Search Results (58)

Seawater reverse osmosis (SWRO) desalination generates a concentrated brine byproduct rich in dissolved salts and minerals. This study presents an extensive economic and technical analysis of recovering all major ions from SWRO brine, which includes Na, Cl, Mg, Ca, SO₄, K, Br, B, Li, Rb, and Sr in comparison to conventional mining and chemical production of these commodities. Data from recent literature and case studies are compiled to quantify the composition of a typical SWRO brine and the potential yield of valuable products. A life-cycle cost framework is applied, incorporating capital expenditure (CAPEX), operational expenditure (OPEX), and total water cost (TWC) impacts. A representative simulation for a large 100,000 m³/day SWRO plant shows that integrated “brine mining” systems could recover on the order of 3.8 million tons of salts per year. At optimistic recovery efficiencies, the gross annual revenue from products (NaCl, Mg(OH)₂/MgO, CaCO₃, KCl, Br₂, Li₂CO₃, etc.) can reach a few hundred million USD. This revenue is comparable to or exceeds the added costs of recovery processes under favorable conditions, potentially offsetting desalination costs by USD 0.5/m³ or more. We compare these projections with the economics of obtaining the same materials through conventional mining and chemical processes worldwide. Major findings indicate that recovery of abundant low-value salts (especially NaCl) can supply bulk revenue to cover processing costs, while extraction of scarce high-value elements (Li, Rb, Sr, etc.) can provide significant additional profit if efficient separation is achieved. The energy requirements and unit costs for brine recovery are analyzed against those of terrestrial or conventional mining; in many cases, brine-derived production is competitive due to avoided raw material extraction and potential use of waste or renewable energy. CAPEX for adding mineral recovery to a desalination plant is significant but can be justified by revenue and by strategic benefits such as reduced brine disposal. Our analysis, drawing on global data and case studies (e.g., projects in Europe and the Middle East), suggests that metals and salts recovery from SWRO brine is technically feasible and, at sufficient scale, economically viable in many regions. We provide detailed comparisons of cost, yield, and market value for each target element, along with empirical models and formulas for profitability. The results offer a roadmap for integrating brine mining into desalination operations and highlight key factors such as commodity prices, scale economies, energy integration, and policy incentives that influence the competitiveness of brine recovery against traditional mining. Full article

Ion-exchange membranes (IEMs) are widely used in reverse-electrodialysis (RED) technology, which can collect the salinity gradient energy between concentrated and diluted solutions and convert it into electromotive force (EMF) to drive power generation and hydrogen production. Recent studies have indicated that the permselectivity of IEMs is vital to determining the performance of an RED stack. In this study, the influences of solution concentration, ion species, and solution temperature on the permselectivity of IEMs were experimentally investigated. The results demonstrate that the permselectivity of IEMs decreases with increasing concentrations of KAc, LiCl, and LiBr solutions for both concentrated solutions (3–5 M) and dilute solutions (0.02–0.2 M). Further, through comparing the LiBr and KBr solutions as well as the LiCl, KCl, and NH₄Cl solutions, respectively, K⁺ demonstrates a higher permselectivity than Li⁺, and both of which are smaller than NH₄⁺ under the same cation and concentration conditions. Moreover, another test was conducted using three potassium salt solutions with different anions, and the experimental permselectivity order is Ac⁻ > Br⁻ > Cl⁻. A slight increase in solution temperature enhances the permselectivity of IEMs due to the increase in ionic mobility. However, an excessive temperature is detrimental to membrane stability and thus reduces permselectivity. It can be seen that ions with low hydration energy, a small hydration radius, and high mobility show a higher permselectivity. Full article

A novel caseinolytic protease (ClpP) of the S14 family from Cobetia amphilecti KMM 296 (CamClpP), comprising 206 amino acids, with a calculated molecular weight of 22.66 kDa and a pI of 4.88, was expressed in Escherichia coli cells to verify the functional annotation of the encoding gene that has low identity with known structures. The proteolytic activity of the purified recombinant enzyme was found to be 2824 U/mg, using 1% casein as a substrate. Enzyme activity was maximal at pH 5.6 and 7.4 in phosphate buffer and was maintained over a wide pH range of 4-10. The optimum temperature for protease activity was 45 °C. The enzyme in its optimal state required the presence of either NaCl or KCl at concentrations of 0.3 and 0.2 M, respectively. The addition of the metal ions Mg²⁺, Ca²⁺, Ni²⁺, Mn²⁺, Li⁺, and Zn²⁺ at 2 mM resulted in a significant inhibition of the protease activity. However, the presence of Co²⁺ led to a marked activation of the enzyme in the absence of ATP. The enzyme activity was inhibited by ethanol, isopropanol, glycerol, SDS, EGTA, and EDTA. The presence of Triton X-100, acetone, DTT, and PMSF resulted in a significant increase in the CamClpP protease activity. The protease CamClpP effectively and preferentially degrades high-polymer wheat and rye flour proteins. This new proteolytic enzyme with unique properties is of great ecological and biotechnological importance. Full article

