卤代酚是水环境中的有毒和持久性污染物,对各种生物造成危害。由于它们的高稳定性和长停留时间,紫外线辐射,重金属和氧化剂已被大量用于处理这些化合物。然而,这些处理方法可能对海洋环境和工厂经营者造成毒性或危险。在这项研究中,合成了一种水溶性卟啉光催化剂,并将其用于无紫外LED白光处理卤酚。卟啉催化剂是由与次甲基桥连接的吡咯组成的大环,高度共轭的环提供了优异的可见光吸收功能。令人惊讶的是,超过99%的卤代酚降解和超过90%的脱卤已实现无金属螯合,甚至高于含Fe3+的过渡金属卟啉,Zn2+,Cu2+,Co2+,Ni2+,和Mn2+。开环反应被确认为羧酸的形成;二羧酸如丙烯酸,和丙二酸;而富马酸是主要产品。总有机碳结果表明在反应过程中没有产生CO2。三重态吸收和清除剂研究还表明,单线态氧和导带电子是卤酚降解的主要自由基物质。与三重态吸收猝灭相比,单重态发射猝灭为100倍,这表明激发的电子倾向于通过单重态转移。这个概念带来了新的方法来解毒卤酚相关的废水没有紫外线,金属和其他添加剂,它更环保,有利于将有毒物质转化为有用的化学前体。
Halophenols are toxic and persistent pollutants in water environments which poses harm to various organisms. Due to their high stability and long residence time, ultraviolet radiation, heavy metals and oxidizing agents have been largely adopted on treating these compounds. However, these treatment methods could pose toxicity or hazardous risks to the marine environment and plant operators. In this study, a water-soluble porphyrin photocatalyst was synthesized and introduced for halophenol treatment using UV-free LED white light. The porphyrin catalyst is a macrocyclic ring consisting of pyrroles linked with methine bridges, the highly conjugated ring provided the superior functionality of visible light absorption. Surprisingly, over 99 % degradation of halophenols and over 90 % dehalogenation have been achieved without metal chelation, even higher than those of transition metal porphyrins with inclusion of Fe3+, Zn2+, Cu2+, Co2+, Ni2+, and Mn2+. Ring-opening reactions were confirmed with the formation of carboxylic acids; dicarboxylic acids like acrylic acid, and malonic acid; while fumaric acid was the main product. Total organic carbon results indicated no CO2 produced during the reaction. Triplet absorbance and scavenger studies also indicated that singlet oxygen and conduction band electrons are the main radical species for halophenol degradation. The 100-fold singlet emission quenching over triplet absorption quenching indicated that the excited electrons tend to be transferred via singlet state. This concept brings along new approaches detoxifying halophenol-related wastewater without UV, metals and other additives, which is more environmentally-friendly and sheds light to the conversion of toxic materials into useful chemical precursors.