RSC Advances最新文献

The selectivity of the full wet leaching process for vanadium extraction using H₂SO₄ is low, resulting in a high impurity content in vanadium extracted from vanadium-bearing shale. This study focused on vanadium extraction and iron separation from vanadium-bearing shale, involving the coordination of H₃PO₄ in an H₂SO₄ leaching system. The effects of the ratio and quantity of H₂SO₄–H₃PO₄, leaching time, leaching temperature, and liquid-to-solid ratio on vanadium-bearing shale leaching were investigated. The dissolution processes of various minerals and the mechanism of iron coordination precipitation were analyzed. Results showed that vanadium leaching efficiency was 91.07% and iron leaching efficiency decreased from 84% to 23.86% under optimal leaching conditions—H₂SO₄-to-H₃PO₄ ratio of 2 : 1, H⁺ content of 8 mol kg⁻¹, liquid-to-solid ratio of 0.8 L kg⁻¹, and leaching time of 12 h at 95 °C. Leaching kinetics showed that the leaching process of vanadium shale was a mixed-control process in the H₃PO₄–H₂SO₄ leaching system; additionally, the leaching process was mainly controlled by a chemical reaction with an activation energy of 67 kJ mol⁻¹. The preferential dissolution order of minerals in the vanadium-bearing shale was calcite, apatite, magnetite, muscovite, and pyrite. Under the H₂SO₄–H₃PO₄ leaching system, the iron content was reduced by inhibiting the dissolution of pyrite and coordination precipitation of Fe³⁺ with PO₄³⁻, thus separating iron and vanadium from the source. This provides guidance for vanadium extraction and impurity separation from vanadium-bearing shale using an all-wet method.

Novel ionene-type cationic copolyimides based on 4,4′-oxydiphthalic anhydride (ODPA), 4,4′-(1,4-phenylenediisopropylidene)bisaniline (BIS P), and 2,6-diaminopyridine (DAP) were synthesized. The copolyimides were obtained in two stages: first, the copolyimides with the 0/1, 0.2/0.8, 0.3/0.7, 0.5/0.5, 0.6/0.4 and 1/0 DAP/Bis P ratios were obtained through thermal imidization, and then quaternization of soluble copolyimides with methyl iodide was conducted for 24 or 48 h. The samples were characterized via FTIR, NMR and EDX methods to confirm their structure and composition. The cationic copolyimides with a DAP content of less than 0.3 showed initial weight loss (onset) at about 250 °C, according to TGA results and demonstrated solubility in chloroform. The highest ionic conductivity value of 0.234 S cm⁻¹ was showed by the sample with 0.3 DAP content and 0.15 degree of quaternization. The stability of the membranes in alkaline media was evaluated using FTIR and TGA. It was shown that samples with a DAP content of more than 0.3 lost their integrity probably owing to partial hydrolysis of imide rings, while copolyimides with a DAP content of 0.2 and 0.3 remained stable.

Breast cancer is the fifth major cause of fatalities associated with cancer worldwide and in Pakistan, 34 066 female breast cancer cases were recorded in 2018. This study was designed to understand extracts of Cheiranthus cheiri (C. cheiri) and to evaluate the epigenetic modulation of microRNA expression for breast cancer therapy using a selected phyto-nanohybrid treatment. The phytochemical screening revealed the presence of potential phytochemicals and antioxidant scavenging activity in the C. cheiri extracts with a DPPH (2-diphenyl-1-picryl-hydroxyl) assay giving an IC₅₀ value of 20.63 μg mL⁻¹. GC-MS (gas chromatography-mass spectroscopy) analysis of the C. cheiri n-hexane extract detected 42 phytocompounds. Titanium oxide (TiO₂) nanoparticles were synthesized and characterized using XRD (X-ray diffraction), SEM (scanning electron microscopy) and EDX (energy dispersive X-ray spectrometry) to confirm the synthesis of anatase (tetragonal) TiO₂. The prepared nanoparticles were conjugated with the selected plant i.e., C. cheiri. The resulting phyto-nanohybrid was used for the subsequent treatment of breast cancer induced in a female rat model. The treatment groups were as follows: doxorubicin as the standard treatment, C. cheiri, TiO₂ and the phyto-nano hybrid treatment. After 8 weeks of treatment, the groups induced to exhibit breast cancer (with and without treatment) and the control groups were dissected and analysed for histopathological, haematological and microRNA expression. Histopathological examination revealed chronic inflammation in the dilated ducts and tumour embolus formation, thus confirming the presence of breast cancer in the DMBA-induced female rat model. MicroRNA expression analysis showed a statistically significant decrease in levels of miR-205 in the plasma of the breast cancer rat model compared to the control (p < 0.05). After treatment with the phyto-nano hybrid, a statistically significant increase in the expression of miR-205 was observed in the rat models induced to exhibit breast cancer compared to the rat model without any treatment (p < 0.05). The downregulation of miR-205 in the plasma of the breast cancer exhibiting model, as compared to the control, and its upregulation after treatment with the selected phyto-nano hybrid indicated its diagnostic and prognostic significance. It is concluded that the phyto-nano hybrid used in this study is effective against breast cancer induced female rat model. All the results support the finding that the selected phyto-nano hybrid has great potential as a possible therapeutic agent for the treatment of breast cancer.

