Innovative Bi5O7I/MIL-101(Cr) Compounds: A Leap Forward in Photocatalytic Tetracycline Removal.

In environmental chemistry, photocatalysts for eliminating organic contaminants in water have gained significant interest. Our study introduces a unique heterostructure combining MIL-101(Cr) and bismuth oxyiodide (Bi5O7I). We evaluated this nanostructure's efficiency in adsorbing and degrading tetracycline (TC) under visible light. The Bi5O7I@MIL-101(Cr) composite, with a surface area of 637 m2/g, prevents self-aggregation seen in its components, enhancing visible light absorption. Its photocatalytic efficiency surpassed Bi5O7I and MIL-101(Cr) by 33.4 and 9.2 times, respectively. Comprehensive analyses, including scanning electron microscopy (SEM) and transmission electron microscopy (TEM), confirmed the successful formation of the heterostructure with defined morphological characteristics. BET analysis demonstrated its high surface area, while X-ray diffraction (XRD) confirmed its crystallinity. Electron spin resonance (ESR) tests showed significant generation of reactive oxygen species (ROS) like h+ and·â€¢O2- under light, crucial for TC degradation. The material maintained exceptional durability over five cycles. Density functional theory (DFT) simulations and empirical investigations revealed a type I heterojunction between Bi5O7I and MIL-101(Cr), facilitating efficient electron-hole pair separation. This study underscores the superior photocatalytic activity and stability of Bi5O7I@MIL-101(Cr), offering insights into designing innovative photocatalysts for water purification.

Large-Scale Observations Support Aboveground Vegetation as an Important Biological Mercury Sink in the Tibetan Plateau.

Mercury, a pervasive global pollutant, primarily enters the atmosphere through human activities and legacy emissions from the land and oceans. A significant portion of this mercury subsequently settles on land through vegetation uptake. Characterizing mercury storage and distribution within vegetation is essential for comprehending regional and global mercury cycles. We conducted an unprecedented large-scale aboveground vegetation mercury survey across the expansive Tibetan Plateau. We find that mosses (31.1 ± 0.5 ng/g) and cushion plants (15.2 ± 0.7 ng/g) outstood high mercury concentrations. Despite exceptionally low anthropogenic mercury emissions, mercury concentrations of all biomes exceeded at least one-third of their respective global averages. While acknowledging the role of plant physiological factors, statistical models emphasize the predominant impact of atmospheric mercury on driving variations in mercury concentrations. Our estimations indicate that aboveground vegetation on the plateau accumulates 32-12+21 Mg (interquartile range) mercury. Forests occupy the highest biomass and store 82% of mercury, while mosses, representing only 3% of the biomass, disproportionally contribute 13% to mercury storage and account for 43% (2.5-1.4+3.0 Mg/year) of annual mercury assimilation by vegetation. Additionally, our study underscores that extrapolating aboveground vegetation mercury storage from lower-altitude regions to the Tibetan Plateau can lead to substantial overestimation, inspiring further exploration in alpine ecosystems worldwide.

A rapid compression machine coupled with time-resolved molecular beam mass spectrometry for gas-phase kinetics studies.

Rapid compression machines (RCMs) are used to simulate a single stroke of an internal combustion engine. After a high-speed compression process, a high-pressure and low-to-intermediate temperature condition can be obtained, under which ignition processes are usually studied. With the help of different diagnostic methods, the detailed speciation information of the ignition process can be quantified. In this study, the molecular beam mass spectrometry (MBMS) diagnostic method was applied on an RCM to realize time-resolved concentration profile measurements. To realize the combination between RCM and MBMS, particle dampers were adopted to suppress the vibrations of the RCM, and a novel flexible interface was designed to maintain a high vacuum, which ensured the safe and effective operation of a high-repetition-rate time-of-flight mass spectrometer (HRR-TOF-MS). The detailed configuration of this diagnostic method is presented, and the data acquisition system and data analysis method are described. The arrangement was validated through the investigation of the well-studied decomposition of 1,3,5-trioxane at temperatures between 697 and 777 K at 10 bars. The measured concentration profiles of 1,3,5-trioxane and formaldehyde were in good agreement with previous experimental and theoretical calculation results. The experimental results showed that the newly developed RCM coupled with the HRR-TOF-MS has advantages in time-resolved speciation measurements at low-to-intermediate temperatures and high pressures, and it can be applied in low-temperature combustion chemical kinetics studies.