Alkali Reaction Research Articles

Optical Properties and Growth Characteristics of 8-Quinolinolato Lithium (Liq) Nano-Layers Deposited by Gas Transport Deposition.

Organometallic complexes containing reactive alkali metals, such as lithium (Li), represent a promising material approach for electron injection layers and electron transport layers (EILs and ETLs) to enhance the performance of Organic Light-Emitting Diodes (OLEDs). 8-Quinolinolato Lithium (Liq) has shown remarkable potential as an EIL and ETL when conveyed in very thin films. Nevertheless, the deposition of nano-layers requires precise control over both thickness and morphology. In this work, we investigate the optical properties and morphological characteristics of Liq thin films deposited via Organic Vapor Phase Deposition (OVPD). Specifically, we present our methodology for analyzing the measured pseudodielectric function <ε(ω)> using Spectroscopic Ellipsometry (SE), alongside the nano-topography of evaporated Liq nano-layers using Atomic Force Microscopy (AFM). This information can contribute to the understanding of the functionality of this material, since ultra-thin Liq interlayers can significantly increase the operational stability of OLED architectures.

Исследование дезинфицирующей способности феррата натрия

More and more attention has been recently paid to the disinfection of industrial wastewater. Food, petrochemical, pharmaceutical, and other industries cannot directly dump wastewater into the environment, therefore, the wastewater is fed to the deep biological treatment lines. A high level of biological threat and the expanding list of potential pathogens cause the need to search for new highly efficient disinfecting agents. The use of ferrates can be a new step in the improvement of the wastewater disinfection process due to the combination of processes of inactivation of pathogenic microflora and the reactant coagulation on ferric hydroxides generated during decontamination (oxidation). Within the framework of the study, the potential use of sodium ferrate as a disinfecting agent obtained by electrochemical dissolution of iron electrodes in alkali solutions has been confirmed. It has been established that sodium ferrate can effectively inactivate conditionally pathogenic cultures A. niger, B. subtillis which are part of activated sludge symbiosis. The efficient dosing of ferrate for complete inhibition of B. subtillis is 0.5 % mass, whereas for A. Niger it is 15 % mass. It has been proved that microflora inhibition occurs directly under the action of sodium ferrate and not due to the alkali reaction of the medium. Industrial tests of the disinfecting ability of ferrates in relation to wasted activated sludge of industrial wastewater deep biological treatment systems have confirmed the results obtained for individual objects (A. niger, B. subtillis). Based on the results, a conclusion about the potential use of ferrates in the deep biological treatment processes for highly bacteriologically contaminated industrial wastewater has been made. The main advantages of the suggested agent include the low toxicity of metabolites, minimum secondary contamination of treated water, and possible reactant advanced treatment (dephosphorization).

New developments of hydrogen impurity online-monitoring in liquid lithium of IFMIF-DONES

On the way to future nuclear fusion power plants, the International Fusion Materials Irradiation Facility (IFMIF) – DEMO Oriented Neutron Source (DONES), is an important key element between ITER and DEMO to study before the influence of DEMO-neutron irradiation on foreseen fusion materials. The core of DONES, currently under construction near Granada, Spain, is based on a circuit containing liquid lithium at elevated temperatures acting as a functional material for the (d,n)-Li reaction in a materials test cell. In addition to this actual function of DONES, there are important aspects of maintenance in which hydrogen isotopes are generated under operating conditions and dissolved in this aggressive and very reactive alkali metal. This implies strong unfavourable effects on the applied structural materials, e.g. hydrogen embrittlement and others.To counteract these unfavourable effects, endangering the safe operation, an Impurity Control System (ICS) is an integral part of the DONES instrumentation. As part of the tasks of the European Neutron Source (ENS) to develop redundant systems for monitoring impurities, a special sub-task was defined for the development of an electrochemical H-sensor for concentrations in liquid lithium, ECHSLL. It is determined by detecting the electrical potentials of the lithium melts compared to a standard Li-based chemical reference system. This allows an inherent material property to be directly correlated (i.e. through appropriate electrochemical instrumentation) with chemical concentration values. This article presents important advancements in the applied ECHSLL technique, such as improving laboratory measurements from stagnant conditions to dynamic and realistic flow conditions of the liquid lithium material, as well as appropriate approaches to overcome the challenges in distinguishing the hydrogen isotopes by ECHSLL system (protium and deuterium among given laboratory conditions).

