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This study aims to develop the alkali activated slag-fly ash concrete (AASFC) using precious slag (PS) ball as the fine aggregate. The slag-fly ash proportion, sodium silicate/sodium hydroxide (SS/SH) ratio and sodium hydroxide concentration are the prime variables. The fresh concrete properties like workability, setting time and the hardened concrete properties of AASFC developed under ambient curing were analyzed and similar way by replacing with fly ash (FA). The sodium hydroxide concentration of 8 M, 10 M and 12 M, SS/SH ratio of 1.0, 1.5 and 2.0, alkaline liquid to binder ratio of 0.35 and variation in slag-fly ash proportion as major inputs for mix design. The test results showed that, the fresh state of AASFC blend has a shorter setting time of 12–16 min, because of calcium mineral from the FA, the workability and setting time of AASFC mix was enhanced by the addition of the tri-sodium phosphate as a retarder. At the higher SS/SH extent, the workability and setting time exaggerated, whereas the increased FA content and sodium hydroxide concentration had a greater influence on the fresh state of concrete. Also, the sodium hydroxide concentration, SS/SH ratio and slag-fly ash proportion are the most inducing parameters on the workability, setting time and strength parameters of AASFC.

Types and contents of alkali metal ions play important role on crystallization and ion-exchange properties in glasses. In this work, effects of Na2O/K2O ratio on crystallization and ion-exchange properties of zinc-alumino-silicate glasses were investigated. The crystalline phases precipitated in glasses changes from ZnO to β-Zn2SiO4 with the progressive replacement of K2O by Na2O in parent glasses. Ion-exchange depth of layer (DOL) decreases gradually with the increase in Na2O content in parent glasses. Precipitation of ZnO and β-Zn2SiO4 nanocrystals facilitated the ion-exchange and enlarged the DOL. Na+ and K+ ions were doped into ZnO and β-Zn2SiO4 nanocrystals during heat-treatment, and the extent of doping was facilitated by ion-exchange. Vickers hardness were improved significantly with the crystallization and ion-exchange. Results reported here are valuable for the controlled preparation and chemical strengthening of ZnO and β-Zn2SiO4 glass-ceramics.

Nowadays, alkali titanate (ATO) fibers are attracting attention because they can provide a reinforcing as well as a functional effect. In this study, ATO fibers were synthesized by a one-step calcination route without specialized equipment and flux using a resorcinol–formaldehyde (RF) resin. Homogeneous mixing of the RF resin dissolved in water, TiO2, and an alkali source led to a uniform dispersion, and the three-dimensional polymerized RF resin formed a closely structured matrix with TiO2 and the alkali source. By carbonizing the RF resins prepared using K or Na as the alkali source, titanate fibers with lengths greater than 1 mm were formed. Growth mechanisms and crystal structures of the titanate fibers synthesized with and without the RF resin were completely different. Effects of the RF resin on the crystal structure and morphology of the titanate fibers were systematically studied by changing the calcination temperature and molar ratio of TiO2 and alkali source (Li, Na, or K). We found that the RF resin played an essential role in producing a suitable reaction field for fiber growth and controlling the morphology of titanate fibers.

The mineral matter contained in feedstocks has a generally limiting impact on the process design of high-temperature conversion processes. In the present study, the composition, mineral phases, and process-relevant properties of ashes are investigated by different experimental and modeling methods, which were reviewed in the literature regarding the frequently applied methods. Various analyses are exemplarily performed for the ashes of a high-sodium coal from China, generated at temperatures of 150–950 °C. X-ray fluorescence (XRF) analysis, microwave-assisted inductively-coupled plasma optical emission spectrometry (MW-ICP-OES), and the same technique with electrothermal vaporization (ETV-ICP-OES) are applied to analyze the chemical composition of the bulk material. The chemical composition of the near-surface region is studied by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Mineral phases are analyzed by X-ray diffraction (XRD) and thermochemical calculations. The process-relevant ash fusion behavior is studied by a common ash fusion test (AFT) and thermomechanical analysis (TMA) and supported by thermochemical calculations. The different ashing temperatures have a recognizable impact on the composition, formation and transformation of mineral phases, and resulting ash fusion behavior, while each property is monitored by at least two different methods. For this purpose, a detailed analysis of the results achieved by the individual methods is performed. Finally, the results obtained by different methods for the same ash property are compared for monitoring the validity of the results and, for example, extracting about the gas phase transfer of selected ash components.

