Pure Reagents Research Articles

Blocking endogenous phosphorus release in sediments by a hydrotalcite mixture synthesized with natural sepiolite and discarded cans

Pure hydrotalcite (LDH) materials prepared from chemical reagents have been investigated as solid-phase phosphorus (P) inactivation materials (SPIM) to manage endogenous P loading in sediments. However, the efficacy and mechanism of LDH mixtures prepared by natural minerals and solid wastes in controlling sediment P release are unclear. Therefore, a Ca/Mg-Al-LDH (CMA-LDH) material was synthesized using sepiolite and cans, and its efficacy, mechanism, and ecological impact in controlling sediment P release were investigated. CMA-LDH-p was prepared as a control material using pure chemical reagents. The CMA-LDH and CMA-LDH-p were both composed of hydrotalcite and hydrocalumite. The maximum P adsorption capacity of CMA-LDH was 123.01 mg/g, comparable to that of CMA-LDH-p. The adsorbed P by CMA-LDH was mostly in the stable P form, accounting for 87.2 % of the total P. The adsorption capacity and immobilization ability of CMA-LDH for P were superior to other reported LDH-based SPIM. Both the CMA-LDH addition and capping successfully blocked sediment P release under anaerobic conditions. Passivation of mobile P in the sediment and DGT-labile P in the interstitial water was critical to preventing sediment P release by the CMA-LDH addition. The CMA-LDH capping inhibited sediment P release through the effective adsorption of CMA-LDH on DGT-labile P at the sediment/overlying water interface. The CMA-LDH addition and capping affected the abundance of microbial communities associated with iron and sulfur cycling, which might affect the stability of endogenous P. These results confirmed that CMA-LDH addition and capping treatments were effective methods for managing sediment P loading.

Effects of CaF2 and La2O3 on the phase structure of rare earth in CaO–SiO2–La2O3–CaF2 slags

The rare earth in the rare earth slag can be separated and enriched by heating and melting the rare earth slag and then slowly cooling crystallisation. In this process, it is of great significance to study the effect of chemical composition on the crystallisation of rare earth phase in slag and the effect of slag viscosity on crystal growth. The rare earth slag melt samples were prepared according to the main chemical composition of rare earth slag by using an analytical pure reagent. The effects of CaF2 and La2O3 contents on the phase structure and morphology of rare earth phase in CaO–SiO2–La2O3–CaF2 slags were studied by SEM-EDS and XRD. The relationship between the viscosity of the slag and the crystal growth behaviour was studied by measuring the melt viscosity with the cylinder rotation method. The results show that the rare earth in CaO–SiO2–La2O3–CaF2 slags exists in the form of CaLa4(SiO4)3O. The change of CaF2 and La2O3 content has no effect on the structure of rare earth phase, but the size of rare earth crystal phase changes obviously. With the increase of CaF2 and La2O3 content, the size of rare earth crystal phase increases gradually. CaF2 and La2O3 can reduce the viscosity transition temperature of slag melt and increase the crystallisation temperature range of rare earth phase to promote crystal growth.

Processing of molybdenum industrial waste into sustainable and efficient nanocatalysts for water electrolysis reactions

AbstractThe increasing need for sustainable energy and the transition from a linear to a circular economy pose great challenges to the materials science community. In this view, the chance of producing efficient nanocatalysts for water splitting using industrial waste as starting material is attractive. Here, we report low-cost processes to convert Mo-based industrial waste powder into efficient catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). pH controlled hydrothermal processing of Mo-based industrial waste powder leads to pure orthorhombic MoO3 nanobelts (50–200 nm wide, 10 µm long) with promising OER performances at 10 mA·cm−2 with an overpotential of 324 mV and Tafel slope of 45 mV·dec−1 in alkaline electrolyte. Indeed, MoS2/MoO3 nanostructures were obtained after sulfurization during hydrothermal processes of the MoO3 nanobelts. HER tests in acidic environment show a promising overpotential of 208 mV at 10 mA·cm−2 and a Tafel slope of 94 mV·dec−1. OER and HER performances of nanocatalysts obtained from Mo industrial waste powder are comparable or better than Mo-based nanocatalysts obtained from pure commercial Mo reagent. This work shows the great potential of reusing industrial waste for energy applications, opening a promising road to join waste management and efficient and sustainable nanocatalysts for water splitting.

