Search Results (29)

A novel recyclable composite, Fe₃O₄/chitin/BiOCl, was synthesized via a solvothermal approach using cetyltrimethylammonium bromide (CTAB), bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O), chitin, and Fe₃O₄ as precursors. The composite was systematically characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett-Teller (BET) analysis, ultraviolet–visible (UV-vis) spectroscopy, and vibrating sample magnetometry (VSM). Characterization results indicated that the incorporation of chitin significantly improved the porosity and specific surface area of the catalyst. Furthermore, the synergistic effects between chitin and Fe₃O₄ effectively reduced the recombination rate of photogenerated electron–hole pairs. The photocatalytic activity of the composite was evaluated by degrading ciprofloxacin (CIP) under visible-light irradiation. When the contents of Fe₃O₄ and chitin were 5% and 2% (by weight), respectively, the catalyst exhibited excellent photocatalytic performance with a degradation rate of 89.54%, and the rate constant was 5.1 times higher than that of pure BiOCl. Additionally, the catalyst exhibited excellent magnetic recoverability and photocatalytic stability. Full article

Gel precursors were formed by reacting bismuth nitrate pentahydrate, acetic acid, sodium metavanadate, and NaOH. pH was adjusted using NaOH solution followed by calcination to obtain bismuth vanadate (BiVO₄) photocatalysts. During synthesis, pH directly influenced the formation and structure of the gel network. Therefore, the effects of pH on the microstructure and photocatalytic activity of BiVO₄ were investigated. At pH 3, the sample consisted of microspheres formed by tightly packed small particles. At pH 5, the microspheres transformed into aggregated flakes. Photocatalytic performance was evaluated through methylene blue (MB) degradation, revealing the sample prepared at pH 7 (7-BVO) demonstrated the highest efficiency. The electronic band structure, bandgap, and band edge positions of 7-BVO were probed by density functional theory (DFT) and UV-vis absorption spectra. Furthermore, photoluminescence spectroscopy, electrochemical measurements, active species trapping experiments and liquid chromatography mass spectrometry technique collectively revealed the possible mechanistic pathways for MB photodegradation by 7-BVO. Full article

In this study, a Bi₂O₃-TiO₂/PAC ternary composite photocatalyst was successfully synthesized via a hydrothermal method, employing powdered activated carbon (PAC) as the support and using bismuth nitrate and tetrabutyl titanate as raw materials. The external morphology, microstructure, elemental composition, and optoelectronic properties of the catalyst were characterized by XRD, SEM, TEM, XPS, UV-Vis DRS, and BET analyses. The photocatalytic activity of the composite toward the degradation of malachite green (MG) was systematically evaluated under various conditions. The results revealed that the composite exhibited excellent photocatalytic activity, achieving a degradation efficiency of up to 99%. Apart from extremely acidic or alkaline conditions, MG removal efficiency increased with a rising solution pH. Moreover, the photocatalyst exhibited excellent adaptability and stability in the presence of coexisting inorganic anions and humic substances, indicating its broad potential for practical applications. Reactive-species-trapping experiments indicated that superoxide radicals (·O₂⁻) were the primary active species in the degradation process, with hydroxyl radicals (·OH) and photogenerated holes (h⁺) acting synergistically. Moreover, the catalyst maintained over 90% removal efficiency after five consecutive cycles, demonstrating its excellent stability and reusability. This work provides a promising strategy and theoretical foundation for the efficient photocatalytic treatment of MG-contaminated wastewater. Full article

Bismuth basic nitrates (BBNs) were synthesized via an electrochemical method, i.e., by electrodeposition from an acidic solution of bismuth nitrate, followed by thermal treatment in an air environment. For the first time, the influence of various electrochemical parameters on the morphology, crystal structure, and chemical structure of BBNs was examined. The following synthesis parameters were investigated: electrodeposition current density, thermal treatment temperature of the obtained deposit, and working electrode material (cathode). The obtained materials were characterized by SEM-EDX, XRD, FTIR, TG, and N₂ adsorption/desorption methods and were applied for the sorption of the textile dye RB19. The results showed that the electrodeposition current density and thermal treatment temperature affect the surface morphology, chemical composition, and crystal structure of the obtained materials, as well as the RB19 sorption efficiency. On the other hand, the working electrode material does not affect the properties of the synthesized materials mentioned. Kinetic, isotherm, and thermodynamic analysis of the sorption process were also examined. Full article