Wide-bandgap (WBG) perovskites play a crucial role for top cells in tandem solar cells (TSCs), which provides a promising avenue to boost the performance of widely used commercial solar cells. However, such WBG perovskite solar cells (PSCs) show poor performance compared to that of ~1.6 eV bandgap PSCs due to high defects density and photo-instability, resulting in relatively large open-circuit voltage loss (Vloss). Herein, we introduce alkali pseudo-halide KBF4 into the perovskite precursor solution for preparing less-defect WBG perovskite film. It is showed that the interstitial occupancy of K+ in the perovskite lattice and the suppression of recombination by BF4−, thereby inhibiting the ion migration and reducing the trap density. As a result, the champion WBG PSC (Energy gap (Eg), Eg = 1.74 eV) delivers a high open-circuit voltage (VOC) of 1.21 V and a power conversion efficiency (PCE) of 17.49%. This work provides new insight into the defect tolerance upon metal pseudo-halides doping in the WBG perovskite.

Use of ordinary portland cement contributes to environmental deterioration by releasing enormous quantities of CO2. To reduce use of cement, this research focuses on preparation of solely ground granulated blast-furnace-slag-based geopolymer binder, activated by a combination of sodium hydroxide and sodium metasilicate cured under ambient temperature at 27 °C. Engineering properties of geopolymer binder are evaluated and compared with conventional cement to assess its suitability as a binder for making geopolymer concrete. Compressive strength, flexure strength, and split tensile strength are determined for geopolymer concrete. Microstructural analysis of geopolymer is performed by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) with energy dispersive X-ray analysis (EDAX), and Fourier-transform infrared spectroscopy (FTIR) tests. The concentration of alkali activators is optimized by laboratory trials and maximum compressive, flexural, and split tensile strengths of 44.07, 5.60, and 4.39 MPa, respectively, are obtained for geopolymer concrete at 2 mol/L concentration of sodium hydroxide solution with the ratio of sodium metasilicate to sodium hydroxide taken as 2.0.

An alkali metal gallium iodate, Cs3[Ga2O(I3O9)(IO3)4(HIO3)] (CGIO), was synthesized by the traditional hydrothermal method. Interestingly, CGIO revealed a novel I3O93− fundamental building block (FBB) constituted by two IO3 tetrahedrons and one IO5 polyhedron through sharing O atoms. The new I3O93− trimer forms a 0D [Ga2O(I3O9)(IO3)4(HIO3)]3− anion cluster together with the [Ga2O11]16− dimer and isolated IO3− units. The UV-vis-NIR diffuse reflectance spectrum of CGIO shows a wide bandgap of 4.05 eV, and the thermal stability could reach above 400 °C. First-principles calculations explicated that the optical properties of CGIO mainly originated from the iodate anion units with a calculated birefringence of 0.04 at 1064 nm.

Cu(In,Ga)Se2 (CIGS) is a promising candidate to replace crystalline silicon solar cells and dominate the photovoltaic market in the future. Alkali elements such as sodium (Na), potassium (K), rubidium (Rb), and Cesium (Cs) are commonly accepted as indispensable parts to boost cell efficiencies of CIGS thin-film solar cells. Therefore, a comprehensive understanding of alkali effects on the electronic and chemical properties of the CIGS layer as well as the underlying mechanisms is of paramount importance for achieving high-performance solar cells. This paper reviews the development process and incorporation pathways of alkalis and then overviews the roles of different alkali elements and their effects on CIGS cells in detail. Furthermore, the unsolved problems and future development prospects are also proposed. Overall, the understanding and development of widely adopted alkali-fluoride post-deposition treatments (PDTs) are still underway, and together with newly updated research, it will likely enable the CIGS technology to make the conversion efficiency closer to its theoretical limit.

