Effect of fulvic acid concentration levels on the cleavage of piperazinyl and defluorination of ciprofloxacin photodegradation in ice

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Abstract

<p class="first" id="d3018784e101">Ice is an important physical and chemical sink for various pollutants in cold regions. The photodegradation of emerging fluoroquinolone (FQ) antibiotic contaminants with dissolved organic matter (DOM) in ice remains poorly understood. Here, the photodegradation of ciprofloxacin (CIP) and fulvic acid (FA) in different proportions as representative FQ and DOM in ice were investigated. Results suggested that the photodegradation rate constant of CIP in ice was 1.9 times higher than that in water. When CFA/CCIP ≤ 60, promotion was caused by FA sensitization. FA increased the formation rate of cleavage in the piperazine ring and defluorination products. When 60 < CFA/CCIP < 650, the effect of FA on CIP changed from promoting to inhibiting. When 650 ≤ CFA/CCIP ≤ 2600, inhibition was caused by both quenching effects of 143.9%-51.3% and light screening effects of 0%-48.7%. FA inhibited cleavage in the piperazine ring for CIP by the scavenging reaction intermediate of aniline radical cation in ice. When CFA/CCIP > 2600, the light screening effect was greater than the quenching effect. This work provides new insights into how DOM affects the FQ photodegradation with different concentration proportions, which is beneficial for understanding the environmental behaviors of fluorinated pharmaceuticals in cold regions. </p>

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Next-generation organic photovoltaics based on non-fullerene acceptors

Pei Cheng, Gang Li, Xiaowei Zhan … (2018)

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Superoxide Ion: Generation and Chemical Implications.

Maan Hayyan, Mohd Hashim, Inas AlNashef (2016)

Superoxide ion (O2(•-)) is of great significance as a radical species implicated in diverse chemical and biological systems. However, the chemistry knowledge of O2(•-) is rather scarce. In addition, numerous studies on O2(•-) were conducted within the latter half of the 20th century. Therefore, the current advancement in technology and instrumentation will certainly provide better insights into mechanisms and products of O2(•-) reactions and thus will result in new findings. This review emphasizes the state-of-the-art research on O2(•-) so as to enable researchers to venture into future research. It comprises the main characteristics of O2(•-) followed by generation methods. The reaction types of O2(•-) are reviewed, and its potential applications including the destruction of hazardous chemicals, synthesis of organic compounds, and many other applications are highlighted. The O2(•-) environmental chemistry is also discussed. The detection methods of O2(•-) are categorized and elaborated. Special attention is given to the feasibility of using ionic liquids as media for O2(•-), addressing the latest progress of generation and applications. The effect of electrodes on the O2(•-) electrochemical generation is reviewed. Finally, some remarks and future perspectives are concluded.

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Effluent from drug manufactures contains extremely high levels of pharmaceuticals.

D Larsson, Cecilia de Pedro, Nicklas Paxeus (2007)

It is generally accepted that the main route for human pharmaceuticals to the aquatic environment is via sewage treatment plants receiving wastewater from households and hospitals. We have analysed pharmaceuticals in the effluent from a wastewater treatment plant serving about 90 bulk drug manufacturers in Patancheru, near Hyderabad, India--a major production site of generic drugs for the world market. The samples contained by far the highest levels of pharmaceuticals reported in any effluent. The high levels of several broad-spectrum antibiotics raise concerns about resistance development. The concentration of the most abundant drug, ciprofloxacin (up to 31,000 microg/L) exceeds levels toxic to some bacteria by over 1000-fold. The results from the present study call for an increased focus on the potential release of active pharmaceutical ingredients from production facilities in different regions.