Search Results (43)

This paper presents the results of studies on the direct production of lead–antimony alloys from sodium antimonate and on the use of antimony obtained through carbothermic reduction for technical purposes. It was shown that during the carbothermic reduction of antimony from sodium antimonate onto a lead collector at 900 °C, antimony recovery into the lead–antimony alloy increased by 10.88–12.93% compared with the process performed without the addition of lead. The process proceeds without the addition of slag-forming components. A decrease in the Sb content in the lead–antimony alloy as a result of changes to the amount of metallic lead in the melt has practically no effect on the process performance. Examples of the production of lead–antimony alloy containing 25.58% and 11.52% antimony during the carbothermic smelting of sodium antimonate are given. It is shown that the alloy containing 25.58% Sb can be used in the technological process of lead refinement at the final bismuth removal stage. The alloy containing 11.52% antimony complies with the standard for the SSuYu grade of lead–antimony alloy (9.0–12.0% Sb), including the regulated impurities, except for iron. The iron content exceeds the specified limit by 0.045%, which will require minor additional purification or the use of this alloy for special purposes. Dilution of the antimony alloy by adding lead to reduce the antimony content to 4.0% Sb at 340–360 °C was also considered. The purpose of the latter is to reduce energy consumption in cases where a significant volume of metallic lead would otherwise need to be heated to the temperature of reduction smelting at 900 ± 20 °C. The proposed technical solutions can be integrated quite easily into the existing technological flowsheet of lead production. Full article

In this study, the carbothermic reduction of sodium antimonate in crucible smelting was investigated. The optimal process temperature was determined to be 900 °C, with 10% coke consumption (with an ash content up to 15.33%) and a feed particle size of minus 1 mm. The process does not involve the addition of slag-forming components. Sodium participates in the formation of the slag phase. According to the smelting results, the amount of antimony recovered as crude metal reached 71–72%, while the Sb content in the crude metal reached up to 94.5%. A significant portion of antimony (up to 27%) volatilizes with off-gases. A notable sodium content was detected in the crude antimony, reaching up to 8% in some samples, while more than 80% of sodium was transferred to the slag phase. Arsenic, present in the initial concentrate at a level of 0.6%, was distributed approximately equally among the metallic, slag, and gas phases. Lead was predominantly concentrated in the crude antimony. Iron preferentially dissolved in the crude antimony. Other impurities were distributed in comparable amounts between the metallic and slag phases. Tellurium, present in sodium antimonate at 0.79%, was detected in some samples within the slag phase. Full article

In this study, we investigate the reduction smelting of antimony concentrate, where sodium antimonate is the primary antimony-bearing component, in alkaline melts. This study aims to reduce the carbon footprint of metallic antimony production. It is shown that traditional carbon reduction is accompanied by significant formation of carbon-containing gases and sodium losses due to volatilization. Based on thermodynamic analysis and experimental investigations, carbon monoxide is established as the key active gaseous reducing agent for antimonate compounds, predominantly operating in the temperature range of approximately 320–900 °C, which corresponds to the stages of coke oxidation and sodium antimonate decomposition. The authors propose introducing sodium hydroxide into the charge to form an alkaline melt with a lowered melting point when mixed with the antimony concentrate, ensuring the sequestration of carbon dioxide through the formation of sodium carbonate. Experiments confirmed the possibility of chemically fixing up to 75.5% of CO₂ into the slag phase at the laboratory stage and up to 87% of CO₂ during pilot tests of reduction smelting under a flux layer. Crude metal with an antimony content of 94–96.2% Sb was obtained, while coke consumption was reduced by 16–20%. The proposed approach ensures a simultaneous increase in the degree of antimony recovery, the utilization of carbon-containing gases, and the formation of a stable eutectic slag melt. This allows the process to be considered an element of carbon-neutral pyrometallurgical technology for processing antimony concentrates. Full article