Effect of CeO2 on the preparation of functional ceramsite and the adsorption effect of ammonia-nitrogen wastewater treatment

This study investigates the effect of rare earth oxide CeO2 on the physical properties of ceramsite and its efficiency in treating ammonia-nitrogen wastewater. Ceramsite was prepared from solid waste with 10 % coal gangue added as a pore-forming agent. Ceramsite sample I with CeO2 and sample II without CeO2 were prepared using pure reagents. The process parameters for both samples were optimized using an orthogonal test. Additionally, the effects of CeO2 on ceramsite performance and the treatment of ammonia-nitrogen wastewater were studied, and the adsorption mechanism of CeO2 on ammonia-nitrogen wastewater was clarified. The process parameters for preparing ceramsite sample Ⅰ were: preheating for 30 min at 600 °C, followed by roasting for 20 min at 1090 °C. The parameters for preparing ceramsite sample Ⅱ were: preheating for 30 min at 600 °C, followed by roasting time for 15 min at 1090 °C. The presence of CeO2 increased the porosity of the ceramsite by 0.89 % and the specific surface area by 0.66 m2/g. Under neutral environmental conditions of water samples, CeO2 increased the removal rate of ammonia nitrogen by 1.85 %. Ceramsite has a high porosity and specific surface area, indicating that it has abundant internal pores, a large contact area with ammonia-nitrogen, a strong ability to remove ammonia nitrogen, and resistance to erosion and water flow shear, which are conducive to the treatment of ammonia-nitrogen wastewater.

Bionanomining: bioengineered CuO nanoparticles from mining and organic waste for photo-catalytic dye degradation.

The novel bioengineered CuO nanoparticles were successfully synthesized directly using green chemistry, the nontoxic and renewable aqueous extract of waste papaya peel (Carica papaya) as a precursor. The XRD analysis indicated a monoclinic phase of CuO nanoparticles and a size of 20nm, and the optical absorption analysis showed a peak in the 264nm range. In TEM, the morphology of the NPs was observed to be almost spherical with a particle size of 15nm. The CuO nanoparticles showed good efficiency in the degradation of methylene, obtaining up to 50% in 40min using 6mg in 60ml of MB at 10mg/L. The novel presented in this work derives from using rock minerals, from which we have directly obtained copper salt and copper oxide nanoparticles. This process not only utilizes ecological green chemistry but also offers an economic advantage by directly producing nanoparticles from the mineral instead of purchasing costly pure chemical reagents and employing novel nanomaterials to purify wastewater.

Continuous preparation and reaction of nonaflyl azide (NfN3) for the synthesis of organic azides and 1,2,3-triazoles

Organic azides are widely used in organic synthesis. Continuous flow processing can be used to bypass their isolation, and can therefore be useful in mitigating the hazards associated with these potentially toxic and explosive reagents. Nonaflyl azide has been reported as an effective, bench-stable, and relatively safe diazo transfer reagent that can be useful in the preparation of azides from amines and so avoid the use of alkyl halides. Here we demonstrate the synthesis and purification of nonaflyl azide in continuous flow with isolation of the neat, pure reagent by membrane filtration. The neat reagent was used in the preparation of organic azides from primary amines, and then applied to the synthesis of triazoles. A variety of triazoles, including the antiseizure drug Rufinamide, were prepared from primary amines and alkynes via the CuAAC click reaction in a semi-batch parallel array without isolation of alkyl azide intermediates. A telescoped two-stage continuous flow process was also designed and demonstrated to form triazoles via the same CuAAC reaction, which avoids the handling of the intermediate reactive azides.

Amphetamine-like substances and synthetic cathinones in Portuguese wastewater influents: Enantiomeric profiling and role of suspended particulate matter

