Salt Type Research Articles

Subsidy-stress responses of ecosystem functions along experimental freshwater salinity gradients

Human activity is increasing salt concentrations in freshwaters worldwide, but effects of freshwater salinity gradients on biogeochemical cycling are less understood than in saline, brackish, or marine environments. Using controlled microcosm experiments, we characterized (1) short-term (one to five days) biogeochemical responses and (2) water column metabolism along a freshwater salinity gradient of multiple salt types. After one day, microcosms were oxic (4.48–7.40 mg O2 L−1) but became hypoxic (1.20–3.31 mg L−1) by day five. After one day in oxic conditions, microbial respiration in magnesium-, sodium-, and sea salt-based salinity treatments showed a subsidy-stress response, with respiration increasing by over 100% as salinity increased from 30 to 350–800 µS cm−1. Conversely, respiration consistently increased along a calcium-based salinity gradient, peaking at 1500 µS cm−1. By day five, an inverse subsidy-stress response was observed with elevated respiration at upper or lower ends of the gradient except for the magnesium treatment, which had the lowest respiration at the highest salinity. Calcium- and magnesium-based salinity treatments also caused considerable changes in phosphorus concentrations and C:P and N:P. In a separate experiment, microbial respiration and water column primary production also displayed subsidy-stress responses, but imbalances in effect sizes caused consistently declining net community production with increasing salinity. Collectively, our results establish that short-term exposure to different salt ion concentrations can enhance freshwater biogeochemical cycling at relatively low concentrations and alter resource stoichiometry. Furthermore, the nature of effects of freshwater salinization may also change with oxygen availability.

Assessment of salt-affected soil in selected rice irrigation schemes in Tanzania: understanding salt types for optimizing management approaches

Salt-affected soils have serious implications for agricultural land quality and productivity, leading to a reduction in the net cultivable area available for food production. This issue has emerged as one of the foremost global challenges in recent years, impacting both food security and environmental sustainability. This research focuses on soil characterizations conducted in three irrigation schemes to understand the types, distribution, and nature of salt-affected soils. Auger observations served as the basic methodology for soil unit delineation in this study. Twelve representative soil pits with a depth of more than 160 cm were described, and undisturbed and disturbed samples were collected and analyzed for physical and chemical properties. The schemes were characterized by low levels of available phosphorus, organic carbon, and total nitrogen, as well as variations in exchangeable bases. Furthermore, 37.5% of the analyzed horizons highlighted the presence of salt-affected soils. Sodium was the predominant cation, followed by magnesium, potassium, and calcium. Likewise, HCO3− was the dominant anion, followed by Cl− and SO42−. The results of this study reveal the existence of two types of salt-affected soil. Uturo irrigation scheme had sodic soils, while the Ndungu irrigation scheme had saline-sodic soils. Additionally, both sodic and saline-sodic soils have been discovered in the Mawala irrigation scheme. The root cause of this challenge is inherent soil conditions, exacerbated by inadequate drainage infrastructure. Therefore, measures such as the application of gypsum followed by salt leaching, improving soil drainage by incorporating organic matter, improving drainage infrastructure, and using rice-tolerant varieties are recommended to mitigate salt stress and improve soil fertility. It is imperative to establish a robust framework for continuous monitoring and regular assessment of soil health to enable timely interventions and informed decisions for sustainable agricultural management.

Characterization of flavor-related compounds and sensory profiles of four fermented fish products prepared from silver rasbora (Rasbora argyrotaenia) and anchovy (Stolephorus sp.)