Analysis of Sodium–Water Reaction as heat source for district heating and cooling

Finding new alternatives is a need to develop disruptive solutions that could be applied to the decarbonized, sustainable, circular systemic change for the energy system transition. In this case, a complete new approach, sodium as energy resource, is described. Traditionally, sodium has been considered a risky element even if it were proposed as coolant in many applications, as nuclear or solar thermal plants. Such applications have been concerned by the explosive reaction of alkali as Na with water. We analysed the alternative of profiting of such highly exothermic reaction for an energy use. Previously, we experimentally tested the utilization of sodium as propellant, as reported in Guerrero et al. (2019), what produced the correlation between the energy release and the sodium consumption in excess of water. We are now developing a boiler fuelled by sodium and water. Based on these previous and ongoing activities, this paper shows the proposal and the process analysis of a sodium–water boiler applied to heating and cooling networks,as one of the sectors to be decarbonized in the energy system. A tentative configuration for the design of such heater, and the heat exchangers to adapt heated water temperatures will be presented. We present the conceptual design of a 13.5 MW district heating plant for a ΔT=10°C heating water from 60 to 70 °C, consuming 1 kg/s Sodium, reaching an efficiency of 95%, comparable with existing boilers.

Porous Ruthenium-Tungsten-Zinc Nanocages for Efficient Electrocatalytic Hydrogen Oxidation Reaction in Alkali.

With the rapid development of anion exchange membrane technology and the availability of high-performance non-noble metal cathode catalysts in alkaline media, the commercialization of anion exchange membrane fuel cells has become feasible. Currently, anode materials for alkaline anion-exchange membrane fuel cells still rely on platinum-based catalysts, posing a challenge to the development of efficient low-Pt or Pt-free catalysts. Low-cost ruthenium-based anodes are being considered as alternatives to platinum. However, they still suffer from stability issues and strong oxophilicity. Here, we employ a metal-organic framework compound as a template to construct three-dimensional porous ruthenium-tungsten-zinc nanocages via solvothermal and high-temperature pyrolysis methods. The experimental results demonstrate that this porous ruthenium-tungsten-zinc nanocage with an electrochemical surface area of 116 m2 g-1 exhibits excellent catalytic activity for hydrogen oxidation reaction in alkali, with a kinetic density 1.82 times and a mass activity 8.18 times higher than that of commercial Pt/C, and a good catalytic stability, showing no obvious degradation of the current density after continuous operation for 10,000 s. These findings suggest that the developed catalyst holds promise for use in alkaline anion-exchange membrane fuel cells.

Mineralogy and geotechnical properties of alkaline-activated kaolin with zeolitic tuff and cement kiln dust as landfill liners

Mixtures of variable proportions of kaolin, quartz sand, zeolitic tuff, and cement kiln dust were blended while adding an 8 M sodium hydroxide (NaOH) solution to allow alkali-activation of kaolin and achieve the optimum strength. This study investigated the mineralogy, microstructure, and geotechnical properties of the prepared mixtures. The aim was to produce a sustainable, environmentally friendly landfill liner. The samples were compacted in stainless steel molds to a maximum dry density and optimum moisture content, extruded from the molds, and left to cure in an oven at varying temperatures from 40°C to 80°C for 24 h. The investigations included XRD, SEM, unconfined compressive strength, and hydraulic conductivity tests. Test results showed the development of a hydroxysodalite binder due to the alkali reaction of kaolin, which caused an increase in strength ranging from 20 to 25 MPa depending on the curing temperature. Alkaline activation was effective even at temperatures as low as 40°C. A mixture of 100 units of kaolin, 45 units of sand, 45 units of zeolitic tuff, and 10% by weight cement kiln dust (CKD) with an 8 M sodium hydroxide activator was found to best achieve the required strength and hydraulic conductivity of 10−9 m/s for the landfill liner. The zeolitic tuff with high cation exchange capacity, available in the mixture, absorbs contaminants in the leachate and prevents pollution of the groundwater. The use of cement kiln dust contributes to enhancing strength and solving an acute environmental problem.