Modern research technology’s goal is to produce multifunctional materials that require low energy. In this work, we have applied polypyrrole (PPy) doped with dodecyl benzenesulfonate (DBS-) with the addition of polyoxometalates (POM) such as phosphotungstic acid (PTA) forming PPyDBS-PT composites. Two different PTA concentrations (4 mM and 8 mM) were used to form PPyDBS-PT4 and PPyDBS-PT8. The higher concentration of PTA created a highly dense and compact film which can be observed from scanning electron microscopy (SEM cross-section image), and also contains fewer phosphotungstate anions (PT³⁻) inclusion (via energy-dispersive X-ray spectroscopy, EDX). Three different aqueous electrolytes, LiCl (lithium chloride), NaCl (sodium chloride), and KCl (potassium chloride), were applied to investigate how those alkali metal ions perform as typical cation-driven actuators. Cyclic voltammetry with linear actuation revealed the tendency LiCl > NaCl > KCl in view of better strain, charge density, electronic conductivity, and Young’s modulus of PPyDBS-PT4 outperformed PPyDBS-PT8. Chronopotentiometric measurements showed high specific capacitance for PPyDBS-PT4 at 260.6 ± 21 F g⁻¹ with capacity retention after 5000 cycles of 88.5%. The sensor calibration of PPyDBS-PT4 revealed that the alkali cations (Li⁺, Na⁺, and K⁺) can be differentiated from each other. The PPyDBS-PT4 has multifunctional applications such as actuators, sensors, and energy storage. Full article

Electroosmosis reduces the available energy from ion transport arising due to concentration gradients across ion-exchange membranes. This work builds on previous efforts to describe the electroosmosis, the permselectivity and the apparent transport number of a membrane, and we show new measurements of concentration cells with the Selemion CMVN cation-exchange membrane and single-salt solutions of HCl, LiCl, NaCl, MgCl₂, CaCl₂ and NH₄Cl. Ionic transport numbers and electroosmotic water transport relative to the membrane are efficiently obtained from a relatively new permselectivity analysis method. We find that the membrane can be described as perfectly selective towards the migration of the cation, and that ${\mathrm{Cl}}^{-}$ does not contribute to the net electric current. For the investigated salts, we obtained water transference coefficients, $t_w$, of 1.1 ± 0.8 for HCl, 9.2 ± 0.8 for LiCl, 4.9 ± 0.2 for NaCl, 3.7 ± 0.4 for KCl, 8.5 ± 0.5 for MgCl₂, 6.2 ± 0.6 for CaCl₂ and 3.8 ± 0.5 for NH₄Cl. However, as the test compartment concentrations of LiCl, MgCl₂ and CaCl₂ increased past 3.5, 1.3 and 1.4 mol kg⁻¹, respectively, the water transference coefficients appeared to decrease. The presented methods are generally useful for characterising concentration polarisation phenomena in electrochemistry, and may aid in the design of more efficient electrochemical cells. Full article

For the first time, thermally stimulated luminescence spectra in the region of high-temperature peaks (up to 770 K) have been measured in NaCl:Li and KCl:Na single crystals (with impurity cations of small ionic radii) exposed to isodose irradiation by X-rays irradiated uniformly. Comparative analysis of these spectra with the spectra of X-ray and tunnel luminescence of the same crystals showed that the luminescence associated with exciton-like formations near impurity cations dominates in all three cases. The formation mechanisms of such bound excitons during a thermal dissociation of complex radiation defects are considered. Integral light sums of high-temperature TSL in NaCl:Li and KCl:Na crystals are significantly higher than that of a standard LiF:Mg, Ti dosimetric crystal (a TLD-100 luminescent dosimeter). Full article