This study proposes the comparison of raw and alkali metal ion free banana peel as potential adsorbent for the removal of Hg2+ ions from aqueous solution. The alkali metal ions from banana peel was removed by protonation process with the help of HCl as protonation agent. Batch adsorption investigations were adopted in order to standardise the batch variables. The equilibrium data and kinetic data tend to fit well with Langmuir and pseudo second order kinetic models. The maximum loading capacity of the adsorbents was found to be 46.8 and 52.2 mg g−1 respectively. Desorption of Hg2+ ions was successfully achieved with the protonating agent used in this study. These investigations suggest that the protonation step enhances the removal efficiency of Hg2+ ions from aqueous solutions.

The CO2 gasification of South Open-pit Mines coal from Zhundong Field of China using Ca(OH)2 or K2CO3 as catalyst with different loading methods and contents were conducted in thermogravimetric analysis. Comparison of the gasification reactivity and rate of coal loaded various concentration of Ca(OH)2 concluded that the increase of Ca(OH)2 loading pronouncedly improved the reactivity and rate for grinding method; nevertheless, for impregnation and high pressure method the increase of Ca(OH)2 loading observed a similar catalytic effect on char gasification. However, the catalytic effect of K2CO3 revealed that the catalytic activity increased with the increase of K2CO3 loading for three loading method. For the same catalyst loading, the highest catalytic gasification reactivity achieved for Ca(OH)2 and K2CO3 were the loading methods of high pressure and grinding, respectively. In addition, the gasification of raw char, K2CO3 loaded char and Ca(OH)2 loaded char were quantitatively evaluated by kinetic analysis using shrinking core, random pore and modified random pore models.

Thermal desorption (TD) is an effective physical remediation technology for polycyclic aromatic hydrocarbons (PAHs) contaminated soil. Reaction temperature is the key of TD, and the increase of the...

During open-pit mining operations of phosphates, huge volume of rocks by products are accumulated and deposited in the mine site. The aim of this paper is to investigate the use of marls as an only aluminosilicate precursor to produce alkali-activated geopolymers. Marls from Moroccan phosphate basins are composed of carbonates, quartz and clays. Raw marl was dried, grinded and calcined at 750 °C. After the heat treatment, the calcined powder was activated using a strong alkali solution, which is a mixture of sodium hydroxide and sodium silicate with a ratio of 0.5. The physical and chemical properties of raw and calcined marls were analyzed using TGA, BET, Pycnometer, particle size analyzer, XRF, XRD, FTIR and SEM. Furthermore, elaborated geopolymers were characterized after 7 and 120 days of curing at ambient temperature using XRD, XRF, TGA, SEM and the mechanical behavior was tested by measuring the compressive strength. The results showed the formation of both; C-A-S-H (Calcium aluminum silicate hydrate) and N-A-S-H (Calcium aluminum silicate hydrate) gels with a compressive strength of 38 MPa confirming that marls from phosphate extraction by-products could be used as a source for the elaboration of geopolymers.

A supported ruthenium catalyst (Ru/Cs+/CeO2) for ammonia synthesis is described which incorporates a large amount of a Cs+ promoter in a porous CeO2 support to enhance the electron donation effect of the alkali promoter on the ruthenium catalyst. Optimization of the Ru and Cs+ promoter contents improves the ammonia synthesis rate to more than 4 times that of the benchmark catalyst (Cs+/Ru/MgO) at 350 °C and 0.1 MPa, and the ammonia synthesis rate is stable for 100 h. Introduction of the Cs+ promoter into the support before the Ru impregnation increases the particle size of the Ru catalyst. Despite a decrease in the number of active sites, the TOF of the catalyst is more than 50 times that of Ru (2 wt%)/CeO2. CO adsorption measurements suggest an electron donating effect by the Cs+ promoter to ruthenium metal. Reaction order analysis indicates this is due to a mitigation of hydrogen poisoning.

The calcium-Looping process is an advantageous candidate for thermochemical energy storage in Concentrated Solar Power plants. Achieving fast thermal energy storage at a moderate temperature would be highly beneficial for the heat storage process. In this study, commercially available alkali carbonates (Li2CO3, Na2CO3, K2CO3) were used as dopants for limestone/dolomite to improve their decarbonation rates and cycling stability. Results show that alkali carbonate doping reduces the decarbonation temperature of limestone and dolomite by accelerating the ion diffusion during decomposition. However, the doping of alkali carbonate also enhanced the sintering of limestone-based CaO so that the alkali carbonate doped limestones fail to maintain their heat storage capacity after multiple cycles. In contrast, the Li2CO3 doped dolomite still maintains excellent cyclic stability, attributed to the inhibition effect of the MgO skeleton on sintering. From these results, we then derived the effect scheme of Li2CO3 on the decarbonation and carbonation of limestone or dolomite. This study presents a simple yet effective method of reducing the heat storage temperature of Ca-based mineral materials and maintaining their cycling stability, simultaneously, with promising potential for industrial use.