Wastewater based epidemiology (WBE) has been used worldwide to estimate drug consumption routinely. Even though WBE provides valuable data to support legal and health interventions associated to drug use, monitoring studies in Portuguese wastewaters are scarce. Hence, this work aimed to estimate the consumption of some conventional abuse and illicit drugs such as amphetamine (AMP), methamphetamine (MAMP), 3,4-methylenedioxymethamphetamine (MDMA), and the synthetic cathinones buphedrone (BPD), butylone (BTL), 3,4-dimethylmethcathinone (3,4-DMMC) and 3-methylmethcathinone (3-MMC), considering not only the liquid phase, but also the suspended particulate matter (SPM). Moreover, the enantiomeric profiling of the samples was studied, exploring for the first time the possible enantioselective sorption of these drugs onto SPM. For that, 24 h composite raw wastewaters were collected from a conventional wastewater treatment plant (WWTP) in Portugal. After extraction, the liquid phase and SPM extracts were derivatized with an enantiomerically pure reagent and then, analysed using a gas chromatography-mass spectrometry (GC-MS) analytical method. The results showed a low and non-enantioselective adsorption to SPM at environmental relevant levels. Only (S)-AMP was detected in two SPM samples, whereas AMP, MAMP, MDMA, BPD, and 3,4-DMMC were detected in the liquid phase. AMP was the most frequently found drug with an estimated load up to 166.0 mg day−1 1000 people−1 and mostly found with enrichment of (S)-AMP. Nevertheless, (R)-AMP was also determined, which may be related to the consumption of either the illicit racemic AMP or the medicine (R)-deprenyl. The use of MDMA, MAMP and synthetic cathinones (BPD and 3,4-DMMC) was also suggested in Portugal. Nevertheless, the levels and the consumption estimate of the target chemicals were lower than in other European countries or worldwide. These findings provide the first step to the implementation of WBE monitoring campaigns to assess the status of drug consumption in Portuguese communities, contributing to the understanding of drug use patterns and trends worldwide and helping enforce preventive measures.

Effect of Fluorine and Phosphorus Impurities in Phosphogypsum on Microstructure and Mechanism of α‐Type Hemihydrate Gypsum Crystals

AbstractIn this study, phosphogypsum (PG) is simulated by doping fluorine and phosphorus ions in an analytically pure reagent of gypsum dihydrate. The influence of fluorine and phosphorus impurity and content on the dehydration reaction process of phosphogypsum and its crystalline micromorphology is assessed during the preparation of α‐type gypsum hemihydrate in the reversed‐phase microemulsion system and its mechanism. The results show that when the fluorine content increases from 0 to 1.0 mol L−1 (ωNaF = 1.0 mol L−1), the dehydration process of dihydrate gypsum will be greatly slowed down. Scanning electron microscopy (SEM) analysis showed that even a small amount of F− (ωNaF = 0.2 mol L−1) can significantly inhibit the formation of α‐type hemi‐hydrated gypsum. When ωH3PO4 = 0.10 mol L−1, the water of crystallization content in the solid phase of the sample decreased to 5.24% after 90 min, which is significantly lower than during the same period of the benchmark group. However, there is a threshold value for the effect of phosphorus on the microscopic morphology of the α‐type gypsum hemihydrate crystals, when ωH3PO4 ≤ 0.04 mol L−1, the crystal morphology is basically unaffected. Moreover, when ωH3PO4 continued to increase, the defects on the crystal surface increased.

Idealization in pharmacology and pharmacy: Symbol of the chemical formula of one molecule of a substance and a real pharmaceutical product

The essence of the two levels of information used in modern pharmacy, pharmacology, and medicine for operations related to theoretical reasoning about medicines and the actual practice of their use for treating specific cases is fundamentally different. In particular, studies have analyzed the essence of theoretical information about medicines and the norms of their use in accordance with medical care standards. Information about medicines and standards of medical care, which dominate textbooks, reference books, encyclopedias, scientific articles , and normative and technical documents, is built on the idealized essence of chemically pure substances and their interaction with an idealized virtual patient. Accordingly, in the fields of pharmacy, pharmacology, and chemistry, physics, and materials science, researchers have traditionally represented chemical elements (and drugs) by certain chemical formulas, names, and symbols for their molecules. Moreover, in pharmacy and pharmacology, the structural formula of one molecule of only one chemical substance belonging to the group of the so-called main active substances most often plays this role. Generally, this chemical symbol of its molecule is identified with the real substance itself. It is assumed that the substance in question is of ideal high quality, is completely free of any impurities, is not combined with other substances, and does not represent a certain pharmaceutical product (it is not a tablet, not a solution, not an ointment, not an aerosol, etc.), and is not manufactured by a certain pharmaceutical company according to a certain recipe. Moreover, modern pharmaceutical products are not separate molecules, not pure chemical reagents, but all sorts of mixtures of different substances of different quality in different ratios. In addition, each pharmaceutical product of each manufacturing plant and each series number has inherent and unique mechanical, physical, chemical, and physicochemical properties and quality indicators. Therefore, the idealized essence of drugs is far from that of real pharmaceutical products. The chemical name and chemical formula are symbols of one molecule of a chemical element, reflecting its idealized chemical essence, but not the essence of a real “tablet”, “ampule”, and/or “tube” with it. In turn, the virtual patient of known sex, average age, average health status, and a body weight of approximately 70 kg implied by the standards of medical care is just an idealized object of interaction with an idealized “medicine”. In this regard, the study of the relationship between the idealized and real drugs and patients is a crucial part of the problem of the relationship between theory and reality in pharmacy, pharmacology, and medicine.

