Chloride Concentration Research Articles

Understanding the influence of sodium chloride concentration on ion diffusion in charged polymers

Previous observations made on sulfonated polysulfones equilibrated with solutions of increasing salinity, where salt diffusion coefficients increase concurrently with reductions in water content driven by osmotic de-swelling, are currently unexplained. To further explain the molecular underpinnings of these observations, we characterized the influence of external salt solution concentration on the average salt and ion diffusion properties of two sulfonated polymers: a model cross-linked material (XLAMPS) and a series of sulfonated polysulfones (HQ:BP – XX). Analysis of the average salt and co- and counter-ion diffusion coefficients in these polymers suggest that the increase in charge screening (of electrostatic interactions between anionic sulfonate groups and co-ions) that occurs with increasing salinity affects the salt diffusion coefficients of sulfonated polysulfone in a manner that is different from what would be expected based on changes in water content alone and from what was observed for XLAMPS. Free volume theory describes the influence of these electrostatic effects on salt diffusion using a parameter related to the characteristic free volume element size necessary for diffusion. The results and analysis suggest that charge screening reduces the characteristic free volume element size necessary for diffusion in sulfonated polysulfone, which provides an explanation for the observed increase in average salt diffusion coefficients with increased salinity.

EIS Investigation of a Single Pit on Cantor Alloy in Acidic Environment

High-entropy alloys (HEA) are an emerging class of materials with promising properties such as high strength and ductility, improved fatigue resistance, fracture toughness, and thermal stability. They show considerable potential for use as corrosion resistant alloys to support our infrastructure especially for use in extreme environments. In this work, we mainly focused on the typical Cantor alloy, which consists in a mixture of 5 elements CrMnFeCoNi in equimolar proportion. A huge amount of works has already been devoted to the study corrosion resistance of alloys in sulfuric acid [1] or in chloride containing solutions [2,3]. For the latter, the study of the pitting propagation remains challenging since this kind of corrosion initiates as a stochastic process.Electrochemical impedance spectroscopy (EIS) is intensively used as a tool for corrosion research and is well suited for the identification of complex mechanisms. However, data analysis remains difficult in the case of pitting studies, which can be described schematically as n anodic sites in parallel at different states of evolution. In this work we report on EIS analysis performed on a single pit (Fig. 1a) in order to describe the various step of its evolution as a function of time, but also as a function of various parameters such as the chloride ion concentration or the corrosion potential. Single pits were obtained by studying the breakdown of the passive film using the pumped-micropipette delivery/substrate collection (Pumped-MD/SC) mode of scanning electrochemical microscopy (SECM). A detailed mechanism is proposed to account for EIS results obtained on a single pit (Fig. 1b) in order to explain results on usuals EIS measurements.[1] J. Yang, J. Wu, C. Y. Zhang, S. D. Zhang, B. J. Yang, W. Emori et J. Q. Wang, « Effects of Mn on the electrochemical corrosion and passivation behavior of CoFeNiMnCr high-entropy alloy system in H2SO4 solution », Journal of Alloys and Compounds, 819, avril 2020, p. 152943, https://doi.org/10.1016/j.jallcom.2019.152943[2] Camila Boldrini Nascimento, Uyime Donatus, Carlos Triveño Ríos et Renato Altobelli Antunes, « Electronic properties of the passive films formed on CoCrFeNi and CoCrFeNiAl high entropy alloys in sodium chloride solution », Journal of Materials Research and Technology, 9, no 6, novembre 2020, p. 13879-92, https://doi.org/10.1016/j.jmrt.2020.10.002[3] Mengjiao Li, Qingjun Chen, Xia Cui, Xinyuan Peng et Guosheng Huang, « Evaluation of corrosion resistance of the single-phase light refractory high entropy alloy TiCrVNb0.5Al0.5 in chloride environment », Journal of Alloys and Compounds, 857, mars 2021, p. 158278, https://doi.org/10.1016/j.jallcom.2020.158278 Figure 1

Title: Investigation of Kinetically Favorable Chromium Speciation Distribution for Iron Chromium Redox Flow Batteries