Alkali metals are commonly used to promote heterogeneous catalysts. For instance, K can enhance the MoS2-catalyzed synthesis of methanethiol, an important industrial chemical, from CO/H2/H2S. Herein, we not only demonstrate that the synergy increases with alkali cation size (Cs > Rb > K > Na) but also that alkali sulfides themselves are the active sites. The alkali-normalized methanethiol formation rate of Cs sulfide is nearly the same as that of Cs-promoted MoS2 with a much lower yield of unwanted methane. Kinetic measurements show that methanethiol on alkali sulfides is formed via the reaction 3 CO + 2 H2S → COS + CO2 + CH3SH. This represents a first example of H2S as a hydrogen donor for the formation of the thiol counterpart of methanol. The role of MoS2 is that of a promoter that disperses alkali and provides spillover H from H2 dissociation.

Understanding the essential roles in adiponitrile hydrogenation is a significant factor to design sparkling nickel catalysts. A series of Ni/Al2O3 catalysts have been synthesized by the deposition-precipitation method and used for the selective hydrogenation of adiponitrile. The formation of Ni compositions and chemical structure of catalysts were modulated by the assistant precipitators. Characterizations including the XRD, N2 adsorption-desorption, TEM, XPS, H2-TPD, and NH3-TPD were carried out. Smaller particles could be obtained via the fast deposition of Ni2+ by NaOH in Ni/Al2O3-OH or the uniform crystal seeds by urea in Ni/Al2O3-U. Strong alkali and the formation of nickel hydroxide facilitated the generation of Ni0 with better H2 activation ability. Whilst huge amount of nickel species in oxidative state and strong acidity were simultaneously generated in Ni/Al2O3-U, leading to the easily cycloaddition by-products. Kinetic study revealed that adiponitrile hydrogenation is a second-order reaction with respect to adiponitrile. The numbers of Ni0 active sites and acid sites could be balanced by the precipitation and crystallization via different processes. The yield of 1,6-hexanediamine reached 75.0% at 90 oC by 20 wt% Ni/Al2O3-OH.

Ions are of central importance in nature, and a variety of potential models was proposed to model ions in different phases for an in-depth exploration of ion-related systems. Here, we developed point charge models of 14 monovalent ions with the traditional 12-6 Lennard-Jones (LJ) potential for use in conjunction with 11 water models of TIP3P, OPC3, SPC/E, SPC/Eb, TIP3P-FB, a99SB-disp, TIP4P-Ew, OPC, TIP4P/2005, TIP4P-D, and TIP4P-FB. The designed models reproduced the real hydration free energy (HFE) of ions and the ion-oxygen distance (IOD) in the first hydration shell accurately and simultaneously, a performance similar to the previously reported 12-6-4 LJ-type ion models (12-6 LJ plus an attractive C4 term for cations or a repulsive one for anions). This work, along with our previous work on di-, tri-, and tetravalent metal cations (J. Chem. Inf. Model. 2021, 61, 4031-4044; J. Chem. Inf. Model. 2021, 61, 4613-4629), demonstrates the feasibility of the simple 12-6 LJ potential in ion modeling. In order for the 12-6 LJ potential to reproduce both the HFE and IOD, the LJ R parameters need to be close to Shannon's ionic radii for the highly charged cations and to the Stokes's van der Waals (vdW) radii for the monovalent ions. With an additional C4 term, the R parameters of 12-6-4 LJ ion models agree well with the Stokes's vdW radii and have a more physical meaning. It appears that the C4 term can be merged into the 12-6 LJ potential by a rational tuning of R and the LJ well depth. Simulations of the osmotic coefficients of alkali chloride solutions and the properties of gaseous and solid alkali halides indicate the necessity of further optimizing ion-ion interactions via, for instance, targeting more properties or using a more physical (polarizable) model.

