KCl Concentration Research Articles

Holey Sheets Enhance the Packing and Osmotic Energy Harvesting of Graphene Oxide Membranes.

Layered membranes assembled from two-dimensional (2D) building blocks such as graphene oxide (GO) are of significant interest in desalination and osmotic power generation because of their ability to selectively transport ions through interconnected 2D nanochannels between stacked layers. However, architectural defects in the final assembled membranes (e.g., wrinkles, voids, and folded layers), which are hard to avoid due to mechanical compliant issues of the sheets during the membrane assembly, disrupt the ionic channel pathways and degrade the stacking geometry of the sheets. This leads to degraded ionic transport performance and the overall structural integrity. In this study, we demonstrate that introducing in-plane nanopores on GO sheets is an effective way to suppress the formation of such architectural imperfections, leading to a more homogeneous membrane. Stacking of porous GO sheets becomes significantly more compact, as the presence of nanopores makes the sheets mechanically softer and more compliant. The resulting membranes exhibit ideal lamellar microstructures with well-aligned and uniform nanochannel pathways. The well-defined nanochannels afford excellent ionic conductivity with an effective transport pathway, resulting in fast, selective ion transport. When applied as a nanofluidic membrane in an osmotic power generation system, the holey GO membrane exhibits higher osmotic power density (13.15 W m-2) and conversion efficiency (46.6%) than the pristine GO membrane under a KCl concentration gradient of 1000-fold.

Flanking Effect on the Structure and Stability of Human Telomeric G-Quadruplex in Varying Salt Concentrations.

The stability of the human telomere G-quadruplex (G4) is directly linked to cancer disease. The human telomere is mostly associated with the flanking nucleobases, which can affect the stability of G4. Hence, in this study, the effect of the flanking nucleobases in the context of their chemical nature, number, and position on the structure and stability of G4 has been investigated in varying concentrations of KCl mimicking the normal and cancer KCl microenvironments. The addition of flanking nucleobases does not alter the G4 topology. However, the presence of merely a single flanking nucleobase destabilizes the telomeric G4. This destabilizing effect is more prominent for thymine than adenine flanking nucleobase, probably due to the formation of the intermolecular G4 topology by thymine. Interestingly, the change in the stability of the telomeric G4 in the presence of thymine flanking nucleobase is sensitive to the concentration of KCl relevant to the normal and cancerous microenvironments, in contrast to adenine. Flanking nucleobases have a greater impact at the 5' end compared to the 3' end, particularly noticeable in KCl concentrations resembling the normal microenvironment rather than the cancerous one. These findings indicate that the effect of the flanking nucleobases on telomeric G4 is different in the KCl salt relevant to normal and cancerous microenvironments. This study may be helpful in attaining molecular-level insight into the role of G4 in telomeric length regulation under normal and cancerous KCl salt conditions.

Interlayered double-doped N,P-MXene/ZnIn2S4 Schottky junction composite photocatalyst: Efficient removal of ciprofloxacin and methyl orange from complex wastewater

In this study, N and P were used to double doping MXene to obtain N,P-MXene with increased layer spacing and structural defects. Schottky junction N,P-MXene/ZnIn2S4 photocatalysts with tight interfacial contacts were obtained by in situ growth of flower-like ZnIn2S4 nanosheets. The N,P-MXene interlayer spatial structure facilitates the uniform dispersion of ZnIn2S4 and the exposure of the active site. The formation of the Schottky barrier enables the two closely contacted interfaces to form a carrier transport channel, which accelerates the arrival of the charge carriers on the catalyst surface for REDOX reactions. 50 N,P-MXene/ZIS degraded 86.1 % of CIP and 93.9 % of MO. In addition, after several cycling experiments, it was proved that the photocatalyst had good structure and chemical stability. The photocatalytic mechanism was demonstrated by UPS and radical quenching experiments. N,P-MXene/ZnIn2S4 is not only suitable for pH = 7–11, but also for salt solution wastewater containing higher concentrations of NaCl or KCl. Therefore, the construction of heteroatom doped N,P-MXene/ZnIn2S4 Schottky junction photocatalysts with excellent photocatalytic degradation performance is of profound significance for the treatment of pollutants.