Chromium is a promising active material for redox flow battery (RFB) electrolytes due to its low cost and reduction potential very near the negative limit of the electrochemical window of water. However, many challenges exist with the performance of the Cr3+/2+, most notably sluggish electron-transfer kinetics and parasitic hydrogen evolution during the charge cycle. This presentation will focus on our recent efforts to overcome these challenges by understanding the interplay between electrolyte composition, speciation, and electron-transfer kinetics for the aqueous Cr3+/2+ redox couple.Among the earliest published work on flow batteries was a program based at NASA introducing the iron chromium redox flow battery (ICRFB) [1,2]. These studies were valuable in demonstrating both the promise and the complications of chromium for flow battery electrolytes. The NASA team went to great lengths to enhance chromium redox kinetics and suppress the hydrogen evolution via extensive modification of the carbon negative electrode with Au, Pb, and Bi additives. The present study is based on a key observation from this early work that the electron-transfer rates for Cr-chloride complexes depend strongly on the inner-sphere coordination environment, and specifically the number of chloride ions directly bound to the Cr center.Extensive prior studies from the inorganic coordination chemistry literature further demonstrate that Cr(III) chloride complexes undergo slow equilibration in aqueous solutions to form distributions of four species where the coordination environment around the metal center can be described generally as [CrClx(H2O)6-x](3-x)+ with 0 < x < 3 [3,4]. Each of these species yields a distinct optical absorption signature, enabling quantification of the composition with UV-VIS spectroscopy. Our overarching hypothesis, based on the early NASA work, was that increased chloride coordination (i.e., higher values of x in CrClx(H2O)6-x) would yield enhanced electron-transfer kinetics by reducing inner-sphere reorganization barriers associated with aquo ligands, or by enhancing catalytic mechanisms mediated by chloride surface adsorbates. Thus, we measured optical absorbance and electrochemical reversibility for Cr(III) chloride solutions with HCl, NaCl, and LiCl supporting electrolytes over a range of total chloride concentration from 0.1 to ~10 mol/L.Representative results are summarized in Figure 1 for 0.1 M CrCl3 in aqueous LiCl. Notably, at Au electrodes the reversibility of the Cr3+/2+ redox feature increases dramatically as chloride concentration increases above 5 mol/L (Figure 1a). This shift in reversibility is broadly correlated with UV-VIS results (Figure 1b) demonstrating that the primary Cr(III) species present initially remains the predominant species in the aqueous environment for high concentrations of chloride over time, but the predominant species shifts significantly at lower concentrations of LiCl. Ongoing work, which will be discussed in this presentation, is focused on full quantification of the relationship between speciation and electron-transfer kinetics as well as performance properties for ICRFBs with a range of supporting electrolyte concentrations. We anticipate that understanding the most kinetically favorable speciation distribution will allow us to develop improved electrolytes for functional ICRFBs.

