改性碳材料强化催化臭氧氧化降解草酸
文献类型：学位论文
| 作者 | 吴光国 |
| 学位类别 | 硕士 |
| 答辩日期 | 2012-06-04 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 曹宏斌 ; 谢勇冰 |
| 关键词 | 催化臭氧化 碳材料改性 硝基化 氨基化 |
| 其他题名 | Enhanced Catalytic Ozonation of Oxalic Acid with Modified Carbon Materials |
| 学位专业 | 化学工程 |
| 中文摘要 | 随着我国工业快速发展，废水排放种类和数量迅猛增加，威胁人类健康和安全。特别是含难降解有机污染物的工业废水，危害程度高，治理难度大。臭氧氧化是在降解有机污染物中有重要应用前景的一种高级氧化技术，但存在臭氧无效分解及选择性降解有机物的缺点，限制了臭氧氧化过程的降解效率。通过加入固体催化剂，可提高污染物的去除效率，且不产生二次污染，因此发展一种催化臭氧化的高效催化剂具有重要研究意义。碳材料是一类来源广泛的廉价工业材料，在催化臭氧化反应中被广泛研究，但催化臭氧化效率还有待提高。本论文选取一种商用活性炭和实验室自制膨胀氧化石墨，进行硝基化和氨基化改性处理，考察材料表面性质变化对催化降解草酸活性的影响。物理吸附结果表明改性碳材料的氮气吸附量剧减，但SEM和TEM检测均未检测出改性碳材料微观结构发生根本性变化，由此猜测吸附量下降可能是改性基团部分占据了材料孔道结构引起。硝基化处理造成材料表面碱性官能团含量和pHpzc降低，氨基化处理则提高材料表面碱性官能团含量和pHpzc。两种碳材料经硝基化和氨基化改性后，在pH=3和pH=7的溶液中催化臭氧化降解草酸的活性均有所提高。其中硝基化改性碳材料在pH=7的溶液中催化活性最高，氨基化改性碳材料在pH=3的溶液中催化活性最高。综合热重分析结果表明，硝基化处理提高了材料表面含氧酸性官能团的含量，发烟硝酸用量越大，pHpzc降低越明显。向不同pH的反应溶液中添加叔丁醇作为羟基自由基捕获剂后，碳材料催化分解臭氧和降解草酸的能力均大大降低，表明碳材料催化臭氧化降解草酸主要是羟基自由基起作用。实验还检测了不同pH条件下溶液中无机碳（IC）浓度变化，发现pH=7的溶液中IC浓度逐渐升高，由于CO32-，HCO3-均易与羟基自由基快速发生反应，造成羟基自由基链式反应中止，这是pH=7溶液中草酸降解速度比pH=7溶液中更快的主要原因。 |
| 英文摘要 | The water quality in China is getting worse and worse, which threatened people’s health and safety. Industrial wastewater with refractory organic pollutants was especially hazardous and hard to deal with. Ozonation is a promising technology in organic compound degradation, but ozone is easy to decompose and has reaction selectivity to different organic pollutants, which restrained its industrial application. Catalytic ozonation can overcome these disadvantages in some extent and has a great potential in industrial wastewater treatment. Carbon materials are widely used in catalytic ozonation process, but the use efficiency of ozone still needs to be improved. In this paper, we selected a commercial activated carbon and prepared an expanded graphite oxide. These two materials were modified by two chemical methods to change the content and amount of functional groups on the surface. The modified materials were used in catalytic ozonation of oxalic acid and the influence of functional groups on the surface was investigated in this process. Physical adsorption results indicated that BET surface area decreased dramatically, but the microstructure change was not found in TEM and SEM results. The decreased adsorption of nitrogen might be caused by that the micropores were partially occupied by the modified functional groups. The amount of basic groups on the surface and pHpzc both decreased after nitration treatment, while those both increased with amination treatment. Carbon materials modified with amino groups showed the highest activity in the solution with pH=3, and nitro-modified carbon materials showed the best performance in the solution with pH=7. This meant the two modification methods were both effective to enhance the catalytic ozonation ability. TGA-FTIR results showed that nitration treatment enhanced the amount of oxygen-containing acidic functional groups on the surface. The more fuming nitric acid was used, the lower the pHpzc became. The ozone and oxalic acid decomposition rate both decreased in the solution with pH=3 and pH=7, after adding t-butyl alcohol as the scavenger of hydroxyl radicals. This meant that carbon materials catalyze ozonation of oxalic acid following the hydroxyl radical reaction mechanism. The concentration of inorganic carbon (IC, mainly CO32- and HCO3-) in the solution with pH=7 was much higher than that in the solution with pH=3. As CO32- and HCO3- react with hydroxyl radicals at a much faster rate, this well explained the phenomenon that oxalic acid decomposed much faster in a neutral solution than in an acid solution. |
| 语种 | 中文 |
| 公开日期 | 2013-09-25 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1791]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 吴光国. 改性碳材料强化催化臭氧氧化降解草酸[D]. 中国科学院研究生院. 2012. |
入库方式： OAI收割
来源：过程工程研究所
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