Advanced ion-selective wood membranes: Leveraging aligned cellulose nanofibers for enhanced osmotic energy conversion

Nanofluidic reverse electrodialysis (RED) is widely recognized as an exceptionally effective method for harvesting osmotic energy. Nevertheless, its progress has been impeded by the high costs and intricate fabrication processes associated with the required ion exchange membranes. The ion-selective wood membranes (ISWM) are derived directly from natural wood through a meticulously designed two-step chemical modification and densification process. The obtained ISWM with a highly charged surface effectively preserves the alignment of nanochannels from the cellulose fibers sourced in natural wood. Moreover, the laminated structure consisting of oriented nanofibers enhances ion conductivity by a factor of 4 compared to natural wood birch under low KCl concentrations. The charged and aligned nanochannels serve as nanofluidic conduits, facilitating selective ion transport. This, in turn, engenders efficient charge separation and the generation of an electrochemical potential difference. In energy harvesting systems such as ISWM-RED, the synergistic interplay between the electrochemical potential difference and ionic flux manifests in a remarkable output power density, reaching up to 658 mW m−2 to a salinity gradient of KCl at a magnitude of 50-fold. ISWM is an outstanding nanofluidic material that provides a cost-effective and easy-to-prepare solution for producing natural nanofluidic materials. Our investigation delineates a promising trajectory for developing high-performance nanofluidic RED devices tailored for efficient osmotic energy harvesting from renewable and abundant natural resources.

Biomimetic kartogenin containing κ-carrageenan hydrogel for nucleus pulposus regeneration

Intervertebral disc degeneration is a clinical disease that reduces the quality of patient's life. The degeneration usually initiates in the nucleus pulposus (NP) and hence the use of hydrogels represents a promising therapeutic approach. However, the viscoelastic nature of hydrogel and its ability to provide biomimetic architecture and biochemical cues influence the regeneration capability. This study focused on tuning the physical nature of a glycosaminoglycan hydrogel (κ-carrageenan) as well as the release kinetics of a chondrogenic factor (Kartogenin - KGN) through physical crosslinking. For this, κ-carrageenan was cross linked with 2.5 % and 5 % potassium chloride (KCl) for 15 and 30 min and loaded with KGN molecule at 50 μM and 100 μM. The tight network structure with low water retention and degradation property was seen in hydrogel cross linked with increased KCl concentration and time. However, optimal degradation along with NP mimicking viscoelastic nature was exhibited by 5 wt% KCl treated hydrogel. All hydrogel groups exhibited burst KGN release at 24 h followed by a sustained release for 5 days. Finally, hydrogel cross linked with 5 wt% KCl enhanced chondrogenic differentiation, mainly at lower KGN dose. In summary, this study shows the potential application of biomimetic KGN laden carrageenan hydrogel in NP regeneration.

Advanced ion-selective wood membranes: Leveraging aligned cellulose nanofibers for enhanced osmotic energy conversion

Nanofluidic reverse electrodialysis (RED) is widely recognized as an exceptionally effective method for harvesting osmotic energy. Nevertheless, its progress has been impeded by the high costs and intricate fabrication processes associated with the required ion exchange membranes. The ion-selective wood membranes (ISWM) are derived directly from natural wood through a meticulously designed two-step chemical modification and densification process. The obtained ISWM with a highly charged surface effectively preserves the alignment of nanochannels from the cellulose fibers sourced in natural wood. Moreover, the laminated structure consisting of oriented nanofibers enhances ion conductivity by a factor of 4 compared to natural wood birch under low KCl concentrations. The charged and aligned nanochannels serve as nanofluidic conduits, facilitating selective ion transport. This, in turn, engenders efficient charge separation and the generation of an electrochemical potential difference. In energy harvesting systems such as ISWM-RED, the synergistic interplay between the electrochemical potential difference and ionic flux manifests in a remarkable output power density, reaching up to 658 mW m−2 to a salinity gradient of KCl at a magnitude of 50-fold. ISWM is an outstanding nanofluidic material that provides a cost-effective and easy-to-prepare solution for producing natural nanofluidic materials. Our investigation delineates a promising trajectory for developing high-performance nanofluidic RED devices tailored for efficient osmotic energy harvesting from renewable and abundant natural resources.