Reinforced concrete (RC) constructions are seriously threatened by chloride-induced corrosion (CIC) and carbonation, which can result in structural degradation, safety issues, and financial losses. Electrochemical methods and microstructural analysis tests are some of the laboratory techniques used to examine key elements of CIC, such as the impact of different variables and the efficacy of mitigation solutions. In situ studies that make use of non-destructive testing, chloride profiling, and half-cell potential measurements offer important new insights into the long-term performance and causes of RC structure deterioration in real-world circumstances. Non-destructive approaches for CIC detection are emerging these days and provide fruitful results. Studies have focused on the use of these approaches for CIC detection on small specimens in the lab as well as on full-scale experiments in the field. This review covers both in situ monitoring and laboratory studies to provide a thorough analysis of CIC.

This study investigates a class of materials known as polymer nanodielectrics, which are formed by incorporating ceramic fillers into polymers. These materials offer the unique advantage of tunable electrical and optical properties. The research focuses on the incorporation of high-purity stannic oxide nanoparticles (SnO₂ NPs) into a ternary blend matrix of hydroxypropyl methylcellulose (HPMC) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) using a solution casting method. Characterization techniques like X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) revealed alterations in the amorphous nature of the HPMC/PEDOT:PSS blend upon the introduction of SnO₂ NPs. These analyses also suggest the formation of interactions between the polymer and nanoparticles. Scanning electron microscopy (SEM) images confirmed the successful dispersion of SnO₂ NPs on the surface of the polymer blend, particularly at lower concentrations. The optical properties of the nanocomposite films were investigated using UV-vis spectrophotometry. This analysis allowed for the calculation of optical constants like the bandgap and refractive index. The results showed a dual-bandgap structure, with the direct and indirect bandgaps ranging from 4.92 eV to 4.26 eV and 3.52 eV to 1.68 eV, respectively. Electrical characterization using AC conductivity and dielectric permittivity measurements revealed a dependence on the SnO₂ NPs concentration within the frequency range of 0.1 Hz to 10 MHz. The relaxation processes and interfacial polarization effects within these nanocomposites are further discussed in the study. At a frequency of 10 Hz, the AC conductivity exhibited a significant increase, rising from 1.85 × 10⁻¹² S m⁻¹ to 1.04 × 10⁻⁹ S m⁻¹ upon the addition of 0.7 wt% SnO₂ NPs. These findings highlight the multifunctional nature of the developed nanocomposites. They hold promise for various applications, including UV blockers, optical bandgap tuners, and optical coatings in advanced optoelectronic devices. Additionally, their tunable high permittivity suggests potential use as dielectric substrates for next-generation, high-performance energy storage devices.

We present a simple and cost-efficient route for the preparation of sulfonated dihalo-monomers for the synthesis of hydrocarbon ionomers. After conventional monomer sulfonation, excess sulfuric acid is quantitatively removed by neutralization with BaCO₃. This leads to the precipitation of excess H₂SO₄ as insoluble BaSO₄, which is easily separated from the sulfonated monomers in their soluble Ba-forms by filtration. Compared to conventional methods, the proposed approach leads to higher yields, drastically reduces the number of purification steps, and can easily be expanded to the preparation of other sulfonated monomers. The specific monomers presented here are suitable for the preparation of sulfonated polyarylenes and sulfonated polyphenylenes.

Three series of spiropyran photoswitches with an auxiliary chiral centre at position 3′ of the indoline unit were synthesized. Using one example, a novel methodology for synthesis of an optically active spiropyran photoswitch with a defined chirality at position 3′ is demonstrated. Furthermore, a new acid-mediated strategy for spiropyran purification affording moderate to excellent yields (up to 96%) is reported herein. Relative diastereomeric ratios of the prepared spiropyrans were evaluated using NMR spectroscopy in five different solvents (syn : anti up to 21 : 79) and their photoswitching properties determined by UV-vis spectroscopy. It was found that substitution at position 8 of the chromene subunit notably accelerates the photoswitching process.

