Salt Ions Research Articles

Optimizing protic ionic liquid electrolyte for pre-intercalated Ti3C2Tx MXene supercapacitor electrodes

Electrical double-layer capacitors (EDLCs) are of increasing importance in energy storage from renewable sources. The properties of the electrode and electrolyte materials influence the energy and power densities of EDLCs. We examined the specific capacitance and ion dynamics of a protic ionic liquid confined in pre-intercalated Ti3C2Tx MXene. Our electrochemical measurements demonstrated that the creation of a protic ionic liquid, 1-butyl-3-H-imidazolium bis(trifluoromethanesulfonyl)imide (BuIMH-NTf2), using a mixture of ionic liquid, 1-butyl imidazole (BuIM), and salt, bis(trifluoromethanesulfonyl)imide (HNTf2), in a ratio of 0.8:0.2 led to the optimal capacitance. Remarkably, quasi-elastic neutron scattering measurements revealed increased particle mobility at this composition, attributed to the more efficient accumulation of BuIMH+ on the electrode surface. This deposit of additional ions results in fewer BuIM molecules away from the surface, enhancing their mobility due to reduced crowding. This composition-dependent electrochemical behavior will guide the formulation of more efficient protic ionic liquid systems, enabling faster ion transport in energy storage devices.

Preparation of adaptive bifunctional reconfigurable polymers and their sand carrying and drag reduction behaviour

AbstractIn order to solve the problem of drag reduction at the front end of shale fractures and sand carrying at the tail end with increased viscosity, the molecular dynamics simulation (MD) method was used to design polymer molecules and simulate the steric resistance, interaction potential energy, mean square displacement, and radial distribution function of the polymer. The polymer AM‐AMPS‐LMA‐DiC12AM (ASLC12) with better solubility, diffusion, and resistance reduction potential was obtained and synthesized. By scanning electron microscope (SEM) and viscoelastic analysis, ASLC12 has a stable mesh structure, good viscoelasticity, and shear resistance, and the mesh structure formed by it is in a dynamic equilibrium state of fracture‐reorganization under shear. We then analyzed the drag reduction, sand carrying, and salt resistance of ASLC12. When the concentration of ASLC12 is 0.09%, the sand‐carrying requirement is satisfied. When the concentration is 0.05%, the drag reduction rate can reach 74.1%, and the resistance reduction rate of ASLC12 in salt ion solution can still reach more than 62%. This shows that the polymer ASLC12 has better sand carrying, drag reduction, and salt resistance.

Long-term rice cultivation enhances root development and yields by improving the structural properties of soil aggregates in saline–alkaline environments

Rice cultivation has the ability to improve saline soils. However, the effects of long-term rice cultivation on saline soil chemistry, salt ions, root characteristics, and aggregate formation remain unclear. In this study, the impact of different planting durations (1, 3, 5, 8, and 10 years) on the spatial and temporal transport of soil salts, soil chemical properties, distribution and stability of aggregates, root characteristics, and yields, were assessed. Long-term rice cultivation reduced soil pH, exchangeable sodium percentage (ESP), and EC in the 0-60cm soil layer compared to 1Y (5.45%, 61.57%, and 81.87% reduction in topsoil (0-20cm) and 8.54%, 72.82%, and 71.94 in subsoil (20-60cm), respectively). However, the soil organic matter (OM), alkaline nitrogen (AN), phosphorus (AP), and potassium (AK) increased (217.09%, 90.18%, 89.23%, and 179.18% increase in topsoil and 223.72%, 81.24%, 174.28%, and 172.57% increase in subsoil, respectively). Additionally, the Cl-, K+, and Na+ in the soil gradually leached downward with the increase in the duration of rice cultivation (55.87%、36.08%、59.80%). Simultaneously, the increased duration markedly elevated the soil macroaggregate content (11.43%-20.04% by dry-sieving and 53.48%-288.09% by wet-sieving), clayey grain content (59.17%-198.33%), and soil aggregate stability, especially for 8Y and 10Y. The improved soil structure and root characteristic under long-term rice cultivation conditions increased the yield (28.89-54.81%). Partial least squares path model displayed that rice cultivation affected the aggregate stability, root characteristics, and rice yield via the corresponding chemical properties (pH, EC, and ESP), nutrient contents (AN, AP, AK, and SOM), and salt ion contents (Cl-, K+, and Na+). These findings are critical to understanding aggregate formation in saline soils.

