Search Results (36)

Alkaline and alkaline earth metal chloride salts are used in molten chloride salt fast reactors (MCFRs) and pyro–electrometallurgical (or –electrochemical) recovering of uranium and transuranic elements (PERUT) from spent nuclear fuel. Reprocessing of MCFR spent fuel with the PERUT process, after recovery of U and transuranic elements (Np, Pu, Am, Cm), results in a chloride salt solvent waste stream containing fission and activation product chlorides. Recycling the chloride salt solvent by separation of fission and light element activation products (FPs and LEAPs) is highly desired because of the low chloride loading in the available glass and ceramic waste forms. This paper reviews the status of chloride salt waste management, chloride salt recycling studies, and potential FP and LEAP chlorides sequestration approaches. The chloride salt solvent recycling studies are represented by chemical precipitation of rare earth (RE) fission product chlorides with carbonate, O₂ gas and phosphate in LiCl and eutectic LiCl-KCl salt solvent, which is then followed by separation of Cs and Sr with distillation or crystallization. More than 99% removal efficiencies are attained for RE FP chlorides, and distillation removes more than 99% of Sr and Ba from the salt solvent. Volatile species released from the operation of MCFRs need to be sequestered. Minor chlorides species, such as SnCl₃, FeCl₃, CrCl₃, and ZrCl_2, will be present in the waste stream, and the separation of these species will be required for salt solvent recycling. Bromine and iodine can form bromides and iodides with metal elements such as alkaline and alkaline earth metal elements, which behave chemically similarly to their chloride counterparts. The presence of these compounds in the salt solvent waste may complexify the recycling process, for which more experimental studies are required. Full article

Riverine detritus is a key nutritional resource for benthic consumers, yet its biochemical quality fluctuates rapidly and is poorly captured by bulk indicators such as elemental analysis. To improve assessment sensitivity, we compared two analytical approaches targeting organic nitrogen. We refined a fluorimetric assay for primary amines using o-phthalaldehyde (OPA), identifying 2 M KCl as an optimal extraction medium that maximizes recovery while minimizing matrix interference. In parallel, we optimized capillary electrophoresis with contactless conductivity detection (CE-C4D) for free amino acid determination using 0.4 M ammonium carbonate. Applied to detritus from multiple river sites and seasons, both methods showed that primary amines and amino acids vary by an order of magnitude more than total nitrogen and exhibit patterns not detectable by elemental analysis, with consistent temporal trends across catchments. Primary amine-based measurements therefore provide a more sensitive and ecologically relevant assessment of detrital nutritional quality than bulk nitrogen metrics. The OPA assay is well suited for routine monitoring due to its simplicity and robustness, whereas CE-C4D enables detailed compositional profiling where amino acid speciation is required. Overall, detrital quality reflects both intrinsic properties and recent hydrological conditions, underscoring the importance of antecedent discharge and precipitation dynamics in its interpretation. Full article

Seawater desalination has emerged as a crucial solution for addressing global freshwater scarcity. However, it generates significant volumes of concentrated brine waste. This brine is rich in dissolved salts and minerals, primarily, chloride (55%), sodium (30%), sulfate (8%), magnesium (4%), calcium (1%), potassium (1%), bicarbonate (0.4%), and bromide (0.2%), which are often discharged into marine environments, posing ecological challenges. This study presents a comprehensive global review of innovative technologies for recovering these constituents as valuable products, thereby enhancing the sustainability and economic viability of desalination. The paper evaluates a range of proven and emerging recovery methods, including membrane separation, nanofiltration, electrodialysis, thermal crystallization, solar evaporation, chemical precipitation, and electrochemical extraction. Each technique is analyzed for its effectiveness in isolating salts (NaCl, KCl, and CaSO₄) and minerals (Mg(OH)₂ and Br₂), with a discussion of process-specific constraints, recovery efficiencies, and product purities. Furthermore, the study incorporates a detailed techno-economic assessment, highlighting revenue potential, capital and operational expenditures, and breakeven timelines. Simulated case studies of a 100,000 m³/day seawater reverse osmosis (SWRO) facility demonstrates that a sequential brine recovery process and associated energy balances, supported by pilot-scale data from ongoing global initiatives, can achieve over 90% total salt recovery while producing marketable products such as NaCl, Mg(OH)₂, and Br₂. The estimated revenue from recovered materials ranges between USD 4.5 and 6.8 million per year, offsetting 65–90% of annual desalination operating costs. The analysis indicates a payback period of 3–5 years, depending on recovery efficiency and product pricing, underscoring the economic viability of large-scale brine valorization alongside its environmental benefits. By transforming waste brine into a source of commercial commodities, desalination facilities can move toward circular economy models and achieve greater sustainability. A practical integration framework is proposed for both new and existing SWRO plants, with a focus on aligning with the principles of a circular economy. By transforming waste brine into a resource stream for commercial products, desalination facilities can reduce environmental discharge and generate additional revenue. The study concludes with actionable recommendations and insights to guide policymakers, engineers, and investors in advancing brine mining toward full-scale implementation. Full article

