Search Results (136)

In this study, the thermodynamic simulation model and system of the copper side-blown smelting process were established using the chemical equilibrium constant method, based on the process reaction mechanism, multiphase equilibrium principle, and MetCal software platform (MetCal v7.81). Under typical production conditions, the composition of the product and the distribution behavior of impurity elements were simulated. The results indicate that the average relative error between the calculated mass fractions of major elements such as Cu, S, Fe, SiO₂, CaO, MgO, and Al₂O₃ in copper matte and smelting slag, and the actual production values, is 4.25%. Additionally, the average relative error between the calculated distribution ratios of impurity elements such as Pb, Zn, As, Bi, Mo, Au, and Ag in copper matte and smelting slag, and the actual production data, is 6.74%. Therefore, this model and calculation system accurately reflects the actual production situation of the copper side-blown smelting process well and has potential to predict process output accurately while optimizing process parameters, effectively guiding production practice. Full article

Bifacial photovoltaic sunshade (BiPVS) is an innovative building-integrated photovoltaic (BIPV) technology. Vertically mounted BiPVS is capable of converting part of the incident solar radiation into electricity, regulating the indoor heat gain from solar penetration and improving daylighting. An excellent BiPVS design should comprehensively consider its impact on building performance and economic viability. This study aims to address this issue by proposing a parametric design-based multi-objective optimization (MOO) framework to maximize indoor useful daylight illuminance, minimize air-conditioning energy consumption, and shorten the payback period by optimizing BiPVS design parameters. The framework utilizes the Ladybug, Honeybee, and Wallacei plugins on the Rhino-Grasshopper simulation platform. It validates the optimization potential of BiPVS in a typical office located in a hot summer and warm winter zone. The results indicate that BiPVS has significant energy-saving and daylighting potential. Compared to the baseline model without BiPVS, useful daylight illuminance is increased by 39.44%, air-conditioning energy consumption is reduced by 12.61%, and the economically satisfactory payback period is 4.80 years. This study provides a practical solution for the competing objectives of daylighting and energy saving in buildings with significant renewable energy utilization. The developed framework is highly efficient and versatile and can be applied to other BIPV designs, which benefits the realization of carbon-neutral goals in the building sector. Full article

The development of highly efficient and stable visible-light-driven photocatalysts for the removal of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water is still a challenge. In this work, Bi₂MoO₆ (BMO) materials with different morphology were successfully prepared via a simple hydrothermal method by altering the solvent. The morphology of the BMO material is mainly influenced by the solvent used in the synthesis (H₂O, ethanol, and ethylene glycol or their mixtures) and to a lesser extent by subsequent thermal annealing. BMO with aggregated spheres and nanoplate-like structures hydrothermally synthesized in ethylene glycol (EG) and subsequently calcined at 400 °C (BMO-400 (EG)) showed the highest adsorption capacity and photocatalytic activity compared to other synthesized morphologies. Complete degradation of 2,4-D on BMO upon irradiation with a blue light-emitting diode (LED, λ_max = 467 nm) was reached within 150 min, resulting in 2,4-dichlorophenol (2,4-DCP) as the main degradation product. Holes (h⁺) and superoxide radicals (⋅O₂⁻) are assumed to be the reactive species observed for the rapid conversion of 2,4-D to 2,4-DCP. The addition of H₂O₂ to the reaction mixture not only accelerates the degradation of 2,4-DCP but also significantly reduces the total organic carbon (TOC) content, indicating that hydroxyl radicals are crucial for the rapid mineralization of 2,4-D. Under optimal conditions, the TOC value was reduced by 84.5% within 180 min using BMO-400 (EG) and H₂O₂. The improved degradation performance of BMO-400 (EG) can be attributed to its particular morphology leading to lower charge transfer resistance, higher electron–hole separation, and larger specific surface area. Full article

