Alkaline Elements Research Articles

Mechanochemical study of a novel Magnesium alloy with trace addition of Gd, Nd, Ce, and La rare-earth and Sr elements

Mg-Zn-Ca-Mn materials micro-alloyed by Gd, Nd, Ce, and La rare-earth and Sr alkaline elements were developed. Optical and scanning electron microscopy, X-ray diffraction spectroscopy, tensile test, immersion, and electrochemical tests were applied to analyze microstructure, mechanical properties, and corrosion behavior. While the development of the equiaxed grain structures were observed in all the alloys, the Gd-containing alloy showed the smallest grain size and lowest fraction of second phases, which resulted in the highest yield and ultimate tensile strength of 310.0 ± 14.1 and 370.4 ± 41.6 MPa, respectively. Moreover, the corrosion studies also indicated the lowest rates in the Gd, and Nd-containing alloys, with the rates of 3.6 ± 2.5 and 3.9 ± 0.2 mm/y, respectively. The mechanisms of microstructure evolution, strengthening and corrosion behavior were discussed.

Enrichment of strontium and magnesium improves the physical, mechanical and biological properties of bioactive glasses undergoing thermal treatments: New cues for biomedical applications

Bioactive glasses (BGs) have emerged as invaluable resources for bone tissue engineering due to their remarkable properties such as bioactivity, resorbability, cell compatibility, and osteoconductivity. However, these materials exhibit certain limitations when subjected to high temperatures, for their tendency to crystallize, thus leading to diminished bioactivity, reduced mechanical strength, and altered dissolution kinetics. One promising approach to counteract this problem is to reduce the alkaline element content in BGs while simultaneously adding strontium and magnesium. Building on previous studies of Bio_MS, a recently developed experimental formulation, we investigated the contributions of strontium and magnesium to the thermal, mechanical, and biological properties of various bioactive glasses, including commercially available options. Differential thermal analysis, heating microscopy, X-ray diffractometry, environmental scanning electron microscopy, measurement of the Young's modulus, simulated body fluid testing, cytotoxicity tests, cell viability, growth, adhesion and morphology were assessed through an integrated approach and compared for a complete evaluation of BGs, and of doped BGs, also undergoing thermal treatments. The results demonstrated improved thermal, mechanical and biological behaviors of the magnesium-strontium-doped BGs, thus paving the way for the development of BGs with enhanced biomedical perspectives.

Application of Torrefaction for Improved Fuel Properties of Sunflower Husks

Sunflower husk (SFH) contributes 45–60% of the total sunflower seed weight and is a by-product of the sunflower oil industry. Among other elements, SFH ash contains K, Na, Ca and Mg. These elements cause rapid growth of ash deposits on convective heating surfaces of the boiler, resulting in reduced efficiency. The aim of this paper is to examine the possibility of producing quality fuel from SFH by its pretreatment with the technique of torrefaction in a fluidized bed in superheated water vapor. Continuous monitoring of the innovative SFH torrefaction process allowed for the determination of optimal process durations. SFH could be converted into a biofuel, having high calorific value and suitable characteristics for co-combustion with coal. Furthermore, the torrefaction in a fluidized bed of superheated water vapor allowed for a 6-fold reduction in the required process duration in comparison with data reported from the literature for the process of torrefaction in a dense bed, along with a 3-fold reduction in the chlorine content in SFH ash. These effects are beneficial to resolve the problem of corrosion on convective heating surfaces of boilers. However, torrefaction in superheated water vapor did not significantly reduce the content of alkaline and alkaline-earth elements in SFH ash. Still, this issue may be alleviated by significantly increasing the duration of SFH pretreatment.

