Aqueous Sulfate Solutions Research Articles

PHYSICO-CHEMICAL PROPERTIES OF MALIN-UROTROPIN- COPPER SULFATE SYSTEM

Before seed treatment, the seed must contain several active ingredients. Because the mail significant part of the saved crop depends on the correct seed dressing technology. Seed dressing, or seed treatment with pesticides, is an activity aimed at protecting plants from pests and diseases, using special preparations. In this study, the physicochemical properties of the formalin-urotropine-copper sulfate system were investigated at 25 oC. It is established that the isotherms of the system confirmed that the density, viscosity, pH of the solution medium and the crystallization temperature are characterized by inflection points corresponding to concentrations. Analysis of the “composition - properties” diagram of the system shows that the isotherms of the refractive index, density, viscosity and pH of the medium are characterized by two inflection points corresponding to 30 % formalin and 15 % urotropine that equals molar ratio of 1:1:1. Thus, it can be assumed that the interaction of formalin with copper sulfate in aqueous solutions results in the formation of a complex compound of the composition [30 % CH2O +15 % C6H12N4]-CuSO4·5H2O. Based on the data obtained, a solubility diagram was constructed, identified by X-ray phase, IR spectroscopic and thermogravimetric. Comparison of the value of the degree of crystallinity of the studied samples shows that the degree of crystallinity increases in the samples.

Transference Number Measurement of Zinc Salts in Aqueous Solution

Transference numbers of the aqueous zinc chloride and zinc sulphate solutions have been measured for the concentrations 0.03, 0.05, 0.07, 0.09 and 0.1 mol.dm-3at 298.15K, by using the modified Hittorf method. The dependence of transference number on concentration of each electrolyte was also investigated in an attempt to explain the value of the limiting transference number. The Longsworth method has been used for the extrapolation of zinc transference number in aqueous solutions, using the values of the limiting transference numbers of the appropriate values of the limiting equivalent conductance, it was possible to determine the corresponding values of the limiting ion conductance for the cations and anions of the electrolytes. The density and specific conductivity of all solutions have been measured at 298.15K.

Numerical and experimental investigation of calcium sulfate crystallization fouling under upward subcooled flow boiling

In this paper, a quasi-unsteady mathematical model was presented to examine the crystallization fouling of the calcium sulfate aqueous solutions under upward subcooled flow boiling (SFB). An experimental set-up is also fabricated to collect experimental data for validating the model results. The developed model can axially and radially determine the temperature variation. An asymptotic predictive model was also used to calculate the heat transfer coefficients. Theoretical results of the bulk and surface temperatures at any desired location of the test section were coupled with the fouling formation equations to provide an integrated model for prediction of variable fouling resistance and deposit thickness along the heat transfer surface. Besides, variation of local heated surface and deposit surface temperatures as well as the pressure drop were theoretically evaluated over time while the deposit grows on the heated surface. The simulation results showed that reaction is the controlling mechanism when SFB is predominant.

Scalable and facile fabrication of sulfonic-acid-functionalized porous hypercrosslinked polymers for efficient recovery of rare earth elements from tailing wastewater

The separation and enrichment of rare earth elements (REEs) from tailing wastewater is of great significance for the sustainable supply of REEs and environmental remediation. As Al3+ exhibits extreme similar properties with REE3+, selective recovery of REE3+ from the sulphate tailing wastewater remains a considerable challenge. Based on the difference in the binding stability of REE3+ and Al3+ with sulfate ions, the utilization of sulfonic acid groups may provide a promising method for enhancing the selectivity of REE3+/Al3+ in the sulphate aqueous solution. Herein, a series of sulfonic-acid-functionalized hyper-crosslinked polymers (SHCP-Ps) were successfully synthesized through a facile, scalable and one-step method catalyzed by chlorosulfonic acid, which has the advantages of high sulfonic acid density (3.27 mmol/g), specific surface area (1044.6 m2/g), abundant micropores and superhydrophilicity. These properties result in SHCP-P exhibiting fast adsorption kinetics (30 min) and high adsorption capacities (106.78 mg/g (La), 111.99 mg/g (Eu) and 126.27 mg/g (Lu)). Additionally, it exhibits extremely high REE3+/Al3+ selectivity (SF(La/Al) = 6929, SF(Eu/Al) = 4810, SF(Lu/Al) = 3003) in sulfate medium, surpassing that of most existing REEs adsorbents. Upon application of SHCP-P to actual wastewater, the recovery rate of total REE3+ was observed to reach 87 %, while the adsorption rate of Al3+ was found to be 0. Simultaneously, SHCP-P exhibits both high reusability and magnification synthesis capabilities. The results indicate that SHCP-P has significant potential for industrial applications in the selective recovery of REEs from tailing wastewater.

