BMC Chemistry最新文献

The global decline in fossil fuel availability and rising environmental concerns have intensified the search for sustainable alternative fuels, with biodiesel emerging as a promising option. This study investigates the performance, combustion, and emission characteristics of a B20 biodiesel blend derived from Used Temple Oil Methyl Ester (UTOME) enhanced with cerium oxide (CeO₂) nano additives. Conducted at constant speed and varying engine loads, the experiments show that CeO₂ additives significantly enhance brake thermal efficiency (BTE), with the B20UTOME100CeO₂ blend achieving efficiency levels comparable to pure diesel. Specific fuel consumption (SFC) decreases as CeO₂ concentration increases, reflecting enhanced fuel efficiency, while higher cylinder pressure (CP) and net heat release (NER) signify improved combustion processes. Emission analysis reveals substantial reductions in hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO_x), with the B20UTOME100CeO₂ blend demonstrating the lowest HC and NO_x emissions due to better fuel atomization, improved combustion efficiency, and lower peak combustion temperatures enabled by the CeO₂ nanoparticles. The B20UTOME100CeO₂ blend demonstrated enhanced performance at maximum load, exhibiting a 1.57% increase in Brake Thermal Efficiency, a 6.67% reduction in Specific Fuel Consumption, a 2.83% elevation in cylinder pressure, and a 5.95% greater heat release when compared to conventional diesel. Emissions analysis revealed a significant reduction in carbon monoxide by 66.67%, hydrocarbons by 13.51%, and nitrogen oxides by 0.20% relative to diesel. A gradient boosting regressor model was trained on experimental data comprising fish oil biodiesel blends with nanoparticle additives, utilizing Python libraries. The accuracy of the model is supported by a mean squared error of 0.7647 for HC emissions and R² scores of 0.9247 and 0.9882 for HC and NO_x emissions, respectively. Overall, the results indicate that B20UTOME with 100 ppm CeO₂ additives offers a viable alternative to diesel, providing improved thermal efficiency, enhanced combustion, and reduced harmful emissions. The marked reduction in toxic emissions, including CO, HC, and NO_x, carries significant biomedical relevance. These pollutants are known to induce respiratory, cardiovascular, and neurological disorders upon prolonged exposure. Therefore, implementing CeO₂-enhanced biodiesel blends offers a potential strategy for protecting public health by diminishing harmful exhaust emissions.

In the oil and gas industry, carbon steel is widely used but suffers from severe corrosion in acidic environments, particularly in the presence of CO₂ and H₂S. This study presents the synthesis and evaluation of a novel eco-friendly compound, 2,2′-(4,6-dihydroxyisophthaloyl) bis(N-phenylhydrazine-1-carbothioamide) (DICA), as an effective corrosion inhibitor for low-carbon steel in 0.5 M HCl solution. Structural characterization was confirmed through NMR, elemental analysis, and mass spectrometry. The corrosion inhibition performance was investigated using weight loss (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). DICA demonstrated outstanding inhibition efficiency, reaching 91.41% at 300 ppm concentration and 298 K, indicating a strong concentration-dependent protective effect. Surface morphology analysis by SEM and AFM revealed a significant reduction in steel surface roughness and corrosion damage due to DICA adsorption. Complementary density functional theory (DFT) calculations and Monte Carlo simulations corroborated the mixed-mode adsorption mechanism involving both chemisorption and physisorption. These findings confirm the potential of DICA as a high-performance, environmentally benign inhibitor for protecting carbon steel in aggressive acidic media.