Water pollution from industrial dyes is a critical challenge due to the resistance of these types of compounds to degradation and potentially harmful effects on living organisms and human health. In this study, the electrochemical degradation of methylene blue (MB) was investigated using ink-based copper foam electrodes with reduced graphene oxide (rGO), antimony trioxide (Sb₂O₃), and rGO/Sb₂O₃ composites. The materials used to synthesize the electrodes were characterized by X-ray diffraction (XRD), which showed the successful synthesis of GO, rGO, and the Sb₂O₃-rGO composite. Additionally, the synthesized electrodes were examined using SEM. The MB degradation was studied using kinetic behavior and removal efficiency at pH levels from 3 through 6, monitored using UV-Vis spectroscopy. The electrocatalytic degradation was studied using sodium sulfate as the electrolyte across a pH range of 3 to 8. All electrodes investigated were determined to follow first-order kinetics. The Sb₂O₃-rGO composite showed the highest rate constants of MB degradation at pH 7 and 8, with rate constants of 0.0160 and 0.0159 min⁻¹, respectively. At the same time, the rGO ink-based electrode worked fastest at pH 3 and pH 4 with rate constants of 0.0178 and 0.0158 min⁻¹, respectively. The Sb₂O₃ also works best at pH 3 and 4 with rate constants of 0.0151 and 0.0152 min⁻¹. SEM analysis shows the composite electrode was more resilient to degradation than other materials. Full article

Background/Objectives: Ash made from juniper trees and added to cornmeal-based dishes may have provided calcium (Ca) to traditional Indigenous diets. Few studies have quantified the mineral content of juniper ash, including its Ca content. The objective of this study was to determine whether juniper ash could serve as a safe source of non-dairy Ca in an intervention study. Methods: Branches from two varieties of Juniper (Rocky Mountain Juniper, or Juniperus scopulorum and Eastern Red Cedar, or Juniperus virginiana) were harvested and burned to ash in a laboratory setting. Juniper ash from the southwestern U.S. available for retail purchase was used for comparison. All samples were tested for content of 10 nutritive elements (Ca, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, selenium, and zinc) and 20 potentially toxic elements (silver, aluminum, arsenic, barium, beryllium, cadmium, cobalt, chromium, mercury, lithium, molybdenum, nickel, lead, antimony, tin, strontium, thallium, uranium, and vanadium) as well as n = 576 pesticide residues. Results: All samples contained both nutritive and potentially toxic elements. Each teaspoon of ash contained an average of 445 ± 141 mg Ca. However, the samples also contained lead in amounts ranging from 1.09 ppm to 15 ppm. Conclusions: Information on the nutritive and potentially toxic elemental content of juniper ash and how it may interact within a food matrix is insufficient to determine its safety as a Ca source. Further investigation is needed on the bioavailability of calcium oxide and its interaction with other dietary components to clarify the potential role of juniper ash in contemporary food patterns. Full article

Pollution by Sb, which is widely used in industry and agriculture, poses serious threats to ecosystems. This study demonstrates, for the first time, that sodium alginate (ALG) modified by polyethyleneimine (PEI) has good adsorption capacity for Sb(III) (the theoretical maximum adsorption capacity was 978 mg/g, and the actual maximum adsorption capacity was 743 mg/g) and can retain 90–98% of the initial removal rate after eight cycles of reuse. The inorganic ions and humic acid in Sb(III)-containing wastewater do not affect the adsorption capacity of PEI/ALG within a certain pH range. However, it was also found that the adsorption was interfered with by Sb(III) precipitation, phosphate ions, and some coexisting cations/metalloids such as Ni, Cd, Pb, and As under higher pH conditions, and the recovery rate of antimony in the desorption process needs to be further improved. Density functional theory calculations reveal that the -OH, -COOH, -NH₂, -NH-, and -N= in PEI/ALG show strong binding with Sb (−56.85, −28.39, −17.98, −25.76, and −17.98 kcal/mol, respectively), enabling these functional groups to easily form stable composite structures with Sb(III). This characteristic enables PEI/ALG to selectively adsorb Sb(III) under certain conditions. Combining these findings with the characterization analysis results indicates that the mechanism of PEI/ALG adsorption of Sb(III) is mainly the formation of H bonds and coordination between -OH, -COOH, and Sb(III). The selective adsorption mechanism of PEI/ALG for Sb(III) has not been investigated previously, and our research results indicate the high potential of this approach. Full article

