Alkaline Ions Research Articles

Alkali activation of blast furnace slag using Bayer red mud as an alternative activator to prepare cemented paste backfill

Alkali-activated materials (AAMs) are increasingly used in mine backfilling as substitutes for Ordinary Portland Cement (OPC) due to their superior performance and environmental advantages. However, the high cost of commercially available alkaline activators such as sodium hydroxide and sodium silicate limit the widespread use of AAMs. This study investigates the use of Bayer red mud (RM) as an alternative activator to sodium hydroxide (SH), with blast furnace slag (BFS) as the precursor. Cemented paste backfill (CPB) was prepared by replacing 75% of OPC with these AAMs, combined with tailings and water. The results showed that CPB made with AAMs exhibited significantly better mechanical properties, with a 57% to 94% increase in uniaxial compressive strength (UCS) at 28 days compared to CPB made with OPC. Even with an RM-to-SH ratio of 2:1, UCS improved by 3% over SH-only samples. Analysis of hydration products and microstructure revealed that RM provides more alkaline ions, enhancing the formation of calcium-alumino-silicate-hydrate (C-A-S-H) and effectively filling capillary pores. This study demonstrates a cost-effective, environmentally friendly approach for producing AAMs, highlighting RM's potential as a sustainable alternative to commercial activators for CPB applications.

Garnet-Type Zinc Hexacyanoferrates as Lithium, Sodium, and Potassium Solid Electrolytes

Sodium-ion batteries offer an attractive alternative to lithium-based chemistries due to the lower cost and abundance of sodium compared to lithium. Using solid electrolytes instead of liquid ones in such batteries may help improve safety and energy density, but they need to combine easy processing with high stability toward the electrodes. Herein, we describe a new class of solid electrolytes that are accessible by room-temperature, aqueous synthesis. The materials exhibit a garnet-type zinc hexacyanoferrate framework with large diffusion channels for alkaline ions. Specifically, they show superionic behavior and allow for facile processing into pellets. We compare the structure, stability, and transport properties of lithium-, sodium-, and potassium-containing zinc hexacyanoferrates and find that Na2Zn3[Fe(CN)6]2 achieves the highest ionic conductivity of up to 0.21 mS/cm at room temperature. In addition, the electrochemical performance and stability of the latter solid electrolyte are examined in solid-state sodium-ion batteries.

Hydro-geochemistry and age-dependent health risk assessment of nitrate, nitrite, and fluoride in health facilities water: a multivariate analysis.

Groundwater from alluvial fan plains is the prevailing water source, especially for arid/semiarid regions, but its contamination poses substantial risks to water supply and public health. The recent study aims to assess the hydro-geochemistry, distribution, and potential health risks of NO3-, NO2-, and F- concentrations in the groundwater of previously unexplored health facilities in District Vehari, Punjab, Pakistan. In total, 75 groundwater samples were evaluated for NO3-, NO2-, and F- levels as well as pH, EC, TDS, CO32-, HCO3-, Cl-, Na+, Fe, K+, Ca2+, Mg2+, taste, odor, color, and turbidity. The Durav graph shows that the water type is Na-HCO3-Ca, with Na and HCO3 dominant, weak acids > strong acids, and alkaline ions > alkalis. Results revealed that drinking water samples (21.73% and 20%) taken from Tehsil Mailsi, and the Basic Health Unit (BHU) exceeded the WHO standard (1.5mg/L) for F- concentration, respectively. Moreover, the mean chronic daily intake (CDI) of F- was 0.044, 0.018, and 0.02mg/kg/day in children, men, and women, respectively. Similarly, the average CDI of NO3- was 0.113, 0.046, and 0.050 in children, men, and women, respectively, and the respective values of NO2- were 0.004, 0.001, and 0.001. The NO2- shows a significant range of hazard quotient (HQ) (0.0-1.172) in children. The range of HQ for F- was 0.0-3.114, 0.0-1.290, and 0.0-1.389 in children, men, and women, respectively. Additionally, the health risks analysis revealed an HQ > 1.0 for children in groundwater, indicating a potential carcinogenic risk from the F-. Pearson correlation and PCA analysis found a significant positive correlation (0.8) between NO3- and NO2- and a negative correlation (0.3) between F- and HCO3-. These findings highlight the need for groundwater treatment in healthcare facilities prior to water consumption. Enforcing international and national drinking water standards in healthcare units is vital to strengthening services and providing equitable access to safe drinking water. Legislative and efficient water management measures must be taken for the protection of public health.

