Salt Ions Research Articles

Chemical structure analysis of chitosan-modified road bitumen after de-icing salt treatment

AbstractAsphalt pavements are constantly exposed to many destructive environmental factors including de-icing salts. The problem of the negative effect of salt ions on the performance and consequently the durability of road pavements occurs mainly in temperate climates and regions directly neighboring saline water areas. The salt ions react chemically with the bitumen components, which consequently changes their electronic structure and results in a weakening of the intermolecular interactions occurring between them. Therefore, this study focused primarily on an investigation into the potential for inhibiting the destructive erosion process of bitumen by its modification with chitosan. Studies involving changes in the acidity of the eroding solution as well as chemical and surface properties of the eroded bitumen were carried out for three different salts (NaCl, MgCl2, CaCl2) at varying concentrations, i.e. 5%, 10%, 15% (w/w) after 7 and 28 days of erosion process. Main findings demonstrate that chitosan prevents negative changes in the bitumen physico-chemical properties occurring during the salt erosion process. This effect is especially visible for the bitumen eroded with a solution of MgCl2 and CaCl2. For these salts, chitosan biopolymer reduces the introduction of Cl− ions into the bitumen-building hydrocarbon structures and formation of C–Cl bonds, which is demonstrated by a reduction in the pH changes of the eroding solutions. In addition, chitosan biopolymer inhibits leaching of organic matter from the bitumen, prevents C = O groups formation and reduces the negative effects of de-icing salts on the cohesion energy of the bitumen.

Experimental and theoretical study of size-dependent phase evolution in NaCl-KCl alloys

In the present investigation, the formation of nanocrystalline bi-alkali halide (NaCl+KCl) obtained by combined low temperature (cryomilling) with room temperature (RT) milling was reported. The cryomilling, which is endowed with special ability to accelerated fracture and form free ionic salt crystals, is utilized for rapid refinement. This is followed by RT milling to form biphasic nanocrystallites. The bi-phase formation with the time of milling was characterized using a scanning electron microscope (SEM) and transmission electron microscope (TEM). The change in lattice parameter and introduction of micro-strain in the lattice (due to cold work and bi-phase formation) have been characterized using X-ray diffraction and deduce using theoretical calculations. The investigation reveals the influence of milling time on the shape and size of the crystallites along with formation of biphasic NaCl-KCl crystallites with inner core being NaCl surrounded by KCl crystals. The KCl powder particles get deposited on the surface of NaCl crystals to maintain the charge neutrality during ball milling. The shape of NaCl undergoes change from cuboid to cuboctahedron with the progression of milling time due to plastic deformation induced roughing. The temperature-dependent mechanical behaviour and associated mechanism of the milled NaCl-KCl system were discussed and supported by the thermodynamic modal. It is evident, NaCl-KCl is phase separating system, which accentuated at nanosized and hence, the formation of biphasic crystalline structure is observed during combined cryo and RT milling.

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.

High efficient synthesis of benzyl lactate through waste PLA alcoholysis by protic ionic salt

Benzyl lactate (BL) is a critical reagent in pharmaceutical and chemical synthesis due to its versatility. Traditional synthesis of BL was constrained by the high cost and low yield, thereby hindering the feasibility of large-scale production. Here, we reported a novel synthesis strategy for BL by utilizing the alcoholysis of waste polylactic acid (PLA) by benzyl alcohol with the protic ionic salt, HTBD-OAc, as the catalyst. The gram-scale experiments achieved a 94.9 % yield, and the robustness of this reaction was evidenced by the yield maintaining 92.5 % across six recycling experiments. More impressively, kilogram-scale synthesis facilitated a complete conversion of PLA to BL, achieving an unprecedented yield of 98.7 % at 180 °C within two hours. The exceptional catalytic efficiency of this reaction is attributed to the synergistic functions between the HTBD+ cation and OAc− anion in the catalyst HTBD-OAc. This study heralds a significant stride towards the sustainable and scalable production of high-purity benzyl lactate, paving the way for extended industrial applicability for this essential compound.

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.

A one-step polyvinyl alcohol/polyacrylamide/polyacrylic acid/dimethyl sulfoxide/CaCl2 hybrid hydrogel enabling anti-fatigue, anti-freeze and anti-dehydration for wearable strain sensor

