Search Results (2,042)

In this study, sustainable polyurea greases were prepared using epoxidized soybean oil (ESO) as bio-based base oil, with octadecylamine (ODA) reacted with three diisocyanates: 4,4′-diphenylmethane diisocyanate (MDI), 1,6-hexamethylene diisocyanate (HDI), and toluene diisocyanate (TDI). The diisocyanate structure dominated the thickener microstructure: MDI-ODA formed a compact short-rod fibrillar network with strong hydrogen bonding and π–π stacking, endowing the grease with the highest consistency (256), dropping point (262 °C), lowest oil separation (2.7%), and optimal thermal stability (T5% = 278 °C). HDI-ODA showed a lamellar structure with moderate performance, while TDI-ODA presented a loose porous network. Rheological tests confirmed MDI-ODA/ESO possessed the highest yield stress and structural recovery (79.5%). Tribological tests showed MDI-ODA/ESO delivered the lowest friction coefficient and wear scar diameter. Compared with non-epoxidized soybean oil (SO), ESO significantly enhanced grease performance. This improvement is attributed to the ring-opening reaction between the N–H of the ureido group and the epoxy groups of ESO, which improves thickener–oil compatibility. In addition, the polar epoxy groups promote the formation of stable lubricating films. This work verifies that diisocyanate structure and base oil epoxidation are critical for high-performance sustainable polyurea greases. Full article

Cross-reactions between peroxy radicals (RO₂) derived from different volatile organic compound (VOC) precursors have been proposed as an important pathway during atmospheric oxidation. However, direct molecular evidence has been limited. In this study, α-pinene and fully deuterated toluene (d8-toluene) were oxidized separately and as a mixture in a potential aerosol mass (PAM) flow reactor, and the resulting secondary organic aerosol (SOA) was characterized by a high-resolution mass spectrometer (ESI FT-ICR-MS). A constrained chemical mass balance (CMB) model attributed 82.9% of the mixed-SOA signal to single-precursor sources (66.5% α-pinene, 16.4% d8-toluene), leaving a 17.1% signal-based residual fraction unexplained by linear mixing. Among 2450 residual molecular formulas exclusive to the mixed-SOA, 1858 were identified as cross-reaction candidates, with carbon, oxygen, and double bond equivalents (DBE) distributions consistent with RO₂-RO₂ cross-reactions between toluene- and α-pinene-derived fragments. We also identified representative monomer-dimer pairs, where one monomer corresponded to a known α-pinene oxidation product, while the other matched a primary oxidation product of d8-toluene oxidation based on the Master Chemical Mechanism (MCM), providing strong molecular-level evidence for RO₂-RO₂ cross-reactions. Our findings demonstrate that the mixed VOCs generate unique SOA products that extend beyond simple additive chemistry, with implications for SOA yield parameterizations and chemical transport models. Full article

Separating heavy oil from solid matrices is still difficult, mainly because of the strong adhesion between oil and solids and the intrinsically high viscosity of heavy oil, both of which restrict efficient large-scale recovery. Ionic liquids have recently attracted attention as additives that may improve extraction performance. In this work, [Bmim][ClO₄] was introduced into toluene- and xylene-based solvent systems to examine its role in heavy-oil recovery. The extraction performance was evaluated through recovery yield, viscosity, contact angle, oil–solid interaction force, and SARA composition. Molecular dynamics simulation was also carried out to probe how [Bmim][ClO₄] interacts with heavy-oil components and how it influences the diffusion of saturates, aromatics, resins, and asphaltenes. The results show that the addition of [Bmim][ClO₄] improved heavy-oil recovery in every solvent system tested, with the highest value, 89.31 wt%, obtained in the toluene system. At the same time, the ionic liquid lowered the viscosity, reduced the contact angle, and weakened the adhesion between the oil phase and the solid surface, all of which favored oil–solid separation. SARA analysis further indicated that the extraction of heavier fractions, especially resins and asphaltenes, became more pronounced after adding the ionic liquid. Simulation results suggest that [Bmim][ClO₄] interacts more strongly with resins and asphaltenes, disrupts their associated structures, and facilitates mass transfer. Taken together, these results suggest that [Bmim][ClO₄] improves heavy-oil extraction by altering interfacial behavior and loosening the aggregated structure of heavy fractions, which may be useful for future process optimization. Full article