The electrochemical conversion of CO₂ into high value-added carbon materials by molten salt electrolysis offers a promising solution for reducing carbon dioxide emissions. This study focuses on investigating the influence of molten salt composition on the structure of CO₂ direct electroreduction carbon products in chloride molten salt systems. Using CaO as a CO₂ absorber, the adsorption principle of CO₂ in LiCl-CaCl₂, LiCl-CaCl₂-NaCl and LiCl-CaCl₂-KCl molten salts was discussed, and the reasons for the different morphologies and structures of carbon products were analyzed, and it was found that the electrolytic efficiency of the whole process exceeded 85%. Furthermore, cathode products are analyzed through Scanning Electron Microscope (SEM), X-Ray Diffractometer (XRD), Thermal Gravimetric Analyzer (TGA), Raman Spectra and Fourier Transform Infrared (FTIR) techniques with a focus on the content and morphology of carbon elements. It was observed that the carbon content in the carbon powder produced by molten salt electrochemical method exceeded 99%, with most carbon products obtained from electrolysis in the Li-Ca chloride molten salt system being in the form of carbon nanotubes. In contrast, the Li-Ca-K chloride system yielded carbon nanospheres, while a mixture was found in the Li-Ca-Na chloride system. Therefore, experimental results demonstrate that altering the composition of the system allows for obtaining the desired product size and morphology. This research presents a pathway to convert atmospheric CO₂ into high value-added carbon products. Full article

The sand–gravel brine deposit in the Mahai Basin is a newly discovered large-scale potassium–bearing brine deposit. The potassium–bearing brine is primarily found at depths exceeding 150 m within the porous alluvial and fluvial sand–gravel reservoir of the Middle to Lower Pleistocene. This deposit is characterized by a relatively shallow water table, moderate–to–strong aquifer productivity, high salinity, and a KCl content that meets the conditions for exploitation, with the advantage of reduced salt crystallization during well mining, making it a potential reserve base for potash development. A geochemical analysis of the sand–gravel brine revealed consistent trends for the major ions K⁺, Na⁺, Mg²⁺, Cl⁻, and SO₄²⁻ along the east–west axis of the alluvial fan, while Ca²⁺ showed an opposite trend compared to Mg²⁺. Along the exploration lines from north to south, the concentrations of the main ions gradually increase. The brine is enriched in Na⁺ and Cl⁻ ions, while SO₄²⁻ and HCO₃⁻ are depleted. In the K⁺-Na⁺-Mg²⁺/Cl⁻-H₂O (25 °C) quaternary phase diagram, the brine falls within the halite stability field, with the hydrochemical type classified as chloride type. The brine coefficient characteristics indicate a multi-source origin involving residual evaporation, salt rock leaching, and metamorphic sedimentary brine. Comparison studies of the ionic composition and isotopic signatures (δD, δ¹⁸O, δ³⁷Cl, and δ⁷Li) of deep sand–gravel brines in the study area with interstitial and confined brines in the southern depression suggest similar geochemical characteristics between them. The genetic analysis of the deposit proposes that during the basin tectonic evolution, the potassium-rich interstitial and confined brines originally located in the southern depression of the Mahai Basin were displaced under compressional forces and migrated northward as the depositional center shifted, eventually backfilling into the loose alluvial and fluvial sand and gravel reservoirs at the front of the Saishiteng Mountains, forming the deep sand–gravel brine deposits in the foreland. Full article

Rubidium and cesium are important strategic resources, and West Taijinar Salt Lake is rich in rubidium and cesium reserves, while the concentration is low and the relationship with coexisting potassium and magnesium ions is complex. In order to understand the evaporative enrichment and salt precipitation patterns of rare elements such as lithium, rubidium, cesium, and boron of the brine after potassium precipitation in West Taijinar Salt Lake, the 288.2 K isothermal evaporation experiment was carried out. The experimental results show that during the evaporation process at 288.2 K, the following salts precipitate from the brine after potassium crystallization: halite (NaCl), bischofite (MgCl₂·6H₂O), carnallite (KCl·MgCl₂·6H₂O), hexahydrite (MgSO₄·6H₂O), epsomite (MgSO₄·7H₂O), boric acid (H₃BO₃), and lithium sulfate monohydrate (Li₂SO₄·H₂O). The concentrations of lithium and boron are significantly enriched, the content of Li⁺ was enriched from 1.7 g/L to 5.63 g/L, and the B₂O₃ content was enriched from 6.72 g/L to 50.78 g/L. The isomorphism phenomenon of Rb⁺, Cs⁺, and K⁺ makes Rb⁺ and Cs⁺ enter potassium ore to form solid solution-type carnallite ((K, Rb)MgCl₃·6H₂O, (K, Cs)MgCl₃·6H₂O)) and reduce the content of brine. This study provides data support for the development and comprehensive utilization of lithium, boron, rubidium, and cesium resources in West Taijinar Salt Lake. Full article