Effect of Salt Content on Solubilization of Hydrophobic Polymer by Wormlike Micelles of Ionic Surfactant

The effect of concentration of inorganic salt KCl on solubilization of hydrophobic polymer poly(4-vinylpyridine) (P4VP) in aqueous solutions of ionic surfactant potassium oleate was experimentally investigated. As was shown by rheology, in the range of concentrations from 1 to 5 wt.% of salt the polymer-free solutions of surfactant mainly contain linear wormlike micelles (WLMs). The formation of branched WLMs was observed in the solutions containing 5-9 wt.% of KCl. In the presence of higher salt content the phase separation occurred, indicating the formation of a highly branched saturated network of WLMs. Enhanced screening of the charged groups of potassium oleate by oppositely charged ions of KCl caused elongation and branching of micelles that reflected in zero-shear viscosity of the solutions passing through the maximum. In the phase diagram, the saturation concentration with P4VP of both linear and branched WLMs decreased with increasing salt content. In the case of linear WLMs, this could be explained by the constant number of embedded polymer chains per 1 WLM, while simultaneously decreasing number of WLMs in the system. As for the branched WLMs, it was caused by shortening of the linear parts of micelles due to the formation of branching points. For this reason, almost no P4VP was dissolved in the solution containing the highly branched saturated network.

Pattern formation by the drying of saline droplets on pillars

The application of saline solutions for surface coating is pertinent across multiple biomedical fields, various technological sectors, and industries, including agriculture. The drying of salt solution droplets is key to understanding and controlling morphological structures on surfaces. In this paper, we report the study of pattern formation from the evaporation of saline drops (NaCl, CsCl, and KCl) placed on pillars. Our findings indicate that regardless of saline concentration and type, the drying process can be categorized into three modes: stable, metastable, and unstable. In both the stable and metastable modes, the droplet fixes to the pillar during the drying process and ensuing pattern formation; however, the crucial distinction lies in the metastable mode, where the droplet additionally undergoes mass loss through fluid drainage from the walls of the pillars. Conversely, in the unstable drying mode, the droplet undergoes rapid collapse, leading to a substantial loss of mass. The distinct drying modes dictate the resulting patterns on the pillars. We employ measurements of configurational entropy and fractal dimension as quantitative metrics to assess the complexity, reproducibility, and similarity of patterns. The texture analysis reveals that, at low concentrations of both CsCl and KCl, significant differences emerge among the patterns produced by the different drying modes, especially highlighting differences in patterns of the stable drying mode. Finally, we analyze fertilizer deposition patterns to prove that all three drying modes can occur in complex fluids.

Fabrication of k-Carrageenan/Alginate/Carboxymethyl Cellulose basedScaffolds via 3D Printing for Potential Biomedical Applications.

Three-dimensional (3D) printing technology was able to generate great attention because of its unique methodology and for its major potential to manufacture detailed and customizable scaffolds in terms of size, shape and pore structure in fields like medicine, pharmaceutics and food. This study aims to fabricate an ink entirely composed of natural polymers, alginate, k-carrageenan and carboxymethyl cellulose (AkCMC). Extrusion-based 3D printing was used to obtain scaffolds based on a crosslinked interpenetrating polymer network from the alginate, k-carrageenan, carboxymethyl cellulose and glutaraldehide formulation using CaCl2, KCl and glutaraldehyde in various concentrations of acetic acid. The stabile bonding of the crosslinked scaffolds was assessed using infrared spectroscopy (FT-IR) as well as swelling, degradation and mechanical investigations. Moreover, morphology analysis (µCT and SEM) confirmed the 3D printed samples' porous structure. In the AkCMC-GA objects crosslinked with the biggest acetic acid concentration, the values of pores and walls are the highest, at 3.9 × 10-2 µm-1. Additionally, this research proves the encapsulation of vitamin B1 via FT-IR and UV-Vis spectroscopy. The highest encapsulation efficiency of vitamin B1 was registered for the AkCMC-GA samples crosslinked with the maximum acetic acid concentration. The kinetic release of the vitamin was evaluated by UV-Vis spectroscopy. Based on the results of these experiments, 3D printed constructs using AkCMC-GA ink could be used for soft tissue engineering applications and also for vitamin B1 encapsulation.