Fermented fish products are grouped into salt and salt-carbohydrate types based on the fermentation substrate. A series of biochemical reactions on the substrate affects the flavor characteristics of the resulting products. This study compared the amino acids, fatty acids, and volatile compound profiles of four fermented fish products: bekasam, rusip, fish paste, and fish sauce made from silver rasbora and anchovy. The quantitative descriptive analysis (QDA) was carried out to determine the sensory profiles of those products. The results indicated that rusip and bekasam, which belong to salt-carbohydrate fermented fish, were characterized as high in arginine, stearic, capric, and oleic acid, with ketones, lactones, and fatty acid derivative compounds dominating their flavor profiles. The flavor profile of fish paste was characterized by high concentrations of aldehydes such as 3- methylbutanal and hexanal, whereas that of fish sauce was characterized by large concentrations of pyrazine and aromatic compounds. Based on the findings of the QDA, no significant difference was observed within the sensory variables of fish sauce and fish paste prepared from anchovy and silver rasbora, indicating that both fish are equally usable as raw materials. Whereas different saltiness was identified in both rusip and bekasam prepared from anchovy and rasbora. The results of PCA on QDA data separated fermented fish type 1 from the type 2. Fermented fish type 1 was more correlated with umami and sweet taste, while type 2 was correlated with fishy, salty, sour, and astringent taste. The result is useful as a basis for further product development and quality control.

Enhanced Adsorption of Methyl Orange from Aqueous Phase Using Chitosan-Palmer Amaranth Biochar Composite Microspheres.

To develop valuable applications for the invasive weed Palmer amaranth, we utilized it as a novel biochar source and explored its potential for methyl orange adsorption through the synthesis of chitosan-encapsulated Palmer amaranth biochar composite microspheres. Firstly, the prepared microspheres were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy and were demonstrated to have a surface area of 19.6 m2/g, a total pore volume of 0.0664 cm3/g and an average pore diameter of 10.6 nm. Then, the influences of pH, dosage and salt type and concentration on the adsorption efficiency were systematically investigated alongside the adsorption kinetics, isotherms, and thermodynamics. The results reveal that the highest adsorption capacity of methyl orange was obtained at pH 4.0. The adsorption process was well fitted by a pseudo-second-order kinetic model and the Langmuir isotherm model, and was spontaneous and endothermic. Through the Langmuir model, the maximal adsorption capacities of methyl orange were calculated as 495.0, 537.1 and 554.3 mg/g at 25.0, 35.0 and 45.0 °C, respectively. Subsequently, the adsorption mechanisms were elucidated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy investigations. It is indicated that electrostatic interactions, hydrogen bonding, π-π interactions and hydrophobic interactions between methyl orange and the composite microspheres were pivotal for the adsorption process. Finally, the regeneration studies demonstrated that after five adsorption-desorption cycles, the microspheres still maintained 93.6% of their initial adsorption capacity for methyl orange. This work not only presents a promising method for mitigating methyl orange pollution but also offers a sustainable approach to managing Palmer amaranth invasion.

Purification of exopolysaccharide produced from Lactobacillus spp. using ionic-liquid as adjuvant in alcohol/salt-based aqueous two-phase system for its antidiabetic properties

Diabetes is a chronic, metabolic disease characterized by hyperglycemia resulting from either insufficient insulin production or impaired cellular response to insulin. Exopolysaccharides (EPS) produced by Lactobacillus spp. demonstrated promising therapeutic potential in terms of their anti-diabetic properties. Extraction and purification of EPS produced by Lactobacillus acidophilus and Limosilactobacillus reuteri were performed using ethanol precipitation, followed by alcohol/salt based aqueous two-phase system (ATPS). The purification process involved ethanol precipitation followed by an alcohol/salt-based ATPS. The study systematically investigated various purification parameters in ATPS, including ethanol concentration, type and concentration of ionic liquid, type and concentration of salt and pH of salt. Purified EPS contents from L. acidophilus (63.30 μg/mL) and L. reuteri (146.48 μg/mL) were obtained under optimum conditions of ATPS which consisted of 30 % (w/w) ethanol, 25 % (w/w) dipotassium hydrogen phosphate at pH 10 and 2 % (w/w) 1-butyl-3-methylimidazolium octyl sulfate. The extracted EPS content was determined using phenol sulphuric acid method. In α-amylase inhibition tests, the inhibitory rate was found to be 92.52 % (L. reuteri) and 90.64 % (L. acidophilus), while in α-glucosidase inhibition tests, the inhibitory rate was 73.58 % (L. reuteri) and 68.77 % (L. acidophilus), based on the optimized parameters selected in ATPS. These results suggest that the purified EPS derived from the postbiotics of Lactobacillus spp. hold promise as potential antidiabetic agents.

