Presence Of KCl Research Articles

Rapid ion pair-based surfactant-assisted liquid-liquid microextraction with solidification of floating organic drop for simultaneous spectrophotometric determination of selected anionic dyes in food samples

Ion pair-based surfactant-assisted liquid-liquid microextraction with solidification of floating organic drops has been developed to extract Allura red (AR), tartrazine (TAR), and fast green (FG) prior to spectrophotometric determination. Cetyltrimethylammonium bromide (CTAB) was employed as ion-pairing agent to enhance the hydrophobic behavior of anionic dyes. 1-undecanol and ethanol were used as the extraction and dispersion solvents, respectively. The dyes were quantitatively extracted in the presence of KCl (0.15 mol L−1) at pH 4.0. The method exhibits wide linearity (15.0–1500.0 μg L−1 for AR, 35.0–2000.0 μg L−1 for TAR, and 3.0–1200.0 μg L−1 for FG) with preconcentration factors of 19.6, 20.1, and 19.9, respectively. The detection limit was 3.7. 9.5, and 0.83 μg L−1 for AR, TAR, and FG, respectively. The relative standard deviation did not exceed 2.1 %. The procedure was applied for the determination of these dyes in food samples.

Advanced smectite alteration and the role of accessory reactants at 180 °C: New experimental constraints on the stability of bentonite

Bentonite clay is commonly accepted as an appropriate material for backfilling the space between the radioactive canisters and the host rock of planned underground repository sites for waste disposal. Despite its favourable properties as a hydrodynamic seal, its long-term stability remains a concern. This experimental study of a Bavarian bentonite investigated advanced montmorillonite (smectite) illitisation at 180 °C in the presence of K-oxalate and/or the accessory minerals of pyrite and calcite. The formation of mixed-layered illite-smectite was quantified by X-ray diffraction Rietveld refinement and the crystal chemistry was determined by transmission electron microscopy. The results showed neocrystallisation of a celadonitic illite-smectite (up to 63% illite-layers) after treatment with KCl or K-oxalate with increased Al3+ in the tetrahedral sheets, reduced amounts in the octahedral locations and increased fixation of non-exchangeable K+ ions in response to the increased layer charges. K-oxalate complexation of Al3+ and enhanced dissolution of the smectite resulted in the formation of a possible intermediate amorphous phase and illite-smectite crystallites with additional vacant sites explaining the lower number of octahedral ions (<2 per formula unit). Adding 10% pyrite, 10% calcite, or 5% of each, did influence the degree of alteration to a recognisable degree in the presence of KCl, but the effects on the rate of illitisation were minimal when reacted with K-oxalate, which further increased illitisation by up to 6.4 times. Although batch reactor experiments do have limitations compared to complex repository conditions, our results do indicate that claystone host rocks low in organic matter should be favoured over organic-rich lithologies that are likely to contain oxalate ligands or similar catalysing compounds.

Viscoelastic Reversibility of Carrageenan Hydrogels under Large Amplitude Oscillatory Shear: Hybrid Carrageenans versus Blends.

The viscoelastic response of carrageenan hydrogels to large amplitude oscillatory shear (LAOS) has not received much attention in the literature in spite of its relevance in industrial application. A set of hybrid carrageenans with differing chemical compositions are gelled in the presence of KCl or NaCl, and their nonlinear viscoelastic responses are systematically compared with mixtures of kappa- and iota-carrageenans of equivalent kappa-carrageenan contents. Two categories of LAOS response are identified: strain softening and strain hardening gels. Strain softening gels show LAOS non-reversibility: when entering the nonlinear viscoelastic regime, the shear storage modulus G' decreases with increasing strain, and never recovers its linear value G0 after successive LAOS sweeps. In contrast to this, strain hardening carrageenan gels show a certain amount of LAOS reversibility: when entering the nonlinear regime, G' increases with strain and shows a maximum at strain γH. For strains applied below γH, G0 shows good reversibility and the strain hardening behavior is maintained. For strains larger than γH, G0 decreases significantly indicating an irreversible structural change in the elastic network. Strain hardening and elastic recovery after LAOS prevail for hybrid carrageenan and iota-carrageenan gels, but are only achieved when blends are gelled in NaCl, suggesting a phase separated structure with a certain degree of co-aggregated interface for mixed gels.