Copper polymetallic sulfide ore from the Asgat copper polymetallic deposit in Mongolia has been found to contain a high grade of antimony and silver in addition to copper. In this research, flotation experiments using sodium butyl xanthate (SBX), ammonium dibutyl dithiophosphate (ADD), isopropyl ethyl thionocarbamate (Z-200), and their mixtures were conducted on a sample from the deposit under natural pH conditions. The results of the flotation tests indicate that optimal conditions were achieved with a feeding of 92% −0.074 mm (92% finer than 0.074 mm), sodium silicate dosage of 800 g/t, sodium humate dosage of 300 g/t, sodium sulfite dosage of 300 g/t, and collectors of 60 g/t of ADD and 60 g/t of Z-200. The closed-circuit flotation tests showed that the recovery of copper, antimony, and silver from the ADD/Z-200 combination was 8.13%, 5.41%, and 9.26% higher than that form the single Z-200 while reducing the reagent cost by 12.75%. Full article

Selective alkaline leaching was evaluated to remove arsenic (As) and antimony (Sb) from a polymetallic copper concentrate from Zimapán, Mexico, where these metalloids cause environmental risk and smelter penalties. Batch tests used sodium sulfide (Na₂S) in alkaline media, varying reagent concentrations and temperature; kinetic modeling identified the rate-controlling step, and X-ray diffraction (XRD) plus scanning electron microscopy/energy-dispersive spectroscopy (SEM–EDS) assessed phase changes. The kinetic analysis indicated chemical control with a higher reaction order for Na₂S than for NaOH. A quadratic regression described the process and identified Na₂S concentration and temperature as the dominant factors. Maximum extractions reached 91.9% for As and 72.1% for Sb while limiting dissolution of value-bearing sulfides, as supported by XRD and SEM–EDS. Environmental indices (I_geo, EF) classified As and Sb as highly contaminating and geochemically enriched in the feed, underscoring the need for selective removal. Overall, alkaline leaching with Na₂S provides a technically feasible and environmentally favorable route to remediate metalloids and upgrade polymetallic concentrates. Full article

Antimony (Sb) is a key material in high-capacity potassium and sodium batteries, particularly in the fabrication of Sb–carbon composites. In this work, nanoscale Sb powder was synthesized directly from SbCl₃, using Al powder as a reducing agent. The reduction process was carried out by gradually adding Al powder to an SbCl₃—acetone solution under continuous cooling and stirring, owing to the highly exothermic nature of the reaction. Acetone was found to be an effective solvent, enabling the formation of Sb nanoparticles with an average particle size of 50 nm and a crystallite size of 25 nm. The purity of the produced powder was nearly 100%, as confirmed via SEM/EDS and XRD analyses. XRD patterns of both commercial and synthesized Sb powders displayed identical and ideal Sb reflections, while FTIR spectra further confirmed their structural similarity. Sintering studies revealed relative densities of 99% for pellets prepared from both commercial and synthesized powders. SEM/EDS examinations of the raw powders and sintered pellets provided complementary microstructural and compositional insights. Overall, this study demonstrates the feasibility of producing high-purity nanoscale Sb powder through a simple, single-step redox process that is both cost-effective and efficient. Full article