A Comprehensive Review on Imperative Role of Ionic Liquids in Pharmaceutical Sciences.

Ionic liquids (ILs) are poorly-coordinated ionic salts that can exist as a liquid at room temperatures (or <100 °C). ILs are also referred to as "designer solvents" because so many of them have been created to solve particular synthetic issues. ILs are regarded as "green solvents" because they have several distinctive qualities, including better ionic conduction, recyclability, improved solvation ability, low volatility, and thermal stability. These have been at the forefront of the most innovative fields of science and technology during the past few years. ILs may be employed in new drug formulation development and drug design in the field of pharmacy for various functions such as improvement of solubility, targeted drug delivery, stabilizer, permeability enhancer, or improvement of bioavailability in the development of pharmaceutical or vaccine dosage formulations. Ionic liquids have become a key component in various areas such as synthetic and catalytic chemistry, extraction, analytics, biotechnology, etc., due to their superior abilities along with highly modifiable potential. This study concentrates on the usage of ILs in various pharmaceutical applications enlisting their numerous purposes from the delivery of drugs to pharmaceutical synthesis. To better comprehend cuttingedge technologies in IL-based drug delivery systems, highly focused mechanistic studies regarding the synthesis/preparation of ILs and their biocompatibility along with the ecotoxicological and biological effects need to be studied. The use of IL techniques can address key issues regarding pharmaceutical preparations such as lower solubility and bioavailability which plays a key role in the lack of effectiveness of significant commercially available drugs.

Photocatalytic ZnIn2S4 for 2-Mercaptobenzothiazole Degradation: Facile Synthesis, Influencing Factors and Mechanism

The development of an efficient, stable and environmentally friendly semiconductor photocatalyst is great research significance in the field of environment and energy. In this paper, ZnIn2S4 semiconductor photocatalysts with flower-like hierarchies were prepared by simple and environmentally friendly method. The influence of ZnIn2S4 dosage, pH and different inorganic salt ions on the photocatalytic degradation of 2-mercaptobenzothiazole (MBT) under visible light was investigated in detail. The results showed that the photocatalyst dosage was 0.05 g, and the photocatalytic degradation efficiency of MBT was the highest in the weakly acidic environment with pH was five. Meanwhile, the addition of some inorganic anions has a significant inhibitory effect on the photocatalytic activity of ZnIn2S4 semiconductor photocatalyst, while cations have less effect. Moreover, the ZnIn2S4 semiconductor photocatalyst had excellent stability and recyclability, and its photodegradation mechanism had been deeply studied. This work provides a theoretical and experimental foundation for exploring the different influencing factors of photocatalytic degradation of organic pollutants in wastewater by other semiconductors.

The effects of counter ion on CO2 capture performance of amino acid salt solutions for direct air capture applications