Preparation of α-calcium sulfate hemihydrate with high mechanical strength from natural fibrous gypsum in KCl-mediated glycerol-water solution

Natural fibrous gypsum is a kind of high-quality gypsum resources, whose high-value added utilization pathway is to be transformed to α-calcium sulfate hemihydrate (α-HH), a cementitious material that can react with water to form pastes with mechanical strength. In this work, α-HH was prepared from natural fibrous gypsum in KCl mediated glycerol-water solution under mild condition. KCl played a simultaneous function on regulating the phase-transition kinetics, morphology and comprehensive strength of α-HH. Addition of low concentration of KCl prominently retarded the nucleation and growth rate of α-HH and decreased its aspect ratio due to the formation of syngenite on the side faces. While further increase of KCl concentration accelerated the nucleation and growth rate and decreased the crystal sizes. In the presence of 0.04 M KCl, the prepared α-HH presented a hexagonal prism shape with a length / width of 257.69–579.71 μm / 13.13–36.61 μm, and its dry comprehensive strength had reached 38.1 MPa that was comparable to those prepared in commercial, chloride and nitrate system. Altogether, the foreign ion-free glycerol-water solution contributed to transforming natural fibrous gypsum to α-HH with high purity and high mechanical strength.

Implications of high homocysteine levels in migraine pain: An experimental study of the excitability of peripheral meningeal afferents in rats with hyperhomocysteinemia.

Investigation of chronic homocysteine action on the excitability and N-methyl-D-aspartate (NMDA) sensitivity of the peripheral trigeminovascular system of rats. Migraine is a neurological disease that affects 15%-20% of the general population. Epidemiological observations show that an increase of the sulfur-containing amino acid homocysteine in plasma-called hyperhomocysteinemia-is associated with a high risk of migraine, especially migraine with aura. In animal studies, rats with hyperhomocysteinemia demonstrated mechanical allodynia, photophobia, and anxiety, and higher sensitivity to cortical spreading depression. In addition, rats with hyperhomocysteinemia were more sensitive in a model of chronic migraine induced by nitroglycerin which indicated the involvement of peripheral nociceptive mechanisms. The present work aimed to analyze the excitability of meningeal afferents and neurons isolated from the trigeminal ganglion of rats with prenatal hyperhomocysteinemia. Experiments were performed on male rats born from females fed with a methionine-rich diet before and during pregnancy. The activity of meningeal afferents was recorded extracellularly in hemiskull preparations exvivo and action potentials were characterized using cluster analysis. The excitability of trigeminal ganglion neurons was assessed using whole-cell patch clamp recording techniques and calcium imaging studies. Meningeal mast cells were stained using toluidine blue. The baseline extracellular recorded electrical activity of the trigeminal nerve was higher in the hyperhomocysteinemia group with larger amplitude action potentials. Lower concentrations of KCl caused an increase in the frequency of action potentials of trigeminal afferents recorded in rat hemiskull exvivo preparations. In trigeminal ganglion neurons of rats with hyperhomocysteinemia, the current required to elicit at least one action potential (rheobase) was lower, and more action potentials were induced in response to stimulus of 2 × rheobase. In controls, short-term application of homocysteine and its derivatives increased the frequency of action potentials of the trigeminal nerve and induced Ca2+ transients in neurons, which are associated with the activation of NMDA receptors. At the same time, in rats with hyperhomocysteinemia, we did not observe an increased response of the trigeminal nerve to NMDA. Similarly, the parameters of Ca2+ transients induced by NMDA, homocysteine, and its derivatives were not changed in rats with hyperhomocysteinemia. Acute incubation of the meninges in homocysteine and homocysteinic acid did not change the state of the mast cells, whereas in the model of hyperhomocysteinemia, an increased degranulation of mast cells in the meninges was observed. Our results demonstrated higher excitability of the trigeminal system of rats with hyperhomocysteinemia. Together with our previous finding about the lower threshold of generation of cortical spreading depression in rats with hyperhomocysteinemia, the present data provide evidence of homocysteine as a factor that increases the sensitivity of the peripheral migraine mechanisms, and the control of homocysteine level may be an important strategy for reducing the risk and/or severity of migraine headache attacks.

