The effect of H2 treatment on the activity of activated carbon for the oxidation of organic contaminants in water and the H2O2 decomposition
The effect of H2 treatment on the activity of activated carbon for the oxidation of organic contaminants in water and the H2O2 decomposition
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DOI：
10.1016/j.carbon.2004.05.003
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发表时间：
2004
期刊：
影响因子：
10.9
通讯作者：
L. Oliveira;Cristina Silva;M. Yoshida;R. Lago
中科院分区：
文献类型：
--
作者：
L. Oliveira;Cristina Silva;M. Yoshida;R. Lago
本文研究了活性炭存在下过氧化氢在水介质中的分解和氧化反应。观察到在300、500、700和800 °C下用H2预处理碳导致两种反应的活性增加。通过BET氮吸附、热重分析（TG）、程序升温还原（TPR）、电子顺磁共振（EPR）、碘量滴定和酸/碱位测定对炭进行了表征。TPR实验表明，活性炭在高于400 °C的温度下与H2反应。处理使表面积略有增加。EPR分析表明碳中不存在未成对电子。碘量滴定和TG分析表明，用H2处理在碳结构中产生还原位点，在25、300、500、700和800 °C下处理的碳的浓度分别为约0.33、0.53、0.59、0.65和0.60 mmol/g。还观察到可能与还原位点有关的碱性位点的出现。这些还原位点可以活化H2 O2产生HO* 自由基，从而导致过氧化氢分解和水中有机物氧化两种竞争反应.
In this work, hydrogen peroxide reactions, i.e. H2O2decomposition and oxidation of organics in aqueous medium, were studied in the presence of activated carbon. It was observed that the carbon pre-treatment with H2at 300, 500, 700 and 800 °C resulted in an increase in activity for both reactions. The carbons were characterized by BET nitrogen adsorption, thermogravimetric analyses (TG), temperature programmed reduction (TPR), electron paramagnetic resonance (EPR), iodometric titration and determination of the acid/basic sites. TPR experiments showed that activated carbon reacts with H2at temperatures higher than 400 °C. The treatment produces a slight increase in the surface area. EPR analyses indicate the absence of unpaired electrons in the carbon. Iodometric titrations and TG analyses suggested that the treatment with H2generates reduction sites in the carbon structure, with concentration of approximately 0.33, 0.53, 0.59, 0.65 and 0.60 mmol/g for carbons treated at 25, 300, 500, 700 and 800 °C, respectively. It was also observed the appearance of basic sites which might be related to the reduction sites. It is proposed that these reducing sites in the carbon can activate H2O2to generate HO*radicals which can lead to two competitive reactions, i.e. the hydrogen peroxide decomposition or the oxidation of organics in water.