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Polybrominated diphenyl ethers (PBDEs), previously incorporated in a wide variety of common products, can now be found throughout the environment. Because of their environmental persistence and the potential health hazards they pose to humans and wildlife, they have been added to the Stockholm Convention on Persistent Organic Pollutants, and they continue to be of significant concern. We report herein the first application of a nanocomposite catalyst consisting of a m -BiVO 4 /BiOBr heterojunction surface-decorated with Pd nanoparticles in the photocatalytic reductive debromination of PBDEs using visible light. Specifically, this system demonstrated both rapid and complete debromination of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47), with an exceedingly large initial pseudo-first-order rate constant of 1.33 min −1 . Analysis of the reaction mechanism identified the stepwise degradation pathway to generate the final diphenyl ether product as well as the role of the alcohol-based sacrificial reagent. Such information provides routes towards new approaches for environmental remediation by identifying reaction pathways for common organic pollutants that remain challenging to degrade via sustainable methods. 

Aerial sprays of the organophosphate pesticide, naled, were intensified over beach areas during the summer of 2016 to control the locally-acquired Zika outbreak in the continental U.S. Concerns were raised in beach frequented areas about contaminated sediments. The aim of this study was to evaluate the persistence and levels of naled and its byproduct, dichlorvos, in sediments obtained from the affected areas. Laboratory experiments were designed to simulate the effect of various natural conditions on the decomposition of naled in three sediment types (beach sand, marl, and calcinated beach sand). The three sediment samples were also exposed to field aerial sprays. After 30 min of exposure, more dichlorvos was detected in the sediments than naled, with 33 to 43% of the molar concentration initially applied as either naled or dichlorvos. Under dark conditions, trace levels of naled were observed after 24 h on sediments. Higher temperature accelerated the natural decomposition of both naled and dichlorvos in sediments. The half-life of naled ranged from 3 to 5 h at 22.5 °C and ranged from 1 to 3 h at 30 °C. Expedited decomposition of naled was observed under sunlight conditions with a half-life of naled of 20 min. In the field, only dichlorvos was detected in the sediment samples at concentrations between 0.0011 and 0.0028 μmol/g 1 h after aerial sprays. This data can be used towards a risk assessment that evaluates exposures to naled and dichlorvos through beach sands impacted by aerial spray activities. 

Nanoparticles have been conjugated to biological systems for numerous applications such as self-assembly, sensing, imaging, and therapy. Development of more reliable and robust biosensors that exhibit high response rate, increased detection limit, and enhanced useful lifetime is in high demand. We have developed a sensing platform by the conjugation of β-galactosidase, a crucial enzyme, with lab-synthesized gel-like carbon dots (CDs) which have high luminescence, photostability, and easy surface functionalization. We found that the conjugated enzyme exhibited higher stability towards temperature and pH changes in comparison to the native enzyme. This enriched property of the enzyme was distinctly used to develop a stable, reliable, robust biosensor. The detection limit of the biosensor was found to be 2.9 × 10−4 M, whereas its sensitivity was 0.81 µA·mmol−1·cm−2. Further, we used the Langmuir monolayer technique to understand the surface properties of the conjugated enzyme. It was found that the conjugate was highly stable at the air/subphase interface which additionally reinforces the suitability of the use of the conjugated enzyme for the biosensing applications.