Mono-/Bimetallic Doped and Heterostructure Engineering for Electrochemical Energy Applications.

Designing efficient materials is crucial to meeting specific requirements in various electrochemical energy applications. Mono-/bimetallic doped and heterostructure engineering have attracted considerable research interest due to their unique functionalities and potential for electrochemical energy conversion and storage. However, addressing material imperfections such as low conductivity and poor active sites requires a strategic approach to design. This review explores the latest advancements in materials modified by mono-/bimetallic doped and heterojunction strategies for electrochemical energy applications. It can be subdivided into three key points: (i) the regulatory mechanisms of metal doping and heterostructure engineering for materials; (ii) the preparation methods of materials with various engineering strategies; and (iii) the synergistic effects of two engineering approaches, further highlighting their applications in supercapacitors, alkaline ion batteries, and electrocatalysis. Finally, the review concludes with perspectives and recommendations for further research to advance these technologies.

Surface modification of geopolymer coatings with polymethylhydrosiloxane-tetraethyl orthosilicate (PMHS-TEOS) for inhibiting efflorescence

Geopolymer coatings, as novel environmentally friendly inorganic coating, hold promising prospects in the field of concrete protection due to their characteristics such as corrosion resistance and fire resistance. However, its vulnerability to efflorescence can alter surface colouration and damage the structural integrity of the surface film, thereby diminishing its concrete protective efficacy. To inhibit efflorescence in geopolymer coatings, this study reports a surface modification method using polymethylhydrosiloxane-tetraethyl orthosilicate (PMHS-TEOS) for the first time. To explore the underlying mechanism, the effects of PMHS-TEOS on the geopolymer gel structure, mechanical properties, and ion leaching concentration were investigated. The experimental results indicate that PMHS-TEOS can penetrate the surface of geopolymer coatings and participate in the activation reaction, generating a new gel phase that effectively fills pore structure. Moreover, its hydrophobic groups facilitate the establishment of a waterproof structure, thereby inhibiting water infiltration and alkaline ion leaching. After PMHS-TEOS modification, the contact angle of the geopolymer coating reached 136.5°, demonstrating excellent wear resistance. The dissolution rate of alkaline cations in the modified geopolymer coatings was reduced by approximately 90 % and no efflorescence was observed in the long-term accelerated tests. This method is convenient for practical engineering of geopolymer coatings.

Effect of Ni Addtion on Electroless Cu for High Density Interconnect PCB Substrate

Introduction Nowadays, high-density interconnect (HDI) printed circuit board (PCB) substrates have been widely applied to high-end electronics to meet the increasing input and output (I/O) density and small footprint area. Micro-via, a tiny structure buried among build-up layers that provide electrical interconnection is a key component in the HDI substrate. However, the preparation of micro-via is facing new challenges. It is not only required that the size of the micro-via scales down to meet the increased interconnect density, but also that the micro-via should withstand severe operating conditions in different scenarios. Therefore, it is of great importance to improve the quality of micro-vias during processing and manufacturing. The micro-via structure is a sandwich structure that is processed by electroless Cu plating and Cu electrolyte plating sequentially, and thus the quality of the electroless Cu layer can significantly affect the reliability of micro-via. In this work, we mainly focused on the electroless Cu plating process and investigated the effect of the electroless Cu deposition speed on the quality of the micro-via structure. SIM and HR-TEM characterizations were employed to investigate the micro-structure inside the electroless Cu layer. Materials and Method In this study, we used the common alkaline ion catalyst method to prepare the electroless Cu layer. The electroless Cu plating and electrolyte Cu plating was conducted on a PCB Resin Coated Copper (RCC) substrate that was cleaned by soft etching in an acid condition. The surface is then pre-dipped in an anionic solution, and palladium ions were adsorbed using an alkaline ion catalyst. The electroless Cu processes adopted in a reaction bath that consists of Cu resource (CuSO4·5H2O), complexing agent (KNaC4H4O6·4H2O) and reductant (HCHO). The whole reaction was conducted in the alkaline condition with a PH of 12.5, and the thickness of the electroless Cu deposition was controlled at around 0.20 µm. NiSO4 is selected as the Ni precursor to alter the Ni concentration in the reation bath. The contents of Ni addition were selected as 50 %, 100 %, 200 % and 300% of a conventional process at a bath temperature of 27 ºC. The thickness of the plated Cu layer was measured by a gravimetric method. Results and discussion TEM observation was used to identify the structure at the interface. Fig. 1 shows the TEM observation of the sample with 50 % and 200 % Ni concentrate. There are some nanovoids found at the interface between the Cu substrate and electroless Cu, which is arguably due to hydrogen generated during electroless Cu plating. The sample with a higher reaction speed has more nanovoids. It can be due to that the higher reaction speed can generate more hydrogen bubbles in the bath that can attach to the electroless Cu layer, leading to nanovoids as shown in Fig. 1. The samples prepared at different bath temperatures are under investigation to illustrate that the reaction speed can significantly affect the Cu electroless layer quality. Conclusions In this work, we investigated the Ni effect in electroless Cu on the RCC substrate. It is found that the higher Ni incorporation can lead to massive nanovoids generation and fine Cu grains in the electroless layer, which is a potential risk for the reliability of the HDI substrate. By reducing the Ni incorporation content, the number of nanovoids can be effectively reduced. Figure 1