Ammonia Decomposition By Microwave Plasma Discharges

The global discourse focuses on future energy vectors, with hydrogen emerging as a robust candidate owing to its established industrial applications. However, a current challenge lies in storing and transporting hydrogen-based fuels. This research focuses on advancing efficient and environmentally friendly techniques for large-scale hydrogen production, leveraging its widespread industrial presence. Ammonia, identified as a promising energy vector, offers advantages in storage and transport over hydrogen. It capitalizes on existing global infrastructures, with approximately 20 million metric tons traded annually, contributing to a total production of 150 million tons annually. If many works focus on producing ammonia by electrical discharges [1], only a few are devoted to ammonia cracking and generally concentrate on catalysis [2]. In this study, we propose an investigation into the decomposition of ammonia by applying microwave (MW) plasma. Utilizing a MW cavity that confines an electromagnetic field excited at 2.45 GHz, we induce electrodeless plasma within a fused silica tube where pure ammonia (NH3) gas flow. At first, the plasma discharge was characterized with Fourier Transform Infrared Spectroscopy (FTIR). This preliminary part of the study exhibited that, for fixed input power (300 W) and fixed working pressure (100 mbar), NH3 decomposition decreased with a flow rate ranging from 0.4 to 2.4 SLM. It also showed that for fixed input power (300 W) and fixed flow rate (2.4 SLM), the NH3 dissociation increased with pressure ranging from 40 to 140 mbar. These experiments exhibited the predominant role of the residence time of ammonia but also reactive species in plasma. To further understand the NH3 cracking mechanisms, we performed optical emission spectroscopy (OES). This technique allowed us to determine the various light-emitting species produced during NH3 dissociation in the discharge and their physical parameters, such as temperatures and relative densities, as a function of different experimental parameters. We study the influence of gas flow rate ranging from 1 to 15 SLM, input power and near-atmospheric pressure on NH3 cracking and hydrogen (H2) recombination mechanisms. Gas chromatography (GC) was employed to measure the dissociation yield of NH3 and assess the efficiency of the H2 production process. In parallel, we synthesize iron (Fe) and nickel (Ni) nanoparticles through a plasma solution process. Both metals are abundant and inexpensive; hence, they are good candidates as catalysts for potential industrial applications. In the experimental setup, a pair of tungsten electrodes, connected by a high-voltage cathode, was submerged in an aqueous solution containing Fe and Ni chlorides. One electrode was the high-voltage cathode, while the other was the grounded anode. Pulsed discharges were generated to produce Fe and Ni compounds. The resulting Fe-Ni nanoparticles (NPs) were characterized by transmission electron microscopy (TEM) to determine their shape, size and composition, which depends on the concentrations of the metal chlorides in the electrolyte solution. Those NPs were then coated on silica tubes inserted in the MW reactor at various positions to establish their influence on the NH3 decomposition and H2 recombination processes. The primary goal of this study is to compare the dissociation of NH3 with and without catalysts, aiming to achieve optimal results for H2 production. This study investigates the impact of experimental parameters on ammonia cracking efficiency within a microwave plasma combined with catalysis. We compare these factors with ruthenium-catalyzed and non-catalyzed thermal processes, recognized as leading methods for ammonia cracking. The goal is to gain insights into the mechanisms of ammonia decomposition in microwave plasmas and evaluate the efficiency of our proposed methodology relative to established thermal processes, contributing to the advancement of sustainable and optimized ammonia cracking practices and decarbonated hydrogen production. Acknowledgements The authors would like to thank the Department of Physics, College of Science, Jazan University, Jazan 45142, Saudi Arabia, for the financial support to M. Awaji and SAKOWIN for the financial support to L. Pentecoste.

Feasibility of Assessment of Habitual Salt Intake Using a 24-h Urinary Salt Excretion Self-Measuring Device.

To assess habitual salt intake, tools are needed to measure 24-h urinary salt excretion repeatedly. We developed and validated a new portable salt monitor, which measures salt excreted per urination and sums the values to provide an accurate estimate of urinary salt excretion over 24 h. A previously developed salt monitor was improved with respect to the capacity, volume sensors, and equation for urinary sodium chloride concentration estimation. In 20 healthy Japanese female volunteers, 24-h urinary salt excretion was measured using the salt monitor and a conventional 24-h urine collection method on eight nonconsecutive days. In a total of 157 days, there were no fixed or proportional errors between the methods. The mean salt intake over 8 days was 8.5 ± 2.0 g/day for the 24-h urine collection and 8.3 ± 2.3 g/day for the salt monitor, showing a strong correlation (r = 0.912, p &lt; 0.001). At a cut-off value of 6 g, the salt monitor was able to completely classify individuals by habitual salt intake. The validity of the new salt monitor was confirmed. The device can be considered an alternative to the traditional 24-h urine collection for repeated surveys and self-management of daily salt intake.