After the high-temperature pretreatment of α-spodumene to induce a phase transition to β-spodumene, a derivative of the silica polymorph keatite, often coexisting with metastable Li-stuffed β-quartz (γ-spodumene)_, the conventional approach to access lithium is through ion exchange with hydrogen using concentrated sulfuric acid, which presents drawbacks associated with the production of low-value leaching residues. As sodium and magnesium can produce more interesting aluminosilicate byproducts, this study investigates Na⁺ ↔ Li⁺ and Mg²⁺ ↔ 2 Li⁺ substitution efficiencies in β-spodumene and β-quartz. Thermal annealing at 850 °C of the LiAlSi₂O₆ silica derivatives mixed with an equimolar proportion of Na endmember glass of equivalent stoichiometry (NaAlSi₂O₆) indicates that sodium incorporation in β-quartz is limited, whereas the main constraint for not attaining complete growth to a Na_0.5Li_0.5AlSi₂O₆ β-spodumene solid solution is co-crystallization of minor nepheline. For similar experiments in the equimolar LiAlSi₂O₆-Mg_0.5AlSi₂O₆ system, the efficient substitution of Mg for Li is observed in both β-spodumene and β-quartz, consistent with the alkaline earth having an ionic radius closer to lithium than sodium. Ion exchange at lower temperatures was also evaluated by exposing coexisting β-spodumene and β-quartz to molten salts. In NaNO₃ at 320 °C, sodium for lithium exchange reaches ≈90% in β-spodumene but less than ≈2% in β-quartz, suggesting that to be an efficient lithium recovery route, the formation of β-quartz during the conversion of α-spodumene needs to be minimized. At 525 °C in a molten MgCl₂/KCl medium, although full LiAlSi₂O₆-Mg_0.5AlSi₂O₆ solid solution is observed in β-quartz, structural constraints restrict the incorporation of magnesium in β-spodumene to a Li_0.2Mg_0.4AlSi₂O₆ stoichiometry, limiting lithium recovery to 80%. Full article

A comprehensive investigation into the design and electrochemical optimization of composite electrodes consisting of poly(3,4-ethylenedioxythiophene) (PEDOT)/graphene oxide (GO)/Methanococcus deltae and reduced graphene oxide (rGO)/Methanococcus deltae hybrids, anchored onto stainless-steel (SS) substrates, has been conducted. The GO and rGO materials were synthesized using a modified Hummer method. The resulting SS/PEDOT/GO and SS/PEDOT/rGO composite electrodes were subjected to systematic electrochemical characterization, focusing on the PEDOT p-type and n-type doping/undoping processes within diverse solvent environments (CH₃CN and H₂O) and electrolyte compositions (LiClO₄ and KCl). Raman spectroscopy analysis confirmed the successful integration of graphene derivatives into the electrode structures, while field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) revealed increased surface roughness upon GO and rGO incorporation. This increase in surface roughness is believed to enhance the adhesion of Methanococcus deltae microorganisms and facilitate efficient electron transport. Electrochemical measurements showed that the resulting SS/PEDOT/GO and SS/PEDOT/rGO anodes exhibit remarkable electrocatalytic activity. The SS/PEDOT/GO electrode achieved a maximum power density of 1014.420 mW/cm², while the SS/PEDOT/rGO electrode reached 632.019 mW/cm². Full article

Nanoporous membranes offer significant advantages in direct contact membrane distillation applications due to their high flux and strong resistance to wetting. This study employs molecular dynamics simulations to explore the performance of membrane distillation in a single nanopore, mainly focusing on wetting behavior, liquid entry pressure, and membrane flux variations across different concentrations and types of salt solutions. The findings indicate that increasing the NaCl concentration enhances the wetting of membrane pores, thereby decreasing the entry pressure of the solution. However, at the same salt concentration, the differences in wetting and liquid entry pressure among various salts, including CaCl₂, KCl, NaCl, and LiCl, are minimal. The presence of hydrated ions significantly reduces membrane flux. As the concentration of NaCl solutions increases, the number of hydrated ions rises, thereby lowering the membrane flux of the salt solution. Furthermore, the type of salt has a pronounced effect on the structure of hydrated ions. Solutions with Ca²⁺ and Li⁺ exhibit the smallest first-layer radius of hydrated ions. Under the same salt concentration, KCl solutions demonstrate the highest membrane distillation flux, while CaCl₂ solutions show the lowest flux. Full article