Organic Rankine Cycles (ORCs) are widely recognized as an effective solution for Waste heat recovery (WHR). However, the design and optimization of these systems must address the tradeoff between computational efficiency and the need to capture complex component behavior. This requires moving beyond purely energetic 0D modeling approaches to account for constructional, spatial, and operational constraints. This work presents a novel modeling framework with a specific focus on the expansion device. Radial inflow turbine stages are selected for their capability to achieve high pressure ratios while maintaining compactness and high efficiency. Heat exchangers follow a generic one-dimensional counterflow configuration, with a shell-and-tube geometry adopted for sizing purposes. The turbine stages are modeled by resolving several internal sections in order to capture local thermofluid dynamic conditions. The framework predicts turbine efficiency and incorporates a newly developed formulation for shock-induced losses, improving performance prediction under trans-sonic flow conditions. After validation against experimental data, the model is applied to a WHR system integrated with an internal combustion engine fueled by biofuels. The results highlight the existence of optimal operating conditions arising from competing physical mechanisms. The analysis also shows the transition from single-stage to two-stage turbine configurations at high pressure ratios and emphasizes the role of real gas effects in determining stage performance and optimal expansion distribution. The results of simulations carried out for three different working fluids (ethanol, toluene, and R1234ze(E)) highlight that the available mechanical power ranges from 10 to 22 kW for single-stage turbine configurations and from 24 to 36 kW for two-stage configurations, with total system volumes varying between approximately 600 and 9000 L. Among the working fluids considered here, ethanol provides the best overall performance for the present case study. Overall, the proposed approach provides a reliable and computationally efficient tool for the preliminary design and optimization of ORC-based WHR systems. Full article

This work examines the influence of the Ce/Fe ratio in Pt/CeO₂-Fe₂O₃ catalysts on the peculiarities of metal–support interaction and catalytic properties in the total oxidation of toluene. The physical-chemical properties of the Pt/CeO₂-Fe₂O₃ catalysts are studied using low-temperature N₂ adsorption–desorption, XRD, TPR-H₂, Raman, and TEM. The citrate method to synthesize the mixed CeO₂-Fe₂O₃ supports makes it possible to obtain dispersed defective oxide particles that actively interact with the supported Pt species. An increase in the oxygen mobility of CeO₂-Fe₂O₃ after the Pt deposition and the cooperation of active oxidative species with the active site of Pt is a key to the catalytic activity in the total oxidation of toluene. This effect is the highest for the Pt/3Ce2Fe catalyst, and the temperature of 50% toluene conversion over this catalyst is 167 °C. Full article

Silicon-doped diamond-like carbon (Si-DLC) coatings against aluminum alloy (A5052) were investigated for reducing friction under humid conditions. The coatings were deposited on high-speed steel (SKH51) substrates using a bipolar-type plasma-based ion implantation and deposition (PBII&D) technique, with Si content controlled by varying the tetramethylsilane (TMS)-to-toluene precursor ratio. Structural characterization by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the progressive evolution of Si–C bonding with increasing TMS ratio. The Si-DLC coating with Si 5.0 at.% exhibited the lowest coefficient of friction (COF) of 0.033 and reduced wear volume under a high normal load of 150 N in humid conditions (relative humidity > 90%). However, Si-DLC coatings with higher Si contents (Si 7.7 and 14.3 at.%) led to deteriorated tribological performance, including coating delamination and severe wear. Surface analyses of the coatings revealed that the low-friction behavior was associated with the presence of oxidized Si species at the outermost surface, which undergo hydroxylation in humid environments to form Si–OH groups. These hydroxylated surfaces promote the formation of a hydrated boundary layer that provides a low-shear sliding interface. Full article