Conversion of Debris-Treated Ash into a Cesium-Adsorbent Using Alkali Reaction

Conversion of Debris-Treated Ash into a Cesium-Adsorbent Using Alkali Reaction

Analysis of the Resistance of Self-Compacting Concrete (SCC) with the Use of Granite Stone Waste to Alkali-Silica Reaction

Aggregates occupy ±70% of the concrete volume and their quality must meet specifications. Concrete surfaces submerged in water for a long time cause concrete failure due to the reaction between aggregate and cement to form silica gel. The wear value of granite is less than gravel, so this study used granite as a substitute for coarse aggregate. This study was conducted to assess the resistance of SCC concrete with 0%, 25%, and 30% granite stone variations to alkali-silica reaction attack. The experimental method was applied to the study with ACI method mix design as well as 25 MPa plan fc'. Concrete cylinder samples 150 mm x 300 mm aged 28 days were used in the compressive strength test, alkali-silica reaction expansion test used mortar block samples 285 mm x 25 mm x 25 mm in 80±2˚C NaOH solution bath for 14 days. The optimum compressive strength of 32.17 MPa and the lowest percentage change in length of 0.04% was obtained by sample BG.25-SCC, indicating that granite stone is not reactive to silica alkali reaction because the percentage change in length &lt;0.10%. This study concludes that granite stone can improve the resistance of concrete to silica alkali reaction.

Thermochemistry of alkalization and etherification of cellulose

In this research, the process of alkalization of cotton cellulose with solutions of sodium hydroxide of different concentrations has been studied. It was found that the enthalpy of cellulose alkalization is exothermic. Moreover, the exothermic enthalpy value of cellulose alkalization with 30-40% NaOH solutions is higher than with 16-20% alkalis. Thus, the cellulose treatment with 30-40% alkalis provides the formation of more reactive alkali cellulose. In addition, the determination of the formation enthalpy of alkali celluloses showed that this thermochemical characteristic is also exothermic, and therefore, the process of cellulose alkalization is energetically favorable. It is most likely that cellulose alkalization is a physicochemical process of forming a molecular adduct of hydrated hydroxide ions with cellulose. A study of the methylation reaction of alkali cellulose with methyl chloride to a degree of substitution of 1.3-1.8 showed that the enthalpy of this reaction is quite exothermic. This means that methylation reaction is energetically advantageous, and obtaining methylcellulose with a higher degree of substitution is preferable.

The Use of De-Icing Salts in Post-Tensioned Concrete Slabs and Their Effects on the Life of the Structure

This article expounds on the problem of the use of de-icing salts in the corrosion of steel rebars in bridge decks and their effect on post-tensioning elements. In particular, this paper focuses this problem on structures affected by an aggregate–alkali reaction and without any waterproof treatment using the example of one structure whose repair was carried out in 2020. In this structure, the internal stresses due to the aggregate–alkali reaction caused longitudinal cracks in the upper face of the deck, through which the penetration of chloride ions was concentrated, causing, finally, the brittle fracture of the steel bars and the corrosion of the prestressing elements. This article also explains some conclusions about the most probable mechanisms that resulted in the brittle fracture of the steel bars due to the extraordinary and unexpected nature of this phenomenon.

In Situ Construction of Ni/Ni0.2Mo0.8N Heterostructure to Enhance the Alkaline Hydrogen Oxidation Reaction by Balancing the Binding of Intermediates

AbstractThe inferior activity of hydrogen oxidation reaction (HOR) in alkali severely hampers the deployment of Ni catalysts in the promising anion exchange membrane fuel cells (AEMFCs), due to the unbalanced binding energies of hydrogen (HBE) and hydroxyl (OHBE) species. Ni‐Mo alloy and nickel nitride have been proven to improve the Ni‐based activities of HOR but they still can be further enhanced. Because it sacrifices the HBE for enlarging OHBE. Herein, it is reported that the activity can be further improved by constructing heterostructure between Ni nanoparticles (NPs) and nitride of Ni‐Mo alloy (Ni0.2Mo0.8N) by an in situ synthetic strategy. The in situ prepared reduced graphene oxide (rGO) supported heterostructure (Ni/Ni0.2Mo0.8N/rGO) possesses the state‐of‐the‐art activity (overpotential of 100 mV to achieve 2.9 mA cm−2), faster kinetics (kinetics current density of 11.20 mA cm−2 and exchange current density of 2.74 mA cm−2), and ultrahigh durability (maintaining the current densities for over 40 h or 10000 cycles). Detailed characterizations together with density functional theory simulations reveal that the tuned d‐band electronic structures optimize and balance the HBE and OHBE, facilitating the HOR process on the as‐fabricated heterostructured catalyst.