Finite Element Analysis of Flow-Electrode Capacitive Deionization

As access to freshwater diminishes due to climate change and population growth, drought-stricken regions across the globe continue to turn to groundwater and desalination. A largely untapped water resource in many parts of the world is brackish water - defined as water with total dissolved solids (TDS) in the range of 500 ppm to 10,000 ppm. Flow Capacitive Deionization (FCDI) is an electrochemical ion removal technology that is well-suited for the continuous desalination of brackish waters. Traditional Capacitive Deionization (CDI) consists of two fixed capacitive electrodes which are charged and discharged cyclically to capture ions from the solution being treated, and then regenerated to create a waste brine stream. During FCDI operation however, an applied potential drives ions out of a center water channel, typically through a pair of cation and anion exchange membranes (CEM/AEM), and into two flowing capacitive slurry electrodes (Figure 1). Because the electrodes are mobile, they can be moved into an adjacent cell for regeneration, thus enabling continuous operation of the desalination system without cyclical charge/discharge. The cathode and anode slurries typically consist of activated carbon suspended in a salt solution.Because the electrodes are flowing in FCDI, models describing this system must translate the Eulerian derivative to describe transient capacitive charge/discharge to a Lagrangian material derivative following the electrode material flowing through space. A flowing capacitive electrode is a significantly more complex system than a stationary porous and capacitive electrode matrix, incorporating the fluid dynamics of the slurries, ion transport within the slurry’s electrolyte medium, etc. Despite nearly a decade of research into FCDI, few researchers have probed the transient and spatially dependent mechanisms of ion transport and electro-adsoprtion within flow electrodes. While the overall electrodialytic contributions to ion capture within FCDI systems have been studied (1,2), the mechanism of competition between the electrodialysis and capacitive ion capture within the flow electrodes remains somewhat elusive. Additional analysis of the ion transport phenomena within these flow electrodes could bring forth insights into optimal design of FCDI devices and/or electrode formulations.In this study, an existing 2-dimensional mathematical model (3,4) for electrochemical flow capacitors is adapted to FCDI and solved via finite element analysis in COMSOL Multiphysics. Transport equations describing the advection of overpotential along with the flowing electrode are coupled with the Nernst-Planck equations which govern ion transport within the CEM/AEM, center water channel, and slurry electrolyte medium. This study investigates the effect of slurry flow velocity and sodium chloride concentration in the influent water on electrical potential profiles within an FCDI cell, and illustrates the active regions of capacitive electro-adsorption through the depth of the flow channel. Models of electrodialysis and FCDI are compared to understand the fundamental differences in driving forces for ion removal between the two technologies. The model shows agreement with experimental data through prediction of salt adsorption rate trends (mmol NaCl m-2 s-1) vs. influent sodium chloride concentrations. Through this analysis, it is shown that this model may serve as a valuable groundwork for expansion of FCDI modeling capabilities to include three dimensional cell geometries and subsequent optimization of operational parameters and cell dimensions. P. Nativ, Y. Badash, and Y. Gendel, Electrochem. Commun., 76, 24–28 (2017). J. Ma, C. He, C. Zhang, and T. D. Waite, Water Res., 144, 296–303 (2018). N. C. Hoyt, J. S. Wainright, and R. F. Savinell, J. Electrochem. Soc., 152, A652–A657 (2015). N. C. Hoyt, R. F. Savinell, and J. S. Wainright, Chem. Eng. Sci., 144, 288–297(2016). Figure 1

Corrosion behavior of steel bar in magnesium oxysulfide cement-based materials: The role of chloride and nitrite

Magnesium oxysulfide (MOS) cement has emerged as a promising cementitious material due to the high strength and excellent durability, but research on its rust inhibition remains limited. In this study, the chloride and nitrite were introduced in the MOS cement composites, aiming to investigate the corrosion properties and reveal the rust inhibition mechanism of steel bar under different W/C ratio. Experimental results show that the corrosion area ratios reach the largest value of approximately 98% and the lowest value of approximately 3%, respectively, as the chloride and nitrite contents increase to 2%. Compared with chloride, the effect of W/C ratio on the mass loss of steel bar is gradually weakened when the nitrite content is larger than 0.5%. Based on the natural potential, the change of corrosion degree mainly occurs after 28d. In addition, the corrosion potential of steel bar decreases and corrosion rate increases with the increase of chloride content in MOS cement composites. Conversely, the presence of Mg(NO2)2 from nitrite engenders an opposite effect. Besides, the increase of W/C ratio results in higher electrochemical parameters. At this time, the rust inhibition mechanism is revealed based on the micro-structure analysis.

Evaluation of the Nonlinear Response of KCl Solution to High-Amplitude Stimulation Using a Four-Point Cylindrical Gold Electrode.