Experimental solubility of FeCO3 in aqueous 3–20 wt% KCl at 25–80 °C

FeCO3 is a mineral, present in both industrial and natural systems. While the solubility of FeCO3 is determining for CO2 storage, and driving for corrosion, it is not well understood. For the development of rigorous modelling, there is a lack of adequate experimental data under relevant conditions to model carbonated systems containing iron.In this work, the solid-liquid equilibrium (SLE) of the ternary system FeCO3-KCl-H2O was measured at atmospheric pressure at temperatures from 25 to 80 °C. The FeCO3 solubility was studied in aqueous KCl solutions from 3 to 20 wt%. 73 new solubility data points for the systems FeCO3–KCl–H2O are presented together with 73 oxidation data points. Results showed that less than 5% of FeCO3 is oxidized in the electrolyte system. The equilibrium concentration of FeCO3 was obtained after 5–10 days with the fastest equilibrium kinetics obtained at the highest temperature, 80 °C. Temperature had a minor impact on the FeCO3 solubility in aqueous KCl solutions. However, the FeCO3 solubility seemed to slightly decrease with temperature. The solubility data was fitted to a first-order rate equation with molality as driving, to obtain kinetic insights. The dissolution rate decreases as a function of KCl concentrations. In some cases, it was 75 % lower than in NaCl. A rate constant of approximately 0.2 1/day was obtained for most experiments. The FeCO3 solubility and kinetic data obtained in this work will allow for a deeper understanding and better prediction of CO2 corrosion and mineralization, suitable for CO2 storage.

A novel sonoelectrochemical approach for preparing of ZnO nanoparticles

A novel, rapid, and facile method for one-step sonoelectrochemical synthesis of zinc oxide nanoparticles (UEZ) was introduced in this study. The optimum operating parameters have been selected at a voltage of 7.5 V, KCl concentration of 0.5 M, and the reaction time of 60 min. The as-prepared UEZ were characterized by XRD, SEM, and HRTEM. It was found that the UEZ has a hexagonal wurtzite structure with high crystalline quality, good purity, a size range of 30–100 nm, and good photocatalytic degradation of methylene blue. This work provides a facile route for large-scale synthesizing ZnO nanoparticles via anodization.

Accurate ion type and concentration detection using two bare electrodes by machine learning of non-faradaic electrochemical impedance measurements of an automated fluidic system

Detecting ion types and their concentrations in multi-ion aqueous solutions poses a complex challenge with significant implications for sensing applications. This paper introduces an automated fluidic system using two bare electrodes to measure electrochemical impedance spectroscopy (EIS) data and evaluates deep neural network (DNN) for ion type and concentration detection. Additionally, a data-augmentation model is proposed for non-faradaic voltage sweep EIS data, intended for neural network training. To validate the effectiveness of our approach, prepared solutions featuring varying concentrations of LiCl, NaCl, and KCl are experimented. Impedance (Z) vs DC bias voltage (V) data, i.e., ZV-EIS are measured from −400 mV to + 400 mV at 9 different frequencies up to ∼ 200 kHz, for 148 automatically prepared solutions, having total salt concentrations up to 200 mM. DNN models are trained with augmented samples and successfully identified individual ions in test set solutions and their concentrations with 4.51 mM average deviation. The study delves into the nuanced impacts of factors such as sampling voltage window, and measurement frequency on the performance of the machine learning models, 8 mV and 20 Hz giving the most significant results.

Experimental investigation of the rheological behavior and micro-morphology of the wormlike micelle cross-linked with polyelectrolyte-grafted nano silica and the associative polymer

This paper has investigated the rheological behavior and micro-morphology of CTAC wormlike micelle (WLM) which cross-linked with polyelectrolyte-grafted nanosilica (PEN) and nonionic hydrophobically-associating polymer (HAP). Cryo-transmission electron microscopy (Cryo-TEM) is adopted to observe the micro-morphology of the associative structure. Results show that PEN cross-linked with CTAC wormlike micelle exhibits higher zero-shear viscosity than the non-modified nano silica, and this viscosity is continuously raised as the PEN concentration is increased. PEN-micelle complex has excellent anti-salt properties and its zero-shear viscosity is increasing in a KCl concentration range of 0–10%. The shear viscosity of wormlike micelle is enhanced by HAP and polymer molecules dominate the rheological characteristic of the mixed fluid. The shear viscosity of HAP-micelle fluid is further increased by PEN. However, the rheological characteristic of the micelle-HAP-PEN complex is identical to that of wormlike micelle. The elasticity of wormlike micelle is noticeably enhanced by cross-linking with PEN and HAP. They stimulate the formation of micelle to significantly increase the length and rigidity of wormlike micelle. Surfactant molecules spontaneously arrange on the surface of PEN and grow outwards, which associates with HAP to generate the tighter three-dimensional network structure.

