Yao Li,Min Zhang,Rongjie Hao,Huihui Wang,Xizhen He,Tingting Du,Xin Yang,Yingying Wang
The rapidly increasing use of graphene oxide (GO) necessitates the immediate investigation of the environmental fate and effects of this unique material. To date, little is known about the transformation of GO in environmental media, especially in water and wastewater treatment systems. This study explored the changes in the physicochemical properties of GO that result from (photo)bromination by simulating the reactions experienced by GO during water and wastewater treatment. The surface oxygen functionalities of GO considerably changed upon treatment. Specifically, the C OH and COOH groups of GO were lost under bromination , and the reduction of GO was enhanced under photobromination. GO sheets wrinkled and fragmented under bromination, and GO decomposition was enhanced by photobromination. The decreases in O/C ratio and GO decomposition in the presence of bromine were mainly attributed to the relatively high oxidation potential of bromine, which can oxidize carbon nanosheets. The oxidation of carbon nanosheets, in turn, resulted in the decomposition and formation of brominated disinfection by-products. Irradiation, hypobromous acid/hypobromite (HOBr/OBr − ), and reactive radicals, such as OH, Br , BrO and Br 2 − , may all affect the physicochemical transformation of GO in the presence of bromine and simulated solar light. Bromination and photobromination drastically changed the aggregation and sedimentation behavior of GO. The findings of this study advance knowledge on the transformations of GO in water treatment systems and provide insight on the environmental fate of the transformation products of GO.
Fujun Li,Peihao Cheng,Xinghai Li,Yun Zou,Shengyang Tao
Bromination reactions involving bromine monomers tend to be polybrominated, resulting in poor product selectivity and subsequent separation difficulties. This proposal outlines a multistep cascade for continuous flow synthesis involving photobromination and debromination. The process comprises five units: bromine generation, photobromination, quenching, water/oil separation, and photodebromination. A full-process continuous and efficient synthesis of the trifluorostrolibin intermediate (E)-Methyl-2-(2-broMoMethylphenyl)-2-MethoxyiMinoacetate (MBPA) was achieved. This process converts the byproduct (E)-Methyl-2-(2-dibroMoMethylphenyl)-2-MethoxyiMinoacetate into the target product MBPA. At a total residence time of 12.9 min, the conversion of (E)-Methy-2-(methoxyimino)-2-(o-toly) acetate reached 99.0%, and the total yield of MBPA reached 94.2%. Machine learning and quantum chemical calculations enhance the comprehension of photodebromination mechanisms. Simultaneously, through comprehensive simulations involving sensitivity and scenario analyses, the optimization of photon utilization emerged as a pivotal factor for improving the overall applicability of the production process. This method of synthesizing halogenated products is anticipated to play a crucial role in pharmaceuticals or pesticides.
Liu Hui,Qiu Xiaojun,Li Zhi,Zhu Xiaomei,Sun Bing,Zhang Xiaoxing
Dissolved organic matter (DOM) in waters, soils, sediments, and organic waste is considered to have major role in the photochemical generation of emerging organobromine contaminants, yet mechanisms are unclear. Here we fractionated soil humic acids into bound quinone-like substances and an effluent fraction, using a new emodin-imprinted polymer. We tested the effect of these fractions on the photobromination of phenol with bromide. Results show that quinone-like substances induce three times more bromophenols than the effluent fraction. Our findings reveal a new method to separate reactive compounds from DOM and imply that formation of organobromine contaminants may be controlled by the composition of organic matter.
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