Graphene-based aerogels (GAs) exhibit outstanding performance in the adsorption of organic contaminants. Consequently, numerous studies have investigated the use of GAs for this purpose. In this work, the synthesis methods commonly used to produce GAs are first briefly described, and their key characteristics are summarized. Subsequently, GAs are classified according to the modifications applied to improve their adsorption properties toward organic pollutants. Furthermore, the quantitative relationships between surface area, density, surface chemistry, and adsorption performance for organic contaminants are systematically reviewed. The analysis revealed that the adsorption of two representative organic contaminants, toluene and methylene blue, is not dependent on the surface area of GAs. In contrast, GAs with lower density exhibit an improved adsorption capacity for toluene. Additionally, the relationship between the surface chemistry of GAs and their adsorption capacity toward methylene blue was analyzed considering the concentration of carboxylic sites. The available data suggests a potential correlation between the concentration of carboxylic groups on the surface of GAs and their adsorption capacity for methylene blue. This observation is supported by the analysis of methylene blue species in aqueous solution and the pH at the point of zero charge of GAs, which indicate that the interaction occurs mainly through electrostatic attractions resulting from the deprotonation of acidic surface sites. Finally, several opportunity areas and future research directions regarding the use of GAs for pollutant adsorption are discussed. Full article

Di(hetero) aryl and alicyclic amine derivatives of thieno[2,3-b]pyridine were synthesized in good to high yields (45–76%) via palladium-catalyzed Buchwald–Hartwig amination. The reactions were performed using methyl 5-bromothieno[2,3-b]pyridine-2-carboxylate, prepared in this work, and a variety of substituted anilines bearing either electron-donating groups (EDGs) or electron-withdrawing groups (EWGs), as well as pyridinyl amines, and saturated heterocyclic amines such as morpholine and piperidine. For most substrates, the optimal conditions involved Pd(OAc)₂, rac-BINAP, and Cs₂CO₃ in toluene at 100 °C under argon. Substrate bearing EWGs and electron-deficient pyridinyl amines required Xantphos as the ligand, while reactions with piperidine were only successful using Pd₂(dba)₃ as a palladium (0) source. The antiparasitic activity of the synthesized compounds was evaluated against Trypanosoma brucei (T. brucei) and Leishmania infantum (L. infantum) in both promastigote and amastigote forms. Most compounds exhibited no significant cytotoxicity (CC₅₀ > 100 μM) in PMA-differentiated THP-1 derived macrophage cells. Analysis of substituent effects focusing on the nature of amino substitution at position C(5) revealed distinct trends in antiparasitic activity. Notably, one compound exhibited activity against Leishmania infantum promastigotes that was nearly four times higher than that of the reference drug miltefosine, and its selectivity index was also approximately fourfold higher. Full article

This study developed poly(lactic acid) (PLA) biocomposites reinforced with pine wood flour (10, 20, and 30 wt%) to achieve the interphase through chemical modification. Specifically, the wood flour was treated with poly(propylene glycol) toluene 2,4-diisocyanate terminated (PEGTDI), while 1 wt% poly(lactic acid)-g-maleic anhydride (PLA-g-MA) was integrated as a reactive compatibilizer during extrusion and thermocompression. Fourier-transform infrared spectroscopy (FTIR) analysis corroborated the occurrence of urethane formation and ester/anhydride linkages, as substantiated by the presence of characteristic bands indicative of surface carbamation at 1645 and 1726 cm⁻¹. Thermal analysis revealed that both the pine wood flour and coupling agents promoted PLA crystallization; however, thermogravimetric analysis (TGA) indicated a decrease in thermal stability for functionalized composites, suggesting a trade-off between enhanced interfacial interaction and heat resistance. Mechanical testing demonstrated a significant reinforcement effect, with the Young’s modulus increasing by up to 22% in untreated composites. The coupling agents effectively optimized stress transfer at low fiber loadings (10 wt%), while flexural modulus improvements were predominant at higher loadings (20–30 wt%) regardless of treatment. These findings underscore the criticality of surface modification and compatibilizer selection for tailoring the structural and thermo-mechanical properties of PLA-based biocomposites, thereby providing a pathway for optimized performance in structural applications. Full article