Direct CO2 capture from the atmosphere has received growing attention driven by the imperative of achieving global net-zero emission targets. Amino acid salt solutions are promising candidates for liquid-based direct air capture processes. Utilised as a neutralized salt by reacting initially with hydroxides, it has been speculated that their performance may vary with the type of counter ion present in the solution. This work investigates the influence of counter ions, potassium, sodium, and lithium, of amino acid salt solutions on the physical properties, the CO2 absorption capacities, and the CO2 absorption kinetics under atmospheric CO2 concentration levels. The potassium-containing amino acid solutions exhibited significantly lower viscosities and mildly elevated densities compared to sodium- and lithium-containing ones. At 25 °C, the potassium-prolinate solution demonstrated the highest viscosity (8.5 mPa⋅s), whereas K-glycinate exhibited the lowest viscosity (2.5 mPa⋅s). Additionally, potassium-based solutions consistently displayed the highest CO2 mass transfer coefficients, followed by sodium- and lithium-containing ones. The CO2 mass transfer coefficient was highest for potassium-prolinate (2.99 mmol m−2⋅s−1⋅kPa−1) with the lowest rate observed for potassium-β-alaninate (1.68 mmol m−2⋅s−1⋅kPa−1). Interestingly, the type of counter ion had minimal impact on the CO2 absorption capacity, with potassium-based solutions exhibiting only a slightly elevated capacity compared to sodium- and lithium-based solutions. Specifically, potassium-lysinate displayed the highest CO2 absorption capacity (0.7 mol CO2 /mol amine), while potassium-β-alaninate showed the lowest (0.65 mol CO2/mol amine). It should be noted that all lithium-based solutions of all amino acids formed precipitates during CO2 absorption. From a practical and operational perspective, these findings suggest that the potassium salt solution of amino acids would be the optimal choice for direct air capture applications due to their enhanced solubility and CO2 mass transfer rates compared to the corresponding sodium and lithium counter ion salt solutions.

The Form of Electrodeposited Iridium Ions in a Molten Chloride Salt and the Effects of Different Iridium Concentrations

A molten salt system was prepared using an optimized method. We studied the complex structure of Ir3+ ions in the molten salt system and the influence their concentration had on the quality of the coatings prepared via electrodeposition. Using TG-DSC and in situ XRD experiments, we studied the high-temperature characteristics and properties of IrCl3 alongside its thermal stability. Using in situ XRD and Raman spectroscopy, we analyzed the Ir ions’ complex structure and the variation in the molten salt system at high temperatures. Finally, the changes in the Ir ion concentration in the molten salt system and the influence of the microstructure of the coatings’ surfaces were investigated under different anode conditions. IrCl3 easily decomposes above 400 °C, and temperature increases accelerate the rate of this decomposition. When the NaCl-KCl-CsCl system is in a high-temperature, molten state, IrCl3 forms stable complex structures (IrCl6)3− and (IrCl6)2−, and the valence state of Ir will be transformed with the increase in temperature. Generating these complex structures is conducive to improving the Ir coating quality. During the electrodeposition process, too few Ir ions in the molten salt can lead to concentration polarization, affecting the quality of the coating. Application of the molten NaCl-KCl-CsCl system is conducive to the electrodeposition of Ir coatings in a suitable temperature range. At the same time, using Ir as the anode can enhance the quality of the coatings.

Distribution and redistribution of salt ions in saline soils with shallow groundwater table

Saline water resources are more abundant than freshwater. Bringing these resources into sustainable, productive use will offer opportunities to reduce competition for freshwater resources, especially in arid and semi-arid areas where freshwater is scarce. Hence, the primary objective of this study was to elucidate the dynamics of salt ions in saline profiles of various soil types (sandy Clovelly and sandy loam Bainsvlei) under malt barley cultivation across 2 seasons where no leaching between the seasons took place. Results of this lysimeter study investigating increasing irrigation salinity (ECi) set at 1.5, 4.5, 6, 9, and 12 dSꞏm−1 over 2 seasons were used to explore ion dynamics of a saline environment. The lysimeter set-up included a saline constant (1.2 m) groundwater table with its salinity corresponding to ECi. Findings showed that ion concentrations are higher closer to the water source only in the Bainsvlei soil and remain variable in the Clovelly soil. Salt dynamics were more predictable in sandy loam soil than in sandy soil, making management of saline sandy soils far more challenging when leaching is not possible. Therefore, our hypothesis that the absence of leaching between seasons will lead to a differentiated progressive accumulation of salt ions in the soil profile, with variable effects on the soil depending on soil texture, was true. We conclude that the desalinized zone, which we determined to be at a depth of 600 mm, should be used to guide crop selection. Furthermore, in addition to the apparent provision for leaching of saline profiles, fertilization should target restoring ion balances, especially provisioning for calcium deficiencies. Both soils were prone to nutritional disorders, most especially calcium deficiency. Therefore, in addition to provision for leaching saline profiles, fertilization should target calcium provisioning for crop production in arid saline environments.