Beyond lithium-ion batteries: Are effective electrodes possible for alkaline and other alkali elements? Exploring ion intercalation in surface-modified few-layer graphene and examining layer quantity and stages

In the pursuit of reliable energy storage solutions, the significance of engineering electrodes cannot be overstated. Previous research has explored the use of surface modifiers (SMs), such as single-side fluorinated graphene, to enhance the thermodynamic stability of ion intercalation when applied atop few-layer graphene (FLG). As we seek alternatives to lithium-ion batteries (LIBs), earth-abundant elements like sodium and potassium have emerged as promising candidates. However, a comprehensive investigation into staging intercalation has been lacking thus far. By delving into staging assemblies, we have uncovered a previously unknown intercalation site that offers the most energetically favorable binding. Here, we study the first three elements in both alkali (Li, Na, K) and alkaline (Be, Mg, Ca) earth metals. Furthermore, the precise mechanism underlying this intercalation system has remained elusive in prior studies. In our work, we employed density functional theory calculations with advanced hybrid functionals to determine the electrical properties at various stages of intercalation. This approach has been proven to yield more accurate and reliable electrical information. Through the analysis of projecting density of states and Mulliken population, we have gained valuable insights into the intricate interactions among the SM, ions, and FLG as the ions progressively insert into the structures. Notably, we expanded our investigation beyond lithium and explored the effectiveness of the SM on ions with varying radii and valence, encompassing six alkali and alkaline earth metals. Additionally, we discovered that the number of graphene layers significantly influences the binding energy. Our findings present groundbreaking concepts for material design, offering diverse and economically viable alternatives to LIBs. Furthermore, they serve as a valuable reference for fine-tuning electrical properties through staging intercalation and the application of SMs.

Multi-stage evolution of the monzonitic Larvik Plutonic Complex (Oslo Rift, Norway) and its implications for the formation of the Kodal Fe-Ti-P(−REE) deposit

The Larvik Plutonic Complex is a monzonitic complex that was emplaced early during the formation of the Permian Oslo Rift (southern Norway). It extends across its entire width (around 50 km), and is made up of a majority of larvikite (augite monzonite) and lardalite (nepheline monzogabbro to nepheline syenite) distributed in ten successive intrusive units that partially intersect each other. The Larvik Plutonic Complex also hosts occurrences of singular Fe-Ti-P-rich rocks of magmatic origin, including the Kodal deposit. These are mainly composed of titanomagnetite, ilmenite, titanaugite and apatite, the latter also featuring rare earth elements (REE) enrichment. Here, we aim to unravel the conditions that allowed the Kodal deposit to form, and determine why other mineralized bodies are not seen elsewhere in the Larvik Plutonic Complex. We compared the petrography and elemental and isotope (Sr, Nd and Hf) geochemistry of both the Kodal mineralization and the neighboring larvikite, in order to provide evidence of their petrogenetic relationship. Both lithologies share the same isotopic ratios (87Sr/86Sr(i): 0.7035–0.7043; εNd(i): +2.37 − +3.48; εHf(i): +3.39 − +9.16), which would suggest a single homogeneous source. The very low dispersion of our isotopic data also suggests that crustal contamination levels in the area were low to negligible. Normalized trace diagrams of larvikite in several localities of the Larvik Plutonic Complex also show enrichments in most incompatible elements, which becomes more prevalent towards the Kodal deposit. Elements like Sr and Eu(2+) follow an opposite trend, because of their compatibility in plagioclase. We therefore infer that the region around the Kodal deposit hosts more fractionated larvikite due to the previous crystallization of successive plagioclase cumulates. We deduce that the Kodal lobe corresponds to a more evolved intrusion, which is no part of Pluton V per se, as considered in the literature until now, but instead derives at least from a monzonitic magma at the origin of the plutons V to VIII). This also implies that the formation of Fe-Ti-P mineralization at Kodal was most likely a consequence of enrichment of the residual melt in alkaline elements and incompatible elements. These conditions support an early hypothesis of formation by silicate-liquid immiscibility, along with petrographic evidence of disequilibrium at the mineralogical scale. However, further analyses would be required to test the hypotheses of silicate-liquid immiscibility against an accumulation of the Fe-Ti-P mineralization from an evolved intermediate magma.