Biosurfactants offer a green, sustainable approach to many environmental bioremediations, especially for oil contamination. In this study, the aim is to evaluate the effectiveness of biosurfactants in accelerating hydrocarbon removal from mature fine tailings under anaerobic conditions. The bacteria were isolated from mature fine tailings and tested for biosurfactant production using different biosurfactant screening methods (i.e., blood agar, cetyltrimethylammonium bromide (CTAB) blue agar, oil displacement, and drop collapse). The most efficient strain showed high similarity to Stutzerimonas stutzeri by 16S rRNA gene sequencing. Results showed that this strain produces rhamnolipids with a critical micelle concentration (CMC) of 600 mg/L and a minimum surface tension of 38.70 ± 0.08 mN/m. Moreover, when supplemented with whey, the strain showed a high emulsification index of 24 toward toluene (66%) and hexane (60%). The bioremediation of mature fine tailings (MFTs) was conducted under anaerobic conditions by adding a consortium of the four strains that were positive in biosurfactant screening tests. The results showed 53% removal of n-alkane C9-C30 and a reduction in surface tension from 69 ± 0.5 mN/m to a minimum of 54.33 ± 0.5 mN/m. The results suggest the potential successful application of bioaugmentation for in situ biological treatment in the oil sands industry. Full article

Background/Objectives: Textile dermatitis seems underdiagnosed, partly due to low awareness of this problem and partly due to imperfect screening methods. The aim of this study was to analyse the diagnostic efficacy and clinical relevance of two textile dye mixes used in routine patch testing. Methods: Retrospective analysis of patch test results and clinical records of patients tested with textile dyes in a specialised patch test practice. Results: Between 2007 and 2024, 207 patients were patch tested with Disperse Blue Mix 106/124 (DBM). Positive reactions were observed in 17.4% of patients, including 10.6% considered clinically relevant. Between 2019 and 2023, 90 patients were tested with Textile Dye Mix (TDM) 6.6%, of whom 14.4% developed a positive reaction, relevant in 4.4%. In a subgroup tested with TDM 6.6%, DBM, all their components and cross-reacting azo dyes, out of eight patients with confirmed textile dermatitis, three cases would have been missed if screening had been performed using TDM alone (6.6%), compared with one case being missed if screening had been performed using DBM alone. The highest rate of positivity (78.6%) to TDM 6.6% was found among patients with an allergy to the common hair dye Toluene 2,5–Diamine Sulfate, all of whom were also positive to Disperse Orange 3 (DO3) present in TDM 6.6%. Among patients with positive tests to Disperse Blue (DB) 106 1% pet. or DB124 1% pet., 68.7% and 85.7%, respectively, reacted also to DBM 106/124 (each component at 0.5%), with respective figures for TDM 6.6% (DB106 and DB124 each at 0.3%) amounting to a mere 12.5% and 14.3%. Conclusions: The detection rates of textile dermatitis can be increased by improving screening tools for textile dye allergy in baseline series for routine patch testing. Based on the results of this study, proposed improvements include removing Disperse Orange 3 from the textile dye mix, tripling the concentrations of Disperse Blue 106 and Disperse Blue 124 in the textile dye mix, and doubling their concentrations in the Disperse Blue Mix 106/124. Full article

Pyrolysis of refuse-derived fuel (RDF) is a promising waste-to-energy route, but its use in higher-value applications remains limited by tar carryover, benzene, toluene, ethylbenzene, and xylenes (BTEX), heteroatom-containing compounds, and pollutant accumulation in recirculated scrubber water. This study evaluated operating windows for RDF pyrolysis coupled with direct wet scrubbing and closed-loop water reuse, with the aim of identifying regimes suitable for different end-use tiers. A Taguchi L27 design of experiments (DOE), i.e., an orthogonal array comprising 27 experimental runs, was applied to evaluate the effects of pyrolysis temperature, residence time, scrubber liquid-to-gas ratio, and scrubber-water temperature, while sequential reuse of the same scrubber-water inventory was evaluated at 5, 10, and 15 cycles. Cleaned-gas pollutants were quantified by compound-resolved gas chromatography–mass spectrometry (GC–MS) after solid-phase adsorption (SPA) sampling, while phenolics and polycyclic aromatic hydrocarbons (PAHs) in scrubber water were determined by extraction followed by GC–MS. Feasibility within each end-use tier was defined as simultaneous satisfaction of tier-specific cleaned-gas thresholds (C_tar, C_BTEX, I_N, and I_S) and the corresponding water-loop hazard limit (I_tox), using literature-informed engineering screening criteria. The results showed that stronger scrubbing reduced gas-phase tar and BTEX burdens, whereas extended water reuse caused systematic accumulation of phenolics and PAHs and increased the composite water-loop hazard index. Boiler-grade operation remained feasible across a broad operating range, with 23 of the 27 tested conditions remaining robust, whereas internal combustion engine combined heat and power (ICE-CHP) feasibility was restricted to a narrow robust regime, and no robust microturbine-grade condition was identified. These findings show that operating windows for RDF pyrolysis must be defined jointly by gas cleanliness and water-loop management constraints. Full article