A four-electrode system and high-voltage amplitude stimulation (with a voltage of more than 1 V) are always used for nonlinear spectroscopy of biological solutions like yeast suspension. Multiple studies indicate that yeast membrane activities are the primary source of the harmonics detected from yeast suspensions. However, other investigations have demonstrated that at least part of the harmonics are mainly due to the nonlinear impedance of the electrode-electrolyte interface. Here, we want to find a mathematical model to analyze the odd harmonics generated by the interface. The KCl solution is the basis of the essential medium used in yeast culture. No study models the nonlinear behavior of the KCl solution using four-electrode. We used a sinusoidal voltage with a low frequency and a high amplitude to test an ionic solution with 1, 30, and 130 mM of potassium chloride. The voltage had no direct current component. Here, we show that the relationship between the amplitude of the excitation voltage and the third harmonic of the current can be accurately represented using the Butler-Volmer equation. Additionally, we analyze the impact of potassium chloride (KCl) concentration on the behavior of the third harmonic. This paper presents a method and model that can be used for nonlinear spectroscopy studies of biological solutions using a four-electrode system with the aim of deriving information from cells without considering the interface effect.

Study on the Binding Behavior of Chloride Ion and Ettringite in Nano-Metakaolin Cement by Seawater Mixing and Curing Temperatures.

Mixing cement with seawater will cause the hydration process of cement to be different from that of ordinary cement, which will significantly affect cement's mechanical properties and durability. This article investigates the effects of chloride ion concentration, curing temperature, and nano-metakaolin content on the evolution process of Friedel's salts and ettringite (AFt) crystals in cement pastes. The study was conducted using X-ray diffraction (XRD), thermal analysis (TG), scanning electron microscopy (SEM), and mercury-intrusion porosimetry (MIP). The results show that chlorine salt can increase the production of Friedel's salt and ettringite, and the delayed AFt production increases by up to 27.95% after the addition of chlorine salt, which has an adverse effect on cement-based materials. Increasing the curing temperature and increasing the nano-metakaolin dosage increased the generation of Friedel's salt and decreased the delayed AFt generation, which resulted in a decrease in the length and diameter of the AFt crystals. After 28 days of high-temperature curing and the addition of nano-metakaolin, Friedel's salt production increased by 13.40% and 14.34%, respectively, and ettringite production decreased by 9.68% and 7.93%, respectively. Increasing the curing temperature and adding nano-metakaolin can reduce the adverse effect of delayed ettringite increases due to chloride ion binding.

Comparative study of various metal‐based reference electrodes

AbstractThis paper compares materials potentially suitable for preparing solid reference electrodes, which could be used in miniaturized flow electrochemical cells. The tested electrodes are based on Sb, Bi, Pd, Pt, and Ag. The stable potential of the reference electrodes was maintained by the pH of the electrolyte, except for the AgCl electrode, whose potential was given by the concentration of chlorides. The performance of the reference electrodes was evaluated through a series of experiments focusing on potential dependences, long‐term and short‐term stability, cyclic voltammetry, and flow injection analysis with amperometric detection. Potentiometric experiments showed that Sb‐based electrodes had the closest slope to theoretical values with minor changes over five weeks. Theory‐consistent results of potential dependence were also observed for AgCl electrodes. The results of the voltammetric and flow amperometric experiment suggest that Sb‐based reference electrodes are the most suitable tools for electrochemical measurement. AgCl electrodes are limited by the necessity of maintaining a high chloride concentration. Bi‐based and PdH electrodes provide unstable results, the latter particularly due to hydrogen desorption. Although able to provide the stable potential to some extent, Pt electrodes are not suitable as the reference electrodes due to the deformation of mainly hydrodynamic voltammograms.

An Experimental Study on the Performance of Materials for Repairing Cracks in Tunnel Linings under Erosive Environments

Addressing the current lining cracking problem in coastal tunnels, this paper independently introduces a novel type of repair material for tunnel lining cracks—the composite repair material consisting of waterborne epoxy resin and ultrafine cement (referred to as EC composite repair material). Through indoor testing, we have analyzed the change rule of the mass change rate, compressive strength, flexural strength, and chloride ion concentration of the repair material samples in erosive environments, with the dosage of each component in the EC composite repair material being varied. We have also investigated the working performance, mechanical properties, and microstructure of the repair material. The results of this study show that when the proportion of each component of ultrafine cement, waterborne epoxy resin, waterborne epoxy curing agent, waterborne polyurethane, defoamer, and water is 100:50:50:2.5:0.5:30, the performance of the EC composite repair material in a chloride ion-rich environment is optimal in all aspects. When the mixing ratio of each component of the EC composite repair material is as stated above, the repair material exhibits the best performance in a chloride ion erosion environment. With this ratio of components in the EC composite repair material, the fluidity, setting time, compressive strength, flexural strength, and bond strength of the repair material in a chloride ion erosion environment can meet the requirements of relevant specifications, and it is highly effective in repairing tunnel lining cracks. The polymeric film formed by the reaction between the waterborne epoxy resin emulsion and the curing agent fills the pores between the hydration products, resulting in a densely packed internal structure of EC composite repair material with enhanced erosion resistance, making it very suitable for repairing cracks in tunnel linings in erosive environments.

