Sánchez-Polo M, Rivera-Utrilla J, von Gunten U
Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Ueberlandstrasse, 133, CH-8600, Dübendorf, Switzerland.
Water Res. 2006 Oct;40(18):3375-84. doi: 10.1016/j.watres.2006.07.020. Epub 2006 Sep 12.
The efficiency of Co(II)-, Mn(II)-, and Ti(IV)-doped carbon aerogels for the transformation of ozone into ()OH radicals was investigated. The carbon aerogels had a markedly acid surface character (pH(PZC approximately equal) congruent with 3-4) with very high surface oxygen concentrations (O approximately equal with 20%). X-ray photoelectron spectroscopy (XPS) analyses of the samples showed the oxidation state of the metals was +2 for Co and Mn and +4 for Ti. The presence of Mn(II)-doped carbon aerogel enhanced ozone transformation into ()OH radicals, whereas the presence of Co(II) and Ti(IV) carbon aerogels presented no activity in this process. Moreover, it was observed that an increase in the concentration of Mn in the surface of the aerogel increases its efficiency to transform ozone into ()OH radicals, with an Rct value ([OH]/[O(3)]) of 5.36 x 10(-8) for the aerogel doped with 16% of surface Mn(II) compared to an R(ct) of 2.68 x 10(-9) for conventional ozonation. Regardless of the aerogel used, XPS analysis of the ozonated aerogel samples showed an increase in the concentration of surface oxygen when the exposure to ozone was longer. However, presence of oxidized metal species after ozone treatment was only detected in the case of the Mn-doped aerogel, (Mn(III) and Mn(IV)). CO(2) activation of carbon aerogel produced a marked increase in its efficiency to transform ozone into ()OH radicals compared with non-activated sample. The efficiency of Mn activated carbon aerogel to transform ozone into (*)OH radicals was greater than that of Witco commercial activated carbon or H(2)O(2) in the ozonation of water from Lake Zurich (Zurich, Switzerland).
研究了钴（II）、锰（II）和钛（IV）掺杂的碳气凝胶将臭氧转化为（）OH自由基的效率。这些碳气凝胶具有明显的酸性表面特征（pH（PZC约等于）与3 - 4一致），表面氧浓度非常高（O约等于20%）。对样品的X射线光电子能谱（XPS）分析表明，钴和锰的金属氧化态为 +2，钛为 +4。锰（II）掺杂的碳气凝胶的存在增强了臭氧向（）OH自由基的转化，而钴（II）和钛（IV）碳气凝胶在此过程中没有活性。此外，观察到气凝胶表面锰浓度的增加会提高其将臭氧转化为（）OH自由基的效率，对于表面掺杂16%锰（II）的气凝胶，Rct值（[OH]/[O(3)]）为5.36×10^(-8)，而传统臭氧化的R(ct)为2.68×10^(-9)。无论使用哪种气凝胶，对臭氧化气凝胶样品的XPS分析表明，当臭氧暴露时间更长时，表面氧浓度会增加。然而，仅在锰掺杂气凝胶的情况下检测到臭氧处理后存在氧化态的金属物种（锰（III）和锰（IV））。与未活化的样品相比，碳气凝胶的CO(2)活化显著提高了其将臭氧转化为（）OH自由基的效率。在对瑞士苏黎世湖的水进行臭氧化处理时，锰活化碳气凝胶将臭氧转化为（*）OH自由基的效率高于威特科商业活性炭或H(2)O(2)。