Dynamics of major plant nutrients and enzymatic activities in soil influenced by application of biochar and organic waste.

The concentration of salt ions influences the availability and plant nutrients dynamics in the soil. Proper management of these ions can enhance food grain production, helping to feed the growing population. In this experiment, nine fertility combinations were followed to enhance the soil organic carbon and reduce the salt toxicity and monitor the plant nutrient availability. An incubation experiment was conducted for the period of one year with different organic soil amendments in combinations including biochar (BC), pressmud (PM), and farm yard manure (FYM) as follow: T1-control, T2-RDF, T3-FYM (10 t/ha), T4-PM (10 t/ha), T5-BC (10 t/ha), T6-FYM (5 t/ha) + PM (5 t/ha), T7-FYM (5 t/ha) + BC (5 t/ha), T8-PM (5 t/ha) + BC (5 t/ha), T9-FYM (5 t/ha) + BC (2.5 t/ha) + PM (2.5 t/ha). Results showed that addition of organic substance (10 t/ha) significantly (p < 0.05) affected soil pH and electric conductivity. Plant nutrient availability (N, K, and S) was also influenced by application of organic substance (10 t/ha). Organic C and available N were recorded the highest in the treatment T7 (FYM-5 t/ha + BC -5 t/ha); whereas, the highest available K and S were observed in treatment T5 (BC-10 t/ha). The microbial soil fertility indicators (alkaline phosphatases, arylsulphatase, dehydrogenase activity and microbial biomass carbon) were measured the highest in FYM (5 t/ha) + BC (5 t/ha) applied treatment. In conclusion, application of organic substance 10 t/ha (biochar alone or with FYM) improved the plant nutrient availability and soil microbial activities in saline soil. It could be a suitable option for enhancing the soil fertility in saline soils.

Surfactant-enhanced dispersion stability of cellulose nanocrystals and enhanced oil recovery performance

Cellulose nanocrystals (CNCs) have attracted more and more attention in EOR. CNCs are abundant and renewable, with nanoscale dimensions, excellent rheological properties, and easy-to-modify surface properties. However, the colloid stability of CNCs under high salinity conditions is poor, which limits their application in enhanced oil recovery (EOR). In order to improve the stability of CNCs in the salt environment, the effect of the mixed system of sodium dodecyl benzenesulfonate (SDBS) and polyoxyethylene sorbitan monooleate (Tween 80) on the dispersion stability of CNCs in the presence of different valence salt ions was investigated systematically. The dispersion stability of CNCs was investigated by using the ζ-potential and dynamic light scattering (DLS) techniques. The mixed surfactants improved the dispersion stability of CNCs within the studied salt ion concentration range (Na+ ≤ 300 mM, Ca2+ ≤ 10 mM, Mg2+ ≤ 10 mM). The stabilization mechanism of CNCs was explained by the electrostatic effect and spatial stabilization effect. In the presence of salt ions, the adsorption behavior of mixed surfactants on the surface of CNCs in the presence and absence of crude oil was revealed through molecular dynamics (MD) simulations. Microscopic displacement experiments indicated that due to the small particle size of CNCs in salt environments, the pores were not blocked, resulting in a significant improvement in the oil displacement performance.

Tailoring Ionic Salt in Chitosan-Activated Carbon-Based Triboelectric Nanogenerators for Enhanced Mechanical Energy Harvesting

Tailoring Ionic Salt in Chitosan-Activated Carbon-Based Triboelectric Nanogenerators for Enhanced Mechanical Energy Harvesting

Zwitterion Modification in Desalination Membrane for Rejecting Salt and Salt Ions in Brackish Water – A Mini Review