In this study, we deployed green Melilotus officinalis extract (MOE) as a corrosion inhibitor for copper. The anticorrosion properties of MOE for Cu in 1 M HNO₃ were investigated by various experimental and numerical techniques, including potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and a weight loss (WL) method at different temperatures. Additionally, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis (EDX) and atomic force microscopy (AFM) were utilized to examine the surface morphology of Cu with and without the extract. By contrasting the inhibition effectiveness with and without the extract, the inhibition efficiency (% IE) was observed. The WL method revealed that 300 ppm of the extract had an IE of 93.8% for Cu immersed in one molar HNO₃ solution. The MOE was classified as a mixed type according to the PDP study since it delayed both cathodic and anodic processes, with a cathodic predominance. At 25–45 °C, MOE's free adsorption energies were 23.1–21.5 kJ mol⁻¹, showing that mixed-type adsorption occurred on the Cu surface. Additionally, the Langmuir adsorption isotherm and the adsorption data from the WL tests of MOE showed a good match. The extract could adsorb spontaneously onto the metal surface, according to the thermodynamic conditions. Analysis of the corrosion product using different techniques revealed that a protective layer had formed on the metal's surface. Hence, MOE had a good corrosive inhibitive effect on Cu in HNO₃ solution. It turned out that all the methods used gave consistent results.

Lead-free Cs₂AgBiCl₆ double perovskite (Cs₂AgBiCl₆-DP) material, as a substitute for lead halide perovskite materials, has the advantages of environmental friendliness and high stability and has attracted much attention. However, the photoluminescence and conductive properties of Cs₂AgBiCl₆-DP have not been well studied. In this study, we prepared Cs₂AgBiCl₆-DP single crystals (SCs) by coordination–dissolution and coordination–precipitation method. Single- and powder-XRD, SEM, EDS, XPS, and EPR characterization were performed to confirm the structural characteristics of Cs₂AgBiCl₆-DP SCs. The Tauc diagram based on UV-visible (UV-vis) absorption spectroscopy reveals that the optical bandgap of Cs₂AgBiCl₆-DP SCs is extrapolated to 2.51 eV. Steady-state fluorescence spectra and time-resolved fluorescence spectra show that Cs₂AgBiCl₆-DP SCs has four fluorescence peaks entered at 443, 615, 650 and 723 nm and a fluorescence lifetime of about 4.16 ns. Cs₂AgBiCl₆/PMMA thin films were prepared by spin coating suspension (Cs₂AgBiCl₆ DP and PMMA in acetone solvent). The intensity of emission peak increases with the increase of light intensity at 369 nm. The intensity of emission peak located at 576 nm decreases with increasing incidence wavelength (from 369 to 454 nm) at 10 W m⁻². The emission intensity remains basically unchanged under continuous illumination for 9 hours at 369 nm at 5 W m⁻², which indicates that the Cs₂AgBiCl₆-DP thin film has good stability. In addition, the resistivity and block resistance show a negative exponential change with increasing temperature. These results provide some interesting ideas for the fields of photoluminescence and thermistors.

Nitrogen doping effectively improves the adsorption properties of activated carbons towards volatile organic compounds (VOCs); however, the role of nitrogen elements with various chemical valence states need further evaluation. In this work, waste polyester fabrics were used as a low-cost source to prepare activated carbon, and melamine, pyridine, dimethylamine, and pyrrole were selected as nitrogen sources to compare their nitrogen-doping ability. The adsorption of low-concentration benzene and ethyl acetate on the resultant carbons and the effects of nitrogen, including its valence states and contents, were investigated. Characterizations showed that the nitrogen contents of carbons after doping with melamine (C-M), pyridine (C-P), dimethylamine (C-D), and pyrrole (C-Y) increased, while their corresponding specific surface areas were about 32.6%, 72.2%, 142% and 14.3%, respectively, of the original carbon value of 188.7 cm² g⁻¹. Dynamic breakthrough experiments verified the increase in adsorbed amounts of both non-polar benzene and polar ethyl acetate molecules, with a more significant enhancing effect on benzene. The specific surface area and pore volume mainly contribute to the adsorbed amounts. Regarding the influence of nitrogen-containing functional groups, pyridinic nitrogen was more conducive to benzene adsorption under dry conditions because of the stronger π–π interaction and N–H hydrogen bond; however, its water resistance was inferior to that of pyrrolic nitrogen. Saturated C-P can be effectively regenerated and the adsorbed capacity of benzene remained about 75% after five adsorption cycles. The increased adsorbed amount and super regeneration property identify pyridine as a nitrogen source with priority consideration in the nitrogen modification of activated carbons for VOC adsorption.