Wetting and evaporation behavior of dilute sodium dodecyl sulfate droplets on soft substrates under a direct current electric field

Wetting and evaporation behavior of dilute sodium dodecyl sulfate (SDS) droplets on planar polydimethylsiloxane (PDMS) surfaces under a direct current (DC) electric field were experimentally investigated. Two characteristic voltages—actuation voltage and saturation voltage were observed in the electrowetting of dilute SDS droplets on PDMS surfaces. It was found that for dilute SDS droplets with a fixed SDS concentration substrate elasticity has an obvious influence on actuation voltage, and saturation voltage increased with the increase of mass ratio of PDMS surfaces. SDS concentration was also found to obviously influence actuation voltage and saturation voltage when SDS concentration was in a certain range. For the case of evaporation of sessile dilute SDS droplets on PDMS surfaces with the application of a DC electric field, substrate elasticity, SDS concentration and the magnitude of applied voltage were all found to have an influence on the duration of CCR stage. Moreover, contact angle hysteresis for dilute SDS droplets on a planar PDMS 10:1 surface under different applied voltage was measured and it was found that the magnitude of applied voltage greatly influenced contact angle hysteresis, which also depends on SDS concentration and KCl concentration.

Evaluation of Chronic Effects of Potassium Chloride and Nickel on Survival, Growth, and Reproduction of a Unionid Mussel (Lampsilis siliquoidea).

The ASTM International standard test method for freshwater mussels (E2455-13) recommends 4-week toxicity testing with juveniles to evaluate chronic effects on survival and growth. However, concerns remain that the method may not adequately address the sensitivity of mussels to longer term exposures (>4 weeks), particularly in relation to potential reproductive impairments. No standard method directly evaluates toxicant effects on mussel reproduction. The objectives of the present study were to (1) evaluate toxicity endpoints related to reproduction in fatmucket (Lampsilis siliquoidea) using two common reference toxicants, potassium chloride (KCl) and nickel (Ni); (2) evaluate the survival and growth of juvenile fatmucket in standard 4-week and longer term (12-week) KCl and Ni tests following a method refined from the standard method; and (3) compare the sensitivity of the reproductive endpoints with the endpoints obtained from the juvenile mussel tests. Reproductive toxicity tests were conducted by first exposing female fatmucket brooding mature larvae (glochidia) to five test concentrations of KCl and Ni for 6 weeks. Subsamples of the glochidia were then removed from the adults to determine three reproductive endpoints: (1) the viability of brooded glochidia; (2) the viability of free glochidia in a 24-h exposure to the same toxicant concentrations as their mother; and (3) the success of glochidia parasitism on host fish. Mean viability of brooded glochidia was significantly reduced in the high KCl concentration (26 mg K/L) relative to the control, with a 20% effect concentration (EC20) of 14 mg K/L, but there were no significant differences between the control and any Ni treatment (EC20 > 95 µg Ni/L). The EC20s for viability of free glochidia after the additional 24-h exposure and parasitism success were similar to the EC20s of brooded glochidia. The EC20s based on the most sensitive biomass endpoint in the 4-week juvenile tests were 15 mg K/L and 91 µg Ni/L, similar to or greater than the EC20s from the reproductive KCl and Ni tests, respectively. When exposure duration in the juvenile tests was extended from 4 to 12 weeks, the EC20s decreased by more than 50% in the KCl test but by only 8% in the Ni test. Overall, these results indicate that a standard 4-week test with juvenile mussels can prove effective for estimating effects in chronic exposures with different life stages although a longer term 12-week exposure with juvenile mussels may reveal higher sensitivity of mussels to some toxicants, such as KCl. Environ Toxicol Chem 2024;43:1097-1111. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Grain growth of ice doped with soluble impurities