The binary heterostructured semiconducting visible light photocatalyst of the iron-doped graphitic carbon nitride/bismuth molybdate (Fe-g-C₃N₄/Bi₂MoO₆) composite was prepared by coupling with Fe-doped g-C₃N₄ and Bi₂MoO₆ particles. In the present study, a comparison of structural characteristics, optical properties, and photocatalytic degradation efficiency and activity between Fe-doped g-C₃N₄ particles, Bi₂MoO₆ particles, and Fe-g-C₃N₄/Bi₂MoO₆ composite was investigated. The results of X-ray diffraction (XRD) examination indicate that the hydrothermal Bi₂MoO₆ particles have a single orthorhombic phase and Fourier transform infrared (FTIR) spectroscopy analysis confirms the formation of Fe-doped g-C₃N₄. The optical bandgaps of the Fe-doped g-C₃N₄ and Bi₂MoO₆ particles are 2.74 and 2.73 eV, respectively, as estimated from the Taut plots obtained from UV-Vis diffuse reflectance spectroscopy (DRS) spectra. This characteristic indicates that the two semiconductor materials are suitable for absorbing visible light. The transmission electron microscopy (TEM) micrograph reveals the formation of the heterojunction Fe-g-C₃N₄/Bi₂MoO₆ composite. The results of photocatalytic degradation revealed that the developed Fe-g-C₃N₄/Bi₂MoO₆ composite photocatalyst exhibited significantly better photodegradation performance than the other two single semiconductor photocatalysts. This property can be attributed to the heterostructured nanostructure, which could effectively prevent the recombination of photogenerated carriers (electron–hole pairs) and enhance photocatalytic activity. Furthermore, cycling test showed that the Fe-g-C₃N₄/Bi₂MoO₆ heterostructured photocatalyst exhibited good reproducibility and stability for organic dye photodegradation. Full article

Hydrotalcite/bismuth solid solution (2D/2D CoAl-LDH/BiO(OH)_XI_1−X) heterojunction photocatalysts were fabricated through a hydrothermal route. Because of their identical layered structure and interlayer hydroxides, CoAl-LDH(2D) and BiO(OH)_XI_1−X(2D) form a tightly bonded heterojunction, resulting in efficient light absorption, excitation, and carrier migration conversion. At the same time, the large specific surface area and abundant hydroxyl groups of the layered structure make the heterojunction catalyst exhibit excellent performance in the photocatalytic degradation of organic pollutants. Under visible light irradiation and in the presence of 1 g/L of the catalyst, 10 mg/L of methyl orange (MO) in water could be completely degraded within 20 min, and the degradation rate of tetracycline (TC) reached 99.23% within 5 min. CoAl-LDH/BiO(OH)_XI_1−X still maintained good photocatalytic degradation activity of tetracycline after five cycles, and the structure of the catalyst did not change. The reaction mechanism related to the degradation of TC by photocatalytic reactions was explored in detail, and the photoexcitation of the semiconductor heterojunction, as well as the subsequent free radical reaction process and the degradation pathway of TC were clarified. This work provides a promising strategy for the preparation of efficient photocatalytic materials and the development of water purification technology. Full article

A binuclear dioxomolybdenum catalyst [(MoO₂Cl₂)₂(L)] (1) (with L (1S,2S)-N,N′-bis(2-pyridinecarboxamide)-1,2-cyclohexane) was prepared and used as catalyst for the desulfurization of a multicomponent model fuel containing the most refractory sulfur compounds in real fuels. This complex was shown to have a high efficiency to oxidize the aromatic benzothiophene derivative compounds present in fuels, mainly using a biphasic 1:1 model fuel/MeOH system. This process conciliates catalytic oxidative and extractive desulfurization, resulting in the oxidation of the sulfur compounds in the polar organic solvent. The oxidative catalytic performance of (1) was shown to be influenced by the presence of water in the system. Using 50% aq. H₂O₂, it was possible to reuse the catalyst and the extraction solvent, MeOH, during ten consecutive cycles without loss of desulfurization efficiency. Full article

The photocatalytic nitrogen reduction reaction (NRR) in aqueous solution is a green and sustainable strategy for ammonia production. Nonetheless, the efficiency of the process still has a wide gap compared to that of the Haber–Bosch one due to the difficulty of N₂ activation and the quick recombination of photo-generated carriers. Herein, a core-shell Bi@Bi₂MoO₆ microsphere through constructing Schottky junctions has been explored as a robust photocatalyst toward N₂ reduction to NH₃. Metal Bi self-reduced onto Bi₂MoO₆ not only spurs the photo-generated electron and hole separation owing to the Schottky junction at the interface of Bi and Bi₂MoO₆ but also promotes N₂ adsorption and activation at Bi active sites synchronously. As a result, the yield of the photocatalytic N₂-to-ammonia conversion reaches up to 173.40 μmol g⁻¹ on core-shell Bi@Bi₂MoO₆ photocatalysts, as much as two times of that of bare Bi₂MoO₆. This work provides a new design for the decarbonization of the nitrogen reduction reaction by the utilization of renewable energy sources. Full article