Cotreatment strategy for hazardous arsenic-calcium residue and siderite tailings via arsenic fixation as scorodite

Siderite tailings is a potentially cost-free iron (Fe) source for arsenic (As) fixation in hazardous arsenic-calcium residues (ACR) as stable scorodite. In this study, a pure siderite reagent was employed to investigate the mechanism and optimal conditions for As fixation in ACR via scorodite formation, while the waste siderite tailings were used to further demonstrate the cotreatment method. The cotreatment method starts with an introduction of sulfuric acid to the ACR for As extraction and gypsum precipitation, and is followed by the addition of H2O2 to oxidize As(III) in the extraction solutions and finalized by adding siderite with continuous air injection for scorodite formation. The dissolution-oxidation of siderite can slowly produce Fe(III) to control aqueous As(V)-Fe(III) precipitation supersaturation for continuous scorodite crystallization. Chemical analyses show that the extraction efficiency of As from the ACR reaches 94.55%, while the precipitation yield of extracted As via scorodite formation arrives at 99.63% and 99.47%, leading to fixation efficiency of 94.20% and 94.04% in terms of the total As in the ACR by using siderite reagent and tailings, respectively. The final solid products show desirable TCLP stability and long-term stability, meeting the requirement for safe storage (GB 5085.3–2007). XRD, FTIR, and TEM results reveal that such high stability is attributable to the formation of scorodite and the surface adsorption of As on the raw siderite and secondary maghemite. This innovative and economical application of siderite tailings for the treatment of hazardous ACR can be extended to the management of hydrometallurgical wastes.

Optimization of a pre-concentration method for the analysis of mercury isotopes in low-concentration foliar samples.

Hg isotope analysis in samples from background regions is constrained by the presence of low Hg concentration and therefore requires a pre-concentration method. Existing Hg pre-concentration methods are constrained by long sample processing time and limited sample loading capacity. Using foliar samples as a test case, an optimized Hg pre-concentration method is presented that involves the microwave-assisted digestion of samples for Hg isotope analysis with the addition of a pre-digestion step. Microwave-digested foliar samples and CRMs were transferred to an impinger, reduced with SnCl2, and collected in a 2.25 mL concentrated inverse aqua regia (3:1 HNO3:HCl, v/v). This resulted in an optimal acid concentration in the solution ideal for analysis on MC-ICP-MS. The time for purging with Hg-free N2 was optimized to 30 min and the efficiency of the pre-concentration method was tested using a combination of approaches. Tests performed on pure reagents and matrix of foliar samples spiked with 197Hg radiotracer showed recoveries averaging 99 ± 1.7% and 100 ± 3.0%, respectively. Mercury at concentrations as low as 1.83 ng g-1 was pre-concentrated by digesting aliquots of foliage samples in individual digestion vessels. Recoveries following their pre-concentration averaged 99 ± 6.0%, whereas recoveries of 95 ± 4.7% and 95 ± 2.5% were achieved for NIST SRM 1575a (pine needle) and reagents spiked with NIST SRM 3133, respectively. Analysis using multicollector-ICP-MS showed low fractionation of δ202Hg during sample pre-concentration with no significant mass-independent fractionation. The proposed method is a relatively simple and robust way to prepare Hg samples for Hg isotopic analysis and is suitable even for complex biological matrices.

New 3D Printed Scaffolds Based on Walstromite Synthesized by Sol-Gel Method.