Ni2Mo3N: crystal structure, thermal properties, and catalytic activity for ammonia decomposition

Abstract Ni2Mo3N was synthesized by ammonolysis of NiMoO4, prepared by a sol-gel-based modified Pechini route. X-ray powder diffraction measurements confirmed that Ni2Mo3N crystallizes in a filled β-Mn type (cubic space group P4132) with a lattice parameter of a = 6.6338 Å. Group theoretical methods were applied to elucidate the relation between the crystal structure of Ni2Mo3N and that of the rock salt type. The high-temperature behavior was investigated in-situ by X-ray diffraction measurements in flowing ammonia gas at temperatures up to 875 °C. Ni2Mo3N exhibits significant catalytical activity for ammonia decomposition, which is critically discussed in comparison to literature.

Effect of metal doping on the microwave absorption performance of multi-element (metal, N, and Cl) doped carbon composites

Multi-element-doped carbons are actively being pursued as efficient lightweight microwave absorbers. In this work, metal, nitrogen and chlorine codoped carbons (metal,N,Cl–C, where metals = Ni, Co, Mn, or Zn) were synthesized through the high-temperature carbonization of polypyrrole doped with hydrochloric acid (PPy-HCl) and prepared in the presence of certain metal chloride salts (NiCl2, CoCl2, MnCl2, or ZnCl2). The dielectric parameters and microwave absorption properties of the metal,N,Cl–C composites could be regulated by simply altering the type of metal salt. Compared with N,Cl–C, it was discovered that Co,N,Cl–C and Ni,N,Cl–C possessed higher graphitization degrees, smaller particle sizes and more surface chemical functional groups (metal−N), which significantly improved the conduction loss and polarization loss effects including interfacial polarization and dipole polarization. At a filler ratio of 9.0 wt%, Ni,N,Cl–C displayed a wide effective absorption bandwidth (EAB, RL ≤ −10 dB) of 7.1 GHz at a thickness of 2.5 mm and a minimum reflection loss (RLmin) of −29.7 dB at 9.7 GHz and 3.5 mm thickness. Similarly, Co,N,Cl–C offered an RLmin value of −48.2 dB at 11.3 GHz and a thickness of 3.0 mm and an EAB of 6.0 GHz at a thickness of 2.5 mm. These results showcase the advantages of metal,N,Cl–C composites as microwave absorbers.

Influence of salt contamination on the rheological and filtration properties of bentonite-based mud

Bentonite-based mud has been widely used in petroleum, geotechnical and civil engineering to lubricate the drill bit, maintain wellbore stability, and lift the drilled cuttings up to the surface during drilling operations. Understanding salt contaminants influences the quality of bentonite-based mud is necessary to create a suitable formula for drilling mud to achieve a successful drilling process in deep formations and coastal regions. In this paper, several experiments were carried out on bentonite-based muds with different types of salt (NaCl and CaCl2) and various concentrations of salts (NaCl - 0.5, 1, 1.5, 2 wt%; CaCl2 - 0.1, 0.2, 0.3, 0.4 wt%). The properties of mud were examined by laboratory equipment, including an 8-speed viscometer, and American Petroleum Institute (API) Filter Press. The findings indicate that salt contamination impairs the characteristics of drilling fluid. The rheological parameters of mud, such as viscosity, yield point, and gel strength, drop dramatically as the concentration of salt increases. Furthermore, the filtration test indicated that the bentonite-based mud encountered severe water loss into the formation with increased salt concentration.