Abstract. The grain size of polycrystalline ice affects key parameters related to the dynamics of ice masses, such as the rheological and dielectric properties of terrestrial ice as well as the ice shells of icy satellites. To investigate the effect of soluble impurities on the grain-growth kinetics of polycrystalline ice, we conducted annealing experiments on polycrystalline ice samples doped with different concentrations of KCl (10−2, 10−3, 10−4 and 10−5 mol L−1) or MgSO4 (10−2 and 10−5 mol L−1). Samples were annealed for a maximum of 100 h at a hydrostatic confining pressure of 20 MPa (corresponding to a depth of about 2 km) and different constant temperatures of 268, 263, 258 and 253 K (corresponding to −5, −10, −15 and −20 °C, respectively). After each experiment, images of a polished sample surface were obtained using an optical microscope equipped with a cold stage. With grain boundaries detected, grains were reconstructed from the images, and an average grain size was determined for each sample. Normal grain growth occurred in all samples. Grain-size data are interpreted using the following grain-growth model: dn-d0n=kt (d: grain size; d0: starting grain size; n: grain-growth exponent; k: growth constant; t: duration). Values of the best-fit grain-growth exponent, n, for all samples range from 2.6 to 6.2, with an average value of 4.7. Pure ice exhibits 3.1 ⩽n⩽ 4.6, with an average value of 3.8. Above the eutectic point, soluble impurities enhance grain growth, as a melt phase is formed, and it could provide a fast diffusion pathway. Below the eutectic point, soluble impurities impede grain growth probably via the formation of salt hydrates that could pin the grain boundaries. Close to the eutectic point, the grain growth of doped ice is similar to pure ice. Natural ice is impure, often containing air bubbles and soluble impurities, and is usually subjected to a hydrostatic pressure. Our data set will provide new insights into the evolution of grain size within and the dynamics of natural ice masses.

The impact of chlorine and sulfur on alkali metal migration and submicron particle formation during solid fuel combustion

Submicron particles (PM1) emission from the incineration of solid fuels rich in chlorine, sulfur, or alkali metal elements pose environmental and health concerns for humans. The current understanding of the interactions between these elements and PM1 formation is extensive, but it still lacks a systematic approach. This paper establishes a comprehensive model to predict the migration process of Cl, S, and alkali metals during solid fuel combustion by adding Cl, S, and K additives. The model is divided into combustion, vaporization, nucleation and condensation, and coagulation sub-models. The model predicts that K, Cl, and S additives will not cause changes in fuel's burnout time and temperature. While these additives each promotes the vaporization rate of sodium to varying degrees, for example, the vaporization rate with +K + S is much lower than with +K + Cl. Also, the model calculates that the addition of SO2 significantly inhibits the formation of KCl. In the Sufco + K condition, introducing SO2 reduces the concentration of KCl by about 80%, but if Cl is added, the concentration increases by approximately four times. Predictions were also made for the changes in K2SO4, NaCl, and Na2SO4 under different conditions. After adding K, Cl, and S, the production of PM1 significantly increased, and the peak shifted towards larger size with +K + Cl producing more PM1. Overall, the predicted results align well with the experimental findings. The model's systematic construction of the interactions between chlorine, sulfur, and alkali metal elements and the formation mechanism of PM1 provides a more complete picture of solid fuel combustion emissions.

Bamboo stem derived biochar for biosorption of Cadmium (II) ions from contaminated wastewater

Cadmium in surface waters and the environment beyond the maximum allowed quantities without pre-treatment is hazardous. Bamboo stem biomass adsorption capability for Cd2+ remediationfrom heavy metal-polluted wastewater will be examined to prevent recurrence. The experiment controlled biosorbent dosage, contact length, pH, temperature, and beginning Cadmium concentration for the optimum remediation. Cd2+ was best removed at pH 5 with contact time was 90 min at 298 K. Adsorption observed was 4.17 mg/g at 298 K with 4.13 mg/g Cd2+ sorbed in 90 min. Metal ion concentration reached upto 80.98 % with qe 2.01 mg/g while the desorption 91.3 % at 0.05 M of HCl. The kinetic study showed that it follows Lagergren psuedo-second order reaction, Langmuir, and Freundlich models. The bamboo stem biomass performed better at all cadmium concentrations, with heavy metal removal increasing with concentration. According to the results, bamboo stem biomass is effective in heavy metal removal from wastewater. SEM shows biochar has longitudinal pores and arough surface. Biochar has significant KCl concentration due to its sharp, strong XRD peaks. These findings suggest that bamboo stem biomass is effective in removing heavy metals from wastewater.