Use of Biostimulants in Energy Crops as a New Approach for the Improvement of Performance Sequestration CO2

This review presents a recent study on improving energy crops (ECs) in the EU and discusses the potential use of biostimulants to enhance CO2 sequestration processes in these plants. The novelty of this study lies in demonstrating alternative directions for improving productivity and increasing plant yield without relying on introducing new hybrids (GM) or using advanced agrotechnology. There is a great deal of discussion about using energy crops for direct combustion or biogas production. However, there is a paucity of information regarding the use of biostimulants and their role in increasing the yield of energy crops, particularly in terms of CO2 compensation. In CO2 sequestration, increasing the intensity of the photosynthetic process is considered crucial for the more efficient growth of energy crops. Traditionally, fertilization aimed at improving photosynthesis results in a large amount of alkaline elements, which can cause negative effects in boilers. This paper describes the use of amino acid biostimulants extracted from industrial waste, either chemically or biotechnologically, and their different forms of application. It addresses the current challenges and benefits of using biostimulants in energy crops to increase photosynthesis without the use of genetic engineering tools in plants.

Spectroscopic characterization of fluorite of Amba Dongar, Gujarat, India: Linking chemical composition with color

This work addresses the long-standing debate surrounding the origin of color variation in fluorite (CaF2) through a novel quantitative approach. By examining eight carefully selected fluorite samples having different hue of colors from the Amba Dongar mine in Gujarat, India, a rigorous quantitative analysis was conducted. This approach combined chemical compositional data and optical spectroscopic features to elucidate the relationship between elemental composition, concentration, and color variation in fluorite. Precise elemental concentration data for trace transition metals, alkali metals, and rare earth elements (REEs) were obtained through inductively coupled plasma mass spectroscopy (ICP-MS) analysis of powdered fluorite samples. Optical spectroscopic techniques, including UV–visible absorption, emission (photoluminescence and fluorescence), and Raman spectroscopy, were employed to capture characteristic spectral signatures for specific color of the study sample. The work unveils a strong correlation between specific elemental concentrations and observed spectral features, particularly influenced by alkaline metals, transition group elements, and REEs. Fluorite’s optical absorption behavior lacks a clear pattern in UV and infrared wavelength ranges but correlates well with transition metal, alkaline element, and REE concentrations in visible wavelength regions, influencing coloration. Luminescent centers in the study fluorite samples correspond to specific REE concentrations, indicating a strong linkage between emission wavelengths with the presence of specific REE. UV–visible and fluorescence in fluorite result from trivalent REE or Eu2+ ions, with emission intensity affected by REE concentration and specific REE or combinations thereof. Raman spectroscopy identifies characteristic modes related to F-substitution and REE impurities, providing insights into fluorite’s structural composition. This quantitative correlation between elemental composition and spectroscopic characteristics represents a novel contribution for understanding color variation mechanisms in fluorite. The comprehensive analysis of this present work underscores the intricate interplay of mineral composition, and element concentration particularly alkaline metals, transition group elements, and REEs, for variation in spectral signatures with variation in fluorite’s visual attributes.

Примесный состав берилла из сподуменовых пегматитов месторождения Пашки (провинция Нуристан, Афганистан)

The SIMS method (secondary ions mass-spectrometry) determined the impurity composition of a beryl crystals (aquamarine) from the pegmatites of the Pashki lithium deposit (Nuristan province, Afghanistan). 12 local determinations of the content of 20 chemical elements (including halogens and water) were performed. In comparison with aquamarine from rare metals, including spodumene pegmatites from other regions of the world, the studied beryl is significantly enriched with large ion lithophile elements: Li (about 1100 ppm), Na (4500 ppm) and K (300 ppm). High concentrations of alkaline elements in the beryl of lithium pegmatites are considered as a genetic sign of the high potential of alkalis created during the crystallization of spodumene associated with beryl and other lithium minerals. This well-known genetically determined feature of beryl, characteristic of productive lithium pegmatites, therefore is promising in the development of search and evaluation criteria for lithium pegmatites of Nuristan and other pegmatite provinces.