Recovery of niobium and titanium from low-grade niobium ores and the evaluation of Fe5Si3 alloy by-product as oxygen evolution reaction electrocatalysts

A low-grade ore containing 4 % niobium and 7 % titanium has been extracted from Bayan Obo tailing, but its potential has not been fully utilized. This study aims to recover the niobium and titanium elements from this low-grade ores in the form of their carbides. The process involves reducing niobium and titanium to (Nb,Ti)C through a carbothermal process. During this process, iron and silicon are also reduced to Fe-Si intermetallic compounds, allowing (Nb,Ti)C to diffuse into them. Subsequently, selective electrochemical oxidation is used to separate (Nb,Ti)C from the Fe-Si intermetallic compounds in an aqueous ferrous sulfate solution. The Fe-Si intermetallic compounds are first oxidized to the Fe3Si phase, and then to the Fe5Si3 phase in the solution with pH 0.35. The (Nb,Ti)C/matrix interfaces are identified as the preferred site of electrochemical pitting corrosion. By exploiting the electrochemical oxidation reaction of iron in the matrix, (Nb,Ti)C powders are separated along these interfaces. The by-products of this process are FeSi alloys, which are evaluated for their electrocatalytic properties in oxygen evolution reactions. It is found that the Fe5Si3 alloy by-product exhibits good electrocatalytic activity and kinetics in the oxygen evolution reaction, demonstrating its potential for practical applications.

Dissolution and early hydration of tetracalcium aluminoferrite (C4AF) in water and in aqueous sulfate solutions

Fe-rich cementitious phases, such as tetracalcium aluminate (C4AF), are likely the least characterized and understood components of ordinary cements, in terms of their reactivity and early-age reactions. In this study, we provided the first in-situ measurements of C4AF's absolute dissolution rates in water and aqueous sulfate solutions (Na2SO4, MgSO4 and CaSO4) along with its early-age hydration characterization. Upon contact with water, C4AF dissolved at a rate of 1.74 ± 0.23 μmol·m−2·s−1, and sulfates were found to inhibit its reaction. Among the three types of sulfates tested, CaSO4 exhibited the strongest inhibition effect, while Na2SO4 showed the weakest inhibition. Soon after the initial dissolution, the precipitation of hydrates occurred, and the presence of sulfates affected the overall hydration process of C4AF. These results enhance our understanding of C4AF's dissolution and early-age hydration behaviours, thereby advancing our knowledge of its hydration mechanisms.

The Anodic Behavior of Manganese Silicide-Germanides in Aqueous Sodium Sulfate Solutions: The Effect of the Germanium Content

The Anodic Behavior of Manganese Silicide-Germanides in Aqueous Sodium Sulfate Solutions: The Effect of the Germanium Content

Temperature dependence of the near infrared absorption spectrum of single-wall carbon nanotubes dispersed by sodium dodecyl sulfate in aqueous solution: experiments and molecular dynamics study.

Single-wall carbon nanotubes (SWCNT) dispersed in water with the help of sodium dodecyl sulfate (SDS) surfactants exhibit a temperature dependent near infrared (NIR) exciton spectrum. Due to their biocompatibility and NIR spectrum falling within the transparent window for biological tissue, SWCNTs hold potential for sensing temperature inside cells. Here, we seek to elucidate the mechanism responsible for this temperature dependence, focusing on changes in the water coverage of the SWCNT as the surfactant structure changes with temperature. We compare optical absorption spectra in the UV-Vis-IR range and fully atomistic molecular dynamics (MD) simulations. The observed temperature dependence of the spectra for various SWCNTs may be attributed to changes in the dielectric environment and its impact on excitons. MD simulations reveal that the adsorbed SDS molecules effectively shield the SWCNT, with ~ 70% of water molecules removed from the first two adlayers; this coverage shows a modest temperature dependence. Although we are not able to directly demonstrate how this influences the NIR spectrum, this represents a potential pathway given the strong influence of the water environment on the excitons in SWCNTs. Optical absorption measurements were carried out in the UV-Vis-NIR range using a Varian Cary 5000 spectrophotometer in a temperature-controlled environment. PeakFit™ v. 4.06 was used as peak-fitting program in the spectral range 900-1400nm (890-1380meV) as a function of the temperature. Fully atomistic molecular dynamics simulations were conducted using the NAMD2 package. The CHARMM force field comprising two-body bond stretching, three-body angle deformation, four-body dihedral angle deformation, and nonbonded interactions (electrostatic and Lennard-Jones 6-16 potentials) was employed.