Against the backdrop of the global search for alternatives to fossil fuels, waste tires have attracted attention as a significant resource due to their enormous production volume and considerable energy potential. However, the application of tar derived from waste tires alone is limited by its poor stability and other deficiencies. This study systematically investigates the co-pyrolysis behavior and synergistic mechanisms of waste tires and beech sawdust at various blending ratios. Thermogravimetric analysis indicates that the addition of beech sawdust reduces the decomposition temperature of the blend and induces a synergistic effect that promotes waste tire pyrolysis within the temperature range of 384–440 °C. Pyrolysis experiments results show that tar yield of the blends reached 64.45 wt.%, while the char yield decreased from 40.67 wt.% to 24.83 wt.%. Also, the presence of beech sawdust synergistically enhanced the formation of aromatic hydrocarbons in the tar of waste tires, with the total yield of aromatics increasing synergistically by up to 54.8%. Specifically, the yields of stable alkylbenzenes such as toluene and xylene were consistently promoted, whereas the yields of unsaturated aromatics such as allylbenzene and 2,4-dimethylstyrene were enhanced at low beech sawdust ratios but suppressed at higher ratios. Based on these findings, the interaction mechanisms underlying the co-pyrolysis process were elucidated, providing theoretical guidance for the high-value utilization of waste tires. Full article

A series of bifunctional hierarchical HZSM-5 catalysts modified with Zn, Ga, Ni, Cr, or Ag were synthesized via impregnation, and their performance in the catalytic fast pyrolysis of walnut shells was systematically evaluated. The influence of the metal species and concentration of NaOH used for desilication (0.20–0.40 mol·L⁻¹) on the yield of light aromatics was assessed. Ga/HZSM-5 and Zn/HZSM-5 exhibited the most pronounced enhancement at 0.35 mol·L⁻¹, significantly outperforming the unmodified HZSM-5. Building on this finding, Zn-Ga bimetallic hierarchical catalysts were developed, and the effect of the Zn:Ga loading ratio (1%:2%, 1.5%:1.5%, 2%:1%) was investigated. The 1%Zn/2%Ga catalyst delivered the highest performance, achieving a total aromatic yield of 3.876 × 10⁴ a.u.·mg⁻¹, with 82% BTX (benzene, toluene, and xylenes) selectivity. The term “a.u.” stands for “arbitrary units,” typically derived from peak area counts obtained through GC-MS analysis. These values represent the relative signal intensity detected by the instrument, rather than absolute quantities of the substance. To more accurately characterize the aromatic hydrocarbon yield, these data are normalized to the yield of aromatic hydrocarbons per unit mass. These findings demonstrate that the combination of Zn-Ga modification and tailored mesoporosity can markedly enhance the production of high-value benzene, toluene, and xylene (BTX) aromatics from lignocellulosic biomass. Full article

6(5H)-phenanthridinone derivatives, as an important class of alkaloids, have broad application value in drug development and functional material synthesis. In this study, a nickel-catalyzed synthetic strategy was developed, using 2-bromobenzamide compounds as starting materials. Through an intermolecular cyclization reaction, a series of 6(5H)-phenanthridinone derivatives bearing amide substituents was efficiently constructed. The optimal reaction system was identified: Ni(acac)₂/Zn as the catalyst, PCy₃ as the ligand, toluene as the solvent, Cs₂CO₃ as the base, under an argon atmosphere at 150 °C for 12 h. The target products were obtained in yields up to 88%. Further substrate scope exploration demonstrated the excellent generality of this method, successfully synthesizing 21 derivatives with various substitution patterns, achieving yields ranging from 51% to 92%, and showing good compatibility with multiple functional groups such as alkyl, aryl, and heterocyclic moieties. Importantly, the reaction remained stable during gram-scale experiments, successfully yielding the desired compound at 85%. This work not only provides an approach for the precise construction of the 6(5H)-phenanthridinone framework but also opens an efficient pathway for the controlled synthesis of amide-substituted derivatives. Full article