Влияние химического состава биомассы на процесс агломерации в псевдоожиженном слое котлоагрегата Е-75-3,9-440 ДФТ

The combustion of biofuels in the fluidized bed is an attractive technology to process biomass. However, the technology of biomass combustion in fluidize beds is characterized by several problems associated with the agglomeration of bed material. The aim of the research is to study the influence of the chemical composition of biomass on the agglomeration process of the fluidized bed of the boiler unit E-75-3,9-440 DFT. The boiler burns a mixture of by-products of pulp and paper production to increase stability of the fluidized bed and the duration of boiler operation between periods of its deslagging. The study has tested two types of biomass burned in a mixture in a steam boiler unit E-75-3,9-440 DFT with a fluidized bed. The authors also have studied the samples of agglomerates, bed, and fly ash to find out more about the agglomeration process. The elemental composition of samples of bark-wood waste, sewage sludge, agglomerates and ash has been studied. Elements affecting the process of agglomeration of the fluidized bed have been identified. The results of the analysis have showed that essential ash- and slag-forming components in the sewage sludge are silicon, calcium, sulfur, and potassium, and in the bark wood waste the essential ash- and slag-forming components are calcium, potassium, and sodium. The main elements influencing the process of agglomeration of the fluidized bed are alkaline elements of potassium and sodium. The results obtained make it possible to predict the agglomeration of the fluidized bed, to select the fuel mixture in the proportion necessary to reduce the agglomeration process.

Isotope fractionation of alkaline and alkaline-earth elements (Li, K, Rb, Mg, Ca, Sr, Ba) during diffusion in aqueous solutions

In this study, we used an improved “diffusion cell” method to precisely determine the diffusion-driven kinetic isotope fractionation factors of the Li, K, Rb, Mg, Ca, Sr, and Ba cations in aqueous solutions under room temperature. The obtained isotope fractionation factors (±2σ errors) are, α7/6Li = 0.996139 ± 0.000140, α41/39K = 0.998572 ± 0.000072, α87/85Rb = 0.999333 ± 0.000020, α26/24Mg = 0.999877 ± 0.000010, α44/42Ca = 0.999704 ± 0.000010, α88/86Sr = 0.999781 ± 0.000014, α138/135Ba = 0.999716 ± 0.000018. The results show that the charge of the cation and the ion-water bond length for the aquo ions are the two predominant factors affecting the mass dependence of isotope fractionation (β factor) during cation diffusion in aqueous solutions. Cations with higher charge numbers and shorter ion-water bond lengths exhibit less kinetic isotope fractionation during diffusion. Therefore, the isotope separation effect during diffusion (or β factor) in fluids is fundamentally controlled by the intensity of ion-water interaction. Weaker ion-water interaction (e.g., lower charge number, longer ion-water bond length) leads to less prominent hydrodynamic behavior for diffusing ions at the molecular level, thus more significant isotope fractionation in bulk solutions, and vice versa. Ions of larger radius would show stronger mass dependence of isotope fractionation (β factor), which can cancel the effect of decreasing relative isotope mass difference for heavier elements, thus kinetic isotope fractionation during diffusion in aqueous solutions remains prominent even for heavy elements such as Rb, Sr, and Ba. The diffusion-driven kinetic isotope fractionation factors measured in this study could provide a useful basis for interpreting specific natural isotopic variability of alkaline and alkaline-earth elements in supergene environments where chemical diffusion takes place.

Synthesis and characterization of complex phosphates of alkaline elements, magnesium and zirconium as potential ceramics for nuclear waste immobilization