A novel photocatalytic nanomaterial, Ho₂YSbO₇, was successfully synthesized for the first time using the solvothermal synthesis technique. In addition, a Ho₂YSbO₇/Bi₂MoO₆ heterojunction photocatalyst (HBHP) was prepared via the hydrothermal fabrication technique. Extensive characterizations of the synthesized samples were conducted using various instruments, such as an X-ray diffractometer, a Fourier transform infrared spectrometer, a Raman spectrometer, a UV-visible spectrophotometer, an X-ray photoelectron spectrometer, and a transmission electron microscope, as well as X-ray energy dispersive spectroscopy, photoluminescence spectroscopy, a photocurrent test, electrochemical impedance spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance. The photocatalytic activity of the HBHP was evaluated for the degradation of diuron (DRN) and the mineralization of total organic carbon (TOC) under visible light exposure for 152 min. Remarkable removal efficiencies were achieved, with 99.78% for DRN and 97.19% for TOC. Comparative analysis demonstrated that the HBHP exhibited markedly higher removal efficiencies for DRN compared to Ho₂YSbO₇, Bi₂MoO₆, or N-doped TiO₂ photocatalyst, with removal efficiencies 1.13 times, 1.21 times, or 2.95 times higher, respectively. Similarly, the HBHP demonstrated significantly higher removal efficiencies for TOC compared to Ho₂YSbO₇, Bi₂MoO₆, or N-doped TiO₂ photocatalyst, with removal efficiencies 1.17 times, 1.25 times, or 3.39 times higher, respectively. Furthermore, the HBHP demonstrated excellent stability and reusability. The mechanisms which could enhance the photocatalytic activity remarkably and the involvement of the major active species were comprehensively discussed, with superoxide radicals identified as the primary active species, followed by hydroxyl radicals and holes. The results of this study contribute to the advancement of efficient heterostructural materials and offer valuable insights into the development of sustainable remediation strategies for addressing DRN contamination. Full article

In this study, a chemical precipitation approach was adopted to produce a photocatalyst based on bismuth tungstate Bi₂WO₆ for enhanced and environmentally friendly organic pollutant degradation. Various tools such as X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), optical spectroscopy and X-ray photoelectron spectroscopy, were employed to assess the structural and morphological properties. Hence, the XRD profiles showed a well crystallized Bi₂WO₆ orthorhombic phase. The photocatalytic performance of the resulting photocatalyst was assessed by the decomposition of Rhodamine B (RhB) and methyl orange (MO) with a decomposition efficiency of 97 and 92%, along with the highest chemical oxygen demand of 82 and 79% during 120 min of illumination, respectively. The principal novelty of the present work is to focus on the changes in the crystalline structure, the morphology, and the optical and the photoelectrochemical characteristics of the Bi₂WO₆, by tuning the annealing temperature of the designed photocatalyst. Such physicochemical property changes in the as-prepared photocatalyst will affect in turn its photocatalytic activity toward the organic pollutant decomposition. The photocatalytic mechanism was elaborated based on electrochemical impedance spectroscopy, photocurrent analysis, photoluminescence spectroscopy, and radical trapping measurements. The overall data indicate that the superoxide O₂^•− and holes h⁺ are the principal species responsible for the pollutant photodegradation. Full article

The binary metal oxide mesoporous interfacial layers (bi-MO meso IF layer) templated by a graft copolymer are synthesized between a fluorine-doped tin oxide (FTO) substrate and nanocrystalline TiO₂ (nc-TiO₂). Amphiphilic graft copolymers, Poly(epichlorohydrin)-graft-poly(styrene), PECH-g-PS, were used as a structure-directing agent, and the fabricated bi-MO meso IF layer exhibits good interconnectivity and high porosity. Even if the amount of ZnO in bi-MO meso IF layer increased, it was confirmed that the morphology and porosity of the bi-MO meso IF layer were well-maintained. In addtion, the bi-MO meso IF layer coated onto FTO substrates shows higher transmittance compared with a pristine FTO substrate and dense-TiO₂/FTO, due to the reduced surface roughness of FTO. The overall conversion efficiency (η) of solid-state photovoltaic cells, dye-sensitized solar cells (DSSCs) fabricated with nc-TiO₂ layer/bi-MO meso IF layer TZ1 used as a photoanode, reaches 5.0% at 100 mW cm⁻², which is higher than that of DSSCs with an nc-TiO₂ layer/dense-TiO₂ layer (4.2%), resulting from enhanced light harvesting, good interconnectivity, and reduced interfacial resistance. The cell efficiency of the device did not change after 15 days, indicating that the bi-MO meso IF layer with solid-state electrolyte has improved electrode/electrolyte interface and electrochemical stability. Additionally, commercial scattering layer/nc-TiO₂ layer/bi-MO meso IF layer TZ1 photoanode-fabricated solid-state photovoltaic cells (DSSCs) achieved an overall conversion efficiency (η) of 6.4% at 100 mW cm⁻². Full article