This study explores the potential utilization of walstromite (BaCa2Si3O9) as a foundational material for creating new bioceramics in the form of scaffolds through 3D printing technology. To achieve this objective, this study investigates the chemical-mineralogical, morphological, and structural characteristics, as well as the biological properties, of walstromite-based bioceramics. The precursor mixture for walstromite synthesis is prepared through the sol-gel method, utilizing pure reagents. The resulting dried gelatinous precipitate is analyzed through complex thermal analysis, leading to the determination of the optimal calcination temperature. Subsequently, the calcined powder is characterized via X-ray diffraction and scanning electron microscopy, indicating the presence of calcium and barium silicates, as well as monocalcium silicate. This powder is then employed in additive 3D printing, resulting in ceramic scaffolds. The specific ceramic properties of the scaffold, such as apparent density, absorption, open porosity, and compressive strength, are assessed and fall within practical use limits. X-ray diffraction analysis confirms the formation of walstromite as a single phase in the ceramic scaffold. In vitro studies involving immersion in simulated body fluid (SBF) for 7 and 14 days, as well as contact with osteoblast-like cells, reveal the scaffold's ability to form a phosphate layer on its surface and its biocompatibility. This study concludes that the walstromite-based ceramic scaffold exhibits promising characteristics for potential applications in bone regeneration and tissue engineering.

Carbon Capture Performance Enhancement of Solid State Synthesized Li4SiO4 Powders by Using Different Kind Steel Slags as SiO2 Source

The potential of lithium orthosilicate (Li4SiO4) as a material to capture carbon dioxide (CO2) is being explored due to its excellent capture capability and thermal stability. Currently, a significant portion of the world's energy needs are met through the burning of fossil fuels, which leads to an increase in atmospheric CO2 and contributes to global warming. While fossil fuels will remain the primary source of energy for several more years, it is crucial to develop cost-effective and environmentally friendly technology for large-scale CO2 capture and storage before its release into the atmosphere in order to mitigate the associated greenhouse effect. This study focuses on optimizing the synthesis of lithium orthosilicate using a solid-state method to enhance CO2 capture. The research involves assessing the key characteristics of the synthesized material that improve CO2 capture efficiency. The starting materials used for comparison include lithium carbonate (Li2CO3), BF (blast furnace), BOF (blast oxygen furnace) and EAF (electric arc furnace) slags, and pure reagents of silicon dioxide (SiO2). The effect of process conditions, such as synthesis temperatures ranging from 850 to 950°C and varying holding times of 4, 6, 8, and 10 hours in a muffle furnace, were studied and compared. X-ray diffraction (XRD) analysis was performed to characterize the samples and slags. CO2 capture performance of the samples were evaluated in thermobalance test under 92 vol% CO2 (N2 balance) gas concentration at 600°C. As to conclude, carbon dioxide capturing sorbent material was produced by utilizing the slags generated as a by-product in steel production. Thus, considering the principles of circular economy, a material defined as waste was used as raw material for the production of another product used for lowering atmospheric CO2 levels.

Development of industrial-grade γ-C2S binder from limestone and sandstone: Preparation, properties, and microstructure

This paper developed a cost-effective and highly carbonatable industrial-grade γ-C2S binder sintered from limestone and sandstone, aiming to advance the industrialization of γ-C2S binder in construction fields. The carbonation behavior of the industrial-grade γ-C2S binder, including the evolution of carbonation kinetics, compressive strength, phase composition, and microstructure with carbonation duration was studied. Results showed that a temperature of 1400 °C and limestone-to-sandstone mass ratio of 2.1 can be regarded as the optimal sintering regime, which can secure a relatively complete self-pulverization of industrial-grade γ-C2S binder. The industrial-grade γ-C2S binder had a milder carbonation reaction, which can reduce the evaporation of water and lead to 48% greater compressive strength, compared to that sintered from analytically pure reagents. During carbonation, the proportion of γ-C2S phase significantly decreased, while the proportions of CaCO3 and silica gel notably increased in the first 1 h, followed with a slight change in proportions of those phases with the carbonation further extending to 24 h. Similarly, the degree of carbonation rapidly increased to 36.3% in the first 1 h, followed with a slight increase to 43.7% at 24 h. The carbonation of industrial-grade γ-C2S, accompanied with the precipitation of CaCO3 on γ-C2S phase surface and the bond of silica gel among CaCO3 grains, contributed to the formation of nacre-bionic interlocking brick-mud microstructure. This led to the rapid enhancement of compressive strength with carbonation of industrial-grade γ-C2S.