The corrosion behavior of 20G and TP347H materials was investigated in molten LiCl-NaCl-KCl salt. The corrosion rates of these materials in molten chloride salt are high and are strongly affected by the alloying surface oxide formation. The 20G shows uniform surface corrosion with almost no protective oxide formation on the surface. In contrast, the austenitic steel TP347H exhibits better corrosion resistance in molten chloride salts due to its high Cr content. Owing to the highly corrosive nature of molten chloride salts, the Cl⁻ in molten salt could react with oxides and alloy, inducing intergranular corrosion of austenitic steel in molten chloride salt environments. Full article

In recent years, hydrogel-based wearable flexible electronic devices have attracted much attention. However, hydrogel-based sensors are affected by structural fatigue, material aging, and water absorption and swelling, making stability and accuracy a major challenge. In this study, we present a DN-SPEZ dual-network hydrogel prepared using polyvinyl alcohol (PVA), sodium alginate (SA), ethylene glycol (EG), and ZnSO₄ and propose a self-calibration compensation strategy. The strategy utilizes a metal salt solution to adjust the carrier concentration of the hydrogel to mitigate the resistance drift phenomenon to improve the stability and accuracy of hydrogel sensors in amphibious scenarios, such as land and water. The ExpGrow model was used to characterize the trend of the ∆R/R₀ dynamic response curves of the hydrogels in the stress tests, and the average deviation of the fitted curves $\overline{ϵ}$ was calculated to quantify the stability differences of different groups. The results showed that the stability of the uncompensated group was much lower than that of the compensated group utilizing LiCl, NaCl, KCl, MgCl₂, and AlCl₃ solutions ($\overline{ϵ}$ in the uncompensated group in air was 276.158, 1.888, 2.971, 30.586, and 13.561 times higher than that of the compensated group in LiCl, NaCl, KCl, MgCl₂, and AlCl₃, respectively; $\overline{ϵ}$ in the uncompensated group in seawater was 10.287 times, 1.008 times, 1.161 times, 4.986 times, 1.281 times, respectively, higher than that of the compensated group in LiCl, NaCl, KCl, MgCl₂ and AlCl₃). In addition, for the ranking of the compensation effect of different compensation solutions, the concentration of the compensation solution and the ionic radius and charge of the cation were found to be important factors in determining the compensation effect. Detection of events in amphibious environments such as swallowing, robotic arm grasping, Morse code, and finger–wrist bending was also performed in this study. This work provides a viable method for stability and accuracy enhancement of dual-network hydrogel sensors with strain and pressure sensing capabilities and offers solutions for sensor applications in both airborne and underwater amphibious environments. Full article

It is well known that the type of counter-ion affects the state of the adsorption layer of ionic surfactants and, consequently, its surface potential. Yet, it is not clear how they affect the foamability, the rate of foam decay or foam production. How is the surface potential of the air/water interface related to the properties of the foam? This work aims to answer these questions. Foam films, stabilized by 0.5 mmol/L sodium dodecyl sulfate (SDS) in the presence of added LiCl, NaCl, and KCl, were studied by means of the interferometric experimental setup of Scheludko–Exerowa. The surface potential values were derived from the equilibrium film thickness by means of the DLVO theory. A linear relation between the values of the surface potential and specific adsorption energy of the counter-ions on the air/water interface was established. The slope of this linear relation depends on the salt concentration. The foamability, the rate of foam decay, and the foam production of the same aqueous solutions of SDS and added salts were studied by means of the shaking method. A correlation was found between the derived surface potential of the foam film’s surfaces and the properties of the foam. The foam production, which is the ratio between the initial foam volume and the rate of foam decay, increases with the decrease in the surface potential. Previous studies in the literature confirm that the lower surface potential promotes higher surfactant adsorption, thus boosting more foam and vice versa. It was also confirmed that the dual effect of KCl on foam production involves converting the best foam stabilizer into a foam suppressor at the highest salt concentration. Full article