Global urbanization is driving high volumes of agricultural and food waste, creating an urgent need for sustainable and effective technologies to convert biomass into valuable products. This study explores the conversion of palm waste into cellulose microfibers (CMF) using Ammonia Fiber Expansion (AFEX) followed by acid hydrolysis, with a focus on structural characterization, thermal stability, and reaction kinetics compared to raw material. The resulting CMF exhibited elongated, uniform fibers with smooth surfaces, with lengths of 0.1–3.0 mm, and diameters of 5–20 μm. X-ray analysis revealed a significant increase in the carbon/oxygen ratio, from 1.8 ± 0.2 in raw palm leaves to 2.7 ± 0.3 in CMF, indicating enhanced carbon content due to dehydration and reduction of carbonyl groups. FTIR spectra confirmed effective removal of lignin and hemicellulose after treatment, further supporting this chemical transformation. Thermal analysis demonstrated that CMF possesses higher heat content than raw leaves, suggesting its potential for energy-related applications. TGA showed that CMF decomposes at slightly higher temperatures, indicating improved thermal stability. Isoconversional kinetic analysis using the Vyazovkin Nonlinear (NLN) and Kissinger-Akahira-Sunose (KAS) methods revealed variable effective activation energies (E_α), consistent with a complex degradation mechanism. Overall, CMF displayed lower E_α values than raw biomass, especially at early and mid-reaction stages. Kinetic modeling at 50% conversion showed a markedly higher pre-exponential factor (A_α) for raw leaves (2.8 × 10¹³ s⁻¹) compared to CMF (7.4 × 10⁹ s⁻¹), reflecting structural alterations from treatment. Both raw and CMF samples exhibited negative activation entropy (ΔS^≠) values of − 237.7 and − 240.3 J mol⁻¹ K⁻¹, respectively, suggesting greater molecular order in activated complexes. The enthalpy of activation (ΔH^≠) was 149.7 ± 3.9 kJ mol⁻¹ for raw leaves versus 120.4 ± 3.9 kJ mol⁻¹ for CMF, Gibbs free energy of activation (ΔG^≠) was slightly higher for raw leaves (297.0 ± 3.9 kJ mol⁻¹) compared to CMF (269.4 ± 3.9 kJ mol⁻¹), primarily due to differences in ΔH^≠. These kinetic parameters are crucial for any future implementation of palm leaves conversion into CMF at the industrial scale.

Titanium dioxide is used in different applications such as paints, plastics, paper, and water treatment. Various routes are applied for the recovery of TiO₂ according to the available raw material. The aim of this work is the application of response surface methodology for optimizing the recovery of TiO₂ from illeminite beach sand deposits (black sand, Kafr-El-Sheikh, Egypt) with high purity using sulfuric acid. Utilizing local raw material to obtain titanium dioxide with high purity for applications in paints and energy applications. Applying a simple method for separating iron, which is present in high weight% (49%). Application of the RSM approach in the extraction of titanium dioxide to determine the interaction of the studied parameters and determine the model relating them to the yield of titanium dioxide. characterizations of raw material are applied; X-ray fluorescence (XRF) indicates the chemical composition, and the weight% of titanium dioxide is 43%. The illeminite phase is confirmed by X-ray diffraction (XRD) of the raw material sample. The average particle size of illeminite powder is measured using screen analysis, and it is around 118 micrometers. Three selected parameters affecting the leaching of illeminite are studied using the Response Surface Methodology (RSM) technique: temperature (60–120℃), sulphuric acid concentration (4–12 M), and time (1–5 h). Maximum conversion (84%) is obtained at the optimum conditions predicted by the RSM model at Temperature (120 ℃), time 4.2 h, Concentration (12 M). The relation between the studied parameters and conversion is represented by a reduced cubic model with R² = 0.973 and p-value = 0.0001, which confirms the accuracy of the model. The prepared titanium dioxide is separated from the filtrate solution by hydrolysis at 109 °C for 3 h, using EDTA as a complexation agent to capture the solvated iron. The hydrated titanium dioxide powder is dried, then calcinated at 500 °C for 3 h to produce titanium dioxide in an anatase phase. The prepared sample is examined using XRF, XRD, and SEM-EDX. 96.4% purity of titanium dioxide is formed; the XRD pattern of the examined sample confirmed the formation of the anatase phase. SEM images display that TiO₂ has a uniform spherical morphology. The EDX spectrum shows that most of the sample is TiO₂. The average particle size of the prepared titanium dioxide using a particle size analyzer is about 78.82 nm.