Pentavalent sodium antimoniate (Sb(V)) has been used for over 50 years in leishmaniasis treatment. Sb(V) is converted into trivalent antimony (Sb(III)) within macrophages acting as a prodrug by disrupting fatty acid beta-oxidation and glycolysis, impairing the energy metabolism of the parasite. Despite extensive use, the effects of antimonials on host mitochondria are not well understood. This study investigated the impact of Sb(V) and Sb(III) on mitochondria isolated from mouse hearts via differential centrifugation and lastly incubated with Sb(V) or Sb(III). Mitochondrial function was evaluated by oxygen consumption, ATP production, reactive oxygen species (ROS) generation, and transmembrane potential. Both Sb(V) and Sb(III) reduced oxygen consumption in complex I respiratory states 1, 2, and 3 at 1 µg/mL and 1 ng/mL. ROS production increased in Sb(V)-treated mitochondria. ATP production was impaired by both drugs starting at 1 ng/mL. Proton leak also increased, and significant changes in transmembrane potential were observed at both concentrations. These findings indicate that Sb(V) and Sb(III) directly compromise mitochondrial function from isolated mouse heart mitochondria by reduced ATP production and increased ROS. Full article

In this study, the catalytic air oxidation method was used to selectively form sodium antimonate from an antimony residue Na₂S-NaOH leaching solution of a high arsenic copper anode slime. In the first stage, the leaching process with Na₂S and NaOH media resulted in more than 98% leaching of antimony. The synergistic oxidation method was used to selectively separate antimony in the second stage. In this study, the oxidation rate of antimony was greater than 98% at the NaOH concentration of 50 g·L⁻¹ and a combined oxidation concentration of 0.75 g·L⁻¹ catechol + 0.75 g·L⁻¹ KMnO₄, under the air flow rates of 1.415 m³·min⁻¹ at 75 °C for 8 h. The pH of the crude sodium antimonate product was adjusted; subsequently, it was redissolved and precipitated to prepare refined sodium antimonate that meets the secondary product standard of China’s non-ferrous metal industry, which recommends an antimony recovery rate of >95.60%. After neutralisation, the liquid contains [As] < 0.10 g·L⁻¹, [Sb] = 0.16–0.38 g·L⁻¹, which can be reused in the composite leaching process. The apparent activation energy (Ea) of the catalytic oxidation reaction was 6.47 kJ·mol⁻¹; the results suggested that the reaction process was diffusion controlled. $-\frac{d\left[Sb\right]}{dt}=8.86\times {10}^{-5}\times e^{\frac{-778.44}{T}}\times {\left[Sb\right]}^{0.4906}\times {\left[NaOH\right]}^{1.190}$. Full article

Localised cutaneous leishmaniasis (LCL) is a common neglected tropical disease in Ethiopia, which is mainly treated with intralesional (IL) pentavalent antimonial such as sodium stibogluconate (SSG) and/or cryotherapy. Both treatments are painful, and studies are lacking on the pain associated with these or affected individuals’ experiences of them. A cross-sectional, observational study was conducted at ALERT Comprehensive Specialized Hospital, Addis Ababa/Ethiopia. The socio-demographic and clinical data of individuals affected by LCL receiving IL SSG and/or cryotherapy was gathered, and their treatment was observed. Participants quantified their treatment-associated pain using the Wong–Baker Pain Scale. Health-related quality of life was measured using the (Children’s) Dermatology Life Quality Index. Adverse effects, participant experiences with local therapies, and dermatologists’ experiences and opinions of local LCL treatment were assessed using structured questionnaires. Of the thirty-six individuals with LCL included (64% male, 14% children), 52% reported a treatment-associated pain score ≥ 8. Cryotherapy administered with a cotton bud was associated with lower pain scores ≤ 6 (odds ratio: 0.15, 95% confidence interval: 0.03–0.89) compared to a cryotherapy spray device. There was wide variation in treatment administration. Local LCL treatment is painful, and most individuals experience significant pain. This study highlights the need for less painful but effective treatments, structured training, and clear standard operating procedures. Full article