Modified QuEChERS method combined with ultra performance liquid chromatography-tandem mass spectrometry for detection of cyclopiazonic acid in feeds

Mycotoxins are toxic secondary metabolites produced by fungal species that can cause acute, subacute, and chronic toxicity in humans and animals. Thus, these toxins pose a significant threat to health and safety. Owing to the lack of effective antimold measures in the agricultural industry, feed ingredients such as corn, peanuts, wheat, barley, millet, nuts, oily feed, forage, and their byproducts are prone to mold and mycotoxin contamination, which can affect animal production, product quality, and safety. Cyclopiazonic acid (CPA), which is mainly biosynthesized from mevalonate, tryptophan, and diacetate units, is a myotoxic secondary metabolite produced by Penicillium and Aspergillus fungi. CPA is widely present as a copollutant with aflatoxins in various crops. Compared with some common mycotoxins such as aflatoxins, fumonisins, ochratoxins, zearalenones, and their metabolites, CPA has not been well investigated. In the United States, a survey showed that 51% of corn and 90% of peanut samples contained CPA, with a maximum level of 2.9 mg/kg. In Europe, CPA was found in Penicillium-contaminated cheeses as high as 4.0 mg/kg. Some studies have shown that CPA can cause irreversible damage to organs such as the liver and spleen in mice. Therefore, the establishment of a rapid and efficient analytical method for CPA is of great significance for the risk assessment of CPA in feeds, the development of standard limits, and the protection of feed product quality and safety. The QuEChERS method, a sample pretreatment method that is fast, simple, cheap, effective, and safe, is widely used in the analysis of pesticide residues in food. In this study, a modified QuEChERS method combined with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to determine CPA levels in feeds. The chromatographic separation and MS detection of CPA as well as the key factors affecting the extraction efficiency of CPA, including the type of extraction solvent, type of inorganic salt, and type and dosage of adsorbent, were optimized in detail. During the optimization of the chromatographic-separation step, the acid and salt concentrations of the mobile phase affected the separation and detection of CPA. During the optimization of the QuEChERS method, the addition of a certain amount of acetic acid improved the extraction efficiency of CPA because of its acidic nature; in addition, GCB and PSA significantly adsorbed CPA from the feed extract. Under optimal conditions, the CPA in the feed sample (1.0 g) was extracted with 2 mL of water and 4 mL of acetonitrile (ACN) containing 0.5% acetic acid. After salting out with 0.4 g of NaCl and 1.6 g of MgSO4, 1 mL of the ACN supernatant was purified by dispersive solid-phase extraction using 150 mg of MgSO4 and 50 mg of C18 and analyzed by UPLC-MS/MS. The sample was separated on a Waters HSS T3 column (100 mm×2.1 mm, 1.8 μm) using 2 mmol/L ammonium acetate aqueous solution with 0.5% formic acid and ACN as the mobile phases and then analyzed by positive electrospray ionization in multiple reaction monitoring mode. CPA exhibited good linearity in the range of 2-200 ng/mL, with a high correlation coefficient (r=0.9995). The limits of detection and quantification of CPA, which were calculated as 3 and 10 times the signal-to-noise ratio, respectively, were 0.6 and 2.0 μg/kg, respectively. The average recoveries in feed samples spiked with 10, 100, and 500 μg/kg CPA ranged from 70.1% to 78.5%, with an intra-day precision of less than 5.8% and an inter-day precision of less than 7.2%, indicating the good accuracy and precision of the proposed method. Finally, the modified QuEChERS-UPLC-MS/MS method was applied to the analysis of CPA in 10 feed samples obtained from Wuhan market. The analysis results indicated that the developed method has good applicability for CPA analysis in feed samples. In summary, an improved QuEChERS method was applied to the extraction and purification of CPA from feeds for the first time; this method provides a suitable analytical method for the risk monitoring, assessment, and standard-limit setting of CPA in feed samples.

Iodine deficiency hypothyroidism in children in recent years: a re-emerging issue?