Groundwater quality analysis in Hail region of northwest Saudi Arabia based on physicochemical investigation

The acquired groundwater data from seventeen wells were hydrochemically analyzed for Sulfate, Chloride, Ammonia, Nitrate, Nitrite, pH, EC (Electrical Conductivity), TDS (Total Dissolved Solids), total hardness, and total alkalinity concentrations and then compared to the national and international standards. The results range as follows: pH (6.65–8.26), EC (382–1214 μS·cm−1), Total hardness (72–310 ppm), TDS (258–775 ppm), Total alkalinity (54–138 ppm), Cl- (19–202 ppm), Ammonia (NH3) (0.0 to 1.5 mg/liter), Nitrate (NO3) (4.7 to 65.6 ppm), Nitrite (NO2) (0.007 to 0.05 ppm), and sulfate (SO4) (29–278 ppm). About 70.58 % of the study area’s groundwater samples have TDS levels below 500 mg/l, which are considered safe for drinking. The EC of the groundwater found that 100 % of the samples fall within the allowed level. Based on these results, the groundwater quality is suitable for drinking and irrigation purposes in Hail region. Hence, this research shows that using GIS and chemical analysis of groundwater could be useful tools for the decision-making process of local and international authorities and water resources management.

Bioaccumulation of Aluminium Chloride in Different Organs of Freshwater Fish Labeo rohita (Ham.)

The present research work was carried out to determine the bioaccumulation of aluminium chloride in the gills, liver, Kidney and muscles of Labeo rohita. Sub-lethal concentration (LC50) for 96 hours of exposure was found to be 32.5 ppm. The accumulation of heavy metal gradually increases in liver during the heavy metal exposure period. In the present study the accumulation of aluminium chloride was not found in tissues like gill, liver, kidney and muscle in control fish, whereas in treated fish the accumulation was found in the following order of liver&gt;kidney&gt;gill&gt;muscle. Changes in the aluminium chloride content of muscle tissue in treated fish against the control fish were statistically significant at P&lt;0.05. In all heavy metal, the bioaccumulation of aluminium chloride proportion was significantly increased in the tissues of Labeo rohita. This study revealed the accumulation of heavy metals in fish Labeo rohita which may act as an indicative measure to address the production, bioaccumulation and health hazardous issues of heavy metals.

Groundwater quality deterioration evaluation for irrigation using several indices and geographic information systems: A case study

Groundwater in the Al-Burayhi and Hethran Basin, Taiz, Yemen, it is important source of irrigation water. However, its quality faces threats from both natural and human activities. This study aims to assess the potential deterioration of groundwater for irrigation purposes using several indices and Geographic Information System (GIS) software. Indices, including salinity (electrical conductivity), sodium hazard (Sodium Adsorption Ratio and Permeability Index), combined salinity and sodium hazard index (electrical conductivity and sodium percentage), magnesium hazard index, and chloride content index. The results indicate that 24.14 % of the samples showed high salinity, while 75.86 % showed very high salinity according to the electrical conductivity indices. For sodium hazards, 79.3 % of the samples posed a medium hazard to soil permeability in the long term based on the Permeability Index. Regarding the combined salinity and sodium hazard, 69 % of the samples were of poor quality for irrigation. For magnesium hazards, 55.17 % of the groundwater samples were of poor quality for irrigation. Concerning chloride content, 72.41 % of the samples exceeded the permissible limits according to Yemeni and international standards (350 mg/L). Therefore, using groundwater in the study area for irrigation impedes crop growth and productivity, leads to soil salinization and/or physical degradation due to increased alkalinity, and necessitates costly soil treatments to restore its productivity. Nevertheless, groundwater in the study area can be conditionally used for irrigation by considering all factors affecting the use of low-quality groundwater for irrigation.