Bismuth (Bi) can be considered for use as a green substitute for lead in bearing applications. However, accelerated Bi oxidation can occur during operation, creating a brittle surface and resulting in premature seizure failure. Thus, the aim of this study was to evaluate the influence of engine oil degradation, especially nitration processes, on the oxidation of Bi. Tailor-made artificially aged oils with different degrees of nitration were produced and utilized in static bearing oxidation tests. By means of X-ray photoelectron spectroscopy (XPS), the Bi surfaces were analyzed regarding their chemical compositions after the tests. The results were correlated with the respective oil conditions determined via conventional parameters as well as high-resolution mass spectrometry. The findings obtained revealed a direct correlation between the amount of Bi-oxide and the nitration values of the oil, proving there was a positive impact of nitration products on the oxidation of the Bi surfaces. A comparison with the Bi content in the oils demonstrated a protective effect of the oxide layer as the Bi content declined with an increase in nitration. Overall, valuable insight into understanding the impact of oil condition on engine parts is given, and the importance of testing engine parts with aged lubricants is emphasized. Full article

The widespread environmental contamination resulting from the misuse of tetracycline antibiotics (TCs) has garnered significant attention and study by scholars. Photocatalytic technology is one of the environmentally friendly advanced oxidation processes (AOPs) that can effectively solve the problem of residue of TCs in the water environment. This study involved the synthesis of the heterogeneous magnetic photocatalytic material of CoFe₂O₄/NaBiO₃ via the solvothermal method, and it was characterized using different characterization techniques. Then, the photocatalytic system under visible light (Vis) was coupled with peroxymonosulfate (PMS) to explore the performance and mechanism of degradation of tetracycline hydrochloride (TCH) in the wastewater. The characterization results revealed that CoFe₂O₄/NaBiO₃ effectively alleviated the agglomeration phenomenon of CoFe₂O₄ particles, increased the specific surface area, effectively narrowed the band gap, expanded the visible light absorption spectrum, and inhibited recombination of photogenerated electron–hole pairs. In the Vis+CoFe₂O₄/NaBiO₃+PMS system, CoFe₂O₄/NaBiO₃ effectively activated PMS to produce hydroxyl radicals (·OH) and sulfate radicals (SO₄⁻). Under the conditions of a TCH concentration of 10 mg/L⁻¹, a catalyst concentration of 1 g/L⁻¹ and a PMS concentration of 100 mg/L⁻¹, the degradation efficiency of TCH reached 94% after 100 min illumination. The degradation of TCH was enhanced with the increase in the CoFe₂O₄/NaBiO₃ and PMS dosage. The solution pH and organic matter had a significant impact on TCH degradation. Notably, the TCH degradation efficiency decreased inversely with increasing values of these parameters. The quenching experiments indicated that the free radicals contributing to the Vis+CoFe₂O₄/NaBiO₃+PMS system were ·OH followed by SO₄⁻, hole (h⁺), and the superoxide radical (O₂⁻). The main mechanism of PMS was based on the cycle of Co³⁺ and Co²⁺, as well as Fe³⁺ and Fe²⁺. The cyclic tests and characterization by XRD and FT-IR revealed that CoFe₂O₄/NaBiO₃ had good degradation stability. The experimental findings can serve as a reference for the complete removal of antibiotics from wastewater. Full article

