铁配合物的环境光化学及其参与的环境化学过程

铁是地壳中含量最为丰富的金属元素之一,而自然界中存在的绝大多数溶解性铁都是以有机络合形式存在的。环境中的铁配合物在光照下会发生直接光解和次级的(光)化学反应过程,生成还原性的Fe(Ⅱ)和有机自由基以及衍生的活性氧物种。铁配合物的环境光化学反应将深刻影响着氧自由基的生成与衰减、有机物降解和其他元素的环境化学循环过程,因此,成为近年来国际环境科学领域的研究热点。本文介绍了铁配合物光还原反应的类型和原理,分析了Fe(Ⅱ)(光)化学氧化的可能机理和影响因素,并对国内外关于铁参与的环境化学过程所开展的研究进行了评述。在此基础上,通过分析目前研究中所存在的问题,对今后的研究方向和趋势作了展望。

Environmental Photochemistry of Iron Complexes and Their Involvement in Environmental Chemical Processes

Iron is one of the most abundant metals in the continental crust,while most of dissolved iron is complexed with organic ligands.The irradiated iron complexes in the environment undergo direct photolysis and secondary(photo)chemical reactions,generating Fe(Ⅱ),organic radicals and some reactive oxygen species(ROS).Environmental photochemistry of iron complexes can greatly affect ROS dynamics,organics degradation and redox cycling of other elements.Therefore,it is becoming a hot topic in the international field of environmental sciences research.This review firstly summarizes three types of iron complexes including inorganic Fe complexes,simple organic Fe complexes and macrocyclic organic Fe complexes,and photoreduction mechanisms of iron complexes.Secondly,the potential oxidants of Fe(Ⅱ) in acidic aquatic environment are introduced.The oxidation kinetics,possible reaction mechanism and influencing factors(such as dissolved oxygen concentration,pH,ionic strength,temperature and natural organic matters concentrations) of(photo)chemical oxidation of Fe(Ⅱ) are elucidated.This review also highlights recent findings in the study of environmental processes involving iron photochemistry.Finally,the future prospects in this field are discussed based on the current status.