In the coming decades, anticipated population growth is projected to escalate the demand for essential resources such as NaCl, KCl, and LiCl, which are critical for human consumption, agriculture, and battery production. A substantial proportion of these salts is produced from brines using solar evaporation ponds. This article presents a one-dimensional surrogate mathematical model of an ideal solar evaporation pond working at a steady state. The ideal pond considers only water evaporation, with a uniform evaporation rate per unit area. The model’s equation, or the ideal solar evaporation law, allows calculating the ion concentration profile in an ideal pond just given the feed and discharge concentrations. The validation of the law was conducted with industrial data collected in the year 2023 in a lithium recovery plant throughout 15 ponds in series at the Salar de Atacama, Chile. The results verified that the model could accurately predict the monthly concentration profiles (R² in the range 0.9646 to 0.9864) if lithium does not precipitate in the pond. The model provides accurate values of pond inventories and area requirements for designing stages. The model’s relevance extends beyond the lithium industry to encompass any solar evaporation processes for salt recovery or solution concentration. Full article

Background: Membrane proteins are preferentially solubilized with sodium dodecyl sulfate (SDS), which necessitates a purification protocol to deplete the surfactant prior to mass spectrometry analysis. However, maintaining solubility of intact membrane proteins is challenged in an SDS-free environment. SDS precipitation with potassium salts (KCl) offers a potentially viable workflow to deplete SDS and permit proteoform analysis. The purpose of this study is to devise a robust detergent-based protocol applicable for processing and analysis of intact membrane-associated proteoforms. Methods: The precipitation conditions impacting SDS removal from spinach chloroplasts and liver membrane proteome preparations were evaluated, capitalizing on optimization of pH (highly basic), addition of MS-compatible solubilizing additives (urea) and adjustment of the KCl to SDS ratio to maximize recovery and purity. Results: Characterization of the SDS-solubilized, KCl-precipitated spinach membrane preparation revealed multiple charge envelope MS spectra displaying high signal to noise, free of SDS adducts. Precipitation at pH 12 or with urea improved protein recovery and purity. Bottom-up analysis identified 1826 distinct liver protein groups from four independent SDS precipitation conditions. While precipitation at pH 8 without urea revealed a greater number of protein identifications by mass spectrometry, precipitation under highly basic conditions (pH 12) with urea provided higher membrane protein recovery and achieved the greatest number (732 of 1056) and largest percentage (69.3%) of membrane proteins identified in the SDS removal workflow. Conclusion: This workflow provides new opportunities for MS-based proteoform analysis by capitalizing on the benefits of SDS for protein extraction while maintaining high solubility and purity of intact proteins though KCl precipitation of the surfactant. Full article

Alkali metals in fuel seriously affect the normal operation of generator sets. Using agricultural waste (AW) from a corn field as raw material, the dynamic change of alkali metal K migration and transformation and the effect of competition between chlorine and sulfur on the behavior of AW were studied systematically. The results showed that transformation between different forms of K, especially water-soluble K, occurred. At low temperatures, K remained in the ash in the form of inorganic salt, and high temperature precipitated K and formed insoluble alkali metal compounds. Via FactSage thermodynamic equilibrium calculations, it was confirmed that KCl reacted with SiO₂ to form a K₂O·nSiO₂ molten mixture in combustion. K initially existed in the form of KCl (s) and K₂SO₄ (s), high temperature promoted its transformation and decomposition, and it was eventually released as KCl (g). During combustion, Cl was more volatile than K, while S reduced the release of K and Cl through sulfation reaction to reduce the sediment viscosity. 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