Engineering an upconversion fluorescence sensing platform with "off-on" pattern through specific DNAzyme-mediated signal amplification for supersensitive detection of uranyl ion.

Anupconversion fluorescence sensing platform was developedwith upconversion nanoparticles (UCNPs) as energy donors and gold nanoparticles (AuNPs) as energy acceptors, based on the FRET principle. They were used for quantitativedetection ofuranyl ions (UO22+) by amplifying the signal of the hybrid chain reaction (HCR). When UO22+ are introduced, the FRET between AuNPs and UCNPs can be modulated through a HCR in the presence of high concentrations of sodium chloride. This platform providesexceptional sensitivity, with a detection limit as low as 68pM for UO22+ recognition. We have successfully validated the reliability of this method by analyzing authentic water samples, achieving satisfactory recoveries (89.00%-112.50%) that are comparable to those of ICP-MS. These results indicate that the developed sensing platform has the capability to identify trace UO22+ in complex environmentalsamples.

Evaluation of turbidity removal efficiency from Karun river water using polyaluminum chloride and chitosan

This study was conducted with the aim of evaluation of turbidity removal efficiency from Karun river water using polyaluminum chloride and chitosan. Chitosan is a linear cationic polyelectrolyte with high positive electron charge (one positive charge per glucose amine unit). Chitosan is used in water purification systems as coagulant along with common coagulants (alum, chlorferric). This biopolymer is also used as a primary coagulant. Chitosan has a higher ability to coagulate colloidal particles than synthetic polyelectrolytes, most of which lack the property of biological degradation in the short term, and some of them cause carcinogenesis and genetic mutation in humans. Therefore, the use of chitosan is preferable to artificial polyelectrolytes from an environmental point of view. This research was conducted on the laboratory scale using a jar test device at the water treatment plant in Ahvaz. In this study, various parameters such as pH, polyaluminum chloride concentration and chitosan concentration were present as variables. After preparing the samples and just before starting jar tests, in the rapid mixing cycle of 200 rounds per minute, the optimal pH to remove the turbidity obtained 8. Also, the optimal dosages of polyaluminum chloride and chitosan were selected as 4 ppm and 0.04 ppm, respectively. Also the main mechanism for destabilizing clots and removing turbidity was bridging between the particles. In this condition, the removal of turbidity showed the highest efficiency. On the other hand, chitosan created clots with a higher weight and, as a result, better settling ability. Therefore, chitosan was a suitable choice to remove turbidity from water.

Assessment on the Impact of Mining and Industrial Activities in Groundwater Quality in Chandrapur, Maharashtra Through Remote Sensing and GIS Applications

This study evaluated the quality of groundwater in Chandrapur Taluka, Maharashtra, using geospatial techniques and data from 2014 and 2018. The study assessed various water quality parameters such as chloride, fluoride, pH, residual sodium carbonate (RSC), and sodium adsorption ratio (SAR). The findings showed that chloride concentrations were mostly within acceptable limits, but there was a slight increase in areas near mining and industrial sites, which was statistically significant (p &lt; 0.05). Fluoride levels were generally within permissible bounds, but there was a noticeable increase near industrial areas in 2018 compared to 2014, which was statistically significant (p &lt; 0.05) and raised environmental concerns. Variations in pH values were also observed, which could impact aquatic ecosystems, with a decrease noted from 2014 to 2018. RSC levels were higher near mining and industrial zones in 2018, exceeding recommended limits, indicating a potential threat to water quality. SAR levels in 2018 were higher, potentially impacting agriculture, but still within acceptable limits. Sulphate levels showed a reduction from 2014 to 2018. These comprehensive findings highlight the specific impacts of mining and industrial activities on groundwater quality and raise broader scientific questions. They can be used to develop evidence-based policies for effective mitigation measures and engage a wider readership.