Phases of variable composition A2−хА'хMg0.5Zr1.5(PO4)3 (АA' – KNa, KRb, KCs, 0 ≤ x ≤ 2) with langbeinite and kosnarite structures can serve as matrices immobilizing radioactive waste. They were synthesized by sol-gel method followed by heat treatment and investigated by X-ray diffraction at different temperatures, IR spectroscopy, scanning electron microscopy and electron probe microanalysis. A Rietveld refinement of the KCsMg0.5Zr1.5(PO4)3 structure showed that the framework is formed by octahedra (Mg/Zr)O6 and tetrahedra PO4 connected by vertices; potassium and cesium cations are located in cavities. When the temperature changes, phosphates with the langbeinite structure expand uniformly in all directions: αа = αb = αc = (4.2−6.6) ∙ 10−6 °C−1, without undergoing polymorphic transitions. Phosphate Na2Mg0.5Zr1.5(PO4)3, which crystallizes in the kosnarite structure type, expands anisotropically: αа = −2.6·10−6, αс = 8.2·10−6, αav = 1.0·10−6 °C−1. The chemical durability test shows that the leaching rate of Cs ions from the solid solution with langbeinite structure is of the order of 10−5 g cm−2 d−1.

Active moss biomonitoring of airborne potentially toxic elements in recreational areas of Moscow.

Active biomonitoring using the moss bag technique was applied to examine the atmospheric deposition of potentially toxic and other elements in recreational areas of Moscow. Moss bags with Sphagnum girgensohnii were placed in the territory of seven parks (Losiny Ostrov, Victory Park, Ostankino, Sokolniki, Izmailovo, Kuzminki-Lyublino, Tsaritsyno) at three locations in each park from June to September 2018. The content of 32 chemical elements: Na, Mg, Al, Cl, K, Ca, Sc, V, Mn, Fe, Co, Zn, As, Br, Rb, Sr, Mo, Sb, Cs, Ba, La, Sm, Tb, Hf, Ta, W, Au, Th, U, Cu, Pb, and Cd in moss samples was determined by instrumental neutron activation analysis and atomic absorption spectrometry. After a 3-month exposure period, high uptake of Sb, U, Th, Sm, La, Mo, Zn, Co, Fe, V, Sc, etc. was observed in some of the moss samples. The physiologically active elements Cl and K and alkaline elements Rb and Cs were depleted from the moss tissue during the exposure. The high accumulation of Zn, Pb, Cu, Co, V, and Sb in moss samples evidenced an anthropogenic impact on the parks, mainly associated with road traffic. To determine the level of pollution, a set of environmental indices was calculated: contamination factor (CF), enrichment factor (EF), total pollution index (TPI), and relative accumulation factor (RAF). The highest RAF values were obtained for Sb on the territory of all parks. According to EF, the samples were enriched in Al, Fe, U, Pb, Cd, Au, Sb, Th, and Ta. High CF values were obtained for sites in Losiny Ostrov, Izmailovo, Tsaritsyno, and Kuzminki-Lyublino located close to roads. According to TPI, the level of air pollution on the territory of the abovementioned parks varied from moderate to high. To identify the major sources of pollution, correlation analysis and principal component analysis were applied.

Spatial variability and hydro/geochemical profiling of the elemental composition of mineral deposits and drip water from caves using unsupervised chemometric modelling

