Abstract The growing demand for aviation fuels and the progressive depletion of petroleum resources pose challenges related to transportation logistics, pollution, and technological development, making the advancement of sustainable aviation fuels (SAFs) imperative. In this context, computational research plays a critical role in optimizing production methodologies and predicting compounds with physicochemical properties comparable to those of conventional kerosenes. In this context, this study evaluated the performance of different DFT approximations (B3LYP, M06-2X, and M08-HX) and composite methodologies (G4 and G4-MP2) in predicting combustion enthalpies of organic molecules with high potential as SAF candidates. Initially, the experimental enthalpies of combustion were analyzed to assess the accuracy of each theoretical approach. The analysis was extended to cycloparaffins synthesized, which are promising SAF candidates due to their high energy content and suitable flash and freezing points. The results showed that the relative error tended to stabilize for molecules with higher combustion energies. The enthalpy of combustion calculated by the M08-HX method presented errors comparable to those of G4-MP2. The DFT methods demonstrated greater accuracy when employing the combustion energy correction proposed in this study, highlighting the viability of density functional theory (DFT) approximations. The analysis of complex structures at a significantly lower computational cost than composite methodological approaches indicates that the careful selection and empirical refinement of theoretical methods allow for a more accurate prediction of the combustion enthalpies.
Abstract This study investigated the removal of long- and short-chain per- and polyfluoroalkyl substances (PFAS) such as perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) using alfalfa-derived biochar produced at different pyrolysis temperatures (300–900 °C). Increasing pyrolysis temperature substantially altered the physicochemical properties of the biochars, resulting in higher surface area, higher fixed carbon content, lower O/C and H/C ratios, and more condensed carbon structures. Among the tested materials, the biochar produced at 900 °C (AF900) showed the highest adsorption performance for both PFOA (0.39417 mg/g BC) and PFBA (0.0972 mg/g BC). Adsorption was strongly pH-dependent, with the highest removal observed at pH 3.0, and PFOA consistently showed much greater adsorption than PFBA. Possible mechanisms may include electrostatic, hydrophobic, and π–π interactions. The batch adsorption studies indicated that PFOA was better fitted to the pseudo-second-order and Freundlich models, and PFBA to the Elovich and Temkin models, while the adsorption of PFOA and PFBA followed endothermic reactions. The reusability experiment for AF900 showed a gradual decrease in regeneration efficiency over three cycles for PFOA and PFBA, with a relatively higher decrease for PFBA. Adsorption of PFOA and PFBA on AF900 in groundwater was lower than that in DI water, although increasing the loading rate of AF900 substantially improved PFAS removal in groundwater. Overall, AF900 was the best-performing material for adsorption of PFOA and PFBA among the alfalfa-derived biochars prepared at various temperatures in this study, whereas its removal performance in groundwater needs to be further studied.
Abstract Elucidating how oxidative tailoring enzymes generate structural diversity in natural products remains a major challenge, because their functions are difficult to predict directly from sequence information. Fungal eremophilanes (EMPs), which share a conserved bicyclic core yet exhibit extensive oxidative diversification, provide an ideal model system to address this problem. Here, we establish a systematic framework linking biosynthetic gene cluster (BGC) to EMP chemical diversity by integrating bioinformatics and chemoinformatics analyses. Analysis of 371 BGCs identified six groups defined by combination of key modification enzymes, which rationalize the major structural features of 195 reported EMPs. This framework enables prediction of core scaffolds and major oxidative modifications, thereby constraining the accessible chemical space of EMPs. It also facilitates structure-guided identification of candidate BGCs, including atypical or divergent clusters that are not readily identified by sequence similarity alone. Experimental validation of a predicted peribysin biosynthetic gene cluster further supported the predictive capability of this framework. Together, these results demonstrate that oxidative diversification in EMP biosynthesis follows a limited and interpretable set of transformation patterns and establish a generalizable strategy for constraining terpenoid chemical space from genomic information.
Abstract Modern technological advancements have greatly improved human life, but at a high environmental cost. Plastic packaging has become nearly ubiquitous, leading to excessive plastic waste generation. Although recycling efforts are widespread, they are often energy-intensive and not always cost-effective. Consequently, there is a growing research interest in repurposing plastic waste into value-added functional materials. In this work, plastic substrates obtained from used beverage cups are used as a substrate for electrochromic electrodes via a simple one-pot electroless deposition and an electrochemical conversion method. This simple, redox-driven, and scalable synthesis method enables the direct deposition of a conductive and electrochromic Ni thin film on a flexible substrate obtained from waste plastic cups. The fabricated electrode exhibits a uniform microspherical morphology, offering a high surface area that enhances its electrochemical performance. The electrode demonstrates excellent electrochromic properties, including fast switching speeds of a few seconds between colored and bleached states with excellent cycling stability. Furthermore, by integrating the conductive and electrochromic functions into a single layer, this approach simplifies device architecture and improves charge transport. This study presents a sustainable and cost-effective strategy for upcycling plastic waste into high-performance electrochromic materials.
Abstract This study reports the synthesis of activated carbon (AC–H3PO4) from tropical almond shell (Terminalia catappa L.), an agro-waste material, using phosphoric acid and evaluates its effectiveness in removing hexavalent chromium (Cr(VI)) from aqueous media, emphasizing regeneration and reuse as strategies aligned with circular economy principles. The adsorbent was characterized in terms of its textural properties and chemical composition using Brunauer–Emmett–Teller (BET) surface area analysis and scanning electron microscopy, zero charge point (PCZ), EDX, and elemental analysis (CHN). Batch adsorption studies were performed to evaluate the removal of Cr(VI) from aqueous solutions. Textural analysis showed that the material CA-H3PO4 has a high mesoporous area (54%), with surface area BET of 1489.72 m2 g–1. The pH at which charges were neutralized between the adsorbent surface and the solution was equivalent to 2. At this pH, Cr(VI) removal exceeded 80.0% under the experimental conditions of 100 mL of solution containing 50.0 mg L–1 Cr(VI) and 0.05 g of the adsorbent. The adsorption kinetics were evaluated using the pseudo-first-order, pseudo-second-order, and Weber–Morris intraparticle diffusion models, with the pseudo-second-order model providing the best fit. Likewise, the equilibrium data were analyzed using the Langmuir, Freundlich, and Temkin isotherm models, with the Freundlich model showing the best agreement with the experimental data. The adsorption process was rapid, exhibiting a rate constant of 0.002 g mg–1 min–1, and was found to be spontaneous and endothermic, as indicated by the values of ΔG (−0.2 to −0.5 kJ mol–1) and ΔH (13.3 kJ mol–1). Desorption experiments demonstrated that the adsorbent could be regenerated using 0.5 mol L–1 NaOH, retaining a Cr(VI) adsorption capacity of 83.6 mg g–1 after the fourth regeneration cycle, corresponding to 55.0% of its original adsorption capacity. These findings suggest that CA-H3PO4 has considerable potential as an adsorbent for the remediation of waters contaminated with hexavalent chromium.
