Dipartimento di Chimica Analitica, Università di Torino, via P. Giuria 5, 10125 Torino, Italy.
Sci Total Environ. 2012 Jun 1;426:281-8. doi: 10.1016/j.scitotenv.2012.03.029. Epub 2012 Apr 13.
The role played by iron oxides (goethite and akaganeite) and iron(II)/(III) species as photo-sensitizers toward the transformation of organic matter was examined in saline water using phenol as a model molecule. The study was carried out in NaCl 0.7 M solution at pH 8, artificial (ASW) and natural (NSW) seawater, in a device simulating solar light spectrum and intensity. Under illumination phenol decomposition occurs in all the investigated cases. Conversely, dark experiments show that no reaction takes place, implying that phenol transformation is a light- activated process. Following the addition of Fe(II) ions to aerated solutions, Fe(II) is easily oxidized to Fe(III) and hydrogen peroxide is formed. Regardless of the addition of Fe(II) or Fe(III) ions, photo-activated degradation is mediated by Fe(III) species. Several (and different) hydroxylated and halogenated intermediates were identified. In ASW, akaganeite promotes the formation of ortho and para chloro derivatives (2- and 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol), while goethite induces the formation of 3-chlorophenol and bromophenols. Conversely, Fe(II) or Fe(III) addition causes the formation of 3- and 4-chlorophenol and 2,3- or 3,4-dichlorophenol. 4-Bromophenol was only identified when irradiating Fe(II) spiked solutions. Natural seawater sampled in the Gulf of Trieste, Italy, has been spiked with phenol and irradiated. Phenol photo-induced transformation in NSW mediated by natural photosensitizers occurs and leads to the formation of numerous halophenols, condensed products and nitrophenols. When NSW is spiked with phenol and iron oxides, Fe(II) or Fe(III), halophenols production is enhanced. A close analogy exists between Fe(III), Fe(II)/goethite in ASW and NSW products. Different halophenols production in the natural seawater samples depends on Fe(II)/goethite (above all for 3-chlorophenol, 2,3-dichlorophenol and 4-bromophenol formation) and on Fe(III) colloidal species (3-chlorophenol).
采用苯酚作为模型分子，在 NaCl0.7M 溶液中（pH8）、人工海水（ASW）和天然海水（NSW）中，考察了氧化铁（针铁矿和纤铁矿）和铁(II)/(III)物种作为光敏剂对有机物转化的作用。在光照下，所有研究情况下的苯酚都会发生分解；而在黑暗实验中，没有发生反应，这表明苯酚的转化是一个光激活过程。向通气溶液中添加 Fe(II)离子后，Fe(II)很容易被氧化为 Fe(III)，并形成过氧化氢。无论添加 Fe(II)还是 Fe(III)离子，光激活降解都由 Fe(III)物种介导。鉴定出几种（和不同的）羟基化和卤化中间体。在 ASW 中，纤铁矿促进邻氯和对氯衍生物（2-和 4-氯苯酚、2,4-二氯苯酚和 2,4,6-三氯苯酚）的形成，而针铁矿则诱导 3-氯苯酚和溴苯酚的形成。相反，添加 Fe(II)或 Fe(III)会导致 3-和 4-氯苯酚以及 2,3-或 3,4-二氯苯酚的形成。只有在照射添加 Fe(II)的溶液时才鉴定出 4-溴苯酚。从意大利的的里雅斯特湾采集的天然海水已被添加苯酚并进行了照射。在 NSW 中，天然光敏剂介导的苯酚光诱导转化发生，并导致产生许多卤代苯酚、缩合产物和硝基苯酚。当 NSW 中添加苯酚和氧化铁、Fe(II)或 Fe(III)时，卤代苯酚的生成会增强。ASW 和 NSW 产物中存在 Fe(III)、Fe(II)/针铁矿之间的紧密类比。天然海水样品中不同卤代苯酚的生成取决于 Fe(II)/针铁矿（尤其是 3-氯苯酚、2,3-二氯苯酚和 4-溴苯酚的生成）和 Fe(III)胶体物种（3-氯苯酚）。
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