The excessive use of pesticides has led to the harmful contamination of water reservoirs. Visible-light-driven photocatalysis is one of the suitable methods for the removal of pesticides from water. Herein, the development of CBO (Co₃O₄-Bi₂O₃) as a heterogeneous catalyst for the visible light-assisted degradation of Fipronil and Acetochlor pesticides is reported. After synthesis via coprecipitation using cobalt (II) nitrate hexahydrate (Co(NO₃)₂·6H₂O), bismuth (III) nitrate pentahydrate (Bi(NO₃)₃·5H₂O) and sodium hydroxide (NaOH) as precursor materials, the prepared CBO was characterized using advanced techniques including XRD, EDS, TEM, SEM, FTIR, and surface area and pore size analysis. Then, it was employed as a photocatalyst for the degradation of Fipronil and Acetochlor pesticides under visible light irradiation. The complete removal of Fipronil and Acetochlor pesticides was observed over CBO photocatalyst using 50 mL (100 mg/L) of each pesticide separately within 120 min of reaction. The reaction kinetics was investigated using a non-linear method of analysis using the Solver add-in. The prepared CBO exhibited a 2.8-fold and 2-fold catalytic performance in the photodegradation of selected pesticides than Co₃O₄ and Bi₂O₃ did, respectively. Full article

Bismuth sulfide (Bi₂S₃) nanostructures have gained significant attention in the fields of catalysis, optoelectronics, and biomedicine due to their unique physicochemical properties. This paper introduces a simple and cost-effective method for producing Bi₂S₃ microstructures at low temperatures (25 and 70 °C). These microstructures are formed by the hierarchical self-assembly of Bi₂S₃ nanoparticles, which are typically 15–40 nm in size. The nanoparticles are synthesized by the co-precipitation of thioglycolic acid, thioacetamide, and bismuth nitrate in water. The study delves into the phase composition and morphological evolution of the microstructures, concerning the chemical composition of the solution and the synthesis temperature. X-ray analysis has confirmed the formation of single-phase bismuthinite Bi₂S₃. The synthesis process generates primary building blocks in the form of 15–40 nm Bi₂S₃ nanocrystals, which then go through a hierarchical self-assembly process to produce a range of micrometer-sized structures. A scanning electron microscopy examination revealed that the primary nanoparticles self-assemble into quasi-1D worm-like nanostructures, which then self-assemble to create sponge-shaped microstructures. These structures subsequently self-organize and refine into either flower- or dandelion-like microstructures, mostly depending on the synthesis temperature and the chemistry of the digestion medium. Full article

The ternary chalcogenide AgBiS₂ has attracted widespread attention in the field of photovoltaic and photoelectric devices due to its excellent properties. In this study, AgBiS₂ powders with an average diameter of 200 nm were prepared via a simple and convenient reflux method from silver acetate, bismuth nitrate pentahydrate, and n-dodecyl mercaptan. The adjustment of the ratios of Ag:Bi:S raw materials and of the reaction temperatures were carried out to investigate the significance of the synthesis conditions toward the composition of the as-synthesized AgBiS₂. The results of XRD indicated that the powders synthesized at a ratio of 1.05:1:2.1 and a synthesis temperature of 225 °C have the lowest bismuth content and the highest purity. The synthesized AgBiS₂ crystallizes in a rock salt type structure with the cubic $Fm\overline{3}m$ space group. Scanning and transmission electron microscopy, thermogravimetric analysis, ultraviolet–visible–near-infrared spectra, and photocatalytic degradation performance were employed to characterize the as-synthesized samples. The results demonstrated that AgBiS₂ powders display thermal stability; strong absorption in the ultraviolet, visible, and partial infrared regions; and an optical bandgap of 0.98 eV. The obtained AgBiS₂ powders also have a good degradation effect on the methylene blue solution with a degradation efficiency of 58.61% and a rate constant of 0.0034 min⁻¹, indicating that it is an efficient strategy for sewage degradation to reduce water pollution. Full article

