To promote the resource utilization of buckwheat hulls, a local agricultural byproduct in Liangshan, China, heterogeneous catalysts were fabricated for hydrogen production via formic acid dehydrogenation, with palladium (Pd) immobilized on buckwheat hullderived activated carbon via high-temperature pyrolysis activation and impregnation-reduction methods. The results show that the optimal preparation parameters were: carbonization temperature of 400 °C, reduction temperature of 90 °C, and Pd loading of 5 wt.%. The catalyst synthesized under these conditions exhibited excellent catalytic activity, achieving a turnover frequency of 3610 h–1. Characterization results demonstrate that buckwheat hull activated carbon obtained via low-temperature carbonization at 400 °C possesses a large specific surface area, a well-developed mesoporous structure, and abundant hydroxyl and carboxyl oxygencontaining functional groups, which can effectively enhance the adsorption capacity toward formic acid. Overall, this work develops a cost-effective catalyst fabrication strategy and valorizes buckwheat hulls for sustainable green hydrogen production.
Indoor air quality is influenced by human activities within buildings as well as by the infiltration of outdoor pollutants. In this study, two approaches are compared to estimate the infiltration factor of PM1, PM2.5, and PM10 (particulate matter with an aerodynamic diameter of ≤ 1.0 μm, ≤ 2.5 μm and ≤ 10.0 μm, respectively): a mechanistic model based on the mass balance equation and a statistical model based on smoothing the indoor/outdoor (I/O) concentration ratio using the LOWESS (locally weighted scatterplot smoothing) algorithm. The analysis was conducted using concentration data monitored in four naturally ventilated residences. The uncertainty associated with the estimates was evaluated using the moving block bootstrap technique, accounting for the temporal dependence of the data. The results indicate that both models capture consistent patterns of outdoor particle penetration into indoor environments; however, they exhibit different sensitivities to temporal variations and data noise. The mass balance model showed greater stability and lower variability in the infiltration factor estimates, whereas the LOWESS model was more sensitive to local fluctuations in outdoor concentrations. These findings highlight the importance of model selection according to data availability and quality.
Teaching nuclear magnetic resonance (NMR) spectroscopy in undergraduate chemistry poses challenges, particularly in developing skills of the student in spectral interpretation and structural analysis. Many curricula present NMR in a fragmented way, limiting the ability of the student to connect theoretical concepts with practical data. This study proposes a didactic, integrated approach that emphasizes active learning through experimental practice and critical analysis. Techniques such as 1H, 13C, and heteronuclear multiple bond correlation (HMBC) NMR are used to explore chemical shifts, coupling constants, and molecular structure. To support this methodology, lapachol, a secondary metabolite from Tabebuia species, was extracted and used in intramolecular cyclization reactions to synthesize β-lapachone and 3-sulfonic-acid-β-lapachone. These compounds enabled comparative structural analysis and discussion of spectral changes. The inclusion of 2D NMR spectra deepened student understanding of long-range heteronuclear couplings and their relation to structural differences. This practice-oriented strategy fosters critical thinking and improves the teaching of NMR, making it more accessible and meaningful in undergraduate chemistry and related programs.