The aim of this study is to determine the characteristics of the chemical and mineral composition of sediment layers in a technogenic settling pond. This pond is located on urban land in Berezniki (Perm Krai, Russia), outside the territory of operating industrial facilities, and contains alkaline saline industrial wastes. The origin of this waste was related to sludge from the Solvay soda production process, which had been deposited in this pond over a long period of time. However, along with the soda waste, the pond also received wastewater from other industries. As a result, the accumulated sediment is characterized by variation in morphological properties both in depth and laterally. Five undisturbed columns were taken to study the composition of the accumulated sediment. The obtained samples were analyzed by X-ray diffraction (XRD), synchronous thermal analysis (STA), and X-ray fluorescence (XRF) analysis. The results showed that the mineral composition of bottom sediments in each layer of all studied columns is characterized by the predominance of calcite precipitated from wastewater. Along with calcite, due to the presence of magnesium and sodium in the solution, other carbonates precipitated—dolomite and soda (natron), as well as complex transitional carbonate phases (northupite and trona). Together with carbonate minerals, the chloride salts halite and sylvin, sulfate minerals gypsum and bassanite, and pyrite and nugget sulfur were established. The group of terrigenous mineral components is represented by quartz, feldspars, and aluminosilicates. The chemical composition of sediments in the upper part of the section generally corresponds to the mineral composition. In the lower sediment layers, the role of amorphous phase and non-mineral compounds increased, which was determined by the results of thermal analysis. The content of heavy metals and metalloids also increases in the middle and lower sediment layers. When categorized according to the Igeo value, an excessive degree of contamination (class 6) was observed in all investigated columns for copper content (Igeo 5.2–6.1). Chromium content corresponds to class 5 (Igeo 4.1–4.6), antimony to class 4 (Igeo 3.0–4.0), and lead, arsenic, and vanadium to classes 2 and 3 (moderately polluted and highly polluted). The data obtained on variations in the mineral and chemical composition of sediments represent the initial information for the selection of methods of accumulated waste management. Full article

The selective catalytic reduction (SCR) of NO_x emissions by hydrocarbons (HCs) using a silver (Ag)-based catalyst offers significant advantages over conventional SCR systems that rely on ammonia reductants and vanadium-based catalysts. However, the conversion rate of SCR is influenced by several factors, among which catalyst poisoning is a major concern. Toxic metals such as sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca) can degrade catalyst activity and lead to deactivation. Poisoned catalysts suffer from reduced conversion rates and premature deactivation before reaching their intended operational lifespan. In particular, calcium poisoning results in the formation of CaO (calcium oxide), which reacts to produce a CaWO₄ compound that severely impairs SCR performance. This study investigates the role of antimony (Sb) in mitigating Ca-induced deactivation in HC-SCR of NO_x. Five catalysts with varying Sb loadings were prepared and tested to evaluate Sb’s effect on NO_x conversion rate at a space velocity of 30,000 h⁻¹. The results demonstrate that Sb effectively suppresses Ca deactivation, enhancing the conversion rate across all engine test conditions. The highest NO_x conversion rate (95.88%) was achieved using a catalyst with 3% Sb. Full article

Silver (Ag) is a precious and valuable metal, and it has many carrier minerals. Through LA-ICP-MS analysis, it was found that jamesonite not only contains lead (Pb) and antimony (Sb) as precious metals but also trace amounts of Ag. In practice, the flotation method is generally used to recover these metals. This paper employs density functional theory calculations to demonstrate that after Ag doping in jamesonite, the Ag atoms exist in the lattice channels of jamesonite, and they form strong covalent bonds with the S atoms, resulting in strong interactions. When Ag is doped in the channels, the adsorption of sodium diethyldithiocarbamate (DDTC) as a collector on the Ag-doped jamesonite surface is the strongest, while that of butyl xanthate is the weakest. The adsorption interactions on the Ag-doped jamesonite surface are also stronger than on pure jamesonite. Coordination chemistry studies reveal that Ag⁺ undergoes a transition from a d¹⁰ to a d⁹s¹ electronic configuration when incorporated into jamesonite, which increases its reactivity by generating unpaired electrons available for π-backbonding with collector molecules. Furthermore, owing to the high polarizability of Ag, the presence of Ag atoms alters the electronic environment of the surrounding Pb atoms, which enhances the π-backbonding interactions between the adsorbate reagent molecules and the Ag active sites. The research results are of great significance for the efficient recovery of Ag-containing jamesonite and provide a reference for the study of the properties of Ag-doped minerals. Full article