In this paper molecular interactions of L-glutamic acid (Glu) in aqueous D-sorbitol (D-SOR) are analyzed by measuring electrical conductivity in the broad temperature range of 293.15–313.15 K at ambient pressure. The density and viscosity data were also measured experimentally required to explore the derived conductometric properties. Meanwhile, the molar conductance ((:{{Lambda:}}_{text{m}})), limiting molar conductance(:{:({Lambda:}}_{text{m}}^{0})), Walden product (( Lambda _{{text{m}}}^{0} eta _{0} )), ion association constants ((:{text{K}}_{text{A}})) and activation energy ((:{text{E}}_{text{A}})) of ion association are derived and discussed in the light of ion-ion and ion-solvent interactions. The Kraus–Bray model was used to analyze the limiting molar conductance ((:{{Lambda:}}_{text{m}}^{0})) of the solutions. For the mixtures under study, the increased (:{{Lambda:}}_{text{m}}) values for Glu in aqueous D-SOR compared to pure water suggest a synergistic interaction. As D-SOR concentration increases, (:{{Lambda:}}_{text{m}}) of Glu decreases due to stronger solute–cosolute interactions and reduced ion dissociation. Glu functions as a structure creator in water, according to the ( Lambda _{{text{m}}}^{0} eta _{0} ) finding. However, in aqueous D-SOR, increasing temperature and D-SOR concentration cause ( Lambda _{{text{m}}}^{0} eta _{0} ) to drop, indicating structure-breaking behavior. Numerous energy and environmental applications may benefit from an investigation of the conductometric properties of Glu and D-SOR in aqueous solutions.

A novel green spectrofluorometric method was developed for the quantification of diltiazem hydrochloride (DLZ), a benzothiazepine-class calcium channel blocker with vasodilatory properties. The assay exploits the rapid fluorescence quenching of Acid Red 87—a fluorone-based dye—upon complexation with DLZ in acidic medium (pH 3.8). This “on-off” mechanism enables selective DLZ detection by measuring the decrease in Acid Red 87 native fluorescence intensity (λ_ex/λ_em = 302.5/545.8 nm). Key parameters (pH, dye concentration, buffer volume) were systematically optimized, yielding a linear response over 50–1100 ng/mL (r² = 0.9991) with a detection limit of 15.5 ng/mL. The method was rigorously validated per ICH Q2(R1) guidelines, confirming precision (RSD < 2%), accuracy (99.76% % recovery), and robustness. It was successfully applied to analyze DLZ in pharmaceutical formulations (tablets/capsules) with no matrix interference, and the statistical comparison (t- and F-tests) showed no significant difference from the reference method. Critically, the procedure uses distilled water as the sole solvent, aligning with green chemistry principles while offering simplicity, cost-efficiency, and high-throughput potential.

The present study explores, for the first time, the physicochemical and molecular interaction behaviour of tetramethylammonium hydroxide (TMAH)–caffeine (CAF) mixtures in aqueous medium. Caffeine (CAF) is a widely consumed central nervous system stimulant, and tetramethylammonium hydroxide (TMAH) is an industrially significant compound with known toxicological implications. Combination of these two solutes represents a novel system where ionic, hydrophobic, and hydrogen-bonding interactions coexist, providing unique insight into mixed solute behaviour and solvation dynamics in aqueous media. This work focuses on the physicochemical, acoustic and thermodynamic properties of aqueous TMAH solutions in the presence of varying concentrations of CAF over a range of temperatures (293.15–313.15 K). Acoustic measurements, including ultrasonic velocity, and density were utilized to compute key thermodynamic parameters such as compressibility, relaxation strength, specific heat capacity, acoustic impedance, internal pressure, and isobaric expansion coefficient. The results reveal complex ion–solvent and ion–cosolute interactions, highlighting significant structural reorganization within the solution matrix. Observations such as decreasing compressibility and relaxation strength with concentration and temperature suggest stronger intermolecular forces, while variations in partial molar compressibility and transfer parameters indicate hydration shell modification due to CAF’s presence. The findings offer valuable insights into hydration dynamics and solvation behaviour, with practical relevance to drug delivery, material design, and toxicity evaluation. This work advances understanding of solute–cosolute interactions, supporting applications in pharmaceutical formulations and chemical process development.