Bismuth ferrite, BiFeO₃, a multiferroic perovskite oxide, has gained significant attention in the field of materials science due to its unique combination of ferroelectric and antiferromagnetic properties. This inherent dual nature makes it essential for various cutting-edge technologies, including non-volatile memories, spintronics, and energy-harvesting devices. However, realizing its full potential requires the precise synthesis of high-purity bismuth ferrite nanoparticles. In this scholarly endeavor, we present a comprehensive exploration of the meticulous fabrication of bismuth ferrite nanoparticles using a microwave-assisted combustion method conducted in the solid-state regime. We utilized bismuth nitrate and iron nitrate as precursor materials, combined with an organic fuel amalgam consisting of ammonium nitrate and glycine. Achieving complete combustion through microwave irradiation required a detailed optimization process for the oxidant-to-fuel ratio and absolute quantities. Our research systematically investigated various fuel-to-oxidant ratios, including 1:1, 3:6, 6:3, and 12:12, all conducted under rigorously controlled microwave irradiation conditions. Subsequent characterization through infrared spectroscopy (IR), X-Ray Diffraction (XRD), and scanning electron microscopy (SEM) confirmed the successful synthesis of high-purity bismuth ferrite nanoparticles. Furthermore, optimizing the synthesis conditions resulted in nanoparticles with superior purity and structural integrity. In conclusion, we meticulously evaluated the photocatalytic properties of the synthesized bismuth ferrite nanoparticles, with a specific focus on their effectiveness in degrading malachite green. Our findings highlight the significant impact of carefully tailored combustion parameters on the photocatalytic performance of bismuth ferrite nanoparticles, positioning them as promising candidates for various environmental remediation and catalytic applications. This study advances our understanding of the custom synthesis of advanced photocatalytic materials, potentially fostering sustainable technological advancements. Full article

Soil contamination with such rare heavy metals as silver (Ag), bismuth (Bi), tellurium (Te), and thallium (Tl) leads to disruption of its agricultural and ecological functions. Each of these rare heavy metals has a different level of soil toxicity, which affects the ecological state of the soil and its recovery degree estimated by biological indicators. The work objective is to assess the ecotoxicity of oxides and nitrates of silver, bismuth, tellurium, and thallium by biological indicators of Haplic Chernozem. Under the conditions of a laboratory simulation experiment, silver, bismuth, tellurium, and thallium were introduced into the samples of soil. The ecological state of the soil for each incubation period was assessed by the activity of soil enzymes (catalase and dehydrogenases), the intensity of seed development in polluted soil (the length of shoots and roots of winter wheat), and microbiological indicators (the total number of bacteria and Azotobacter sp. abundance). For 90 days, when contaminated with oxides of silver, bismuth, tellurium, and thallium, the most sensitive biological indicator was the length of wheat roots; when contaminated with nitrates, the total number of bacteria was the most sensitive biological indicator. The most informative biological indicator for contamination with both chemical forms of rare elements (silver, bismuth, tellurium, and thallium) was the Azotobacter sp. abundance. The most ecotoxic elements among those studied were thallium and tellurium, both in the form of oxides and nitrates. The results of the study may be useful for biomonitoring and diagnostics of the state of soils contaminated with silver, bismuth, tellurium, and thallium. Full article

Heterojunction photocatalytic materials show excellent performance in degrading toxic pollutants. This study investigates the influence of calcination temperature on the performances of floral Bi₂O₃/TiO₂ composite photocatalyst crystal, which was prepared with glycerol, bismuth nitrate, and titanium tetrachloride as the major raw materials via the solvothermal method. XRD, SEM/TEM, BET, Uv-vis, and XPS were employed to analyze the crystal structure, morphology, specific surface area, band gap, and surface chemical structure of the calcined temperature catalysts. The calcination temperature influence on the catalytic performance of composite photocatalysis was tested with rhodamine B (RhB) as the degradation object. The results revealed the high catalytic activity and higher photocatalytic performance of the Bi₂O₃/TiO₂ catalyst. The degradation efficiency of the Bi₂O₃/TiO₂ catalyst to RhB was 97%, 100%, and 91% at 400 °C, 450 °C, and 500 °C calcination temperatures, respectively, in which the peak degradation activity appeared at 450 °C. The characterization results show that the appropriate calcination temperature promoted the crystallization of the Bi₂O₃/TiO₂ catalyst, increased its specific surface area and the active sites of catalytic reaction, and improved the separation efficiency of electrons and holes. Full article