Investigation of the Corrosion of Heating Treatment Medium Carbon Steel in Sulfur Aqueous Solution

Investigation of the Corrosion of Heating Treatment Medium Carbon Steel in Sulfur Aqueous Solution

Investigation of ion association kinetics in Na2SO4-H2O by excess Raman spectroscopy and 2D correlation Raman spectroscopy

The ion association of salts aqueous solutions have long captivated the attention of researchers within the field of physical chemistry. In this paper, we have performed a comprehensive analysis of ion interactions in sodium sulfate (Na2SO4) aqueous solutions using a combination of high-resolution techniques, including excess (ERS) and two-dimensional correlation (2DCRS) Raman spectroscopy in conjunction with molecular dynamics (MD) calculations. The Raman spectrum shows that two inflection points in the Raman shift of the O–H vibration are observed with the increase in Na2SO4 concentration. Simultaneously, a new peak of the SO42- vibration appears at first inflection point, representing the formation of ion association. Further analysis based on ERS and 2CRS reveals that these two inflection points correspond respectively to the formation of ion pairs (CIPs) and small ion clusters. Importantly, MD simulations confirm the above experimental results. Our study provides evidence for ion association and clustering in aqueous in salt ion aqueous solutions.

Synthesis of Nano-electrolytic Manganese Dioxide for Alkaline Batteries Mediated by Organic Additives

This article discusses the impact of adding organic additives like glycine (GLY), sucrose (SUC), and saccharine (SACCH) on the electrical characteristics and microstructure of electrolytic manganese dioxide (EMD), which is made from an acidic aqueous sulphate solution. The structure and chemistry of EMD were ascertained by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). To assess the material's potential for use in alkaline batteries, its charge-discharge properties were ascertained. It was found that the majority of MnO2 in all the EMD samples was in the γ-phase, which is electrochemically active and useful for energy storage applications. When glycine, sucrose, and saccharine were added to the solution as organic additives, the electrochemical deposition of manganese dioxide (MnO2) resulted in an increase in current efficiency and a decrease in energy consumption. The SEM images demonstrated that when EMD was deposited with an additive, small grain sizes and discrete particles free of agglomeration were formed, but large grain sizes were obtained in the absence of additives. Charge-discharge characteristics suggested that the additions improve the ability of MnO2 structure to store energy. This suggested that the additions may have an impact on the morphology and size of the particles, and consequently, the electrochemical activities of the material that was electrodeposited. In the case of the additives examined in this paper, the outcome was the creation of a material with possible use in battery technology.

Interfacially self-assembled Fe2O3 nanoparticles decorated kaolinite for high performance anti-bacterial and anti-cancerous agents

Nano-engineering of naturally occurring layered materials incorporates enhanced inherent properties for bionanotechnology. Here, kaolinite was treated with a concentrated aqueous ferrous sulfate solution at 100 °C for 1 h for surface modification. Therefore, interfacially self-assembled nanostructure of ferric oxide (Fe2O3) decorated kaolinite composites (FDKC) was fabricated from cationically (Fe2+) modified kaolinite (CMK) after calcinations at 680 °C. Characterized nanocomposites by ATR-IR, EDS, XRD and SEM were tested for antimicrobial activity and antibiofilm activity against Gram negative bacteria Escherichia coli (E. coli), Klebsiella spp (K. spp) and Salmonella typhi (S typhi), as well as Gram positive Staphylococcus aureus, while cytotoxic activity was observed against HeLa cell. CMK and FDKC showed significantly higher antimicrobial activity and biofilm destruction ability than virgin kaolinite (p < 0.05). Besides, FDKC showed the highest anticancer activity in HeLa cell at moderate concentration. The synergistic effect of nanocomposites would offer the modulation of enhanced electronic and physical properties from a simple technology to improve inherent antimicrobial activity and cell toxicity of kaolinite for targeted assay.