Fly ash washing wastewater was carbonated with carbon dioxide (CO₂) to remove calcium (Ca) by forming a calcium carbonate (CaCO₃) precipitate. An investigation of the factors affecting carbonation showed that Ca removal was highly dependent on the initial pH of the wastewater. The Ca removal was 10%, 61%, 91% and more than 99% at initial wastewater pH levels of 11.8, 12.0, 12.5 and 13.0, respectively. The optimal conditions for carbonation were initial pH of 13.0, carbonation time of 30 min and CO₂ flow rate of 30 mL/min. The Ca concentration in the wastewater decreased to <40 mg/L, while 73 g of CaCO₃ precipitate was produced per liter of wastewater. However, heavy metals, specifically Pb and Zn, co-precipitated during carbonation, which resulted in a CaCO₃ product that contained as much as 0.61 wt% of Pb and 0.02 wt% of Zn. Activated carbon modified by a quaternary ammonium salt was used to selectively adsorb the Pb and Zn first. The Pb- and Zn-free water was then carbonated. By combining adsorption with carbonation, the Ca concentration in the treated wastewater was decreased to about 28 mg/L, while the Na, Cl and K were retained. The wastewater thus treated was ready for NaCl and KCl recovery. In addition, the precipitate had a Ca content of more than 38 wt% and almost no heavy metals. The average particle size of the precipitate was 47 μm, with a uniform cubic shape. The quality of the precipitate met the requirements for the industrial reuse of CaCO₃. In summary, adsorption and carbonation combined were able to remove pollutants from wastewater while recovering useful resources. Full article

Groundwater plays an important role in ecological environment protection in arid and semi-arid areas. Therefore, understanding the characteristics of hydrochemical evolution is of great significance for the sustainable use of groundwater in the area of the Tailan River Basin. The Tailan River Basin is located in an arid, ecologically sensitive area in western China. In this study, we collected 42 groups of representative water samples from the Tailan River Basin and analyzed the chemical distribution in the groundwater using mathematical statistics, Piper and Gibbs diagrams, ion ratio analysis, and hydrogeochemical simulation methods. We also discussed the water–rock interactions in the groundwater hydrochemical evolutionary process. The results were as follows: (1) The chemical types of groundwater changed from HCO₃·SO₄-Ca·Na to SO₄·Cl-Na·Ca, Cl·SO₄-Na, and Cl-Na, and the total dissolved solids content increased from less than 1 g/L to more than 40 g/L from the gravel plain to the fine soil plain. (2) The Gibbs diagram, the ion ratio analysis, and the saturation index showed that the groundwater chemical characteristics in the study area were mainly controlled by water–rock interactions, as well as evaporation and concentration. Along the runoff of groundwater, halite and gypsum were dissolved. Nevertheless, dolomite and calcite precipitated. The relationship between the chlor-alkali index and [(Na⁺ + K⁺)-Cl⁻] and [(Ca²⁺ + Mg²⁺)-(HCO₃⁻ + SO₄²⁻)] indicated that cation exchange also affects the chemical composition of groundwater in the area. (3) Through reverse hydrogeochemical simulation, the main water–rock effect of the groundwater runoff process revealed by qualitative analysis was quantitatively verified. Full article