Recovery of indium by solvent extraction with crown ether in the presence of KCl and stripping with HCl: A mechanistic study

Hydration of In3+ is the main factor limiting its extraction efficiency from an aqueous solution during a liquid-liquid extraction process. In this study, KCl was introduced into the aqueous solution to facilitate the formation of InCl4− of low charge density, which is expected to possess much weaker hydration compared with In3+, promoting the solvent extraction of indium. The crown ethers (CEs) with varied cavity sizes, benzo-18-crown-6 (B18C6), benzo-15-crown-5 (B15C5), and benzo-12-crown-4 (B12C4), were synthesized. The extraction performance of the CEs toward indium in the presence of sufficient KCl in the aqueous solution was investigated. The liquid-liquid extraction process was analyzed theoretically based on density functional theory (DFT) from the aspects of thermodynamics, geometric structure optimization, electrostatic potential (ESP), and independent gradient model (IGM). The theoretical evaluations agreed well with the experimental results that the hydration of indium could be significantly weakened through the formation of InCl4− and the complexation ability of the CEs toward indium is in the order of B18C6 > B15C5 > B12C4. The complexation mechanism between the CEs and indium during the extraction process was further explored with the assistance of 1H NMR spectrum and SEM-EDS. The results indicate that crown ether coordinates with K+ to form [CE-K]+ at the two-phase interface, which further associates with InCl4− to create the complex of CE-KInCl4, realizing the efficient indium extraction. Moreover, B18C6 showed excellent selectivity toward In3+ over the competing ions such as Fe3+, Al3+, Zn2+, Sn2+ and Ca2+ in a complex system. Indium could be efficiently recovered from the loaded organic phase by using 1 M HCl as the stripping agent with a stripping efficiency of 98.1%.

Influence of cations and low molecular weight organic acids on Cs(I) adsorption on montmorillonite and vermiculite

To predict the mobility of radiocesium (RCs) in the environment, it is essential to understand the adsorption and desorption processes. In this study, we focused on the effects of certain environmental factors, including typical cations (K+, Na+, and NH4+) and low molecular weight organic acids (LMWOAs) such as acetic acid, malic acid, and citric acid on the behavior of RCs on montmorillonite and vermiculite. The results showed that montmorillonite possesses the strongest adsorption capacity for Cs+ than that of vermiculite. Since K+ and NH4+ exhibit similar physicochemical properties to Cs+, there is a significant inhibition of Cs+ adsorption on montmorillonite and vermiculite during the competitive interaction with K+ and NH4+. Compared to NH4Cl, the desorption ratios of Cs+ on montmorillonite and vermiculite are higher in the presence of KCl as the background solution. Low molecular weight organic acids can cover the surfaces of montmorillonite and vermiculite to different extents, which effectively blocks the adsorption sites for Cs+, and leads to an obvious decrease in the adsorption and desorption of Cs+. Due to the high expandable performance, Cs+ is primarily reversibly adsorbed by montmorillonite. Nevertheless, the adsorption of Cs+ on vermiculite exhibits typical irreversible characteristics due to the interlayer collapse. After the adsorption of LMWOAs on montmorillonite and vermiculite, the irreversible adsorption of Cs+ is increased obviously, mainly due to the blocking effect of organic matters on the adsorption sites with high affinity to Cs+.

Solubility and the solution thermodynamics of l-proline in the aqueous binary mixture of NaCl and KCl solution

This paper presents a comprehensive investigation into the equilibrium solubility and thermodynamic behavior of l-proline, a biologically and pharmaceutically significant protogenic non-essential amino acid, in both aqueous and aqua-electrolytic solutions. The study explores the effects of concentration variations at specific temperatures and temperature variations at specific concentrations. The experimental analysis is conducted using analytical gravimetric techniques. The observed phenomena are explained based on various chemical interactions, including ion-dipole and dipole-dipole interactions, present in electrolytic and pure aqueous solutions of the amino acid. The salting in/out effect is also considered to support the solubility results. The experimental results demonstrate that l-proline exhibits increased solubility in the presence of electrolytes compared to pure aqueous solutions, considering the variations in both temperature and concentration. Furthermore, the solubility of l-proline is found to be higher in the presence of KCl than NaCl as an electrolyte in aqueous media. The physical properties and sizes of both the amino acid and electrolytes are identified as crucial factors influencing the observed solubility trends.