In this study, 3-dimensional molybdenum disulfide (MoS₂) structures, integrated with hematite (α-Fe₂O₃) nanoparticles, were fabricated under a convenient two-step hydrothermal route. The fabricated photocatalytic nanocomposites consist of well-arranged MoS₂ flakes, resembling spherical flower-like morphology, and the nanoparticulate α-Fe₂O₃ structures decorate the 3D network. By raising the α-Fe₂O₃ weight ratio, the composites’ specific surface area and morphology were not affected, regardless of the partial cover of the cavities for higher hematite content. Moreover, the crystallinity examination with XRD, Raman, and FTIR techniques revealed that the precursor reagents were fully transformed to well-crystalized MoS₂ and Fe₂O₃ composites of high purity, as no organic or inorganic residues could be detected. The photocatalytic oxidation and reduction performance of these composites was evaluated against the tetracycline pharmaceutical and the industrial pollutant hexavalent chromium, respectively. The improvement in the removal efficiencies demonstrates that the superior photoactivity originates from the high crystallinity and homogeneity of the composite, in combination with the enhanced charge carriers’ separation in the semiconductors’ interface. Full article

The intermetallic PtBi/MgO/Mg monolithic catalyst was first prepared using non-equilibrium plasma electrolytic oxidation (PEO) technology. Spherical aberration-corrected transmission electron microscope (ACTEM) observation confirms the successful synthesis of the PtBi intermetallic structure. The efficiency of PtBi/Mg/MgO catalysts in catalyzing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH₄ was demonstrated. The activity factor for the catalyst is 31.8 s⁻¹ g⁻¹, which is much higher than reported values. In addition, the resultant catalyst also exhibits excellent catalytic activity in the organic pollutant reaction of p-nitrobenzoic acid (p-NBA) and methyl orange (MO). Moreover, benefiting from ordered atomic structures and the half-embedded PtBi nanoparticles (NPs), the catalyst demonstrates excellent stability and reproducibility in the degradation of 4-NP. This study provides an example of a simple method for the preparation of intermetallic structures as catalysts for organic pollutant degradation. Full article

This study investigates the impacts of bismuth and tin on the production of CH₄ and volatile fatty acids in a microbial electrosynthesis cell with a continuous CO₂ supply. First, the impact of several transition metal ions (Ni²⁺, Fe²⁺, Cu²⁺, Sn²⁺, Mn²⁺, MoO₄²⁻, and Bi³⁺) on hydrogenotrophic and acetoclastic methanogenic microbial activity was evaluated in a series of batch bottle tests incubated with anaerobic sludge and a pre-defined concentration of dissolved transition metals. While Cu is considered a promising catalyst for the electrocatalytic conversion of CO₂ to short chain fatty acids such as acetate, its presence as a Cu²⁺ ion was demonstrated to significantly inhibit the microbial production of CH₄ and acetate. At the same time, CH₄ production increased in the presence of Bi³⁺ (0.1 g L⁻¹) and remained unchanged at the same concentration of Sn²⁺. Since Sn is of interest due to its catalytic properties in the electrochemical CO₂ conversion, Bi and Sn were added to the cathode compartment of a laboratory-scale microbial electrosynthesis cell (MESC) to achieve an initial concentration of 0.1 g L⁻¹. While an initial increase in CH₄ (and acetate for Sn²⁺) production was observed after the first injection of the metal ions, after the second injection, CH₄ production declined. Acetate accumulation was indicative of the reduced activity of acetoclastic methanogens, likely due to the high partial pressure of H₂. The modification of a carbon-felt electrode by the electrodeposition of Sn metal on its surface prior to cathode inoculation with anaerobic sludge showed a doubling of CH₄ production in the MESC and a lower concentration of acetate, while the electrodeposition of Bi resulted in a decreased CH₄ production. Full article