Assessment of Water Quality Index Study of River Chambal at Gandhisagar, Mandshour Madhya Pradesh, India

Abstract: Water is one of the earth most important resources that use for Human life and it, s quality is totally depend on geological environment. Chambal is an important river in Mandshour M.P. Hence made to WQI and Pollution or change in the quality of water. The Quality Index (WQI) Is an important tool to determine the drinking water quality in rural, urban, agriculture and industrial area. WQI follows four step parameter selection, sub-indices, establishing weight, and final index aggregation. Assessment of WQI of River Chambal includes physic-chemical parameter viz. Biological Oxygen Demand, Dissolved Oxygen, PH , Total Hardness, Total alkaline ions and solids thate indicate the extent of pollution.

Excellent performance of Ag6Si2O7 oxidase mimic endowed by self-released ions for rapid colorimetric determination with reduced operational interference

Increasing attention has been directed towards oxidase mimics due to their catalytic ability toward enzyme substrates in the absence of H2O2, offering great colorimetric sensing potential in assays and diagnostics. However, slow electron-transfer and unstable absorbance over time often lead to unsatisfactory enzymatic reaction rates and unreliable readouts, significantly reducing detection efficiency and accuracy. Herein, we report on an Ag6Si2O7 nanozyme utilizing 3,3′,5,5′-tetramethylbenzidine (TMB) as a chromogenic substrate, demonstrating excellent oxidase-like activity and long-term stable colorimetric signals. Experimental results reveal that the excellent catalytic kinetics of Ag6Si2O7 (Km = 0.197 mM, Vmax = 5.1 × 10−7 M/s) are attributed to ultrafast electron transfer between Ag+ and TMB, mediated by Ag2O intermediates formed from self-released alkaline ions. Additionally, self-released H2SiO42− improves the stability of the oxidized substrate, resulting in a long-term stable colorimetric signal (∼20 min), which exhibits reliable accuracy regardless of the time point at which analyte is added within 20 min, thus eliminating the interference of individual operation time errors. Ascorbic acid (AA) is selected as the target molecule to assess the performance of the Ag6Si2O7-TMB colorimetric sensing system. This approach demonstrates a wide detection range from 5 to 300 μM and a detection limit of 0.452 μM. The developed colorimetric sensing strategy exhibits good stability, specificity, rapidity, and potential application in real sample detection.