Iodine nutrition is a growing issue within the USA due to newer trends of non-iodized salts. There are no recent reviews looking at the current state of iodine deficiency-induced hypothyroidism in children in the USA. We performed a retrospective chart review at our tertiary pediatric endocrine clinic; four met the diagnostic criteria for iodine deficiency defined by a low urine iodine level. We further characterized severity of disease, risk factors, goiter, thyroid labs and antibodies. All cases had significant goiter and were diagnosed within the last 2 years. One case had iodine deficiency due to no iodized salt intake along with concurrent diagnosis of developmental delay and multiple food allergies, while others involved the use of non-iodized salts. Two cases had iodine deficiency along with autoimmunity. It is critical to obtain a dietary history for all patients who present with goiter and/or hypothyroidism. There may be a need to consider reevaluating current preventative measures for iodine deficiency, especially for certain vulnerable populations such as children who do not consume iodized salt. In recent decades, iodine nutrition has become a growing concern due to changing dietary patterns and food manufacturing practices. A dietary history is crucial to obtain in children presenting with hypothyroidism and goiter, especially in children with restrictive diets due to behavioral concerns, developmental delays, or multiple food allergies. Of the 12 different types of salts commercially available, only table salt contains iodine in an appropriate amount; thus, individuals using specialty salts can develop mild to moderate iodine deficiency-related thyroid disease.

Untargeted metabolomics and molecular docking studies on green silver nanoparticles synthesized by Sarocladium subulatum: Exploring antibacterial and antioxidant properties

The biological synthesis of silver nanoparticles (Ag-NPs) with fungi has shown promising results in antibacterial and antioxidant properties. Fungi generate metabolites (both primary and secondary) and proteins, which aid in the formation of metal nanoparticles as reducing or capping agents. While several studies have been conducted on the biological production of Ag-NPs, the exact mechanisms still need to be clarified. In this study, Ag-NPs are synthesized greenly using an unstudied fungal strain, Sarocladium subulatum AS4D. Three silver salts were used to synthesize the Ag-NPs for the first time, optimized using a cell-free extract (CFE) strategy. Additionally, these NPs were assessed for their antimicrobial and antioxidant properties. Various spectroscopic and microscopy techniques were utilized to confirm Ag-NP formation and analyze their morphology, crystalline properties, functional groups, size, stability, and concentrations. Untargeted metabolomics and proteome disruption were employed to explore the synthesis mechanism. Computational tools were applied to predict metabolite toxicity and antibacterial activity. The study identified 40 fungal metabolites capable of reducing silver ions, with COOH and OH functional groups playing a pivotal role. The silver salt type impacted the NPs' size and stability, with sizes ranging from 40 to 52 nm and zeta potentials from −0.9 to −30.4 mV. Proteome disruption affected size and stability but not shape. Biosynthesized Ag-NPs using protein-free extracts ranged from 55 to 62 nm, and zeta potentials varied from −18 to −27 mV. Molecular docking studies and PASS results found no role for the metabolome in antibacterial activity. This suggests the antibacterial activity comes from Ag-NPs, not capping or reducing agents. Overall, the research affirmed the vital role of specific reducing metabolites in the biosynthesis of Ag-NPs, while proteins derived from biological extracts were found to solely affect their size and stability.

