Sánchez-Polo M, Rivera-Utrilla J, Salhi E, von Gunten U
Departamento de Química Inorgánica, Facultad de Ciencias, Campus Fuentenueva s/n, Universidad de Granada, 18071 Granada, Spain.
Water Res. 2007 Mar;41(5):1031-7. doi: 10.1016/j.watres.2006.07.009. Epub 2006 Sep 12.
The objective of this study was to analyze the efficiency of silver(Ag)-doped carbon aerogels for the removal of bromide (Br(-)) and iodide (I(-)) from drinking waters. Textural characterization of Ag-doped aerogels showed that an increase in the Ag dose added during the preparation process produced: (i) a reduction in the surface area (S(BET)) and (ii) an increase in mesopore (V(2)) and macropore (V(3)) volumes. Chemical characterization of the materials revealed an acidic surface (pH of point of zero charge, pH(PZC)=4.5, O(surface)=20%). The oxidation state of Ag was +1 and the surface concentration of this element ranged from 4% to 10%. The adsorption capacity (X(m)) and affinity of adsorbent (BX(m)) increased with a reduction in the radius of the halogenide. Furthermore, an increase in the adsorption capacity was observed with higher Ag concentrations on the aerogel surface. The high adsorption capacity of the aerogel may be due to the presence of Ag(I) on its surface, with the formation of the corresponding Ag halides. Our observations indicate that the halogenides adsorption on commercial activated carbon (Sorbo-Norit) is much lower than that of the Ag-doped carbon aerogels. The presence of chloride and natural organic matter (NOM) in the medium reduced the adsorption capacity of Br(-) and I(-) on Ag carbon aerogels.
本研究的目的是分析掺银（Ag）的碳气凝胶从饮用水中去除溴化物（Br(-)）和碘化物（I(-)）的效率。掺银气凝胶的结构表征表明，制备过程中添加的银剂量增加会导致：（i）比表面积（S(BET)）减小，以及（ii）中孔（V(2)）和大孔（V(3)）体积增加。材料的化学表征显示其表面呈酸性（零电荷点pH值，pH(PZC)=4.5，表面氧含量O(surface)=20%）。银的氧化态为+1，该元素的表面浓度范围为4%至10%。吸附剂的吸附容量（X(m)）和亲和力（BX(m)）随着卤化物半径的减小而增加。此外，气凝胶表面银浓度越高，吸附容量越大。气凝胶的高吸附容量可能归因于其表面存在Ag(I)，并形成了相应的卤化银。我们的观察表明，卤化物在商用活性炭（Sorbo-Norit）上的吸附远低于掺银碳气凝胶。介质中氯化物和天然有机物（NOM）的存在降低了Br(-)和I(-)在银碳气凝胶上的吸附容量。
