMs with low aluminum content such as silica fume (SF) mitigates the Na2SO4 attack by reducing the content of corrosion products. After sulfate attack, Friedel's salt has been all transformed to ettringite by the substitution of Cl− with SO42-, which leading to the desorption of chemically bound chloride. The corrosion products formed during Na2SO4 attack are ettringite and gypsum while the gypsum transforms to syngenite in the specimen after K2SO4 attack. In the specimens with MgSO4 attack, the formation of gypsum is promoted accompanied by the formation of brucite. The crystal size of corrosion products after MgSO4 attack is the largest due to the large growth space through the formation of large cracks. Note the fact that the degree of silicon polymerization for C–S–H gel is increased by sulfate attack. The C–S–H gel partly transforms to sodium or potassium silicate-like gel after Na2SO4 and K2SO4 attack while it mostly transforms to M-S-H after MgSO4 attack. This leads to the desorption of physically absorbed chloride. The use of MK, GGBS, and FA improves the stability of physically absorbed chloride while SF contributes to the further release of physically absorbed chloride after sulfate attack.
01 Jan 2023
TL;DR: In this paper , the authors show that during deliquescence, the abundant salt mirabilite (Na 2 SO 4 ·10H 2 O), behaves differently than anhydrous salts.
Abstract: Abstract Deliquescence is a first-order phase transition, happening when a salt absorbs water vapor. This has a major impact on the stability of crystalline powders that are important for example in pharmacology, food science and for our environment and climate. Here we show that during deliquescence, the abundant salt sodium sulfate decahydrate, mirabilite (Na 2 SO 4 ·10H 2 O), behaves differently than anhydrous salts. Using various microscopy techniques combined with Raman spectroscopy, we show that mirabilite crystals not only lose their facets but also become soft and deformable. As a result, microcrystals of mirabilite simultaneously behave crystalline-like in the core bulk and liquid-like at the surface. Defects at the surface can heal at a speed much faster than the deliquescence rate by the mechanism of visco-capillary flow over the surface. While magnesium sulfate hexahydrate (MgSO 4 ⋅6H 2 O) behaves similarly during deliquescence, a soft and deformable state is completely absent for the anhydrous salts sodium chloride (NaCl) and sodium sulfate thenardite (Na 2 SO 4 ). The results highlight the effect of crystalline water, and its mobility in the crystalline structure on the observed softness during deliquescence. Controlled hydrated salts have potential applications such as thermal energy storage, where the key parameter is relative humidity rather than temperature.
TL;DR: In this paper , three variables were chosen for the experiment in order to better understand the variables influencing the supercooling of sodium decahydrate sulfate solution: stirring rate, purity of SDS, and variable temperature cooling of the water bath.
TL;DR: In this article , the authors used nuclear magnetic relaxation dispersion measurements to better understand the dynamic properties of water within two types of salt crusts: sodium chloride (NaCl) and sodium sulfate (Na2SO4).
Abstract: The evaporation of water from bare soil is often accompanied by the formation of a layer of crystallized salt, a process that must be understood in order to address the issue of soil salinization. Here, we use nuclear magnetic relaxation dispersion measurements to better understand the dynamic properties of water within two types of salt crusts: sodium chloride (NaCl) and sodium sulfate (Na2SO4). Our experimental results display a stronger dispersion of the relaxation time T1 with frequency for the case of sodium sulfate as compared to sodium chloride salt crusts. To gain insight into these results, we perform molecular dynamics simulations of salt solutions confined within slit nanopores made of either NaCl or Na2SO4. We find a strong dependence of the value of the relaxation time T1 on pore size and salt concentration. Our simulations reveal the complex interplay between the adsorption of ions at the solid surface, the structure of water near the interface, and the dispersion of T1 at low frequency, which we attribute to adsorption-desorption events.
TL;DR: In this paper , metakaolin-based colemanite and red mud substituted geopolymer concrete were exposed to combined sulfate and freezing-thawing effects to simulate the effects of cold locations with a sulfate environment.
TL;DR: In this article , the stable phase equilibria of the ternary system NaBr−Na2SO4H2O at 273.2 K and 308.2 k were determined using the isothermal dissolution equilibrium method.
TL;DR: In this article , the aluminizing was carried out in the presence of a thermal barrier yttrium oxide at 1000 oC, and the oxidation kinetics of the coated structures were studied at 1050 oC and in an atmosphere of mixture of mixture sodium chloride vapor and sodium sulfate.
Abstract: Increasing the efficiency of work and extending the life of metal equipment, which operates under very harsh conditions, requires making the best complex changes in its crystalline structure and properties. In many of the properties of this equipment as a result of the formation of multi-layered metal and ceramic layers in the surface construction of the ingot, thus increasing the efficiency of the ingot and extending its life. The aluminizing was carried out in the presence of a thermal barrier yttrium oxide at 1000 oC, and the oxidation kinetics of the coated structures was studied at 1050 oC and in an atmosphere of mixture sodium chloride vapor and sodium sulfate.
TL;DR: In this paper , the effect of inorganic salts on the dyeing properties of reactive dyes in a non-aqueous medium dyeing system was investigated at various concentrations of sodium sulfate.