L-methioninase is an enzyme that has recently gained significant interest in the scientific community because of its potential as a targeted therapy for cancer. This study aims to isolate and identify extremophilic bacteria that could produce L-methioninase and to access the enzymatic potential of isolated bacteria under stress conditions, specifically in agro-industrial waste. In this study, a rare marine bacterium, Alcaligenes aquatilis BJ-1, exhibited the highest specific activity of 4.61 U/mg at an optimum pH of 8.3. The L-methioninase was purified 4.3-fold and 7.15-fold by acetone precipitation and Sephadex G-100 gel filtration chromatography, which revealed a molecular weight of 46 kDa. In addition, agriculture waste materials such as cottonseed oil cake had the highest L-methioninase production. Moreover, A. aquatilis BJ-1 can tolerate and produce enzymes in the presence of 10% NaCl, 6% KCl, and 4% MgSO₄. Similarly, substrates such as L-asparagine, L-glutamine, L-alanine, and L-tyrosine were found suitable to increase enzyme production. The strain produced L-methioninase in the presence of various heavy metals. Maximum enzyme activity was found in Zn²⁺ at 0.1% (2.52 U/mL), Li²⁺ at 0.03% (2.90 U/mL), and Ni²⁺ at 0.01% (2.78 U/mL), as compared to the control (2.23 U/mL) without metal. Enzyme production was also observed at a high temperature (60 °C), with the produced enzymes possessing antioxidant properties. In addition, no hemolytic activity was observed. The results indicate that A. aquatilis BJ-1 is an appropriate bacterium for metal bioremediation procedures in unfavorable circumstances. Full article

Despite numerous studies on ion release from orthodontic appliances, no clear conclusions can be drawn due to complex interrelations of multiple factors. Therefore, as the first part of a comprehensive investigation of cytotoxicity of eluted ions, the objective of this study was to analyze four parts of a fixed orthodontic appliance. Specifically, NiTi archwires and stainless steel (SS) brackets, bands, and ligatures were immersed in artificial saliva and studied for morphological and chemical changes after 3-, 7-, and 14-day immersion, using the SEM/EDX technique. Ion release profiles were analyzed for all eluted ions using inductively coupled plasma mass spectrometry (ICP-MS). The results demonstrated dissimilar surface morphologies among parts of the fixed appliance, due to variations in manufacturing processes. The onset of pitting corrosion was observed for the SS brackets and bands in the as-received state. Protective oxide layers were not observed on any of the parts, but adherent layers developed on SS brackets and ligatures during immersion. Salt precipitation, mainly KCl, was also observed. ICP-MS proved to be more sensitive than SEM/EDX and exhibited results undetected by SEM/EDX. Ion release was an order-of-magnitude higher for SS bands compared to other parts, which was attributed to manufacturing procedure (welding). Ion release did not correlate with surface roughness. Full article

The original composition of Laguocuo Salt Lake was found in the mirabilite area of the 15 °C isothermal phase diagrams of the Li⁺, Na⁺, K⁺//Cl⁻, SO₄²⁻-H₂O system. Four phases comprise the isothermal evaporation procedure. The first stage is the unsaturated stage except for carbonate. The second stage is made up of sodium chloride, mirabilite, and borax precipitate simultaneously, where the halogenation rate is 31.58%, and the water loss rate is 68.32%. The penultimate step is the lithium salt precipitation section, where primarily NaCl, Na₂SO₄·10H₂O, and Li₂SO₄·3Na₂SO₄·12H₂O are formed, where the water loss rate is 91.38%, the halogenation rate is 7.42%, and the salt precipitation rate is 1.20%. The final stage is the eutectoid stage of lithium and potassium salts, where primarily NaCl, Li₂SO₄·3Na₂SO₄·12H₂O, and 3K₂SO₄·Na₂SO₄ precipitate simultaneously. The rates of water loss, halogenation, and salt precipitation are 93.60%, 5.73%, and 0.67%, respectively. NaCl, Li₂SO₄·3Na₂SO₄·12H₂O, and 3K₂SO₄·Na₂SO₄ were all precipitated through dispersion precipitation of borax with the evaporation process following precipitation. The UNIQUAC model was employed to predict the isothermal evaporation at 15 °C. The theoretical calculation and the experimental were in good agreement. The present work can offer a fundamental theoretical framework for the development and use of Laguocuo Salt Lake resources at 15 °C. Full article

