RSC Advances最新文献

Coconut shells (CS) are a promising renewable precursor for carbon black synthesis. By optimising carbonisation parameters for CB synthesis and introducing a low-temperature alkali treatment method using KOH, this study investigates the potential of utilising CS-derived activated carbon black (ACB) as a sustainable black colourant in electrically conductive toner powders. The most efficient synthesis parameters were determined by analysing 36 CB samples that were produced by combining three variables: carbonisation temperature, carbonisation duration, and particle size. The best CB sample was treated using different weight ratios of KOH at 120 °C. The results obtained from FT-IR, XRD, and SEM coupled with EDS, EIS, and TGA revealed that optimised carbonisation and low-temperature KOH treatment caused well-defined porous structures with an amorphous nature. Increasing KOH concentrations result in the formation of large spherical micropores (0.656 µm), however, excessive concentrations lead to smaller or closed pores. The ACB sample synthesised with lower KOH concentration showed the lowest resistance, thermal stability up to 400 °C, and low moisture and ash content. The reduced resistance indicates enhanced electrical conductivity, suggesting the potential of synthesised ACB as a conducting agent, while its high thermal stability indicates suitability for high-temperature printing applications. Moreover, high carbon content (69.2 wt%) and fine particle size (10-15 µm) may ensure good dispersion in polymer matrices while facilitating uniform colour and print quality. Hence the synthesised ACB samples with the lowest KOH concentrations could be used as a black colourant and a conducting agent in the synthesis of toner powders.

Triphenylenes are a class of polycyclic aromatic hydrocarbon that have been attracting increasing attention owing to their widespread applications in areas such as liquid crystals, organic electronics, photovoltaics, light emitting diodes, and catalysts. The utility of triphenylenes stems from their flatness, rigidity, and aromatic nature. This review provides an exploration of triphenylene derivatives, with an emphasis on recent advancements in their synthesis, properties, and multifaceted applications. Highlighting their synthetic strategies, we discuss both classical methods and modern approaches, including metal-catalyzed reactions and photochemical techniques, which have enabled the development of a wide range of substituted triphenylenes, as well as their dimers, trimers, twinned molecules, and oligomers. The electronic structure of triphenylene, characterized by a delocalized π-electron system, underpins its remarkable charge transport properties. In terms of applications, triphenylene-based liquid crystals are particularly notable for forming columnar mesophases with highly ordered structures, facilitating advantageous macroscopic molecular orientation. These properties underscore its potential for next-generation functional materials across diverse domains, including organic electronics, photovoltaics, light-emitting diodes, and catalysis. By integrating insights into its properties and future potential, this review aims to provide a valuable resource for researchers investigating triphenylene and its derivatives.

This study investigates the recovery of uranium(vi) using a novel functionalized polyglycidyl methacrylate (PGMA) adsorbent, PPA-PGMA, modified with polyamine-phosphonic acid. The adsorbent's structure was confirmed by CHNP, BET, SEM, TGA, XRD, XPS, and FTIR analyses. Batch adsorption studies from synthetic solutions revealed an optimal pH range of 3.0-6.0, where the saturation adsorption capacity reached 0.828 mmol g^-1. The adsorption process exhibited fast kinetics (180 min) and was endothermic. Experimental data fitted well with the Langmuir and pseudo-second-order (PSO) kinetic models. The adsorption process was quantitatively described using a new three-dimensional (3D) nonlinear mathematical model, which was verified using MATLAB software against several theoretical models (generalized Langmuir, PSO with Arrhenius, shrinking core, and Floatotherm models). Thermodynamic analysis indicated a spontaneous (ΔG < 0) and endothermic (ΔH > 0) reaction. The adsorbent demonstrated excellent reusability, maintaining high efficiency over six cycles. Metal desorption was successfully achieved using NaHCO₃, with adsorption capacity remaining at 88-90% of the initial value after the sixth cycle. Finally, PPA-PGMA was applied to recover U(vi) from acidic ore leachates (El-Sella and Gattar areas) following precipitation pre-treatment. The adsorbent exhibited marked selectivity for U(vi) over co-existing Fe and Si, achieving adsorption capacities of 0.71 mmol U per g (El-Sella) and 0.65 mmol U per g (Gattar). These results confirm the potential of PPA-PGMA as a durable and selective adsorbent for uranium recovery from complex acidic matrices.