Abstract: Traditional dyeing usually consumes a significant amount of water and salts, thus causing environmental pollution. Salt-free and low-water dyeing has become an important research direction in the cotton fabric dyeing industry. The non-aqueous media dyeing technology, using decamethylcyclopentasiloxane (D5) as the dyeing medium, has achieved energy saving and emission reduction in this industry. To investigate the influence of inorganic salts on the dyeing properties of reactive dyes in a non-aqueous medium dyeing system, the adsorption kinetics and level dyeing property of C.I. Reactive Red 120 were investigated at various concentrations of sodium sulfate. When no salts were included in the siloxane non-aqueous dyeing system, 80% of the reactive dye could diffuse onto the cotton fabric surface after 10 min. However, if 13% salts were added during dyeing, 87% of the reactive dye could diffuse to cotton fabric surface over the same amount of time. Moreover, the adsorption rate of dye was increased from 3.85 mg/g·min to 5.04 mg/g·min when the quantity of salts was increased from 0% to 13%. However, the concentration of sodium sulfate had minimal effect on the color depth of the dyed fabric and the final uptake of dye. But, when the concentration of sodium sulfate was significant, the level dyeing property of the dye became poor as the Sγ(λ) value was increased from 0.020 to 0.042. The adsorption kinetic of C.I. Reactive Red 120 in D5 dyeing solution may be best described by the pseudo-second-order kinetic model. As the sodium sulfate concentration increases, the half-dyeing time gradually decreases and the adsorption rate of dye increases. The repulsive force between the dye and the cotton fiber was lowered by the addition of sodium sulfate. Consequently, in the D5 dyeing system, the level dyeing property of reactive dye may be affected by the adsorption rate. Therefore, the formula of reactive dyes that do not contain salts can be applied successfully in non-aqueous dyeing systems.
TL;DR: In this article , the authors investigated the frost resistance of concrete exposed to sulfate and acid attacks after two years and found that the concrete with the highest compressive strength, the highest ultrasonic pulse velocity, and the lowest weight loss were the samples with 500 kg/m3 cement content subjected to combined freeze-thaw and 1% acid attack.
Abstract: This study investigated the frost resistance of concrete exposed to sulfate and acid attacks after two years. The cement content was selected as 300 kg/m3, 350 kg/m3, 400 kg/m3, 450 kg/m3, and 500 kg/m3 in this study. 100 mm cubic specimens were prepared for experiments. After the specimens were cured in the water at 20 ± 2 °C for 28 days, they were kept in the laboratory conditions at 20 ± 2 °C for 23 months+2 days. Then, these samples were subjected to freeze-thaw cycles after being exposed to 5% sodium sulfate, 5% magnesium sulfate, 1% sulfuric acid, and 2% sulfuric acid for four days. Thus, the samples were exposed to the four different combined attacks. Lastly, the mechanical properties, weight change, and relative dynamic modulus of elasticity of these specimens were determined. Furthermore, the SEM and EDS analyses were carried out on samples. This study found that the highest compressive strength, the highest ultrasonic pulse velocity, and the lowest weight loss were the samples with 500 kg/m3 cement content subjected to combined freeze-thaw and 1% acid attack.
01 Jan 2023
TL;DR: In this article , volume expansion was produced by adding sodium sulfate or gypsum into aluminum powder blended grouting materials to enhance the expansion and strength, and the results indicated that the optimum contents of the mixture were 0.5 wt% and 4 wt%, respectively, which had highest compressive strength and good expansion behaviors.
TL;DR: In this article , the degradation of mortar buried in saline soil containing sulfate ions was investigated, and an evident and movable degradation interface in the eroded mortar was observed based on a color difference along the direction of degradation.
TL;DR: In this paper , the influence of fly ash (FA) and chlorides on the behavior of sulfate attack in blended cement pastes was quantitatively characterized by the contents of bound sulfates.
TL;DR: In this paper , the compressive strength of PCC concrete immersed in magnesium sulfate for 1 month (28 days) is more than 28 MPa, which meets the standard as well.
Abstract: Concrete performances have weaknesses; one of those weaknesses is that it is significantly affected when put in a high sulfate and chloride environment. This study aims to investigate sulfate's effect on PCC concrete's performance. In this research, PCC concrete was immersed in water for 28 days and conducted after the casting. After being soaked in water, three immersed specimens were removed and immersed in magnesium sulfate solution for 24 days and 84 days, whereas three others were removed and immersed in natrium sulfate solution for 24 days and 84 days. The observation showed that PCC concrete's average compressive strength test with water immersion was 42.17 Mpa. It meets the SNI 2847:2019 Indonesian standard for sulfate classification S1. The specimens decreased to 30.74 Mpa after being soaked in the magnesium sulfate solution for 28 days and again reduced to 25.39 Mpa at 84 days. The average compressive strength of specimens bathed in the sodium sulfate solution for 28 days was 32.19 Mpa. It decreased to 28.03 Mpa at the age of 84 days. The results of this study show that the compressive strength of PCC concrete soaked in sodium sulfate meets the SNI 2847:2019 standard for sulfate classification S1, which is more than 28 Mpa. The compressive strength of PCC concrete immersed in magnesium sulfate for 1 month (28 days) is more than 28 MPa. It meets the standard as well. Yet, the compressive strength of PCC concrete soaked in magnesium sulfate for 3 months (84 days) does not meet the standard.