ABSTRACTDesalination membrane using zwitterion modification provides a significant opportunity to enhance excellent properties for rejecting salt and salt ions. The outstanding properties are designed by positive and negative charges attached to the membrane surface, including water permeability, salt permeability, fouling, and hydrophilicity of the membrane surface. The hydrophilic membrane, which is mentioned as one of the types of desalination membrane, presents the ability to repel salt and salt ions and pass the water. The modification of hydrophilic membranes is also affected by several factors, including water permeability, salt permeability, fouling of membrane surfaces, crossflow velocity, transmembrane pressure, and temperature. Regarding membrane modification, zwitterion has been applied for several ranges, such as the hemodialysis process, live cell imaging, antibacterial surfaces, and wound dressing. However, using a zwitterion modification membrane for desalinating water containing salt content, including brackish water, has yet to be developed. In addition, literature reviews related to polymer membranes for brackish water desalination have never been comprehensively documented. Thus, this review article addresses the zwitterion modification for desalination membranes, which can reject salt and salt ions in brackish water. Furthermore, the mechanism of zwitterion modification for desalination membranes has been presented. Finally, the challenge of zwitterion modification for desalination membranes has been evaluated to inspire insight for future studies.

Mining and urbanization affect river chemical water quality and macroinvertebrate communities in the upper Selenga River basin, Mongolia (revised version).

Mongolia is a country with a quickly growing economy mainly based on the mining of gold, copper, coal, and other minerals. Mining, urbanization, and agriculture impact the water quality in the upper Selenga River basin in northern Mongolia, which is the center of the Mongolian economy. Previous measurements of pollution loads were alarming, but restricted to chemical measurements. Here, for the first time, we combine freshwater biomonitoring and laboratory water quality data across a broad gradient of water quality and land use intensity. We track the effects of different types of pollution on aquatic invertebrates and test their use as bioindicators. We collected water samples, environmental parameters, and macroinvertebrates at 36 sampling sites at the rivers of Tuul, Kharaa, and Orkhon and their tributaries Sugnugur, Boroo, Sharyn Gol, Gatsuurt, and Yeröö. PCA of catchment water quality distinguished three groups of pollutants prevalent at the sites, (1) nutrients, (2) salt ions(Cl-, Na+, Mg2+, So42-, Ca2+) and mining by-products (B, Sr, U, Mo), and (3) (heavy) metals, which often exceeded regulatory standards. We recorded a total of 59 macroinvertebrate taxa belonging to 31 families in seven insect orders plus Amphipoda and Gastropoda. Species diversity declined with higher impact. Five environmental factors structured macroinvertebrate community composition in RDA: elevation of sample location, site total nitrogen, dissolved oxygen, electrical conductivity, and water chemistry. We conclude that macroinvertebrate communities are an appropriate and inexpensive tool for monitoring water quality in Mongolia and suggest government action to establish a long-term monitoring program.

Low-Energy Desalination Techniques, Development of Capacitive Deionization Systems, and Utilization of Activated Carbon

Water desalination technology has emerged as a critical area of research, particularly with the advent of more cost-effective alternatives to conventional methods, such as reverse osmosis and thermal evaporation. Given the vital importance of water for life and the scarcity of potable water for agriculture and livestock—especially in the Kingdom of Saudi Arabia—the capacitive deionization (CDI) method for removing salt from water has been highlighted as the most economical choice compared to other techniques. CDI applies a voltage difference across two porous electrodes to extract salt ions from saline water. This study will investigate water desalination using CDI, utilizing a compact DC power source under 5 volts and a standard current of 2 amperes. We will convert waste materials like sunflower seeds, peanut shells, and rice husks into activated carbon through carbonization and chemical activation to improve its pore structure. Critical parameters for desalination, including voltage, flow rate, and total dissolved solids (TDS) concentration, have been established. The initial TDS levels are set at 2000, 1500, 1000, and 500 ppm, with flow rates of 38.2, 16.8, and 9.5 mL/min across the different voltage settings of 2.5, 2, and 1.5 volts, applicable to both direct and inverse desalination methods. The efficiency at TDS concentrations of 2000, 1500, and 1000 ppm remains between 18% and 20% for up to 8 min. Our results indicate that the desalination process operates effectively at a TDS level of 750 ppm, achieving a maximum efficiency of 45% at a flow rate of 9.5 mL/min. At voltages of 2.5 V, 2 V, and 1.5 V, efficiencies at 3 min are attained with a constant flow rate of 9.5 mL/min and a TDS of 500 ppm, with the maximum desalination efficiency reaching 56%.