Osmotic and Activity Coefficients of Aqueous Lithium Sulfate Solutions within the Temperature Range 293.15–498.15 K to 40 MPa

Osmotic and Activity Coefficients of Aqueous Lithium Sulfate Solutions within the Temperature Range 293.15–498.15 K to 40 MPa

Supercapacitor Performance of MXene-Coated Carbon Nanofiber Electrodes

MXenes consisting of thin layers of transition metal carbides or nitrides are good candidates for electrode materials due to their excellent electrical conductivity and fast ion transfer. Electrospun carbon nanofibers are highly porous and electrically conductive, making them attractive for electrode materials. In this study, free-standing electrodes were prepared by the dip-coating of carbon nanofibers (CNFs) in the MXene (Ti3C2) colloidal solution, which was synthesized via the wet-etching of MAX (Ti3AlC2) phase, and their chemical structures were investigated by X-ray diffraction and Fourier transform infrared spectroscopy. In addition, scanning and transmission electron microscopy were used to investigate the morphological and crystallographic features of MXene-coated CNFs. Surface area and pore volumes were investigated by nitrogen adsorption/desorption measurements. Supercapacitor performance was studied by assembling a 3-electrode system with 1M aqueous sodium sulfate solution as an electrolyte. MXene-coated CNFs exhibited a maximum specific capacitance of 514 F/g at 0.5 A/g, with energy and power densities of 71.4 Wh/kg at 0.5 A/g and 2.3 kW/kg at 5 A/g, respectively, which are relevantly higher compared to the pristine CNFs due to the pseudocapacitive behavior of MXenes. They also showed comparable cyclic stability during 5000 cycles with the CNFs. This result indicates that MXene-coated carbon nanofibers can be effective electrode materials for electrochemical energy storage.

Thermodynamic analysis for the dissolution of two similar amino acids in sodium sulfate aqueous solution

In the current work, the analyti cal static gravimetric technique was used to assess the solubilities of DL-α-amino butyric acid and DL-valine in an aqueous binary solvent mixture of sodium sulfate (Na2SO4) under equilibrium saturation conditions in between temperature range 288.15 and 308.15 K. Different thermodynamic factors along with transfer Gibbs energetics and entropies under standard conditions were estimated by using computational as well as theoretical method by using the experimental solubilities. Several modes of interactions that occur during solvation were also explained. The manner that solvent molecules of solute amino acids are surrounded in the aforementioned medium employed during the process is taken into consideration. Amino acids become more soluble as the temperature rises. The study also helps us to reach the conclusion that physical properties of electrolyte (Na2SO4), mixed solvent, and the size of the amino acids’ molecules are the main governing factors for the chemical stability as well as other thermodynamic and physical property like solubility of solute amino acids.

Ionic liquid as a cosurfactant for critical heat flux enhancement during boiling with aqueous surfactant solutions

Surfactants are often used to improve boiling heat transfer due to the ease of their implementation. While aqueous surfactant solution significantly increases the heat transfer coefficient (HTC), it is known to deteriorate the critical heat flux (CHF) relative to the base fluid water. The high foamability of most surfactant solutions causes vapor crowding on the heater surface, making surface modification techniques ineffective for CHF enhancement. Here, we address the issue of relative degradation of CHF due to surfactant by using an ionic liquid as a cosurfactant. We employ a unique boiling fluid, where 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), a low-foaming ionic liquid, is introduced as a co-surfactant in aqueous sodium dodecyl sulfate (SDS) solution. Motivated by the synergistic increase in foamability of the aqueous surfactant solution due to the addition of ionic liquid, we examine the boiling performance at various combinations of concentrations of the two additives in the solution. The mixture consistently exhibits higher CHF and HTC than an SDS only solution, with the best enhancement observed for a mixture of ≈ 30 ppm SDS and ≈ 750 ppm [C2mim][Cl], resulting in ≈1.6× and ≈1.5× enhancements in CHF and HTC, respectively, compared to the SDS only solution (≈ 30 ppm). We next fine-tune the concentration of cosurfactant to demonstrate an exceptionally high HTC of ≈93 kW/(m2 – ℃) with a CHF value comparable to that of pure water. Enhanced foamability and in-situ improvement in the wettability of the heater surface enhance the HTC and the CHF, respectively. This facile technique for enhancing HTC with water as the base fluid, without compromising on CHF, holds promise for high heat flux thermal management applications.