High-Temperature corrosion of P91/T91, 304L, Sanicro 28 and Inconel 625 exposed at 600 °C under continuous KCl deposition

This study investigates the corrosion attack after breakaway oxidation on four commercial alloys (T91/P91, 304L, Sanicro 28 and Inconel 625) in the presence of KCl(g)/KCl(s) at 600 °C. The study suggests that an increase in corrosion resistant alloying elements (mainly nickel and chromium) results in the decrease of the thickness of the general oxide scale and not equally deep alloy grain boundary attack for the austenitic alloys. The corrosion attack in the presence of KCl is suggested to proceed by chromate formation and chlorine-induced acceleration of the diffusion of ions through the scale.

Electrochemical investigations of the multicopper oxidase from Aquifex aeolicus under direct electron transfer with carbon electrodes

The study of redox proteins confined over an electrode surface is a powerful approach enabling precise modulation of the driving force for interfacial electron transfer through the control of the electrode potential. In this work, we present the investigation of a protein variant of the multicopper oxidase from Aquifex aeolicus obtained by directed evolution. Motivated by the enhanced performance of the protein variant for the oxidation of organic compounds in solution, the enzyme is studied under direct electron transfer with the electrode. A marked dependence of the redox potential with the pH of the electrolyte solution is observed, which is further confirmed by studies under non-turnover conditions. Further investigations show the need for an initial reductive activation to attain maximum bioelectrocatalytic activity for O2 reduction, in agreement with similar observations made for other multicopper oxidases (MCOs). Moreover, the influence of chloride ions on the bioelectrocatalytic reaction is described. The O2-reduction activity is barely affected at KCl concentrations as high as 100 mM. However, a shift in the O2-reduction potential towards more negative values is observed at low pH, explaining the apparent loss in activity for the oxidation of organic substrates in the presence of KCl. The obtained results contribute to a more detailed understanding of the electrochemical properties of metallo-oxidases and other MCOs.

Pharmacological disadvantages in the spasmolytic effects by using the mixture known as “three toronjiles” in folk medicine

Ethnopharmacology relevanceIn Mexico, Agastache mexicana subsp. mexicana (PT) and subsp. xolocotziana (WT), and Dracocephalum moldavica (BT), are used together as the “three toronjiles” to treat gastrointestinal spasms. Aim of studyTo evaluate if the spasmolytic activity of these three medicinal species is better in combination or in an individual manner. Materials and methodsSpasmolytic effect of PT, WT and BT alone or combinate were evaluated in rings of the guinea-pig ileum contracted with potassium chloride (KCl), electrical field stimulation (EFS), or acetylcholine (ACh). Chemical analysis by thin layer and ultra-high pressure liquid chromatography of the aqueous extracts of each species were done for their comparison, and their acute toxicity were determined in mice. ResultsPT and WT diminished in a dose-dependent manner the contractions induced by KCl, EFS, and ACh. Whereas BT did not altered contractions in any experimental protocol. A combination of the PT (EC50) and WT (EC50) diminished the contractions induced by KCl or EFS. Interestingly, the addition of BT extract (10 μg/ml) to the combination (PT EC30 + WT EC30) blocked the inhibitory effect produced on the contracted tissue in the presence of KCl, EFS, or ACh. Moreover, addition of BT extract (100 μg/ml) to the same combination blocked the inhibitory effect on the pre-contracted tissue only in the presence of EFS. None of the aqueous extracts produced toxicity in its individual administration in mice. Chemical analysis demonstrated similarities between PT and WT, but differences with BT. ConclusionsThe results of this study confirmed that either combined or by themselves aqueous extracts of PT and WT produced a spasmolytic action on guinea pig ileum, suggesting that this combination of medicinal plants could relieve gastrointestinal diseases in human, but when BT aqueous extract is added to those obtained with PT and WT, the spasmolytic activity diminished or even was blocked. Our results give evidence that mixture of several plants might produce disadvantages in the medicinal properties of their individual activity.