Comparison of the electrochemical decarbonation of different-grade limestones used in cement manufacturing

Electrochemical decarbonation (ED) of CaCO3 is a promising method to reduce CO2 emissions from limestone calcination for cement manufacturing. Most cement plants are located near accessible deposits of limestone; therefore, the feasibility of ED deployment depends on the efficiency of natural limestone decarbonation, which has variable CaCO3 content. Accordingly, this research compares the ED efficiency of different limestones (CaCO3 content between 84 % and 68 %) and the chemical and physical characteristics of precipitate materials (PM) obtained from this process. The obtained PMs were comprised mainly of CaOH2 (~59 %) and had similar particle size distributions. At the same time, the efficiency of CaOH2 precipitation, energy consumption, and CaO recovery were comparable to the ED of a pure CaCO3 reagent (>99 %). The PMs were found to have higher CaO content and lower loss on ignition than the feedstock material, independent of the type of limestone, facilitating the future ED implementation in cement manufacturing.

Co-treatment of spent automotive catalyst and copper-bearing electroplating sludge to alloy platinum group metals with base metal matrices

Spent automotive catalyst (SAC) is an important secondary metal resource of platinum group metals (PGMs). However, the traditional smelting process for recovering valuable metals from SAC generally has the problems such as high reagents consumption and increased solid waste. Thus, a novel co-treatment process of SAC and copper-bearing electroplating sludge (CBES) was proposed in this study, where CBES was first used as the capture agent and fluxing material in the pyro-capture process of PGMs. The effects of separation behaviors of PGMs and copper under different smelting conditions were studied systematically. The optimum conditions for this process are as follows: m(CBES)/m(SAC) of 2.0, m(SiO2)/m(Al2O3) of 3.00, basicity of 0.80, 5.0 wt% Na2B4O7, oxidative temperature of 1460 ℃, oxidative time of 30 min, NC/Cu of 1.250, reductive temperature of 1300 ℃, and reductive time of 90 min. Under these conditions, the sulfur removal rate exceeds 99% while the recoveries of Pt, Pd, Rh and Cu are 99.26%, 98.53%, 99.96% and 97.60%, respectively. The addition of pure reagents is only about 47% of the total waste mass. Furthermore, the capture process of Cu-Fe alloy for PGMs was discussed, which can consist of three steps: reduction of copper and iron, mutual migration and collision of the reduced metal atoms, and alloying. Finally, the produced slag was synthesized into non-hazardous glass-ceramics material successfully. To sum up, this study achieved the efficient recycling of two hazardous wastes simultaneously.

Towards a closed loop recycling process of end-of-life lithium-ion batteries: Recovery of critical metals and electrochemical performance evaluation of a regenerated LiCoO2

The growing demand for lithium-ion battery technology emphasizes the critical need to establish effective recycling and proper disposal methods for used batteries, ensuring the long-term sustainability and security of the battery supply chain. This study addresses this need by exploring two hydrochemical routes, using sulfuric acid and nitric acid, respectively. The objective is to investigate the influence of the acid used in the leaching process on the properties of the regenerated final product, LiCoO2. Moreover, a novel and simplified approach for extracting lithium as lithium carbonate is proposed.In evaluating the recycled batteries, careful examination of their physicochemical properties and electrochemical performances reveals striking similarities to batteries produced from commercial sources. This comparison provides evidence of the successful recycling process. By optimizing the leaching conditions, we were able to extract more than 98% of both cobalt and lithium from the used cathode materials of cell phone batteries.Significantly, our study demonstrates that nitric acid offers a straightforward method for separating and obtaining a pure product, surpassing the outcomes achieved with sulfuric acid using the same steps. Additionally, we thoroughly investigate and compare the electrochemical performances of the synthesized cathode materials with those synthesized from pure commercial reagents. This systematic analysis confirms the effectiveness and viability of the proposed recycling process.The key advantage of this approach lies in its ability to achieve a complete recycling of the initial spent cathodic elements, which is crucial for establishing a circular economy. This comprehensive recycling method not only addresses the increasing demand for lithium-ion battery technology but also contributes to the sustainable utilization of resources and the preservation of the battery supply chain's integrity.