Involvement of Hg-bearing methane seeps in forming Ediacaran cap carbonate in South China

During the Cryogenian-Ediacaran transition, an extremely cold climate transitioned into a warm climate which was accompanied by the worldwide precipitation of cap carbonates showing striking negative carbonate carbon isotope (δ13Ccarb) anomalies. High mercury (Hg) contents up to 180 ppb have been reported from the Doushantuo cap carbonates, but the origin of Hg anomalies and its relationship with cap carbonate precipitation remain unclear. To address these issues, we measured Hg concentrations and isotopes along with total organic carbon (TOC) content and δ13Ccarb from the basal Ediacaran carbonates at the Jiulongwan section of western Hubei Province, South China. The results show that in laterally persistent intervals, Hg spikes (as high as 77 ppb) co-occur with decrease of Δ199Hg values (as low as 0.07‰), increase of δ202Hg values (−1.47‰), and conspicuous negative δ13Ccarb shifts (as low as ca. -17‰). Such Hg isotopic signature with high Hg concentration are comparable to those of natural gas hydrates and thus are ascribed to be an involvement of Hg-bearing methane seeps in precipitation of cap carbonate after melting of ice-sheets of the Marinoan glaciation (latest Cryogenian). Anaerobic oxidation of methane from hydrates via sulfate reduction may have produced bicarbonate (HCO3−), which was transformed into cap carbonate when combining with alkaline ions transported from continent to seawater via weathering process. This study provides the first evidence for Hg-bearing methane oxidation during cap carbonate precipitation.

Multiscale Dynamic Diffusion Model for Ions in Micro- and Nano-Porous Structures of Fly Ash: Mineralization Experimental Research

The leaching concentration of alkaline ions plays a crucial role in the efficiency of the CO2 mineralization reaction in fly ash. The multi-scale structural characteristics of micro–nano pores in fly ash are the primary factors that control the leaching and diffusion rate of alkaline ions. However, the existing theoretical models do not account for the multi-scale pore structure, leading to challenges in accurately describing the ion diffusion in fly ash and predicting the reaction rate and efficiency of CO2 mineralization. To address this issue, a multi-scale dynamic diffusion model of ions was developed based on the micro–nano pore structure of fly ash. This model established the relationship between the ionic leaching rate and pore structure, as well as macroscopic changes over time, which were validated through experiments. Mineralization experiments with varying soaking times and uniaxial compression experiments on mineralized specimens were conducted to investigate the relationships among soaking time, ion leaching concentration, mineralization degree, and mechanical strength. The results elucidated the impact of alkaline ion concentration on the mineralization degree and mechanical strength of fly ash materials, offering theoretical insights to enhance mineralization and material properties.

Solvation Free Energies from Machine Learning Molecular Dynamics.

The present work proposes an extension to the approach of [Xi, C; et al. J. Chem. Theory Comput. 2022, 18, 6878] to calculate ion solvation free energies from first-principles (FP) molecular dynamics (MD) simulations of a hybrid solvation model. The approach is first re-expressed within the quasi-chemical theory of solvation. Then, to allow for longer simulation times than the original first-principles molecular dynamics approach and thus improve the convergence of statistical averages at a fraction of the original computational cost, a machine-learned (ML) energy function is trained on FP energies and forces and used in the MD simulations. The ML workflow and MD simulation times (≈200 ps) are adjusted to converge the predicted solvation energies within a chemical accuracy of 0.04 eV. The extension is successfully benchmarked on the same set of alkaline and alkaline-earth ions.

Hierarchical Ni3V2O8@N-Doped Carbon Hollow Double-Shell Microspheres for High-Performance Lithium-Ion Storage.

Transition metal oxides (TMOs) are highly dense in energy and considered as promising anode materials for a new generation of alkaline ion batteries. However, their electrode structure is disrupted due to significant volume changes during charging and discharging, resulting in the short cycle life of batteries. In this paper, the hierarchical Ni3V2O8@N-doped carbon (Ni3V2O8@NC) hollow double-shell microspheres were prepared and used as electrode materials for lithium-ion batteries (LIBs). The utilization efficiency and ion transfer rate of Ni3V2O8 were improved by the hollow microsphere structure formed through nanoparticle self-assembly. Furthermore, the uniform N-doped carbon layer not only enhanced the structural stability of Ni3V2O8, but also improved the overall electrical conductivity of the composite. The Ni3V2O8@NC electrode has an initial discharge capacity of up to 1167.3 mAh g-1 at a current density of 0.3 A g-1, a reversible capacity of up to 726.5 mAh g-1 after 200 cycles, and still has a capacity of 567.6 mAh g-1 after 500 cycles at a current density of 1 A g-1, indicating that the material has good cycle stability and high-rate capability. This work presents new findings on the design and fabrication of complex porous double-shell nanostructures.

