Enhanced photodegradation of diphenhydramine in aqueous solution containing natural sand particles |
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Authors: | Chunlin Yi Lihong Song Qingfeng Wu Zhaohui Li Weibin Zhang Ke Yin |
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Institution: | School of Physics and Optoelectronic Engineering, Yangtze University, 1 Nanhuan Road, Jingzhou Hubei 434023 China.; Department of Geosciences, University of Wisconsin-Parkside, 900 Wood Road, Kenosha WI 53144 USA.; Faculty of Earth Sciences, China University of Geosciences, 388 Lumo Road, Wuhan Hubei 430074 China |
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Abstract: | Understanding the effects of natural solid particles on the phototransformation of pharmaceuticals in aqueous environments is very important, but studies on this are still limited. In this study, natural sands were selected as a solid particle model due to their wide distribution in surface waters during the rainy season, and the phototransformation of diphenhydramine (DP) in the presence of the sands was investigated. The kinetic studies showed that the natural sands exhibited significant photocatalytic activity for the DP photodegradation, and the activity varied depending on their sources. Scavenging experiments and electron paramagnetic resonance analysis demonstrated that O2−˙ and ˙OH were produced in the irradiated natural sand systems, and O2−˙ played a more important role than ˙OH in the photodegradation of DP. The results obtained from H2O2 treatment and deoxygenation experiments verified that the generation of radicals was mainly attributed to the low content of natural organic matter (NOM) in the sands. The possible reaction mechanism was that the NOM in the sands was excited and became triplet-state NOM after irradiation, and then induced the generation of free radicals through an electron transfer mechanism, resulting in DP oxidation. This work indicated that natural sand particles were a key factor affecting the phototransformation of drugs, and should be considered in evaluating their fate in natural waters.Natural sand particles induced the generation of free radicals under simulated solar irradiation, resulting in the enhanced photodegradation of diphenhydramine. |
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