Process of preparing chloride-free KNS compound fertilizers from phosphogypsum waste using a quaternary phase diagram

Phosphogypsum (PG), commonly known as calcium sulfate, is a waste by-product generated during the production of phosphoric acid by the wet phosphoric acid process (WPA). It is well known that every year the phosphate industries produce a large quantity of PG around the world (i.e., Currently, global production of this waste is estimated at 300 Mt/ year), but the valorization processes of this waste are limited and low valuable. In this study, we investigated the recycling of PG by-product, which can be considered very promising sources of sulfate ions (SO42-) for the manufacturing of chloride-free KNS compound fertilizer based on potassium-ammonium sulfate ([K1−x(NH4)x]2SO4). The primary objective of this study was to develop a methodology for [K1−x(NH4)x]2SO4 synthesis and its separation process using the quaternary phase diagram K+, NH4+ / Cl-, SO42- - H2O at 25 °C. The experiment results show that it is possible to recover relatively pure (NH4)2SO4 from PG to re‐synthesize in presence of KCl the [K1−x(NH4)x]2SO4 phase, whose high quality and purity were confirmed by the combined use of several analytical and characterization techniques such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and gamma spectrometry analysis. The thermal decomposition was supplemented by Thermo-Gravimetric Analysis (TGA) coupled with Differential Thermal Analysis (DTA). The main findings of this study may assist in developing methods for valorizing PG waste by converting it into valuable fertilizer products, which are particularly suitable for cultivating chloride-sensitive crops. Thus, total or partial substitution of non-renewable resources by PG not only helps to solve the environmental pollution caused by this waste, but also reduces production costs and improves farm economics.

Divalent cation contributions to the co-transport and deposition of functionalized multi-walled carbon nanotubes in porous media in the presence of bentonite or goethite nanoparticles: Experiment and simulation

This work investigates the influence of cation type (Ca2+ as compared to K+) on the co-transport and deposition of functionalized multi-walled carbon nanotubes (MWCNTs) with negatively (bentonite nanoparticles, BNPs) or positively (goethite nanoparticles, GNPs) charged natural nanoparticles under the same ionic strength (IS = 1 mM) conditions. In packed column tests with quartz sand (QS), the co-transport of MWCNTs was slightly increased by BNPs and inhibited by GNPs in both CaCl2 and KCl solutions, whereas the co-transport of BNPs or GNPs was facilitated by MWCNTs in both solutions. However, the co-transport of MWCNTs in the presence of BNPs or GNPs exhibited a different dependency on the cation type in quartz crystal microbalance with dissipation (QCM-D) tests. No deposition of MWCNTs and BNPs was observed in QCM-D studies in the presence of KCl, while enhanced deposition of MWCNTs and GNPs occurred in this same solution. In contrast, the deposition of both MWCNTs and BNPs or MWCNTs and GNPs increased in QCM-D in the presence of CaCl2. In both column and QCM-D studies, Ca2+ exhibited a more significant impact on co-transport than K+, especially for MWCNTs with GNPs than BNPs. Results from molecular dynamic simulations, aggregation studies, and interaction energy calculations indicate that non-DLVO interactions (e.g., H-bonding and cation-π interaction) between two nanoparticles (MWCNTs with BNPs or GNPs) played a non-negligible role in interpreting the deposition and co-transport in the presence of the divalent cation Ca2+. Mathematical modeling of breakthrough curves and retention profiles and aggregation results suggest that both straining and competitive blocking were enhanced and played dominant roles in the co-transport of MWCNTs in the presence of BNPs or GNPs in QS, especially in the presence of Ca2+. This work sheds novel insights on the contribution of divalent cations to interactions between two colloids and their co-transport in porous media. This information is needed to assess the environmental fate and risks of engineered nanoparticles (ENPs) and natural nanoparticles in aquatic and soil environments with abundant divalent cations.

High-temperature corrosion of weld overlay coating/bulk FeCrAl exposed in O2 + H2O + KCl(s) at 600 °C – A microstructural investigation

This work investigates the impact of high-temperature corrosion behavior of the newly developed FeCrAl alloy Kanthal® EF101 bulk material and weld overlay coating in the presence of KCl(g)/KCl(s) at 600 °C. The oxide scale formed within the secondary corrosion regime after exposure and the impact of alloy microstructure on corrosion behavior was investigated using scanning transmission electron microscopy. The findings indicated the key microstructural differences is the alloy grain size which influences the formation of a protective scale. In addition, It is indicated that coating exhibited inferior performance than the bulk material, primarily attributed to the microstructural differences.