Following the worldwide increasing demand for Critical Raw Materials (CRMs), the Hellenic Geological Survey (HSGME) implemented a national project focused on the re-evaluation of certain Public Mining Areas in Greece. In this framework, exploration activities, including geological mapping, and mineralogical, geochemical, and geophysical studies, revealed significant mineralization targets which possibly host elevated contents of certain CRMs in the Kimmeria Fe skarn deposit. The mineralization is related to the contact metamorphic aureole of the Oligocene Xanthi pluton. Various skarn minerals form the following paragenetic zones in order of decreasing temperature: (i) garnet–wollastonite, (ii) garnet–clinopyroxene, (iii) garnet–epidote, and (iv) vesuvianite–scapolite. The skarn deposit consists of magnetite-rich ore occurring along with sulfides (chalcopyrite, pyrite, bismuthinite, and molybdenite), scheelite, minor sulfosalts (aikinite, wittichenite, and cubanite) and native elements (Au and Bi). Bulk-rock geochemical analyses yielded significant values, as follows: Fe₂O₃, up to 58 wt%; Cu, up to 6.6 wt%; Bi, up to 1100 ppm; W, up to 670 ppm; V, up to 200 ppm; Mo, up to 200 ppm; and Au, up to 2.1 g/t. Soil and stream sediment geochemistry reveals spatial and linear trends for certain groups of associated elements (i.e., Fe₂O₃-Cu-Bi-W and Mo-W-Zn). These trends reflect the surficial distribution of mineralized zones and imply the existence of partially unexposed mineralization in the western part of the study area, a fact also supported by geophysical evidence. A preliminary drilling project has been proposed to evaluate the qualitative characteristics of the deeper parts of the mineralization, investigate buried ore zones in the western part, and overall, reassess the economic potential of the deposit. Full article

The Biche-Kadyr-Oos epithermal Au-Ag ore occurrence is a prospective object in the Ak-Sug porphyry copper ore cluster (Eastern Sayan) in the northern part of the Central Asian orogenic belt (CAOB). The mineralization consists of gold-sulfide-quartz and gold-polysulfide-carbonate-quartz veins with argillic zones in the Lower Cambrian volcanic-sedimentary rocks. The origin of the Au-Ag ore occurrence is still debatable. To determine the origin, we examined the mineralogical and geochemical features, conditions of formation, and fluid sources of the Biche-Kadyr-Oos ore. A mineralogical and geochemical investigation outlines three stages of mineral formation: early argillic stage; gold-sulfide-quartz stage with pyrite, marcasite, pyrrhotite, arsenopyrite, chalcopyrite, less frequently sphalerite, hessite, gold, and electrum; and late gold-polysulfide-carbonate-quartz stage with gold, electrum, Hg-electrum, Se-acanthite, Se-galena, bornite, tennantite, tetrahedrite, hessite, tellurobismuthite, bismuthinite, matildite, jamesonite, ourayite, native Bi, and barite. Fluid inclusion study (thermometry, Raman spectroscopy) in quartz and mineral thermometry (electrum and sphalerite paragenesis) determined that ore veins were formed at P~0.5 kbar from CO₂-water Na-K-chloride fluid (4.9–9.6 wt % NaCl eqv) and temperatures from 300 to 200 °C (early gold-sulfide-quartz veins at 300–230 °C, and late gold-polysulfide-carbonate-quartz veins at 290–200 °C) and variations in fO₂, fS₂, fSe₂ and fTe₂. The S isotopic composition in sulfides and δ³⁴SH₂S values of the fluid are +1.3‰ and +4.7‰, respectively, (T = 300–275 °C) indicating magmatic S in ore formation. The oxygen isotope data indicate that during the formation of veins, the magmatic fluid mixed with meteoric water (δ¹⁸O_fluid is from +3.4 to +6.4‰). The isotopic data that were obtained combined with mineralogical and geochemical features and conditions of ore formation indicate the similarity of Biche-Kadyr-Oos ore occurrence with epithermal Au-Ag deposits of intermediate sulfidation (IS) type. The presence of epithermal Au-Ag mineralization of the Biche-Kadyr-Oos IS type in ore cluster of the Ak-Sug Cu-Au-Mo porphyry deposit indicates the existence of a single porphyry-epithermal ore-magmatic system. Full article