DESALINATION OF UNDERWATER CERAMIC CULTURAL HERITAGE: THE EXAMPLE OF KERPE UNDERWATER EXCAVATION

Salinity, which is one of the chemical properties of the marine environment, is mixed into seawater due to the dynamic exchange processes between the atmosphere and the hydrosphere and the dissolution of the shells of marine organisms on the seabed. The amount of soluble salts is measured in parts per million (ppm), but in this article, it is measured in parts per thousand (ppt). When soluble salts are not removed by appropriate conservation methods, they crystalize in the pores of artefacts that constitute underwater cultural heritage. These crystals cause physical deterioration in ceramics, which are porous cultural heritage, such as fragmentation from the surface and microscopic cracks. For this reason, the first step in repairing cultural remains recovered from underwater archaeological excavations is to determine the physical properties of the artefacts, such as porosity and salt absorption capacity, as well as the type and amount of salt accumulated in their pores. Thus, the appropriate desalination method can be selected, and estimates can be made on how long the desalination process will take. This paper studied ceramic sherds of Roman and Byzantine amphorae and cooking vessels recovered during underwater excavations in the ancient harbor of Kerpe Bay in Kocaeli, Turkey, in 2022. The aim of the study was to make a preliminary examination for further studies, including instrumental analyses, and to determine the types and amounts of salt deposited on the samples. The samples were desalinated for one month in 200 ml containers with weekly changes of deionized water, and the desalination water was tested to measure salinity and determine the dissolved salt species. Spot tests were used to determine dissolved salts. Sulphate, chloride and carbonate were found in the samples due to these tests. The porosity of the samples was determined by the water absorption method.

Lithium ion Speciation in Cyclic Solvents: Impact of Anion Charge Delocalization and Solvent Polarizability.

The increasing demand for lithium batteries has triggered the search for safer and more efficient electrolytes. Insights into the atomistic description of electrolytes are critical for relating microscopic and macroscopic (physicochemical) properties. Previous studies have shown that the type of lithium salt and solvent used in the electrolyte influences its performance by dictating the speciation of the ionic components in the system. Here, we investigate the molecular origins of ion association in lithium-based electrolytes as a function of anion charge delocalization and solvent chemical identity. To this end, a family of cyano-based lithium salts in organic solvents, having a cyclic structure and containing carbonyl groups, was investigated using a combination of linear infrared spectroscopy and ab initio computations. Our results show that the formation of contact-ion pairs (CIPs) is more favorable in organic solvents containing either ester or carbonate groups and in lithium salts with an anion having low charge delocalization than in an amide/urea solvent and an anion with large charge delocalization. Ab initio computations attribute the degree of CIP formation to the energetics of the process, which is largely influenced by the chemical nature of the lithium ion solvation shell. At the molecular level, atomic charge analysis reveals that CIP formation is directly related to the ability of the solvent molecule to rearrange its electronic density upon coordination to the lithium ion. Overall, these findings emphasize the importance of local interactions in determining the nature of ion-molecule interactions and provide a molecular framework for explaining lithium ion speciation in the design of new electrolytes.

Ionic Rectification by Dynamic Regulation of the Electric Double Layer at the Hydrogel Interface.

Hydrogels play a pivotal role in the realm of iontronics, contributing to the realization of futuristic human-machine interactions. The electric double layer (EDL) between the hydrogel and electrode provides an essential ionic-electronic coupling interface. While prior investigations primarily delved into elucidating the formation mechanism of the EDL, our study shifts the focus to showcasing the current generation through the mechanical modulation of the EDL at the hydrogel-metal interfaces. The dynamic EDL was constructed by the mechano-driven contact-separation process between the polyacrylamide (PAAm) hydrogel and Au. Influencing factors on the dynamic regulation of the EDL such as ion concentration, types of salt, contact-separation frequency, and deformation degree were investigated. Dehydration usually limits the practical applications of hydrogels, and it is a long-standing and difficult problem. However, it seemed to be able to slow the EDL formation process here, resulting in a sustained continuous direct current signal output. Such hydrogel iontronics could rectify the displacement electronic current of a triboelectric nanogenerator by the ionic current. The directional migration of ions could be further enhanced by using charge-collecting metals with different work functions, for example, Au and Al. It offers a paradigm to enable ionic rectification that could be seamlessly incorporated into electronic systems, ushering in a new era for efficient energy harvesting and biomimetic nervous systems.

A Biomimetic "Salting Out-Alignment-Locking" Tactic to Design Strong and Tough Hydrogel.