The effect of Cl, Br, and F on high-temperature corrosion of heat-transfer alloys

The impact of small alkali halide additions on the melting behavior and corrosivity of a synthetic sulfate deposit at 500, 550, and 600 °C was investigated. Three differently alloyed commercial heat-transfer materials; low-alloyed 10CrMo9-10, stainless AISI 347, and high-alloyed Sanicro 28, were studied. The samples were exposed for 168 h in a tube furnace to a K2SO4 + Na2SO4 mixture containing 0.85 mol% KCl, KBr, or KF. The extent of material degradation was determined by weight loss measurements, while the morphology, thickness, and composition of the formed oxide scale were characterized with SEM-EDS. Additionally, the melting behavior of the mixtures was studied with TG-DTA. It could be concluded that already small amounts of reactive alkali halides in an otherwise inert K2SO4 + Na2SO4 mixture change significantly the corrosion and melting behavior of the mixture.

PENGARUH ALKALI SILIKA REAKTIF PASIR TERHADAP KUAT TEKAN MORTAR RENDAMAN

Mortar is a building material made of cement, fine aggregate, and water. To get a good mortar strength, the properties, and characteristics of each of the mortar constituents must also be studied further. Aggregates containing silica can be reactive or non-reactive to alkaline elements in cement. The purpose of this study was to determine the effect of alkaline silica reactive sand on the compressive strength and flexural strength of mortar immersed in seawater. This research uses an experimental method, namely Rangkas sand, Bangka sand and Lumajang sand which have gone through the XRF (X-Ray Fluorescence) testing process to determine the percentage of compound content contained. The research method to determine the reactivity of the sand refers to ASTM C 1260. The compressive strength and flexural strength of the mortar were tested with two variations of immersion, namely by using fresh water and sea water. The immersion of the mortar was carried out for 7, 14, 28 and 56 days. From the results of testing the compressive strength and flexural strength of mortar at the age of 28 days had the same results for fresh water and seawater immersion, namely sand with high potential for reactive alkali silica has low compressive strength and flexural strength values ​​for all types of immersion. The freshwater immersion method has been used to test the mortar's flexural and compressive strength. It has a higher compressive and flexural strength value than the seawater immersion mortar, with a percentage ratio of 27.1% of compressive strength and 17.3% of flexural strength in mortar, with an immerse age of 28 days.

Prediction of alkali-silica reaction expansion of concrete using artificial neural networks

This paper presents a hybrid machine learning method for the prediction of concrete expansion induced by alkali-silica reaction (ASR) and assembles a comprehensive and reliable experimental database comprising of around 1900 sets of ASR expansion data from literature to calibrate and validate the machine learning-based prediction model. The hybrid machine learning method employs a beta differential evolution-improve particle swarm optimization algorithm (BDE-IPSO) to tune weights and biases of the artificial neural network (ANN) model. The model adopts 11 variables as input, in terms of material composition, specimen geometry and environmental conditions, and can predict ASR expansion with great accuracy. The results demonstrate that the established prediction model is able to capture all available experimental aspects of ASR expansion, including: (a) effects of reactivity, size, content of reactive aggregate, water-to-cement ratio, and alkali concentration; (b) effects of temperature and relative humidity; (c) size effects of specimen geometry; and (d) the time-dependent behavior.

Direct CO2 Capture by Alkali‐Dissolved Cellulose and Sequestration in Building Materials and Artificial Reef Structures (Adv. Mater. 11/2023)

Cellulose–CO2 Grapes In article number 2209327, Guillermo Reyes, Orlando J. Rojas, and co-workers demonstrate carbon capture and utilization (CCU) in industrially relevant and reactive alkali cellulose solutions, which are transformed into hybrid, mineralized materials. They can be molded into supports for coral-reef restoration and in the production of structures relevant to ceramics and cement composites (Image: scanning electron microscopy (SEM) image of a sample with ca. 7 nm Au/Pt coating, colored according to energy-dispersive spectroscopy.

Direct CO2 Capture by Alkali-Dissolved Cellulose and Sequestration in Building Materials and Artificial Reef Structures.