Multiple heteroatom-doped urea and thiourea-derived polymeric carbon nitride for high-performance visible light-driven photocatalytic O2 reduction to H2O2

To photocatalytically reduce O2 to H2O2 over polymeric carbon nitride (PCN) in high efficiency is essential for practical application but remains a considerable challenge. Herein, we synthesized a K, S, and O co-doped PCN (akut-CN) via one-pot polymerization of urea and thiourea in the presence of KCl and NaOH, which afforded an unprecedentedly high H2O2 production rate of 4.46 mM h–1 under visible light irradiation, about 210 times that over the un-doped PCN. The heteroatom doping and the incorporation of the cyano and hydroxyl groups into akut-CN are identified to enhance light absorption, accelerate the separation and transfer of the photogenerated charges, and improve the surface electronegativity and the O2 adsorption capacity and strength, which collaboratively boosted the reaction kinetics. This work highlights the great potential of the elaborately decorated PCN in photocatalytic O2 reduction to H2O2 and paves the way to the decentralized production and application of H2O2.

Helicity degree of carrageenan conformation determines the polysaccharide and water interactions

The polysaccharide in solution at critical concentration, Cc (g/L), is assimilated to a nano hydrogel (nHG) made of a single polysaccharide chain. Taking as reference the characteristic temperature of 20 ± 2 °C at which kappa-carrageenan (κ-Car) nHG swelling is greater with a Cc = 0.55 ± 0.05 g/L, the temperature of the minimum deswelling in the presence of KCl was found at 30 ± 2 °C for 5 mM with a Cc = 1.15 ± 0.05 g/L but not measurable above 100 °C for 10 mM of which Cc = 1.3 ± 0.05 g/L. Lowering the temperature to 5 °C, contraction of the nHG and further coil-helix transition with self-assembly increases the sample's viscosity, which steadily evolves with time in a logarithmic scale. Accordingly, the relative increment of the viscosity per unit of concentration, Rv (L/g), should increase in agreement with increasing polysaccharide concentration. But the Rv decreases for κ-Car samples above 3.5 ± 0.5 g/L in the presence of 10 mM KCl under steady shear 15 s−1. This reflects a decrease of κ-Car helicity degree knowing that the polysaccharide is rather hydrophilic when its helicity degree is the lowest.

The long-term corrosion behavior of FeCrAl(Si) alloys after breakaway oxidation at 600 °C

The long-term corrosion behavior of three FeCrAl(Si) alloys has been investigated in two environments (K2CO3 and KCl+H2O) at 600 °C. The FeCrAl alloy experienced breakaway oxidation in both environments but displayed a higher corrosion rate in KCl+H2O. The FeCrAlSi alloys retained the primary protection in the presence of K2CO3 but underwent breakaway oxidation in the presence of KCl+H2O. The FeCrAlSi alloys displayed considerably reduced corrosion rates, suggested to be an effect of the prevention of internal oxidation and the formation of non-continuous corundum-type oxide dispersed within the inward-growing scale.

A green strategy to prepare nitrogen-oxygen co-doped porous carbons from macadamia nut shells for post-combustion CO2 capture and supercapacitors

In the process of preparing heteroatom-doped carbon materials by activating biomass with conventional activators (e.g. KOH or NaOH), not only the activators are highly corrosive to the equipment, but also the heteroatom content of the prepared carbon materials is low, which limits their large-scale production. In this study, a green method was proposed to synthesize nitrogen-oxygen co-doped porous carbons in one step under air atmosphere. In the preparation process, macadamia nut shells, potassium chloride(KCl) and melamine were used as precursors, templating agents and nitrogen sources, respectively. KCl can be used as a flame retardant to allow pyrolysis in the gas stream. This process promotes pore formation and the introduction of oxygen species. The presence of KCl also reduced the loss of nitrogen during pyrolysis. The prepared porous carbon had a high nitrogen and oxygen content of 20.2 wt% and 23.3 wt%, respectively. The highest CO2 uptake of the samples was 1.39 mmol/g at 0.15 bar and 25 °C, with a selectivity of 39.33. In addition, the material exhibited an impressive specific capacitance of 254.5 F g−1 at 1 A g−1. The unique green preparation method is expected to provide new ideas for post-combustion CO2 capture and energy storage.

