华中科技大学 硕士学位论文 活性炭高选择性净化医用一氧化氮中二氧化氮的特性研究 姓名：陆僖 申请学位级别：硕士 专业：环境工程 指导教师：胡辉 2011-02-22 华 中 科 技 大 学 硕 士 学 位 论 文 华 中 科 技 大 学 硕 士 学 位 论 文 I 摘摘 要要 一氧化氮（NO）因是“血管内皮衍生的舒张因子”而在临床医学救治方面逐步 得到广泛应用。针对现有钢瓶稀释获得的可吸入性 NO（iNO）中存在少量有毒二氧 化氮（NO2） ，以及空气电弧放电合成医用 NO 过程中产生的少量 NO2必须高效净化 去除问题，本文采用活性炭为吸附剂，实验研究了活性炭选择性吸附去除 NO 中的 NO2特性，通过对活性炭孔结构特征及表面酸碱官能团的分析，研究了活性炭高选 择性去除 NO 中的 NO2的吸附机理。在此基础上，研制出对 NO2具有高选择性吸附 特性的吸附剂。主要研究成果如下： （1）为了评价不同时间节点活性炭吸附 NO 中 NO2的特性，在实验研究四种活 性炭吸附剂（1#、2#、3#、4#）吸附 NO 中 NO2性能的基础上，利用定积分原理， 提出利用吸附容量进行活性炭选择性评价公式。利用比表面积分析仪分析了活性炭 的孔结构特征，并计算了其分形维数。结果表明：1#和 4#吸附剂对 NO2的高选择性 吸附与其具有高的总比表面积有关，而分形维数说明活性炭表面粗糙程度与比表面 积没有直接关系。 （2）Boehm 滴定测试分析研究表明：1#和 4#吸附剂表面官能团主要是酸性基 团，碱性基团甚微，2#和 3#则以碱性基团为主，酸性基团较少。这暗示酸性基团有 利于对 NO2酸性气体的吸附，这与文献报道的酸性基团有利于碱性物质的吸附现象 不同。为了解释该现象，本文首次提出利用偶极矩和键级理论解析了酸性基团有利 于对 NO2的吸附， 可能是由于 NO2极性强于 NO， NO2中的 N-O 更易受到破坏所致。 （3）H2O2，HNO3，NH3H2O，NaOH 分别对活性炭进行改性的结果表明：酸 改性比碱改性要好， 酸改性活性炭能提高其对NO2的选择性吸附。 Boehm滴定和FTIR 的测试表明了酸性改性强化了羧基 C=O 在非芳香羧酸或内酯结构上的伸缩振动而 碱改性则弱化甚至让该基团消失，即经过酸性（氧化）试剂改性的活性炭其酸性基 团明显增加，碱性亦然。浸渍 Mg(NO3)2的两种活性炭在高温处理后对 NO 的吸附基 本不变，而对 NO2的吸附性能更好。 （4）常温常压下的变温吸附试验表明，活性炭受温度变化的影响极易脱附。两 次加热再生后的活性炭对 NO2的吸附效果都比 H2O2首次再生的效果好。 （5） 通过正交实验设计， 研制出 9 组颗粒状核桃壳活性炭。 通过吸附容量评价， 华 中 科 技 大 学 硕 士 学 位 论 文 华 中 科 技 大 学 硕 士 学 位 论 文 II 得到了制备核桃壳活性炭的最佳工艺参数：壳碱比 6:1，活化温度为 600C，活化时 间为 1h。 该工艺条件下制备的核桃壳活性炭对 NO 中 NO2的选择性吸附达到 U=0.73, 2, UNONO S=32.96，NO2/NO 在吸附的 5.5h 中都维持在 2%左右，比前面研究的四种活性 炭的选择性吸附性能好； （6）用聚乙烯醇制备的成型活性炭对 NO 中 NO2也具有高的选择性吸附性能。 在进行 6060min 的寿命吸附实验接近结束前(5500min)，混合气体中 NO2/NO 的比值 仍然满足临床医用 NO2/NO5%的要求。 关键词：关键词： NO，NO2，活性炭，选择性吸附，表面官能团，核桃壳 华 中 科 技 大 学 硕 士 学 位 论 文 华 中 科 技 大 学 硕 士 学 位 论 文 III Abstract Nitric Oxide (NO) was extensive used in clinical treatment when it was identified as an “endothelium derived relaxing factor”. However, the inhaled NO (iNO) diluting from bottled gas has a little toxic gas of nitrogrn dioxide (NO2) which is also existed in the product of NO starting from air arc discharge. In order to purify the NO2 efficiently, activated carbon was used as the adsorbent to selectively adsorb NO2 in NO. The mechanism of selective adsorption is discussed by the analysis of the pore structure and acid-basic surface functional groups. On the base, an adsorbent having the character of highly selective adsorption of NO2 is developed. The research achievements are as follows: (1) In order to evaluated the adsorption character of NO2 in NO using activated carbon, the assessment equations of adsorption capacity were designed by definite integral principle on the base researches of selective adsorption of NO2 on the four activated carbon (1#, 2#, 3#, 4#). An automatic specific surface area and porosity analyzer was used to analysis the pore structure of activated carbon and the fractal dimension was calculated. The results showed that the adsorbent of 1# and 4# had the highly selective adsorption of NO2 and it related to the highly specific surface. The fractal dimension illustrated that the rough level on the surface of activated carbon hadnt direct relation with the specific surface. (2) The results from the analysis of Boehm method showed that the surface functional groups on adsorbents were mainly acidic groups but little basic groups; 2# and 3# were mainly basic groups and acidic groups can hardly be found. It implied that the acidic groups may be more conducive to the adsorption of NO2. However, this conclusion was different from the reports which were about the acidic groups were conducive to the adsorption of basic matter. In order to explain the phenomenon, dipole moment and bond order theory were used to resolve it for the first time. The mechanism may be the polarity of NO2 was stronger than that of NO and the bond of N-O in NO2 was more sensitive. (3) H2O2, HNO3, NH3H2O, NaOH were used to modify the activated carbon. It suggested that acidity modify was better than basic modify, acidity modify showed the better selectivity adsorption of NO2. The analysis results of Boehm method and FTIR showed that the increase and decrease in the intensities of C=O stretching of non-aromatic carboxylic acid and lactone structures suggested that acidity intensified it but alkalescence 华 中 科 技 大 学 硕 士 学 位 论 文 华 中 科 技 大 学 硕 士 学 位 论 文 IV weakened it. The acidity (oxidation) modify increases the acidic groups and the basic modify was in the same. The two kind of activated carbon treated by impregnation of Mg (NO3)2 and high temperature treatment remained the character of NO adsorption but performed better with NO2. (4) It was found that the desorption of activated carbon was easy to occurred because of the variation of temperature under normal temperature and pressure. The adsorption property of activated carbon after twice heating treatment was better than the first regeneration by H2O2. (5) The orthogonal experiment design was carried out to prepare the granular walnut shell activated carbon in 9 groups. Using the assessment of capacity, the best technological parameter w