Recently, hydrogel-based soft materials have demonstrated huge potential in soft robotics, flexible electronics as well as artificial skins. Although various methods are developed to prepare tough and strong hydrogels, it is still challenging to simultaneously enhance the strength and toughness of hydrogels, especially for protein-based hydrogels. Herein, a biomimetic "salting out-alignment-locking" tactic (SALT) is introduced for enhancing mechanical properties through the synergy of alignment and the salting out effect. As a typical example, tensile strength and modulus of initially brittle gelatin hydrogels increase 940 folds to 10.12±0.50MPa and 2830 folds to 34.26±3.94MPa, respectively, and the toughness increases up to 1785 folds to 14.28±3.13MJ m-3. The obtained strength and toughness hold records for the previously reported gelatin-based hydrogel and are close to the tendons. It is further elucidated that the salting out effect engenders hydrophobic domains, while prestretching facilitates chain alignment, both synergistically contributing to the outstanding mechanical properties. It is noteworthy that the SALT demonstrates remarkable versatility across different salt types and polymer systems, thus opening up new avenues for engineering strong, tough, and stiff hydrogels.

Exploring the Voltage Stability of Birnessitic Bi-MnO2 Cathodes Formed In Situ in NaOH and KOH-Based Electrolytes

MnO2, in its many phases, is abundant, non-flammable, non-toxic, reliable, made with abundant materials using simple manufacturing methods, and can have a high theoretical capacity for some phases (up to 617 mAh g−1). Here we have investigated the sensitivity of the performance ofbirnessite—produced in situ—to the presence of Bi2O3, depth-of-discharge, electrolyte salt type, and relative electrolyte volume. We prepared cathodes composed of 45 wt% MnO2, 22.5 wt% Bi2O3, and 22.5 wt% carbon additives, and compared cycling stability in two electrolytes—6.6 M KOH (27 wt%) and 6.6 M NaOH (21 wt%), and two types of 3-electrode test fixtures (flooded beaker or electrolyte-lean T-cell). Our results showed that birnessite can be synthesized electrochemically in NaOH, and cycling the cathode in NaOH improves its stability when compared to cycling in KOH. We tested the cathode in electrolyte-lean environments and found a drastic improvement in cycling stability in NaOH. The cathode exhibited higher initial capacity in lean amounts of KOH, but capacity retention plummeted after the first 20 cycles. In contrast, the cathode in NaOH delivered 65% of the theoretical capacity for over 400 cycles.

Theoretical and experimental research of polyelectrolyte multilayer membrane prepared by layer by layer self-assembly

Layer-by-layer self-assembly of polyelectrolytes is one of the most promising methods for preparing nanofiltration membranes. Here poly (sodium 4-styrenesulfonate) (PSS) and poly (diallyldim-ethylammonium chloride) (PDADMAC) were chosen to prepare polyelectrolyte multilayer (PEM) membrane. The effects of background salt concentration, PSS concentration, background salt types, the number of layers and the outermost functional groups on the separation performance of the PEM were investigated systematically. Molecular dynamic simulation was employed to simulate the influence of background salt on the diffusion of PDADMAC. The simulation results agree well with the experimental results. The optimized (PSS/PDADMAC)4.5 membrane with Na2SO4 as background salt shows permeance of 15.9 LMH/bar, Na2SO4 rejection of 98.2 %, and an excellent stability. Our study provides both theoretical and experimental supports for the preparation of PEM membranes using LBL method.