Hydrogel with fatigue resistance, freezing tolerant and dehydration resistance are peculiarly attractive in strain sensors. The hydrogel soaked in organic solvent is an effective strategy to improve freezing resistance and dehydration resistance, while this may result in poor conductivity. Moreover, ion-incorporation is considered to be the most feasible method for solving above concern, while high concentration of salt ions will result in weak mechanical properties. Therefore, the facile preparation of anti-freezing and anti-dehydration hydrogels with excellent fatigue resistance remains a challenge. Herein, a polyvinyl alcohol/polyacrylamide/polyacrylic acid/dimethyl sulfoxide/CaCl2 hybrid hydrogel was designed and fabricated through a facile one-step method to balance a variety of outstanding properties. On account of the hybridization design of multi-materials, the hybrid hydrogel exhibited high ionic conductivity (∼0.2 S/m), strength (∼0.36 MPa) and stretchability (∼825 %). Meanwhile, the hybrid hydrogel demonstrated prominent freezing resistance, dehydration resistance and fatigue resistance. The mechanical properties almost no deterioration after 1000 stretching cycle at 100 % strain, exposure to environment for 30 days or freeze at low temperature. Besides, the hybrid hydrogel-based stain sensor showed a linear sensitivity (GF = 1.12 over 0–400 % strain), quickly responsivity (200 ms), and could monitor various human activities steadily, demonstrating distinguished potential for use in wearable health monitoring and flexible electric skins.

Effects of sodium chloride on the textural attributes, rheological properties, microstructure, and 3D printing performance of rice starch-curdlan composite gel

This study explores the impact of varying concentrations of salt ions (0, 2.5, 5, 7.5, 10, and 12.5 mmol) on the physicochemical properties and 3D-printing performance of rice starch-curdlan composite gel. The relationship between gel structure, properties, printability, and printing accuracy was clarified through the evaluation of each parameter. The inclusion of an appropriate concentration of NaCl positively influenced the properties and printing characteristics of the composite gel. Specifically, a NaCl concentration of 7.5 mmol yielded the highest printing performance, achieving 98.61 % accuracy. Microstructural analysis indicates that the addition of ions promoted the formation of a denser network structure in the composite gel. Fourier-transform infrared spectroscopy reveals enhanced hydrogen bonding in the rice starch-curdlan gels with the addition of NaCl. Lastly, dysphagia testing demonstrates that the composite gels with 0–5 mmol NaCl concentrations exhibited grade 5 characteristics (clastic and wet) with satisfactory swallowing performance.

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.

Construction of high strength PVA/cellulose conductive hydrogels based on sodium citrate/aluminium chloride dual ions regulation

Hydrogels used for flexible sensing usually require a good balance between mechanical strength and conductivity. In this study, polyvinyl alcohol/carboxymethyl cellulose/cellulose nanofibers (PVA/CMC/CNF) hydrogels with multi-hierarchical structures were firstly prepared by adjusting the CNF content. Then, PVA/CMC/CNF-xM with excellent mechanical properties and conductivity were prepared by cyclic freezing-thawing and sodium citrate/aluminium chloride (Na3Cit/AlCl3) dual ions salt equilibrium methods. Results showed that at an ion concentration of 3 mol/L, PVA/CMC/CNF-3 M hydrogel exhibited a tensile strength, elongation at break and conductivity of 3.41 MPa, 1271 % and 0.35 S/m, respectively. The structural evolution of PVA/CMC/CNF-xM conductive hydrogels were studied, and the results indicated that Cit3− formed numerous intermolecular hydrogen bonds, while Al3+ could strongly coordinate with carboxyl and hydroxyl groups between the polysaccharide chains. Meanwhile, PVA/CMC/CNF-3 M possessed a low strain detection limit of 1 %, making it not only can be used for human motion monitoring, but also information encoding and transmission. This work may provide a facile approach for preparing high-strength and conductive hydrogels, which can be applied in flexible wearable electronic devices and information transmission.

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.

Enhanced lipase production and characterization from Aeromonas media VBC8: Applications in biodegradation of lubricating oil waste

This study aimed to explore the potential of a novel indigenous strain for the improved production of lipase from castor oil-contaminated soil. Among the various isolates, Aeromonas media VBC8 was found to be the most effective for lipase production. The effect of different inducer oils (olive, peanut, soybean, rice bran, sunflower, coconut, sesame, and fish liver oil) on the biomass of A. media VBC8 and its lipase activity was determined. Among the various oils assessed, fish liver oil exhibited highest lipase activity, with 89 U/mL with 9.1 g/L of biomass. Furthermore, Box-Behnken Design was used to optimize the cultural conditions resulting in an enhanced lipase activity of 1156 U/mL. The lipase was purified through ammonium salt (60 w/v %) precipitation, desalting and ion exchange column, achieving a yield of 16 % and specific activity of 98.4 U/mL. The purified lipase remained active over a wide range of pH 4.0–11.0 and temperature of 10–80 °C with maximum activity at pH 8.0 and 40 °C. SDS-PAGE analysis revealed the lipase's molecular weight to be 94 kDa. The study also evaluated the role of crude and purified lipase in the biodegradability of lubricating oil waste, achieving a maximum fatty acid conversion of 39 and 76 %, respectively, after 7 h incubation at room temperature.

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.