This work systematically examines the interactions of alkali metal cations and their isoelectronic halide counterparts with up to six solvating Ar atoms (M+Arn and X-Arn, where M = Li, Na, K, and Rb; X = H, F, Cl, and Br; and n = 1-6) via full geometry optimizations with the MP2 method and robust, correlation-consistent quadruple-ζ (QZ) basis sets. 116 unique M+Arn and X-Arn stationary points have been characterized on the MP2/QZ potential energy surface. To the best of our knowledge, approximately two dozen of these stationary points have been reported here for the first time. Some of these new structures are either the lowest-energy stationary point for a particular cluster or energetically competitive with it. The CCSD(T) method was employed to perform additional single-point energy computations upon all MP2/QZ-optimized structures using the same basis set. CCSD(T)/QZ results indicate that internally solvated structures with the ion at/near the geometric center of the cluster have appreciably higher energies than those placing the ion on the periphery. While this study extends the prior investigations of M+Arn clusters found within the literature, it notably provides one of the first thorough characterizations of and comparisons to the corresponding negatively charged X-Arn clusters.

TThe electronic and optical properties of sphalerite (ZnS) are modulated by adsorbing alkali metals (Li, Na, K, Rb, Cs) and halogen (F, Cl, Br, I, At). Simulations based on density‐functional theory are used to study the electronic and optical properties of pristine sphalerite and alkali‐halogen adsorbed sphalerite structures. The results suggest that pristine sphalerite has high absorption in several portions of ultraviolet (UV) region (λ < 250 nm) and negligible absorption in the visible and IR region. The alkali‐halogen adsorbed structure of sphalerite results into red‐shift phenomenon in which an increase in absorption coefficient with wavelength is observed or spectrum shifting towards the red end is observed. Strong absorption for both alkali and halogen adsorbed nanostructures is found throughout the visible zone (~410 to 780 nm) of the spectrum. Bromine adsorbed sphalerite structure results in highest value of absorption in visible region in comparison to other alkali and halogen adsorbed structures. This shift in absorption peaks from UV region to desired visible region range is beneficial for optoelectronic applications and in fabrication of optoelectronics devices such as LED, ARC, solar cells, CRTs and sensors.

The effect of alkali metal doping on the electrical conductivity of Li3(1−x)Na3x VO4 (x = 0.0, 0.2, 0.4 and 0.6) is the axiom of this paper. The samples are synthesized using the conventional solid-state reaction technique. The X-ray diffraction results show the polycrystalline behavior of alkali-doped lithium vanadate (Li3VO4). It was also observed that sodium (Na+) ions have not shown their presence in the diffraction pattern, which indicates that alkali metal ions were well substituted in the interstitials and did not disturb the crystal planes of the lithium vanadate matrix. The X-ray diffraction studies also suggest an increment in the crystallite size of the prepared samples. The optical study shows excellent absorbance in UV range (200–300 nm) and also that with an increase in the alkali-doping concentration, shifts absorbance peaks slightly toward higher wavelengths, suggesting enhancement in the particle size. In these alkali-doped samples, it was observed that ionic conductivity decreases, and conversely, the dielectric constant and loss tangent increase subsequently with an increase in the sodium doping concentration due to the ionic radius of the dopant metal. High ionic conductivity within the range 1.1374 × 102–7.9326 × 100 Ω−1 m−1 (99.98% of total conductivity) is obtained in superionic phase of the material. These materials can be utilized in field of capacitors, transparent battery and electrode for batteries.

Summary Alkali and alkaline earth metals (AMs) play indispensable roles in dinitrogen activation and ammonia synthesis. AM oxides have been used as catalyst promoters for industrial ammonia synthesis, while AM metals are common reducing agents in dinitrogen fixation by organometallic complexes. With the strong push toward green ammonia synthesis, AM is now on a greater platform, playing a more prominent role in mediating dinitrogen reduction via a variety of processes that can be coupled with renewable energy harvest and storage. This perspective discusses the rich chemistry among AM, N2, H2, and NH3; summarizes the classic understandings and new exciting progress in the exploration of AM for both heterogeneous and homogeneous nitrogen fixation; and highlights the multifunctional roles of unconventional and reactive AM-containing materials for future greener ammonia synthesis.