This study investigates the catalytic hydrothermal conversion of heterogeneous end-of-life automotive shredder residues (ASR) waste in near-supercritical water, focusing on process optimization, thermodynamic behavior, and multi-phase product characterization. Factorial screening identified temperature and residence time as critical parameters, with 350 °C and 90 minutes yielding maximum hydrochar through enhanced carbonization and repolymerization, accompanied by reduced liquid yields and CO₂-rich gas production. Thermodynamic analysis revealed significant increases in water ionization constant (K _w) during non-isothermal heating, peaking at 1.44 × 10^-12 mol² kg^-2 at 350 °C, while density decreased to 0.619 g cm^-3 under autogenous pressure. Isothermal reactions at 350 °C exhibited highly exothermic behavior (ΔH ≈ -143 kJ mol^-1) and strong ordering effects, correlating with peak hydrochar and gas yields. Catalyst screening demonstrated Ni-based catalysts' superior selectivity for phenolics and aromatic amines in the oil-phase, increased aqueous-phase total organic carbon, and minimized tar formation. Ru/Al₂O₃ favored ketone production, while non-catalyzed runs produced a broad range of C₆-C₂₉ oil products and 341 g (CO₂)/kg(feed) as the only gas product. The optimized NiSiAl catalyst yielded a maximum hydrochar of 64.4 wt% with enhanced thermal stability (onset degradation ∼425 °C), higher calorific values at 5 wt% feedstock concentration and feedstock-to-catalyst ratio of 9. The highest H₂ production (5 g kg^-1 feed) occurred at a catalyst ratio of 5, while the best liquid yield (36%) was achieved at the lowest ratio of 1. The GC-MS analysis revealed feedstock concentration influenced reaction pathways, shifting from phenolics and amines at low solids loading to hydrocarbons and ketones at higher concentrations. These findings highlight catalytic hydrothermal conversion as a viable circular-economy route for ASR valorization, combining thermodynamic efficiency with targeted fuel and chemical production.

In this study, Se-doped CeO₂@Fe₃O₄ nanoparticles (NPs) were synthesized and applied to a Carthamus tinctorius (safflower) cell suspension culture using liquid medium (B5). The application of these NPs at various levels (0, 5, 10, 15 and 20 mg L⁻¹) was studied for its effects on cell growth, physio-biochemical traits and antioxidative activities. The addition of NPs to the culture media significantly improved the cell biomass, antioxidant potential and phenolic contents. The addition of NPs at the rate of 15 mg L⁻¹ (T₃ treatment group) significantly improved the dry biomass of cells (128.72%), total chlorophyll contents (76.02%), and reduced levels of hydrogen peroxide (5.15%) and reactive oxygen (26.51%) compared to the control group (0 mg L⁻¹). Furthermore, this study identified 29 differentially expressed genes (DEGs) in the jasmonate signalling pathway. Notably, only the two DEGs from the MYC2 family showed mixed expression at different time points (6 h, 24 h, 48 h, and 72 h) following treatment with Se-doped CeO₂@Fe₃O₄ NPs. In conclusion, these findings demonstrate that this approach is effective, adaptable, biocompatible, and cost-efficient, offering a promising strategy for enhancing the production of antioxidant and bioactive metabolites in industrial-scale safflower cultivation.

Vanadium dioxide (VO₂) is a promising material for mid-infrared optical modulation due to its reversible metal-insulator transition. This study presents an efficient and stable method for fabricating VO₂ thin films with enhanced optical limiting performance via crystallinity control and microstructural optimization. The process combines magnetron sputtering with gradient annealing, and the effects of annealing temperature on film structure and optical properties were analyzed using X-ray diffraction, X-ray spectroscopy, and SEM. Annealing at 550 °C yielded high-quality monoclinic VO₂(M₁) films with excellent crystallinity, low defect density, and island-like grains (250-300 nm). The optimized film showed reduced oxygen vacancies (17.3%) and increased V⁴⁺ content. Optical measurements revealed strong thermal switching: mid-infrared transmittance dropped from 85% at 25 °C to 35% at 80 °C, achieving a 50% modulation depth-12.5-fold higher than that of unannealed films. Under 3.8 µm laser irradiation, modulation depth tripled. The annealing process effectively improved phase purity and reduced defects by encouraging grain growth and oxygen vacancy repair. This work provides key insights into the structure-defect-property relationships in VO₂ and offers a scalable route for producing high-performance phase-change oxide thin films.