Caves are complex systems characterized by high variability in trace element signatures that simple geochemical analysis cannot detect since useful information hidden in the dataset may be lost. Sufficiently robust unsupervised statistical approaches may provide these significant signatures for cave hydro/geochemical profiling. The present study focused primarily on quantifying the relevant contributions of elements and their relationships to the variability of the hydro/geochemical profiles of speleothems, sediments and drip water within a cave using Principal Component Analysis (PCA) after Varimax rotation and two-way joining analysis as a clustering method. This prospective study was conducted on the Urșilor (Bears') show cave (Romania). The contents of Ca, Mg, Sr, Al, P, S, Fe and Zn in the mineral deposits were determined via X-ray fluorescence, while the content of these elements in drip water was determined via inductively coupled plasma–optical emission/mass spectrometry. The contents of HCO3−, Cl−, F−, NO3−, and SO42−; pH; electrical conductivity; and organic and inorganic carbon fractions were also determined. In the case of speleothems, the determinations were performed on randomly selected spots, reflecting the composition at various growth times. The PCA revealed that the geochemical profile of speleothems can be described by four principal components (PCs), represented by 71% for stalactites and 82/92% by three PCs for stalagmites/sediments. The strong signatures of Ca, Mg/Ca, K, and detrital elements (Al, Si, P, S) in stalagmites/sediments in proportions of 41/46%; K, Fe and Zn 30/32%; and Sr and Sr/Ca 11/15% were retained by PCA. The geochemical profile of the stalactites was described by Mg (35%), P, Zn, and Sr (21%); Al and Si (15%); and S, Ca and Mg/Ca (10%). Reducing the dimensionality of the data matrix to alkaline earth elements, two PCs described 95% of the mineral deposits, including the strong signatures of Mg/Ca and Sr/Ca, exceeding 50% of the variability in the first PC. Stalactites and stalagmites were primarily grouped based on their geochemical profile and less so on location, yielding two clusters/four subclusters of stalagmites. The PCA plot did not show a separation between stalactites and stalagmites, as their geochemical profiles differ significantly only in terms of Fe concentration. The hydrochemical profile of drip water was described by 4 PCs at a percentage of 95%: (i) alkaline elements, alkaline earth elements, anions and organic carbon and (ii) trace elements and DOC. The profile of Ca2+–HCO3− imprint drip water was described by two PCs at proportions of 66% (Ca, Mg, Na, K, Mg/Ca, Sr/Ca, Ba/Ca ratios, HCO3− and organic carbon) and 74% by trace elements (Co, Ni, Ti, Fe, Mn, V and Si). The transition trace elements have very complex chemical behaviour and appear in drip water as Ca-/Si-rich inorganic/organic colloids and simple ions. Although complementary to the PCA, the two-way joining analysis in a heatmap did not offer relevant information in the description of the hydro/geochemical profile of the karst system compared to PCA. A study of a farmed calcite sample highlighted its difference in composition compared with stalagmites in terms of Mg, Si, K, Zn, Sr and Sr/Ca. Future development could include the application of PCA to seasonally collected farmed calcite and drip water samples to obtain hydro/geochemical profiles of stalagmites in the making to determine the seasonal leaching of metals from bedrock/soil by drip water, inclusion in stalagmites, and seasonal growth. The practical significance of this paper for trace element research is of great concern because it allows these recorded indicators to be connected to the ancient climate and environment of stalagmites.

О роли соленых углей при превращении каолинита в гидрослюду парагонитового типа в тонштейнах Донбасса

The character of kaolinite hydromicatization within the Donetsk Basin tonsteins in the course of metamorphism depends on the types of enclosing coals: either normal or salty ones. Alongside with terrigenous minerals within the coal-bearing masses and the fossil sea waters, indicator authigenous minerals fromsaltycoals – halite and glauberite –should bespecified as thesources ofsodium and potassium for kaolinite hydromicatization. The conditions, most favorable for formation of the most stable phase of paragonite-type hydromica in kaolinite interlayers, arise within paralic formations over the areas of alkaline caustobioliths formation in the course of metamorphism. In the case when halite and glauberite from salty coals make the principal source of sodium, brammalite generation begins in matatonsteins during anthracite formation. The process goes on until feldspars and micas begin active supply of potassium into chloride Cl-Ca-Na brine. From this moment on, brammalite in clay interlayers is being rapidly replaced with illite. Eventually, association of paragonite and muscovite-type hydromicas arises within the clay interlayers. If the principal source of the alkaline elements responsible for kaolinite hydromicatization consists of terrigenous minerals from normal (nonsaline) coal-bearing masses (potassium feldspars, micas, plagioclases), exclusively illite develops within metatonsteins.