Due to a suitable band gap and high light absorption behavior, Bi₂S₃ is showing major success in photo-to-current conversion applications. In this current work, the authors used a low-cost nebulizer spray pyrolysis method to create nano-sized pure and unique Eu contents (1–5 wt.%)-loaded Bi₂S₃ thin layers by taking bismuth nitrate and thiourea as the source materials. The parent and Eu doped Bi₂S₃ thin films, deposited on a well-cleaned glass substrate at 350 °C, were analyzed using a variety of characterization approaches, including FESEM, EDS, XRD, PL, UV-Vis, and I-V, to describe the morphologies, compositions, crystallinity, defect states, band gap, and photodetection capability, respectively. The X-ray diffraction outcomes confirmed an orthorhombic polycrystalline structure for all Eu concentrations, and they were highly oriented along the (130) plane. Incorporation of Eu into the host matrix improves the intensity of all the peaks, and the crystallite size (25 nm) was found to be highest for the 3% Eu doped Bi₂S₃ thin film. The formation of a nanowire-like morphology was confirmed thorough field emission electron microscopy analysis, which is preferred for photo detectors. Upon excitation at 325 nm, grown pure and Eu doped Bi₂S₃ thin films indicated five emission peaks at 387, 418, 439, 480, and 523 nm, respectively. All the films showed significant absorption in the UV region, and importantly, a narrowing of the band gap is seen from 2.29 to 2.17 eV. Finally, the current-voltage characteristics of the pure and Eu doped Bi₂S₃ thin films were tested using silver contacts as electrodes. The results showed that the 3% Eu doped Bi₂S₃ sample showed a higher UV photocurrent characteristic, with high specific detectivity (1.82 × 10¹⁰ Jones), photoresponsivity (3.88 × 10⁻¹ AW⁻¹), external quantum efficiency (125%), and rapid photo response, as well as a recovery speed of 0.3 s and 0.4 s, due to the effective light absorption and photocarrier generation. We believe that our study may provide a cost-effective approach for UV photosensor applications. Full article

Sustainable agriculture is only possible if the agroecological services of the soil are preserved. Soil contamination with rare elements such as silver (Ag), bismuth (Bi), tellurium (Te), and thallium (Tl) is less studied, but their toxicity is no less high than in other heavy metals. Activity of soil enzymes is of great importance for the healthy functioning of soils, agroecosystem services, and their fertility. It is necessary to assess the ecological state of black soil using the most sensitive and informative indicators of the state of soils—their enzymatic activity. The objective of this research was to evaluate changes in activity of five priority soil enzymes (catalase, dehydrogenases, invertase, phosphatase, and urease) when contaminated with oxides and nitrates of Ag, Bi, Te, and Tl in a laboratory model experiment. The integral toxicity of nitrates and oxides of Ag, Bi, Te, and Tl was assessed by the integrated index of soil enzymatic activity. A comparison of the toxicity of oxides and nitrates of each element, according to the integrated index of soil enzymatic activity, allowed us to establish that Ag oxide is more toxic than Ag nitrate; Bi oxide is equivalent in its toxicity to Bi nitrate; and Tl and Te oxides are less toxic than Tl and Te nitrates. When contaminated with oxides, the most informative indicators are activity of invertase (Ag), urease (Bi, Tl), and phosphatase (Te). When contaminated with nitrates, the most informative indicators are activity of phosphatase (Ag) and invertase (Bi, Tl, and Te). Activity of phosphatase and catalase are the most sensitive to contamination by oxides and nitrates of Ag, Bi, Tl, and Te, and dehydrogenases, invertase, and urease are the least sensitive. Full article

An efficient and practical catalytic system for the oxidation of alcohols to aldehydes/ketones using catalytic amounts of Bi(NO₃)₃ and Keto-ABNO (9-azabicyclo [3.3.1]nonan-3-one N-oxyl) with air as the environmentally benign oxidant was developed. Various primary and secondary alcohols were smoothly oxidized to the corresponding products under mild conditions, and satisfactory yields were achieved. Moreover, this methodology avoids the use of a ligand and base. The gram-scale reaction was demonstrated for the oxidation of 1-phenyl ethanol, and the product of acetophenone was obtained at an isolated yield of about 94%. Full article