Department of Chemical Engineering, Grupo IMAES, ETSII, Instituto de Investigaciones Energéticas y Aplicaciones Industriales (INEI), Universidad de Castilla-La Mancha, Avda. Camilo José Cela 3, 13071 Ciudad Real, (Spain).
Department of Chemical Engineering, Grupo IMAES, ETSII, Instituto de Investigaciones Energéticas y Aplicaciones Industriales (INEI), Universidad de Castilla-La Mancha, Avda. Camilo José Cela 3, 13071 Ciudad Real, (Spain).
Sci Total Environ. 2019 Dec 20;697:134086. doi: 10.1016/j.scitotenv.2019.134086. Epub 2019 Aug 28.
The solar photodegradation of aniline using reduced graphene oxide-based composites (rGO/TiO) and different electron acceptors such as HO and persulfate (PS) has been studied. To this end, an innovative self-sufficient drum reactor (operating with solar irradiation and artificial UV light) has been employed. The role of radicals and the new graphene morphology is evaluated. Finally, changes in the degradation/mineralization mechanism are explained according to intermediates evolution (obtained from mass spectroscopy). In the Solar/rGO/TiO/HO system, hydroxyl radicals react with the reduced graphene oxide (rGO) producing oxidized rGO (OrGO). The process creates new pores increasing surface area favouring adsorption. Also, other radicals such as superoxide or singlet oxygen are also formed, affecting the degradation mechanism. The hole reacts with adsorbed aniline to form the aniline-radical-cation. Nitrosobenzene is then formed with the active participation of superoxide radical anion, finally yielding azobenzene. It was found that the addition of 2.5% wt of rGO increases mineralization from 0 to 14% during the solar stage after 120 min, reaching 82.5% when lamps are switched on after 240 min. On the other hand, activation of PS with UV-C light is a very efficient process, since aniline is wholly degraded in 10-20 min depending on PS initial concentration, reaching a high mineralization degree close to 90% in 120 min. During this process, degradation occurs in a very different route, via the formation of phenol. In the first stage (t < 25 min), sulfate radical is the primary oxidant involved to yield benzoquinone. In a second step (t > 25 min), hydroxyl radicals play the leading role to reach C-C organic acids.
采用基于还原氧化石墨烯的复合材料（rGO/TiO）和不同电子受体（如 HO 和过硫酸盐（PS））的太阳能光降解苯胺已经过研究。为此，采用了一种创新的自给式鼓式反应器（在太阳能照射和人工紫外线照射下运行）。评估了自由基和新的石墨烯形态的作用。最后，根据中间产物的演化（从质谱获得）解释了降解/矿化机制的变化。在 Solar/rGO/TiO/HO 体系中，羟基自由基与还原氧化石墨烯（rGO）反应生成氧化的 rGO（OrGO）。该过程会产生新的孔，增加表面积，有利于吸附。此外，还形成了其他自由基，如超氧自由基或单线态氧，影响降解机制。空穴与吸附的苯胺反应生成苯胺自由基阳离子。然后在超氧自由基阴离子的积极参与下形成亚硝基苯，最后生成偶氮苯。研究发现，在太阳能阶段 120 分钟后，添加 2.5%wt 的 rGO 可将矿化率从 0 提高到 14%，当在 240 分钟后打开灯时，矿化率达到 82.5%。另一方面，用 UV-C 光激活 PS 是一个非常有效的过程，因为在 10-20 分钟内，根据 PS 初始浓度的不同，苯胺完全降解，在 120 分钟内达到接近 90%的高矿化度。在这个过程中，降解发生在一个非常不同的途径中，通过苯酚的形成。在第一阶段（t < 25 分钟），硫酸根自由基是主要的氧化剂，生成苯醌。在第二步（t > 25 分钟）中，羟基自由基起主要作用，生成 C-C 有机酸。