Regulating the Electronic Structure of Cu Single-Atom Catalysts toward Enhanced Electro-Fenton Degradation of Organic Contaminants via 1O2 and •OH.

Heterogeneous electro-Fenton degradation with 1O2 and •OH generated from O2 reduction is cost-effective for the removal of refractory organic pollutants from wastewater. As 1O2 is more tolerant to background constituents such as salt ions and a high pH value than •OH, tuning the production of 1O2 and •OH is important for efficient electro-Fenton degradation. However, it remains a great challenge to selectively produce 1O2 and improve the species yield. Herein, the electronic structure of atomically dispersed Cu-N4 sites was regulated by doping electron-deficient B into porous hollow carbon microspheres (CuBN-HCMs), which improved *O2 adsorption and significantly enhanced 1O2 selectivity in electro-Fenton degradation. Its 1O2 yield was 2.3 times higher than that of a Cu single-atom catalyst without B doping. Meanwhile, •OH was simultaneously generated as a minor species. The CuBN-HCMs were efficient for the electro-Fenton degradation of phenol, sulfamethoxazole, and bisphenol A with a high mineralization efficiency. Its kinetic constants showed insignificant changes under various anions and a wide pH range of 1-9. More importantly, it was energy-efficient for treating actual coking wastewater with a low energy consumption of 19.0 kWh kgCOD-1. The superior performance of the CuBN-HCMs was contributed from 1O2 and •OH and its high 1O2 selectivity.

Organic Cationic-Coordinated Perfluoropolymer Electrolytes with Strong Li+-Solvent Interaction for Solid State Li-Metal Batteries.

The practical application of solid-state polymer lithium-metal batteries (LMBs) is plagued by the inferior ionic conductivity of the applied polymer electrolytes (PEs), which is caused by the coupling of ion transport with the motion of polymer segments. Here, solvated molecules based on ionic liquid and lithium salt with strong Li+-solvent interaction are inserted into an elaborately engineered perfluoropolymer electrolyte via ionic dipole interaction, extensively facilitating Li+ transport and improving mechanical properties. The intensified formation of solvation structures of contact ion pairs and ionic aggregates, as well as the strong electron-withdrawal properties of the F atoms in perfluoropolymers, give the PE high electrochemical stability and excellent interfacial stability. As a result, Li||Li symmetric cells demonstrate a lifetime of 2500 h and an exceptionally high critical current density above 2.3 mA cm-2, Li||LiFePO4 batteries exhibit consistent cycling for 550 cycles at 10 C, and Li||uncoated LiNi0.8Co0.1Mn0.1O2 cells achieve 1000 cycles at 0.5 C with an average Coulombic efficiency of 98.45 %, one of the best results reported to date based on PEs. Our discovery sheds fresh light on the targeted synergistic regulation of the electro-chemo-mechanical properties of PEs to extend the cycle life of LMBs.

Plant‐Based Biosynthesis of Metal and Metal Oxide Nanoparticles: An Update on Antimicrobial and Anticancer Activity

AbstractNanotechnology has changed and developed all the sectors and working fields. Nanoparticles are one of the important evolutionary materials that have application in almost all the working areas such as catalysis, bioengineering, photoelectricity, antibacterial, anticancer, and medical imaging due to their unique physical and chemical properties. Traditionally used chemical and physical method of synthesis of nanoparticles have several disadvantages like using different chemicals, high cost, and most importantly they are hazardous to the environment. Counter to these disadvantages, a more eco‐friendly, easy, and cost‐effective green synthesis method is widely employed nowadays. Various parts of a plant are used as a fuel for reducing the metal ion salt. Plant extracts act as reducing, stabilizing, and capping agents. Besides these advantages, photosynthesized nanoparticles are nontoxic, more stable, and more uniform in size than their counterparts prepared by the traditional method. In this present review, the synthesis of various plant extract‐mediated metal and metal oxide nanoparticles is discussed along with their different applications. This review provides a comprehensive overview of key findings in green synthesis of metal and metal oxide nanoparticles and attempts to determine their possible synthesis mechanism. This article also focuses on factors affecting their synthesis, characterization, potential applications, and prospects.

