Perfluoroalkyl carboxylic acids (PFCAs) are ubiquitous contaminants known for their bioaccumulation, toxicological harm, and resistance to degradation. Remediating PFCAs in water is an ongoing challenge with existing technologies being insufficient or requiring additional disposal. An emergent approach is using activated persulfate, which degrades PFCAs through sequential scission of CF 2 equivalents yielding shorter-chain homologues, CO 2 and F − . This transformation is thought to be initiated by single electron transfer (SET) from the PFCA to the activate oxidant, SO 4•− . A pronounced pH effect has been observed for thermally activated persulfate PFCA transformation. To evaluate the role of pH during SET, we directly determined absolute rate constants for perfluorobutanoic acid and trifluoroacetic acid oxidation by SO 4•− in the pH range of 0.5−4.0 using laser flash photolysis. The average of the rate constants for both substrates across all pH values was 9 ± 2 × 10 3 M −1 s −1 (±2σ), implying that acid catalysis of thermal persulfate activation may be the primary culprit of the observed pH effect, instead of pH influencing the SET step. In addition, density functional theory was used to investigate if SO 4•− protonation might enhance PFCA transformation kinetics. We found that when calculations include explicit water molecules, direct SO 4•− protonation does not occur.

Aerial LiDAR measurements at 7474 oil and gas production facilities in the Permian Basin yield a measured methane emission rate distribution extending to the detection sensitivity of the method, 2 kg/h at 90% probability of detection (POD). Emissions are found at 38.3% of facilities scanned, a significantly higher proportion than reported in lower-sensitivity campaigns. LiDAR measurements are analyzed in combination with measurements of the heavy tail portion of the distribution (>600 kg/h) obtained from an airborne solar infrared imaging spectrometry campaign by Carbon Mapper (CM). A joint distribution is found by fitting the aligned LiDAR and CM data. By comparing the aerial samples to the joint distribution, the practical detection sensitivity of the CM 2019 campaign is found to be 280 kg/h [256, 309] (95% confidence) at 50% POD for facility-sized emission sources. With respect to the joint model distribution and its confidence interval, the LiDAR campaign is found to have measured 103. 6% [93.5, 114.2%] of the total emission rate predicted by the model for equipment-sized emission sources (∼2 m diameter) with emission rates above 3 kg/h, whereas the CM 2019 campaign is found to have measured 39. 7% [34.6, 45.1%] of the same quantity for facility-sized sources (150 m diameter) above 10 kg/h. The analysis is repeated with data from CM 2020−21 campaigns with similar results. The combined distributions represent a more comprehensive view of the emission rate distribution in the survey area, revealing the significance of previously underreported emission sources at rates below the detection sensitivity of some emissions monitoring campaigns.

Slurries of ammonia-borane and functionalized amine-boranes form liquid spent fuels after heating in batch or flow-thru reactors.

Aerial LiDAR measurements of methane emissions at 7920 oil and gas production facilities in the Permian Basin yield an emission rate distribution extending to the detection sensitivity of the method, 2 kg/h at 90% probability of detection. The LiDAR measurements are analyzed in combination with the heavy tail portion (> 600 kg/h) of a distribution obtained from an intensive airborne solar infrared imaging spectrometry study by Cusworth et al. to yield a more complete emission rate distribution. Comparison of the data sets supports an assessment of the detection sensitivity of the solar infrared study at 300 kg/h at 50% probability of detection. Emissions detected by LiDAR increase the total emission rate for the survey region by a factor of 3.0 after controlling for scale factors such as survey area and number of scans per facility. Additionally, the role of spatial aggregation is highlighted as the cumulative emission rate distribution shifts toward larger source emission rates by a factor of three when detections are aggregated to facility size scales (150 m) rather than resolved to equipment size scales (2 m). The combined distribution derived for this study represents previously underreported emission sources at rates below 300 kg/h resolved at equipment-level spatial precision.

Ionic liquids incorporating an amine-borane functionality can remain liquid below −20 °C and remain liquid after H2 release.