Citrate synthase from Cyanidioschyzon merolae exhibits high oxaloacetate and acetyl-CoA catalytic efficiency.

Citrate synthase (CS) catalyzes the reaction that produces citrate and CoA from oxaloacetate and acetyl-CoA in the tricarboxylic acid (TCA) cycle. All TCA cycle enzymes are localized to the mitochondria in the model organism, the red alga Cyanidioschyzon merolae. The biochemical properties of CS have been studied in some eukaryotes, but the biochemical properties of CS in algae, including C. merolae, have not been studied. We then performed the biochemical analysis of CS from C. merolae mitochondria (CmCS4). The results showed that the kcat/Km of CmCS4 for oxaloacetate and acetyl-CoA were higher than those of the cyanobacteria, such as Synechocystis sp. PCC 6803, Microcystis aeruginosa PCC 7806 and Anabaena sp. PCC 7120. Monovalent and divalent cations inhibited CmCS4, and in the presence of KCl, the Km of CmCS4 for oxaloacetate and acetyl-CoA was higher in the presence of MgCl2, the Km of CmCS4 for oxaloacetate and acetyl-CoA was higher and kcat lower. However, in the presence of KCl and MgCl2, the kcat/Km of CmCS4 was higher than those of the three cyanobacteria species. The high catalytic efficiency of CmCS4 for oxaloacetate and acetyl-CoA may be a factor in the increased carbon flow into the TCA cycle in C. merolae.

High temperature corrosion resistance of FeCr(Ni, Al) alloys as bulk/overlay weld coatings in the presence of KCl at 600 °C

The long-term high temperature corrosion behavior of FeCr(Ni, Al) alloys, both in bulk form and as overlay welds, was investigated in a new experimental setup, in the presence of KCl at 600 °C. All the alloys experienced breakaway oxidation, with the bulk materials exhibiting better corrosion resistance than the overlay weld coatings with similar compositions. All results indicate diffusion-controlled kinetics, and the analysis revealed an improved corrosion behavior connected to an increased Cr content in the inward-growing scale.

Sulfate groups position determines the ionic selectivity and syneresis properties of carrageenan systems

The salt sensitivity and selectivity feature of α-carrageenan (α-Car) were investigated and compared with κ-carrageenan (κ-Car) and iota-carrageenan (ι-Car). These carrageenans are identified by one sulfate group on the 3,6-anhydro-D-galactose (DA) for α-Car, D-galactose (G) for κ-Car and on both carrabiose moieties (G and DA) for ι-Car. The viscosity and temperature, where order-disorder transition have been observed, were greater in presence of CaCl2 for α-Car and ι-Car compared with KCl and NaCl. Conversely, the reactivity of κ-Car systems were greater in presence of KCl than CaCl2. Unlike κ-Car systems, the gelation of α-Car in presence of KCl was observed without syneresis. Thus, the position of sulfate group on the carrabiose determines the importance of counterion valency too. The α-Car could be a good alternative to κ-Car to reduce the syneresis effects.

Effect of electrolyte solubility and column inclination on the performance of monoethylene glycol regeneration process

AbstractIn this study, the solubilities of potassium‐chloride (KCl) in aqueous monoethylene glycol (MEG) solution and the vapour pressure of aqueous MEG solution containing KCl were investigated. A thermodynamic model was modified based on the data obtained to predict the solubilities of KCl, which was then applied to optimize the MEG regeneration process that is widely used in offshore gas fields. The solubility of KCl in the aqueous MEG solution decreased with an increase in MEG concentration and a decrease in temperature. The presence of KCl in aqueous MEG solution decreased the vapour pressure, thus increasing the boiling temperature at the corresponding pressure. A thermodynamic model based on the electrolyte non‐random two‐liquid (NRTL) coupled with the Redlich–Kwong (RK) equation of state was employed by modifying the binary interaction parameters using the experimental data. The modified model predicted the solubilities of KCl and the vapour pressure of aqueous MEG solutions, which were in good agreement with the experimental data. Moreover, the distillation column in pilot‐scale MEG regeneration was inclined to simulate the movement of the offshore platform, showing decreasing MEG concentration, possibly due to the distribution issues inside the column.