For the first time, the stability of KCl single crystals doped with sodium impurity ions was analyzed via the optical absorption and luminescence methods. Using the characteristic bands of optical absorption, as well as of X-ray and tunnel luminescence, ascribed to radiation defects and exciton-like formations localized near sodium impurity, the removal of Na⁺ ions from regular cation sites into nanosized clusters in KCl:Na crystals stored for a long time at room temperature was demonstrated. At the same time, the subsequent annealing of such “decayed” crystals at high temperature (400–700 °C) led to a partial incorporation of sodium impurity ions back into cation sites and the restoration of a homogeneous distribution of Na⁺ in the KCl:Na lattice. With an increase in the quenching temperature, the restoration degree continuously increased until it reached the saturation level (about 80% of the characteristics of a freshly grown crystal). The detectable/disappearing X-ray-induced absorption bands at 6.3 and 3.5 eV (respectively ascribed to interstitial chlorine ions and atoms localized near Na⁺), as well as the luminescence bands at 2.8 and 3.1 eV, typical of recombinationally generated exciton-like formations near Na⁺ or Na⁺-Na⁺, were the indicators of sodium ion redistribution in the crystal lattice. Full article

The objective of this study was to create a fermentation process for the production of inulinase, an important enzyme with numerous applications in the food and pharmaceutical industries, using low-cost agricultural waste as substrates for Rhizopus oryzae NRRL 3563. High titer inulinase production in chicory roots by Rhizopus oryzae in a submerged culture was accomplished using a statistical experimental design. A two-level Plackett–Burman design followed by a three-level Box–Behnken design producing a high inulinase titer of 1085.11 U/mL, 2.83-fold the maximum level, was obtained in the screening experiment. The optimal levels were as follows: chicory root, 10 g/L; NaNO₃, 5 g/L; and KCl, 0.2 g/L. The produced inulinase enzyme was purified using 70% ammonium sulfate precipitation and ultra-filtration causing 3.63-fold purification with 60% activity recovery. The enzyme had a molecular weight of approximately 130 KDa. The purified enzyme showed optimum activity at 50 °C and pH 6.0. The pH stability range was three to six and the temperature stability was up 70 °C. The purified inulinase could hydrolyze inulin and sucrose, but not cellobiose or soluble starch. Km and Vmax for inulin were determined to be 0.8 mg/mL and 50,000 U/mg, respectively. The two-level Plackett–Burman design was applied followed by a Box–Behnken model for optimization of fermentation conditions. Accordingly, the optimal combination of fermentation was a reaction time of seven hours, a temperature of 60 °C, and an enzyme concentration of 40,000 U/mL, which resulted in a 58.07% saccharification yield. The characteristics of the enzyme and its kinetic parameters suggested that it was highly effective in the fermentation of inulin and inulin-containing substrates. Additionally, it raises the potential of using inulinase enzymes in pharmaceutical and food industries. Full article

The enzyme β-galactosidase catalyzes the hydrolysis of lactose into glucose and galactose, although for its effective application it is necessary to establish techniques for purification, concentration, or polishing, such as membrane separation processes, in particular ultrafiltration. The present study aimed to investigate ultrafiltration and diafiltration applied as initial steps for concentration and salt removal, respectively, in the β-galactosidase purification processes. Additionally, the influence levels of the pH (6.5, 7.7, or 7.5), membrane molecular weight cut-off (30, 50, 60, or 100 kDa), operating pressure (1.5, 2.0, or 2.5 kgf/cm²), and ionic strength of the ultrafiltration using NaCL or KCl (0.01–0.1 M) were evaluated considering the enzyme recovery, purification, retention, and concentration factors in relation to the proteins, volume, activity, and protein flux and yield of the processes. The ultrafiltration of the crude enzyme extract at pH 7.5 and 1.5 kgf/cm² with a 50 kDa polyethersulfone membrane resulted in a volume concentration of the β-galactosidase extract up to 7.1-fold greater, a purification factor 1.2-fold greater, and an enzyme recovery rate of 108.9% by eliminating metabolites during the purification process. In addition, the lowest flux variation range (16.0 to 13.1 L/m²·h) was observed under these same conditions, thereby representing a decrease of 18.0%. An increase in the operating pressure and the addition of salts results in reduced enzyme recovery (up to 38% of the process yield (734.1 to 453.7 U/h) and up to 40% of the enzyme recovery rate (108.9 to 60.6%) during the ultrafiltration using NaCl, respectively). The operation in the diafiltration mode allowed salt removal after the purification of β-galactosidase (enzymatic recovery rates above 93.4%) via precipitation and ion-exchange chromatography elution and as part of an aqueous two-phase system using 6 diafiltration cycles, thereby revealing its application potential. Full article