¹⁷O Nuclear Magnetic Resonance (NMR) spectroscopy has become an increasingly valuable technique for investigating the structure, dynamics, and reactivity of polyoxometalates (POMs), a diverse class of metal-oxygen clusters with broad applications in catalysis, energy storage, and materials science. The oxygen framework of POMs plays a very important role in dictating their physical and chemical properties, making direct probing of oxygen environments essential. However, the quadrupolar nature and low natural abundance (0.037%) of ¹⁷O nuclei impose significant experimental challenges, including low sensitivity and broad line shapes. Recent methodological breakthroughs such as the development of ultra-high-field NMR instrumentation, the use of magic angle spinning (MAS) to minimize anisotropic broadening, and the implementation of dynamic nuclear polarisation (DNP) to boost signal intensity have greatly enhanced the resolution and feasibility of ¹⁷O NMR studies. These advances now enable the differentiation of terminal, bridging, and internal oxygen sites, offering unique insights into structural isomerism, substitution effects, and protonation states in various POM archetypes including Lindqvist, Keggin, and Dawson structures. Beyond structural assignments, ¹⁷O NMR has provided mechanistic understanding of catalytic processes by tracking oxygen participation in redox transformations and proton-coupled electron transfer. When integrated with computational approaches such as density functional theory (DFT) and artificial intelligence (AI), ¹⁷O NMR delivers predictive power for interpreting chemical shifts, quadrupolar parameters, and dynamic behaviour. This review consolidates recent progress, highlights case studies, and underscores the emerging role of ¹⁷O NMR as a cornerstone for advancing POM chemistry at the interface of structural science, catalysis, and theoretical modeling.

Herein we report the self-powered biosensor for detection of dissolved oxygen (DO) detection using a paper-based enzymatic biofuel cell (BFC) employing screen-printed electrodes composed of MgO-templated mesoporous carbon (MgOC). The sensor used an anode modified by flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) and a cathode modified by bilirubin oxidase (BOD) to enable selective oxygen reduction under glucose-rich conditions. Electrochemical analyses revealed a linear relationship between the cathodic current and DO concentration over the range of 0-22 mg L^-1, with a maximum power output of 398 µW cm^-2 at 20 mg L^-1 DO. The biosensor system was successfully used to quantify DO in both pure water and a commercial soft drink, without requiring external power sources. These findings demonstrate the feasibility of low-cost, disposable, and scalable DO sensing by using cathode-targeting enzymatic BFCs, thereby opening new avenues for environmental and food quality monitoring.

In the present study, biodegradable polyvinyl alcohol/graphene oxide-based thin films were prepared as a topical drug delivery system via the solvent casting method for the loading and controlled release of the antibacterial drug cephalexin. Results showed that all the fabricated thin films had highly uniform and smooth-surface textures. The chemical structure and crystallinity of the samples were investigated by FTIR spectroscopy and XRD analysis, and the SEM and EDX techniques revealed the successful loading and uniform dispersion of cephalexin within the prepared films. Investigations on the thermal properties of the samples indicated that the thermal stability of the samples increased with the addition of graphene oxide, while it decreased with the addition of cephalexin. Water contact angle measurements revealed an increase in the hydrophobicity of thin films upon the addition of graphene oxide and cephalexin, and the final scaffolds displayed a contact angle of 104.6° ± 1.72°. The fabricated thin films also displayed pH-dependent degradation, swelling, and release behaviors in PBS solutions of pH 7.4 and 5.5. Moreover, a two-stage release profile was observed for drug-containing films during the liberation of cephalexin into release media. Additionally, the drug-containing films exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria. Evaluating the cytocompatibility of the samples revealed desired cell viability up to 64 mg mL^-1 during 24 h, and the toxic effect of the samples was increased in a concentration-dependent manner.

The sustainable conversion of lignocellulosic residues into renewable fuels and chemicals is vital to advancing a circular bioeconomy. This study presents a dual-scale thermochemical framework for the valorisation of pine needles (PN) and cashewnut shells (CNS) through integrated analytical and pilot-scale pyrolysis. Analytical pyrolysis using Py-GC/MS was employed to evaluate the temperature-dependent formation of bio-volatiles between 400 and 800 °C, revealing that 500 °C yielded the highest fraction of desirable compounds. PN generated aromatic-rich volatiles suitable for advanced fuel formulations, while cashewnut shells produced phenolic-rich vapours with applications in the renewable chemicals sector. The scale-up experiments conducted in a semi-pilot rotary kiln reactor confirmed the reproducibility of product yields and compositional trends observed at the laboratory scale. The maximum pyrolysis oil yields reached 40% for PN and 33% for CNS, while char and gas yields varied according to lignocellulosic composition. The elemental analysis indicated superior fuel quality for PN-derived bio-oil (higher heating value (HHV) = 35.08 MJ kg^-1, O/C = 0.23) compared with CNS oil (HHV = 28.14 MJ kg^-1, O/C = 0.43). Furthermore, biochars exhibited porous morphologies, indicating potential for environmental applications. This dual-scale methodology effectively bridges mechanistic understanding with process scalability, enabling tailored valorisation routes for underutilised biomass residues.