Enhancing the Stability and Practical Application of CO2-Responsive Foam with Nanoparticles: The Role of Salt Ions

Enhancing the Stability and Practical Application of CO₂-Responsive Foam with Nanoparticles: The Role of Salt Ions

Effect of shear rate, temperature, and salts on the viscosity and viscoelasticity of semi‐dilute and entangled xanthan gum

AbstractXanthan gum, a naturally‐occurring, high‐molecular‐weight, anionic polyelectrolyte, exhibits significant drag‐reducing properties at low concentrations in water, suggesting promising applications in geothermal networks. The flow behavior of xanthan solutions are explored, specifically at concentrations in the semi‐dilute (1000 ppm by mass) and entangled (4000 ppm) regimes as well as in both water and various salt solutions across a temperature range of 5–85°C. The viscosity and viscoelastic properties of xanthan solutions examine relationships between polyelectrolyte concentration, temperature, and salt concentration. Viscosity decreases by two orders of magnitude in 4000 ppm xanthan solutions in deionized water and with 50 mM NaCl (in the high salt limit) as the temperature increases from 5 to 85°C. Next, the addition of salts affects viscosity differently in the two concentration regimes. Specifically, at 25°C, the zero‐shear rate viscosity upon salt addition decreases by 63% for 1000 ppm solutions (from 0.54 to 0.2 Pa s) but increases by 280% for 4000 ppm solutions (from 28 to 107 Pa s). At 1000 ppm, salt ions cause chain collapse, reducing viscosity; At 4000 ppm, entanglements led to structural changes, resulting in higher viscosity. Furthermore, three salts commonly found in geothermal waters, namely NaCl, Na2CO3, and NaHCO3, exhibited similar changes in viscosity and shear thinning behavior in the entangled regime across temperatures from 5 to 85°C.

Effect of the Dispersion Medium on NMR Relaxation Properties of Superparamagnetic Iron Oxide Nanoparticles between 0.24 mT and 14.1 T.

Due to weak exchange interactions, magnetite particles at a critical diameter of about 20 nm are considered monodomain. At this size, they exhibit a phenomenological magnetic property called superparamagnetism, making them useful as magnetic resonance imaging contrast agents, or MRI CAs. However, questions persist regarding the impact of using different physiological solvents and varying the environment in which these particles are dispersed on their performance, determined by their relaxivity. A colloidal suspension of superparamagnetic iron oxide nanoparticles (SPIONs) electrostatically stabilized by citrate ligand was synthesized using a fast, reliable, and reproducible developed microwave approach, ensuring high stability over time at pH 7. We studied the effects of three physiological media on these MRI CAs. Ultrapure water was used for the synthesis, while phosphate-buffered saline and physiological liquid were used to disperse the nanoparticles, as these media contain essential electrolytes for the functioning of the human body. The SPIONs underwent systematic characterizations to determine their physicochemical and magnetic properties. This study reports the longitudinal relaxivities of SPIONs at medically relevant magnetic field strengths. Field dependence of their relaxivity (efficacy) was evaluated using a nuclear magnetic resonance dispersion (NMRD) profile measured over a wide range of proton resonance frequencies between 5 kHz and 600 MHz. The Roch et al. model (Roch, A.; et al. J. Chem. Phys., 1999, 110, 5403-5411) was used to analyze the NMRD profile and evaluate the impact of SPIONs on water proton relaxation in the different redispersion media. It was observed in this study that the dynamics of water protons are not influenced by the redispersion media of these citrate-coated SPIONs. However, the presence of salt ions notably reduces their relaxivities by lowering the saturation magnetization of SPIONs.