Current carbon capture and utilization (CCU) technologies require high energy input and costly catalysts. Here, an effective pathway is offered that addresses climate action by atmospheric CO2 sequestration. Industrially relevant highly reactive alkali cellulose solutions are used as CO2 absorption media. The latter lead to mineralized cellulose materials (MCM) at a tailorable cellulose-to-mineral ratio, forming organic-inorganic viscous systems (viscosity from 102 to 107 mPas and storage modulus from 10 to 105 Pa). CO2 absorption and conversion into calcium carbonate and associated minerals translate to maximum absorption of 6.5gCO2 gcellulose -1 , tracking inversely with cellulose loading. Cellulose lean gels are easily converted into dry powders, shown as a functional component of ceramic glazes and cementitious composites. Meanwhile, cellulose-rich gels are moldable and extrudable, yielding stone-like structures tested as artificial substrates for coral reef restoration. Life Cycle Assessment (LCA) suggests new CCU opportunities for building materials, as demonstrated in underwater deployment for coral reef ecosystem restoration.

Synergistic effect of waste glass powder and fly ash on some properties of mortar and notably suppressing alkali-silica reaction

In this study the mitigation influence of incorporating waste glass powder (G) and class F fly ash (F) in mortar as partial cement replacement on the alkali-silica reaction (ASR) between reactive aggregate and alkali contents of cement were investigated. Waste G and F replaced cement separately and together on mass basis at 10%, 20%, and 30%. The unit weight (28 days), water absorption, porosity, compressive, and flexural strength tests were conducted at 28- and 90-day water curing time on 40×40×160 mm prismatic hardened samples and flow table test on fresh mortar. There was a slight reduction of the unit weight, an increased workability, and decreased water absorption and porosity; a little reduction of the compressive strength and flexural strength were seen after the tests. In addition, the expansions of mortar were measured up to 90 days. When 14 days expansions were considered according to ASTM C1260, addition of waste G and F separately reduced the expansion that occurred due to ASR. However, the mixture containing 15% waste G and 15% F together (GF-30) exhibited the lowest expansion in the order of 0.02% which was far lower than 0.10%. The higher replacement ratio of waste G and F together and separately caused lower expansion in mortar.

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

Interactive effect of lithium on concentration of alkali cations in sugar beet (Beta vulgaris L.) under saline conditions

AbstractBackground and aimsIncreasing demand for lithium (Li+) for portable energy storage is leading to a global risk of Li+ pollution from the manufacture, use, and disposal of Li+‐containing products. Although Li+, a reactive alkali metal, has no essential function in plants, they readily take it up and accumulate it in large amounts in their tissues. The underlying mechanisms for this Li+ uptake and accumulation are, however, not well described. Our aim has been to investigate the effects of other alkali metals with similar physicochemical properties on the uptake, accumulation, and toxicity of Li+ at low and high osmolarity.MethodsTo determine the way in which Li+ affects the accumulation of other cations under saline conditions, sugar beet plants were grown in hydroponic culture with equimolar amounts of Li+, potassium (K+), and sodium (Na+) at low and high concentrations in various combinations.ResultsSugar beet plants tolerated high Li+ concentrations in the leaf and petiole. Low Li+ concentrations had no impact on plant growth but induced stomata closure. The presence of other monovalent cations at equimolar concentrations did not affect Li+ accumulation, but Li+ application altered the ratio of monovalent and divalent cations in leaves. Plants treated with high Li+ in combination with Na+ or K+ showed reduced plant growth and leaf necrosis, indicating the severe stress caused by Li+ toxicity.ConclusionThe presence of cations with similar physicochemical properties to those of Li+ cannot mitigate its toxicity.

Bimetallic carbides of Ni6W6C as efficient non-precious metal electrocatalysts for hydrogen oxidation reaction in alkaline medium

• Nickel foam supported Ni 6 W 6 C nanoparticles (Ni 6 W 6 C NPs/NF) was successfully synthesized. • Ni 6 W 6 C NPs/NF exhibited high catalytic activity towards hydrogen oxidation reaction (HOR) in alkaline medium. • Ni 6 W 6 C NPs/NF possessed fast kinetics and high durability for HOR in alkaline medium. To optimize the adsorption of hydroxyl species, Ni–W bimetallic carbides are proposed to apply for enhancing the catalytic activity of hydrogen oxidation reaction (HOR) in alkali, owing to the oxyphilic element of W and tuning d band. Herein, nickel foam supported Ni 6 W 6 C nanoparticles (Ni 6 W 6 C NPs/NF) exhibit efficient catalytic activity for HOR in alkaline medium, which can reach 2.5 mA cm −2 at 0.1 V vs . RHE. It is even superior to Pt/C. Additionally, Ni 6 W 6 C NPs/NF exhibits fast kinetics and high durability towards HOR.