The role of chemical properties of the material deposited in nests of white stork in shaping enzymatic activity and fungal diversity

Organic debris accumulated in bird nests creates a unique environment for organisms, including microbes. Built from various plant materials that are typically enriched by animal residues, bird nest favours the development of various fungal groups. The aim of this study was to investigate the chemical properties of the material deposited in the white stork Ciconia ciconia nests and the link between extracellular enzyme activity and the diversity and composition of culturable fungi. Our findings revealed low C/P and N/P ratio values in the nest materials, which indicate a high P availability. Nest material C/N/P ratio ranged from 67/8/1 to 438/33/1. Enzymatic activity strongly correlated with the content of carbon, nitrogen, and pH of the material deposited in the nests. A total of 2726 fungal isolates were obtained from the nests, from which 82 taxa were identified based on morphology and DNA sequence data. The study indicates that white stork nests are microhabitat characterised by diverse chemical and biochemical properties. We found relationship between the fungal richness and diversity and the C/P and N/P ratios of materials from the nests. Our study showed that culturable fungi occurred frequently in materials with high levels of C, N, and P, as well as high concentrations of base alkaline elements (Ca, Mg, and K).

Method for Low-Temperature Vacuum-Thermal Cleaning of Surface Single Crystals Si and GaAs

The paper reports on a method of low-temperature vacuum-thermal cleaning of the surface of Si and GaAs single crystals developed by the authors, which consists in implanting Ba+ ions (or alkaline elements) into Si and GaAs crystals preliminarily cleaned by ultra-high vacuum by ion etching and subsequent annealing in two stage at 800 K - 15 minutes and at 1000 K for 30 minutes. The effect of effective cleaning is achieved due to the fact that the introduced ions of Ba+ and alkaline elements, being active, form compounds with impurity atoms (O, C, S, N, etc.) at the first stage and are removed together with impurities after the second stage of heating.

Renewable diesel synthesis from sesame indicum (bene) seed oil using novel heterogeneous biocatalyst derived from the Chrysophyllum albidium seed coat

The synthesis, characterization, optimization and oxidation stability improvement of biodiesel from the seed oil of sesame indicum using a novel nano-heterogeneous bio-catalyst derived from the Chrysophyllum albidium seed coat (CASC) is reported. The heterogeneous catalyst was produced by calcination and activation at 400 °C, 600 °C and 800 °C using acetic acid. The catalyst was characterized using scanning electron monograph (SEM), Fourier transform infrared (FTIR), and x-ray diffraction (XRD). The seed oil was extracted using mechanical press milling and the biodiesel produced were characterized using AOAC 2019 edition and ASTM D-6151, Fourier transform infrared (FTIR) and gas chromatography (GC) methods. The results indicated that calcined Chrysophyllum albidum seed coat contains nano-particles and alkaline elements (75 % graphite). The calcination process improved the size reduction and structural arrangement of the particles. The 600 °C calcination temperature had the highest biodiesel yield of 88 % at 3.0 wt % catalyst concentration, 12:1 M ratio of alcohol to oil and 500 rpm. The reusability of catalyst indicated 71.50 % after fifth (5th) cycle. After 28 days storage duration in the presence of the natural, renewable and eco-friendly antioxidant (1 % turmeric), the oxidation instability of the produced biodiesel was reduced by 50 %. The quality of the biodiesel indicates agreement with standards and literature as well as high potential for effective application in diesel engine.

Synthesis and Structure of New Potassium and Cesium Zinc Diphosphates

This article presents the results of a study of new solid solutions formed in the system of diphosphates of alkaline elements and zinc: K2Zn3(P2O7)2–Cs2Zn3(P2O7)2. The obtained materials are promising as matrices for creating phosphors. The formation of phases containing two alkali cations is established on samples obtained by solid-phase synthesis by X-ray phase analysis, and the results of studying their thermal stability are presented.