Production of nutritionally active compounds from Spirulina platensis under various stress conditions

The free-floating, filamentous cyanobacteria Spirulina platensis is highly valued and in great demand worldwide for its high-value colors and phytonutrients. These compounds find use in health foods, feed, medicines, and diagnostics. The primary objective of this work was to enhance the growth of Spirulina under both oxidative and physiological stress conditions in order to maximize the synthesis of phycocyanin and carotenoid pigments. Cultures were subjected to different concentrations of hydrogen peroxide (H2O2) and sodium chloride for varying temperatures and pH levels. Under lower concentrations of H2O2 (4mM), the maximum carotenoid content was increased, but the phycocyanin content was found to be stimulated at 10mM. Moreover, the synthesis of both pigments was shown to be highest under physiological stress circumstances (40mM and 60mM NaCl concentration) and at an optimal pH of 8-9, helped by a temperature range of 25-30℃. The experimental results demonstrate that both carotenoid and phycocyanin exhibit antioxidant properties even in the presence of oxidative stress. This suggests that the aforementioned circumstances can be applied in future investigations to extract different antioxidants from S. platensis.

Real-world data confirm elexacftor/tezacaftor/ivacaftor modulators halves sweat chloride concentration in eligible people with cystic fibrosis.

Sweat chloride concentration, a diagnostic feature in cystic fibrosis (CF), reflects CF transmembrane conductance regulator (CFTR) activity. CFTR modulator therapies, especially elexacaftor/tezacaftor/ivacaftor (ETI), has improved CF outcomes. We report nationwide, real-world data on sweat chloride concentration in people with CF (pwCF) with and without modulator therapies. All Danish pwCF with a minimum of one F508del allele were included. Sweat chloride measurements were stratified by genotype and modulator treatment. Differences were assessed using mixed-effects models. We included 977 sweat chloride measurements from 430 pwCF, 71% of which were F508del homozygous. Heterozygous and homozygous ETI-treated pwCF had an estimated mean sweat chloride concentration of 43 mmol/L (95% confidence interval: 39; 48) and 43 mmol/L (39; 47), respectively-48% and 59% lower than those without treatment. High variation in concentrations remained regardless of treatment status. Despite ETI treatment, 27% heterozygous and 23% homozygous pwCF had elevated concentrations (≥60 mmol/L). These real-world data confirm a substantial decrease in sweat chloride concentration during modulator treatment, especially ETI, where mean concentrations halved. However, large variation remained, including persistently high concentrations. These findings emphasize the potential of sweat chloride concentration as a treatment response biomarker and the need to explore its heterogeneity and relationship with clinical outcomes.

Understanding the conversion of nitrogen compounds during ammonia electrooxidation: effect of current density, chloride concentration and pH on nitrate formation

AbstractBACKGROUNDAmmonia removal from wastewater by electrooxidation (EO) is an interesting approach because of its efficiency and easy maintenance and operation. In this process, ammonia is oxidized to nitrate or nitrogen gas. Ammonia conversion to the latter is desirable to remove nitrogen from the liquid; however, the influence of several operating parameters on nitrate generation has not been systematically evaluated. Therefore, this work aimed to investigate the effect of current density (200–800 A m−2), chloride concentration (0–10 000 mg L) and initial pH (5–9) on the electrooxidation of an ammonia‐containing solution and the associated generation of nitrate. For this purpose, a laboratory‐scale electrochemical reactor containing two Ti/RuO2 electrodes was used.RESULTSThe results indicated high ammonia removal efficiency – 98% within 150 min at 800 A m−2 and 97% within 240 min at 500 A m−2 – generating around 70 and 102 mg ‐N L−1 under these conditions, respectively. Increasing the chloride concentration from 5000 to 7500 mg L−1 reduces the electrolysis time needed to remove all ammonia from 180 to 150 min. However, with increasing initial chloride concentration, the amount of nitrate generated rose from 69.5 to 135.9 mg N L−1. On the other hand, in the test without chloride, nitrate generation was considerably lower (0–0.61 mg L−1).CONCLUSIONThe higher the current density applied, the greater the ammonia removal by EO. Although current density influenced the ammonia oxidation rates, it did not directly affect nitrate formation. The lower the concentration of ammonia in the solution, the more significant was the fraction of nitrate generated. Most of the inlet ammonia was oxidized to nitrogen gas, nitrite was rapidly oxidized to nitrate and higher chloride concentrations enhanced ammonia oxidation. © 2024 Society of Chemical Industry (SCI).