Green zinc/galactomannan-based hydrogels push up the photovoltage of quasi solid aqueous dye sensitized solar cells

In the present work, we implement environmentally friendly water-based Quasi-Solid Electrolytes (QSE) for Dye Sensitized Solar Cells (DSSCs), displaying an unprecedent open circuit voltage (VOC) as high as 750 mV. The production of the hydrogel for QSE-DSSCs is achieved by exploiting the concept of fully green design and fabrication, through the selection of components such as the natural polysaccharide galactomannan (GM), biocompatible zinc salts, and the employment of eco-friendly synthetic procedures to produce the hybrid gelating agents. In the process, moderate temperature (<40 °C), only aqueous solutions are employed, and, at most, ethanol is used in some phases of the procedure. Depending on the type of the initial salt, either zinc hydroxysulfate lamellae or zinc oxide nanoparticles are created within the gel matrix, with a more extended nanoporous structure in the latter case. The nanostructures and the gels are investigated by multiple techniques, including X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Upon ensuing addition of I-/I3- redox mediator and assembling of the device, state-of-the-art aqueous QSE-DSSCs are achieved. The latter couples a 2 % efficiency (limited by charge diffusion as proved by Electrochemical Impedance Spectroscopy) with a good Average Visible Transmittance (AVT), and Light Utilization Efficiency (LUE), a couple of coveted features in wave-selective or semi-transparent devices. Finally, Linear Response-Time Dependent DFT (LR-TDDFT) simulations are carried out on a model iodine/iodide layered zinc hydroxy sulphate structure towards a better understanding of the mechanism responsible for the high AVT.

Microstructural study of the Praid Salt Diapir (Transylvanian basin, Romania) and its implication on deformation history and hydrogen storage potential

The Transylvanian basin is one of the major Tertiary sedimentary basins in the Carpathian-Pannonian region. Its thick sedimentary fill contains prominent Middle Miocene age salt that forms major diapir structures at the basin margins. The microstructural characteristics of the rock salt represent one of the main factors that determines the potential of a salt body for storage of hydrogen. The main aim of this study is to extend our understanding of the deformation mechanism of Praid rock salt located at the eastern margin of the Transylvanian basin. Based on petrography, we identified two types of rock salt: (1) layered salt with rather uniform grain size distribution showing alternation of greyish (clay mineral bearing) and white (clear halite) layers, and (2) massive grey salt with large, elongated halite crystals, accompanied by sub-micrometer size grains of halite. To shed light on the microstructure of the rock salt, we performed electron backscatter diffraction (EBSD) mapping, and studied gamma-irradiated samples both in the massive and layered salt samples. Dislocation creep and pressure solution creep were identified which acted concurrently in the Praid rock salt. The total strain rate falls between 1.2 and 1.3×10−10 s−1. The results of this study reveal a complex deformation history of the salt body where coexisting and migrating fluids have played an important role. The outcome of this project contributes to the hydrogen storage potential assessment for the Transylvanian salt and to a better understanding of the structural evolution of the Transylvanian basin.

Nanoparticle depressants in froth flotation – The effect of colloidal silica with different size and surface modifications on the selective separation of semi-soluble salt type minerals

Colloidal silica has been presented as a selective depressant in froth flotation separation of scheelite and calcite by our group in 2020. Here we analyze the effects of colloidal silica dosage, specific surface area (i.e. size), and modification with microflotation on pure scheelite, calcite, fluorite, and apatite minerals. In a reagents scale-up procedure batch flotation experiments were conducted on a low-grade scheelite ore using statistical experimental design methodology. Microflotation experiments showed colloidal silica selectively depressing calcite flotation with increasing intensity with reduced size of colloidal silica. The nanoparticulate depressant did not affect the recoveries of scheelite, apatite, and fluorite – typical ore minerals that occur associated with calcite. Batch flotation of a low-grade scheelite ore confirmed the observations made at the microscale: colloidal silica significantly improves the scheelite-calcite selectivity index. Here, we observe a series of relations between colloidal silica specific surface area and modification on different process indicators such as scheelite-calcite selectivity index, recoveries, and froth properties. These relations are assumed to be due to the different aggregation mechanisms of the colloidal silica dispersions. The aluminate-modified colloidal silica, which tends to form a coherent gel network in the presence of Ca2+, shows the strongest effect on reducing calcite recovery accompanied by a significant reduction in scheelite recovery compared to the non-functionalised and silane-modified colloidal silica.