Towards Room Temperature Thermochromic Coatings with controllable NIR-IR modulation for solar heat management & smart windows applications

Solar heat management & green air-conditioning are among the major technologies that could mitigate heat islands phenomenon while minimizing significantly the CO2 global foot-print within the building & automotive sectors. Chromogenic materials in general, and thermochromic smart coatings especially are promising candidates that consent a noteworthy dynamic solar radiation Infrared (NIR-IR) regulation and hence an efficient solar heat management especially with the expected increase of the global seasonal temperature. Within this contribution, two major challenging bottlenecks in vanadium oxide based smart coatings were addressed. It is validated for the first time that the NIR-IR modulation of the optical transmission (∆TTRANS = T(T〈TMIT) − T(T〉TMIT) of Vanadium oxide based smart coatings can be controlled & tuned. This upmost challenging bottle-neck controllability/tunability is confirmed via a genuine approach alongside to a simultaneous drastic reduction of the phase transition temperature TMIT from 68.8 °C to nearly room temperature. More precisely, a substantial thermochromism in multilayered V2O5/V/V2O5 stacks equivalent to that of standard pure VO2 thin films but with a far lower transition temperature, is reported. Such a multilayered V2O5/V/V2O5 thermochromic system exhibited a net control & tunability of the optical transmission modulation in the NIR-IR (∆TTRANS) via the nano-scaled thickness’ control of the intermediate Vanadium layer. In addition, the control of ∆TTRANS is accompanied by a tremendous diminution of the thermochromic transition temperature from the elevated bulk value of 68.8 °C to the range of 27.5–37.5 ºC. The observed remarkable and reversible thermochromism in such multilayered nano-scaled system of V2O5/V/V2O5 is likely to be ascribed to a noteworthy interfacial diffusion, and an indirect doping by alkaline ions diffusing from the borosilicate substrate. It is hoped that the current findings would contribute in advancing thermochromic smart window technology and their applications for solar heat management in glass windows in general, skyscraper especially & in the automotive industry. If so, this would open a path to a sustainable green air-conditioning with zero-energy input.

Hierarchical high K content birnessite MnO2 nanosheet arrays as high capacity cathode for asymmetric supercapacitor with broaden potential window of 2.6 V

High specific capacitance and energy density for energy storage devices are dependent on the types of electrodes selection and operational working potential windows. Birnessite MnO2 is reported as the astounding material to show strong electrochemical performances due to it's widen inter-planar spacing, capable to accommodate the alkaline ions for the better outcomes. Herein this article, high K content Birnessite MnO2 nanosheet arrays at carbon cloth substrate (K0.46MnO2 NSAs@CC) are successfully fabricated to optimize its structural, morphological and electrochemical performances as cathode for supercapacitors (SCs). K0.46MnO2 NSAs@CC is operated at broaden potential window from 0 to 1.3 V to achieve excellent specific capacitance of ∼375 F g−1. Reported broaden potential window provides the opportunity for the construction of aqueous asymmetric supercapacitors (ASC) to operate above 2.0 V. For the construction of efficient ASC, Bi2S3 nanoflakes interconnected nanosheets at carbon cloth (Bi2S3 NFNS@CC) are synthesized as anode capable to operate at negative (−1.3 to 0 V) potential window. The 2.6 V ASC is constructed by K0.46MnO2 NSAs@CC as cathode and Bi2S3 NFNS@CC as an anode (K0.46MnO2 NSAs@CC//Bi2S3 NFNS@CC). K0.46MnO2 NSAs@CC//Bi2S3 NFNS@CC as ASC is presenting excellent energy density of ∼72 Wh kg−1 on top of outstanding cycle performance and rate capability compatible with the earlier reported MnO2-based ASCs. This work is elaborating the new guidelines for novel electrode materials scheme and possibilities to achieve broaden potential windows capable to be utilized in practical devices.