Experimental study on heat transfer performance enhancement of pulsating heat pipes induced by surfactants

Pulsating heat pipe (PHP) is considered as a promising technique to address the thermal dissipation issues in micro-electronic devices, but its heat transfer performance needs to be further enhanced urgently. In this study, the PHP comprehensive performance experimental system was established. Then, the influence of surfactant sodium dodecyl sulfate (SDS) aqueous solution on the heat transfer performance of PHP was experimentally investigated and the visualization of PHP with surfactant was also accomplished. Additionally, based on Marangoni effect and surface tension, a comprehensive analysis was conducted on the impact mechanism of surfactants on PHP. The experimental results indicated that the oscillatory disturbance of the liquid slug inside the PHP is enhanced by the addition of SDS, and the resulting pressure imbalance and temperature difference enhance the directional flow of the working fluid. Meanwhile, under the operating conditions of 30 W working thermal power and the solution concentration of 0.001 wt%, the thermal resistance of PHP was reduced by 30.7 % compared with that of deionized water (DI water). This indicated that the working fluid with low concentration SDS could increase the area of liquid film and reduce the thermal resistance, which is induced by the surface tension and Marangoni effect due to the uneven distribution of surfactants. However, the thermal resistance of PHP with the SDS concentration of 0.2 wt% is higher than that of DI. This means that high concentration of SDS would deteriorate the startup characteristics and the heat transfer performance of PHP. Therefore, high concentrations of surfactants should be avoided from practical application of PHP.

Direct recovery of electro-synthesized ammonia from low-concentration nitric oxide using pulse electrodeposited Cu/C catalyst in a catholyte-free system

Electrochemical production of ammonia (NH3) from nitric oxide (NO) offers a sustainable and environmentally friendly way to convert a nitrogenous pollutant into a valuable chemical feedstock and energy carrier. However, practical challenges in the electrochemical NO-to-NH3 conversion stem from mass transport limitations due to low NO concentrations in real-world streams and the need for post-purification of synthesized NH3. In this study, by synergistically developing an electrocatalyst (pulse-electrodeposited copper) and implementing a catholyte-free cell configuration with advantages of (i) facile NO transport, (ii) inhibited side reaction, and (iii) direct NH3 recovery in an external acid, we showcase an NH3 Faradaic efficiency of 85.6 % and a production rate of 53.4 μmol cm−2h−1 starting from 500 ppm NO. Crucially, the electro-synthesized NH3 was directly recovered as a high-purity aqueous ammonium sulfate solution comparable to industrial-grade quality. This approach opens the door to transforming waste into resources in a more energy-efficient and straightforward manner.

Flow-Driven Self-Propulsion of Oil Droplet on a Surfactant Solution Surface, as Observed by Time-Resolved Interfacial Tension and Surface Flow Speed Measurements.

The imbalanced force of the interfacial tension applied to an object has often been taken into account in the analysis of the motion mechanism of self-propelled systems. However, heterogeneous distributions of the interfacial tension also cause Marangoni flows, and these flows also contribute to the self-propulsion through the viscous force. The contribution of such flows has not been observed directly, while the interfacial tension difference has been measured in some systems. In this study, simultaneous measurements of the interfacial tension and surface flow speed of the unidirectional self-propelled motion of a butyl salicylate (BS) droplet in a circular channel on a sodium dodecyl sulfate (SDS) aqueous solution were achieved by the quasi-elastic laser scattering method. The droplet position was also recorded by observing its fluorescence excited by a UV light. The BS droplet speed dependence of the interfacial tension and surface flow speed were measured by varying the initial BS concentration codissolved in the SDS aqueous solution. As a result, a periodic decrease of the interfacial tension and a periodic increase of the speed of both forward and backward flows were observed when the droplet passed the sampling position of the time-resolved measurements. When they were converted to the distribution in space of the droplet position, no droplet speed dependence of the interfacial tension difference between the front and rear of the droplet was observed. On the other hand, the speed of both forward and backward flows increased as the droplet speed increased. By analysis of the above results with a simplified model, it was clarified that the forward flow driven by the interfacial tension gradient at the droplet front is actually important in the mechanism of the unidirectional self-propelled motion of a droplet.

Structure and dynamics of aqueous VOSO4 solutions in conventional flow through cell design: a molecular dynamics simulation study.

A theoretical model has been proposed to study the structure and dynamics of aqueous vanadyl sulfate (VOSO4) solution used in the conventional flow (CF) through cell design operating under varying thermodynamic conditions. Classical molecular dynamics simulations have been carried out for aqueous solutions of vanadyl sulfate (VOSO4) and sulfuric acid (H2SO4) at two different concentrations and temperatures considering the temperature dependent degree of dissociation of sulfuric acid. The MD trajectories are used to study the equilibrium structural, dynamical properties such as viscosity, diffusivity and surface tension of the aqueous solution of vanadyl sulfate (VOSO4). According to the new model, the cation-cation and cation-anion interaction should be low in order to have a good current density in the conventional flow through cell design and further explains the importance of considering mass transport when designing high energy density redox flow batteries. The model is further validated by calculating the viscosity of each system, individual diffusion coefficient of each ion and by comparing them with the experimental data wherever they are available.