Graphical abstract

This study presents an ultrasensitive electrochemical sensor aimed at the detection and quantification of ertugliflozin l-pyroglutamic acid (EGZ), an anti-diabetic agent, using molecularly imprinted polymer (MIP) technology. The sensor was fabricated by electropolymerizing o-phenylenediamine (o-PD) onto a pencil graphite electrode (PGE), with EGZ serving as the template molecule. The detection of EGZ was achieved through indirect sensing, where EGZ competes with the redox-active probe ferrocyanide/ferricyanide ([Fe (CN)₆]^3−/4−) for the binding sites of the MIP. The resulting electrical signal was measured using differential pulse voltammetry (DPV). The sensor demonstrated excellent sensitivity, with a linear response range from 1 × 10⁻¹² to 1 × 10⁻¹⁰ M and a limit of detection (LOD) of 6.3 × 10⁻¹⁴ M. A non-imprinted polymer (NIP) was prepared under the same electropolymerization conditions but without the inclusion of EGZ. The NIP sensor served as a control, and the imprinting factor (IF) was determined to be 6, confirming the success of the imprinting process and the formation of selective recognition sites. Characterization of the proposed sensor was conducted using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis (EDX). Additionally, the sensor successfully detected EGZ in spiked human plasma, demonstrating its practical applicability in complex biological samples. The environmental impact of the proposed method was assessed using the AGREE and GAPI green evaluation tools, which confirmed its environmentally friendly nature. Furthermore, the sensor exhibited high selectivity in the presence of commonly co-formulated drugs, such as sitagliptin and metformin, indicating its potential for pharmaceutical applications.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (NP) interaction with viral RNA is vital for viral replication and immune evasion, making it an attractive target for antiviral development. Inspired by adenosine triphosphate (ATP)’s competitive inhibition of NP–RNA binding, we screened 121 FDA-approved ATP-competitive kinase inhibitors, identifying mitoxantrone (IC₅₀ = 1.22 µM) as a potent inhibitor. Considering its known topoisomerase inhibitory activity, we further screened 23 additional topoisomerase inhibitors, uncovering four active compounds—pixantrone (IC₅₀ = 5.67 µM), doxorubicin (IC₅₀ = 20.19 µM), epirubicin (IC₅₀ = 7.23 µM), and suramin (IC₅₀ = 0.44 µM). Biolayer interferometry (BLI) revealed distinct inhibition mechanisms: suramin bound directly to the NP C-terminal domain (CTD) with a K_D of 0.26 µM, whereas the other compounds primarily targeted RNA, with pixantrone showing the highest RNA affinity (K_D = 0.63 µM). Complementary molecular docking analyses supported these observations, indicating suramin’s preference for NP binding and anthracycline derivatives engaging RNA. Our findings demonstrate the feasibility of a mechanism-informed repurposing strategy and identify FDA-approved topoisomerase inhibitors and suramin as valuable chemical starting points. Although these compounds are not directly suitable as antivirals due to toxicity concerns, they provide promising scaffolds for further optimization aimed at selective disruption of SARS-CoV-2 NP–RNA interactions.

1,3,4-Oxadiazoles are a vital class of heterocyclic compounds known for their diverse biological activities. In this study, a series of eight novel 1,3,4-oxadiazolyl sulfide derivatives 4a–h were synthesized and characterized using IR, NMR, and elemental analysis. The antioxidant activity of these derivatives was evaluated via DPPH and ABTS assays, revealing promising radical scavenging capabilities Compound 4 h emerged as the most potent antioxidant with SC₅₀ values of 9.88 µM (ABTS) and 12.34 µM (DPPH), outperforming standard antioxidants surpassing standard antioxidants such as ascorbic acid (SC₅₀ = 23.92 µM) and gallic acid (SC₅₀ = 21.24 µM). The impact of electron-donating and electron-withdrawing substituents on activity was demonstrated through a comprehensive structure-activity relationship (SAR) study. Molecular docking against α-glucosidase (PDB: 3W37) validated the potential of these compounds as enzyme inhibitors, with docking scores ranging from − 8.59 to -9.81 kcal/mol and similar modes of binding. Insights into electronic properties were obtained through density functional theory (DFT) calculations, emphasizing that compound with the lowest HOMO–LUMO energy gaps (4b) exhibited higher polarizability and enhanced reactivity, which correlates with their biological antioxidant performance. This integrated study underscores the therapeutic potential of these derivatives as antioxidants and enzyme inhibitors, offering paths for further drug development.