A novel potassium‐containing layered oxide for the cathode of sodium‐ion batteries

AbstractLayered oxides are successful cathode materials for sodium‐ion batteries. Many of these oxides show interesting kinetic behavior but have poor structural stability. To overcome this limitation, an alternative material containing potassium in the interlayer space in trigonal prismatic coordination is studied here. The transition‐metal layers are formed by sustainable transition elements such as iron and manganese. The solid was prepared using a sol–gel procedure that led to a product with relatively high purity, with a Pʹ3‐type structure indexable in the C2/m space group of the monoclinic system. Its electrochemical behavior was studied in sodium metal half‐cells. When the cell is charged up to 4.3 V, it is observed that the potassium extraction is not complete. The subsequent discharge of the cell is associated with the intercalation of sodium from the electrolyte. Thus, it is possible to incorporate a greater number of alkaline ions than those extracted in the previous charge. The residual potassium in the structure was found to be favorable to maintaining the structural integrity of the compound upon cycling. This can be explained by the beneficial effect of potassium, which would act as a structural “pillar” in the interlayer, which would reduce structural degradation during cycling.

Efficient inhibition of ASR by microbially induced calcium carbonate precipitation on aggregates at a low degree of saturation

Alkali-silica reaction (ASR) is a chemical reaction between alkaline ions (Na+, K+), silicon phases and aluminum phases in the aggregate, causing volume expansion and cracking of the concrete, leading to a deterioration in the mechanical properties of the structure. In previous studies, microbially induced carbonate precipitation (MICP) technology had been demonstrated to be effective in inhibiting ASR. In this study, in order to explore better inhibition effect, MICP treatments of alkali active aggregates under different saturation degrees were tested. The results showed that when treated at a low-saturation degree (35 %), the inhibition effect of ASR was better comparing with that obtained at higher saturation degrees in the presence of same CaCO3 content. When the CaCO3 content was about 6 %, mortar bar specimens made of low-saturation treated aggregates possessed a 75 % reduction in the expansion and a 37 % increase in the compressive strength compared to the control group. In addition, through microstructure and component analysis of the aggregate surface, it was found that under the low-saturation treatment, the CaCO3 layer could be formed on the surface of the aggregate more uniformly and efficiently, with a higher binding strength to the aggregate and a greater Vickers hardness. Thus, it could better block the invasion of external alkaline ions to react with the active SiO2 inside the aggregate, leading to a better inhibition of ASR.

Computational electrocatalysis beyond conventional hydrogen electrode model: CO2 reduction to C2 species on copper facilitated by dynamically formed solvent halide ions at the solid-liquid interface.

The reduction of CO2 into value-added chemicals and fuels has been actively studied as a promising strategy for mitigating carbon dioxide emissions. However, the dilemma for the experimentalist in choosing an appropriate reaction medium and neglecting the effect of solvent ions when using a simple thermochemical model, normally leads to the disagreement between experimental observations and theoretical calculations. In this work, by considering the effects of both the anion and cation, a more realistic CO2 reduction environment at the solid-liquid interface between copper and solvent ions has been systematically studied by using ab initio molecular dynamics and density functional theory. We revealed that the co-occurrence of alkali ions (K+) and halide ions (F-, Cl-, Br-, and I-) in the electric double layer (EDL) can enhance the adsorption of CO2 by more than 0.45 eV compared to that in pure water, and the calculated energy barrier for CO-CO coupling also decreases 0.32 eV in the presence of I ion on a negatively charged copper electrode. The hydrated ions can modulate the distribution of the charge near the solid-liquid interface, which significantly promotes CO2 reduction and meanwhile impedes the hydrogen evolution reaction. Therefore, our work unveils the significant role of halide ions at the electrode-electrolyte interface for promoting CO2 reduction on copper electrode.

(Digital Presentation) Hybrid Membranes Engineered from Sustainable Sources Exhibit Improved Ionic Conductivity