KARAKTERISTIK MINERALOGI PADA VEIN TEMBAGA KLUWIH, PACITAN, JAWA TIMUR

The southern mountains of Java are a path of copper-gold mineralization that has proven to have high economic value. Pacitan is part of the geological system and mineralization of the southern mountains, which are part of the Sunda Arc magmatism. The research area is located in the copper mining location in Kluwih village, Tulakan, Pacitan, East Java. The presence of copper mineralization in the form of massive sulfide/sulfosalt veins in the Kluwih area is evidence of an epithermal mineralization system which is rare and has not been studied intensively. This study intends to carry out mineralogical tests both physically and chemically for the characteristics and mineralogical composition of vein in the Kluwih area. The research was conducted using geological mapping methods in mine tunnels, rock sampling, laboratory analysis using petrographic methods, ore microscopy, rock geochemistry using ICP OES/MS – XRF – AAS, mineralogy using SWIR and XRD spectral analysis. The geomorphology of the Kluwih area and its surroundings consists of the morphology of alluvial plains and intrusive hills. Lithology is composed of volcanic–subvolcanic rocks in the form of porphyry dacite, dacite, dacite breccia, and alluvium. Mineralization forms in structural openings that cut and alter dacite rocks and dacite breccias. The alteration that develops in the Kluwih area, especially in the area around the mine (tunnel) is dominated by kaolinite-illite, pyrophyllite-little-sericite, chloritization, and mineralization found in the form of veins that have massive sulphide composition with the dominant internal texture being breccia. The texture or structure of the mineralization is in the form of brecciation (hydrothermal breccia), sulfide-pyrophyllite-kaolinite, quartz- sulfide/sulfosalt, and massif sulfide/sulfosalt. The results showed that the ore had a density of 4.65 gr/cm3 while the highly argillic altered side rocks had a density of 2.54 gr/cm3. In the ore, visible massive sulfide/sulfosalt minerals consist of mosaic bonds and intergrowth between similar or different minerals. The detected ore minerals are pyrite, enargite, covellite, chalcopyrite, and bornite. Enargite and pyrite are the dominant metallic minerals found in ores. Enargite crystals appear to have a size of 56 - 160µm, pyrite accumulates in anhedral crystal forms with a size of 120 - 900µm and inclusions in enargite measuring 50 - 140µm, along with covellite-chalcopyrite ± bornite minerals with a fine size of 5 - 20µm. The geochemistry of the ore is seen as sulfide filling, as evidenced by the SiO2 value of only 4.5% followed by metal enrichment in the form of 27.6% Fe, 12.6% Cu, 4.15% As, and 46.2% S. Alteration minerals which is present is probably a mica group such as phengite with a marked presence of elements of 0.7% MgO and 1.9% Al2O3. The geochemistry of the side rock is seen to have a high SiO2 value of 71.7%, followed by a high alkaline element forming alteration minerals such as pyrophyllite with an Al2O3 value of 15.3% with a low total Ca-Na-K value of 0.25%, and there is residual TiO2 by 0.38%. Terraspectral analysis and XRD confirmed that the main peaks were pyrophilite-phengite, followed by the minerals enargite and pyrite. The Kluwih vein is a copper vein associated with advanced argillic alteration, as part of a rich high sulfidation epithermal system with Cu-Au-As-Sb mineralization.

The Pillar Effect of Large-Size Alkaline Ions on the Electrochemical Stability of Sodium Manganese Hexacyanoferrate for Sodium-Ion Batteries.

Sodium manganese hexacyanoferrate (NaMnHCF) is an attractive candidate as a cathode material for sodium-ion batteries due to its low cost and high energy density. However, its practical application is hindered by poor electrochemical stability caused by the Jahn-Teller effect of Mn and the unstable structure of NaMnHCF. Here, this paper aims to address this issue by introducing highly stable AMnHCF (where A = K, Rb, or Cs) through a facile method to composite with NaMnHCF. The findings reveal that all AMnHCFs have a "pillar effect" on the crystal structure of NaMnHCF. It is observed that the degree of pillar effect varies depending on the specific AMnHCF used. The less electrochemically inactive the alkaline ion is and the greater the degree of compositing with NaMnHCF, the more dramatic the pillar effect. KMnHCF shows limited pillar effect due to its rough composition with NaMnHCF and the loss of K+ upon (de)intercalation. RbMnHCF has lower electrochemical activity and can be better composited with NaMnHCF. On the other hand, CsMnHCF exhibits the strongest pillar effect due to the inactivation of Cs+ and the excellent coherent structure formed by CsMnHCF and NaMnHCF. This research provides a new perspective on stabilizing NaMnHCF with other alkaline elements.