APPLICATION OF RED SLIME IN THE SYNTHESIS OF INORGANIC PIGMENTS IN THE OXIDE SYSTEM Al2O3- Fe2O3-Cr2O3-ZnO-TiO2

In Article substantiates the possibility of using red slime as a basic raw material for the processes of formation of color-determining spinel structures of brown pigments. The possibility of complete replacement of pure reagent oxides of aluminum (III) a

Comparison of sphalerite, djurleite, and chalcopyrite leaching by chemically and biologically generated ferric sulfate solutions

Ferric leaching, including the oxidation of sulfide raw materials of nonferrous metals in a ferric sulfate solution, is a well-known hydrometallurgical process that is widely applied in practice. Recent studies have indicated differences in the leaching kinetics of sphalerite concentrates when using solutions of ferric sulfate obtained by dissolving a commercial reagent or after bio-oxidation of iron-containing substrates by acidophilic chemolithotrophic microorganisms. In this research, the leaching of powder samples of natural zinc and copper sulfide minerals (sphalerite, djurleite, and chalcopyrite) was compared using two different solutions. The first one was an aqueous solution of a chemically pure ferric sulfate reagent, and the second solution contained ferric sulfate obtained via biooxidation of the chemically pure reagent of ferrous sulfate by an acidophilic bacterium Leptospirillum ferriphilum. The leaching solutions contained 10.1 g/L of ferric iron, pH 1.3. The experiments were carried out in batch mode in a mechanically stirred reactor. When using a solution of the chemical reagent of ferric sulfate, the level of dissolution of sulfide minerals was higher than in the case of the biological reagent: by 21.3% after 5 h (80 °C; 1% pulp density) for sphalerite, by 11.8% after 3 h (80 °C; 1% pulp density) for djurleite, and by 9.1% after 5 h (80 °C; 0.5% pulp density) for chalcopyrite. A comparison of the results of experiments with the biological reagent throughout from which microbial cells were preliminarily removed and the chemical reagent to which microbial cells were added confirmed the pivotal role of microbial cell lysis products in decreased efficiency of leaching with the biological reagent. Metabolomics analysis revealed several potential metabolites of L. ferriphilum involved in the observed negative effect on the leaching effectiveness, including nucleosides, alkaloids, and benzaldehydes. By contrast, the efficiency of zinc leaching from sphalerite was improved in the presence of metabolism products of L. ferriphilum in the first hours of the process.

Reduction Kinetics of Compact Hematite with Hydrogen from 600 to 1050 °C

Reduction of iron ores with hydrogen is a solution to replace fossil fuels. For this reason, it is important to discuss previous discrepancies. Some previous studies suggest a rate minimum with respect to temperature. Our research work indicates that a rate minimum can be avoided. Thermogravimetric isothermal reduction experiments were carried out from 600 to 1050 °C with pure reagent ferric oxide and hydrogen using a tubular furnace. The morphology and chemical composition of the initial sample, consisting of particulate hematite (Fe2O3), and the final product, consisting of metallic iron (Fe°), was defined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The reduction rate for the conversion from hematite to magnetite (Fe2O3 to Fe3O4) was the highest, around 5 %/min, decreasing to around 2–5%/min for the second stage of conversion from magnetite to wüstite (Fe3O4 to FeO). This reduction rate remains almost constant from about 20–80% reduction, decreasing to 0.3–1%/min for the completion of reduction from wüstite to metallic iron (FeO to Fe°). The reduction controlling mechanism was evaluated based on the calculated apparent activation energy and fitting the experimental data to one gas-solid reaction equation. Under the experimental conditions in this work, the reduction rate of pure hematite with hydrogen linearly increased with temperatures from 600 to 1000 °C, without a rate minimum in this temperature range. Above 1000 °C, the reduction rate decreased due to sintering phenomena. This result suggests a maximum reduction temperature of 1000 °C using pure hematite and hydrogen as the reducing gas. The reduction controlling mechanisms identified using hydrogen as a reducing gas were chemical reaction for the conversion from hematite to wüstite and diffusion control for the final reduction from wüstite to metallic iron. Since the reduction rate from wüstite to metallic iron is the one that affects the overall rate of reduction, overall changes in porosity were also evaluated. Finally, the reduction of wüstite is schematically described.