Ion-conducting membranes are crucial in electrochemical storage and energy conversion technologies such as fuel cells, alkaline ion batteries, and redox-flow batteries. The purpose of the membrane is to prevent direct contact between the electrodes while allowing selective ions to pass through. The characteristics of the ion-conducting membranes include excellent mechanical and thermal stability, chemical resistance, high ionic conductivity, and selectivity. Polymers and polymer-based precursors make up the majority of the materials that have been used as ion-conducting membranes. However, most polymer-based membranes have issues related to poor chemical resistance, recyclability, and thermal and mechanical stability. In addition, as more sustainable materials are being sought to create a sustainable society, new environmentally friendly and economically viable materials are in high demand. The clay-based material could be an alternative for ion-conducting applications due to its porous structure, high surface area, tunable interlayer spacing, excellent thermal and mechanical stability, and high ion conductivity. Clay minerals are primarily used in water treatment, pharmaceutics, ceramics, paints, and coating industries. Furthermore, clay minerals have been used as a filler material in energy storage and conversion system to improve the thermal stability and ion conductivity in electrodes, electrolytes, and separators.Herein, we report a novel approach to making non-polymeric hybrid clay membranes using environmentally benign materials such as clay and zwitterion (i.e., sulfobetaine). These membranes with improved ionic conductivity will find immense potential in applications in energy storage and conversion systems. Such membranes have been synthesized by intercalating sulfobetaine molecules into the interlayer spacing of the bentonite clay matrix. Sulfobetaine is a zwitterion composed of quaternary ammonium cations and sulfonate anions. Leveraging the unique structure-property features that exist in zwitterions helps to alter the interlayer spacings in the clay matrix, thereby enabling ion diffusion through the silicate layers. Furthermore, it helps in the formation of a self-supporting membrane. The functionalized membrane's crystal structure and chemical composition were investigated using XRD, XPS, and ATR-FTIR. XRD was used to identify the layered structure of the silicates in clay and the increased interlayer spacing (1.15 nm to 1.8 nm) of the hybrid clay membrane. Data from XPS and ATR-FTIR confirmed the successful functionalization of clay with sulfobetaine. Furthermore, the ionic conductivity of the hybrid clay membrane was characterized using a non-aqueous lithium electrolyte solution, and found a conductivity of . This is one of the first reports showcasing how zwitterions can impart conductivity in clay silicate motifs. It suggests an easy and novel approach to transport lithium-ion through silicate layers, thereby making it suitable for use as membranes in batteries and supercapacitors. The current study demonstrates an easy and versatile approach to developing cost-effective and eco-friendly membranes from sustainable materials such as clay, which, when functionalized, has the potential to be a highly efficient ion-conducting material with applications in energy storage, devices, and technologies.

Corrosion effect of acid/alkali on cementitious red mud-fly ash materials containing heavy metal residues

High-strength cementitious red mud-fly ash materials (RFMs) were formed from sodium hydroxide and water glass mixed solutions, and their abilities to solidify heavy metal ions (HMs, e.g., copper and cadmium) were assessed. The mechanism for precipitation of the HMs by corrosive acid/alkali solutions was explored via toxicity leaching tests, as well as SEM, XRD, FT-IR and XPS. The results showed that when the added alkaline activator was not fully consumed, the presence of small amounts of HMs consumed the excess alkaline ions to form hydroxide precipitates that filled the pores of the RFM, so the compressive strength of the RFM increased. Otherwise, the presence of excess HMs reduced the compactness of the RFM and eventually resulted in a highly porous structure, leading to weakening of the material. Additionally, small amounts of anhydrite phases were produced in the RFM. In neutral and alkaline environments, the HMs formed precipitates or coordination complexes with hydroxyl groups, and the solidification efficiencies exceeded 99%. In acidic environments, the HMs converted from their original precipitated forms or ion–hydroxide complexes to free cations. As a result, the HMs were more likely to be separated from the RFMs. Moreover, the RFMs were more prone to disaggregation under acidic conditions, which led to destruction of the RFM microstructure and rerelease of the HMs fixed in the microstructure.

Mechanism of Cs Immobilization within a Sodalite Framework: The Role of Alkaline Cations and the Si/Al Ratio

Conditioning of radioactive waste generated from the operation of medical institutions, nuclear cycle facilities, and nuclear facilities is important for the safety of the environment. One of the most hazardous radionuclides is radioactive cesium. There is a need for more effective solutions to contain radionuclides, especially cesium (Cs+). Geopolymers are promising inorganic materials that can provide a large active surface area with adjustable porosity and binding capacity. The existence of nanosized zeolite-like structures in aluminosilicate gels was shown earlier. These structures are candidates for immobilizing radioactive cesium (Cs+). However, the mechanisms of their interactions with the aluminosilicate framework related to radionuclide immobilization have not been well studied. In this work, the influence of alkaline cations (Na+ or K+) and the aluminosilicate framework structure on the binding capacity and mechanism of interaction of geopolymers with Cs+ is explored in the example of a sodalite framework. The local structure of the water molecules and alkaline ions in the equilibrium state and its behavior when the Si/Al ratio was changed were studied by DFT.