Alkali aluminosilicates are potential materials for high temperature applications under alkali load. This study investigated the corrosion behaviour of potassium aluminosilicates of the nominal compositions of KAlSi2O6 and KAlSiO4 synthesized at different temperatures and dwell times and exposed to alkali load at 1100 °C. For understanding the corrosion behaviour depending on the synthesizing parameters, the produced materials and corroded samples were investigated by XRD and NMR spectroscopy (29Si, 27Al). The combination of both analytical techniques showed that characteristics of the synthesized materials on a structural level played an important role for the corrosion behaviour. It was shown that amorphous and disordered components in the samples occurred which were not registered by XRD. The application of 29Si and 27Al NMR spectroscopy yielded that materials having already after synthesis a structural arrangement similar to the equilibrium target phase of the batch showed a high structural stability under alkali load and gave positive results in the applied corrosion test. Materials with large structural rearrangements during alkali load exhibited volume changes and therefore failed the corrosion test. Based on these observations it should therefore be possible to design materials with high chemical and mechanical stability suitable as furnace linings and to evaluate end-of-life aluminosilicates for an application as alkali corrosion resistant recyclates.

Catalytic pyrolysis has recently aroused great interest for the high potential in upgrading bio-oils as renewable energy. However, conventional catalysts often exert diffusion resistance to large intermediate oxygenates. In this study, Fe-modified hierarchical ZSM-5 prepared by alkali and Fe loading of 2, 4, 6, 8 wt% were characterized by the analysis of XRD, BET, TEM, and NH3-TPD. Catalytic pyrolysis of poplar sawdust via Fe-modified hierarchical ZSM-5 was conducted using Py-GC/MS and TG-FTIR. The results indicated that alkali treatment and Fe loading of the catalyst introduced a hierarchical and porous structure and improved its acidity, leading to high mono-aromatics and olefins selectivity. The hierarchical ZSM-5 with 4 wt% Fe loading exhibited superior performance with high selectivity towards mono-aromatics of 15.30%. TG-FTIR analysis shows the volatiles release characteristics and FTIR spectra were consistent with pyrolysis behavior. Kinetic analysis reveals Fe-modified hierarchical ZSM-5 lowers the apparent activation energy in catalytic pyrolysis of poplar sawdust.

Excess thermodynamic properties of a wide variety of aqueous electrolyte solutions at elevated temperatures have been determined with the ORNL high-temperature isopiestic facility. This unique experimental apparatus provides very precise results over the useful temperature range of 110 to 250 C. The isopiestic method is a comparative technique which, in the present case, uses the Pitzer-Peiper-Busey formulation for NaCl(aq) as the reference electrolyte. At elevated temperatures the ion-interaction model of Pitzer continues to be the most useful description of the experimental results. The authors experimental program has included the alkali metal chlorides, sulfates, hydroxides, bromides, and bisulfates, the alkaline earth metal chlorides, and several specific compounds of scientific and practical interest. Numerous common-ion mixed electrolyte solutions have also been investigated in this program. In general, the activity coefficients of all the studied electrolytes decrease with increasing temperature. However, prominent differences between members of the same family remain, particularly when considered as the excess Gibbs free energy. The tendency for ion association increases with increasing temperature and becomes a factor at the higher temperatures. Trends and specific effects are illustrated with examples taken from the database generated in their high-temperature thermodynamic program.

The new predictive electrolyte model COSMO-RS-ES is evaluated and refined for the calculation of solubilities of salts in mixed solvent systems. It is demonstrated that the model is capable of predicting solid-liquid equilibria at 25 °C for ammonium and alkali metal salts quite accurately in a wide variety of solvent mixtures. Furthermore, through the introduction of Gibbs free energies of transfer of single ions it is shown that the model performance can be improved even further. This new data type also allows for an ion-specific way of evaluating the model for the first time. For some systems when calculating the solubility, larger deviations are observed, but for the vast majority of systems the model delivers good predictions. This shows that COSMO-RS-ES is a valuable tool for calculation of phase equilibria in electrolyte systems especially when the scarcity of data impede the application of models that require a higher number of parameters.