血红蛋白修饰电极降解三氯乙酸的机制研究

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摘要制备了一种新型的海藻酸钠包埋血红蛋白修饰碳纳米管石墨电极用于降解三氯乙酸，通过考察不同温度、pH等工艺参数对三氯乙酸降解过程中平均电流效率影响，探明生物负载电极降解三氯乙酸的基本规律；采用循环伏安和离子色谱，开展了生物负载电极降解三氯乙酸的产物分析和机理等研究。研究结果表明：脱氯平均电流效率随着温度的升高而提高，当反应温度达到310 K时，脱氯平均电流效率最大；此后，随着温度的进一步增大，脱氯平均电流效率则反而降低。脱氯平均电流效率随着pH的降低而增大，当反应pH为3时，脱氯平均电流效率达到最大。通过考察生物电极在TCA脱氯反应中稳定性实验表明，经连续使用5组实验后，平均电流效率只从87%降到83%。此外，通过中间产物的分析，推测了三氯乙酸降解途径。电生物还原脱氯主要以平行的脱氯反应机理为主而不以连续性脱氯反应机理进行。该研究的相关结果为电生物修复实际废水的应用提供了借鉴意义。46667

毕业论文关键词：血红蛋白；三氯乙酸；海藻酸钠

Abstract A gel immobilized method was used to prepare a sodium alginate/hemoglobin-multiwalled carbon nanotubes-graphite composite electrode (Hb/SA-MWCNT-GE) for the degradation of trichloroacetic acid (TCA). The bioelectrochemical mechanism and the production of the degradation of TCA were investigated through cyclic voltammetry and ion chromatography in this study, and the average current efficiency was influenced by the pH and temperature of the systems. The results showed that an increase of average current efficiency was achieved until 310 K, while temperatures higher than 310 K led to a decrease of the average current efficiency. The average current efficiency of TCA was higher at pH 3.0 than in other pH conditions. average current efficiency decreased from 87% to 83% when the Hb/SA-MWCNT-GE was used 5 times, Based on the intermediates detected, a pathway was proposed for TCA degradation in which it undergoes dechlorination process. A reduction by sequential reactions is not a main degradation mechanism for the dechlorination of TCA in Hb-MWCNT-GE system but a reductive dechlorination by parallel reaction mechanism can rather be the one for the TCA degradation. Such studies provide relevant information about the applicability of bioelectrocatalytic systems for remediation of raw wastewaters.

Keywords: Hemoglobin; trichloroacetic acid; Sodium alginate

1 引言 4

2 实验材料 6

3 分析方法 6

4 电极稳定性与反应产物的定性定量分析 8

4.1 温度的影响 8

4.2 PH的影响 9

4.3 电极的稳定性 10

4.4 反应产物的定性定量分析 10

5 TCA的降解途径探讨 11

6 结论 12

参考文献 13

致谢 14

1 引言

目前，我国水资源严重短缺，人均占有量仅为世界平均水平的1/4，90%的城市水域污染严重，50%的城镇水源不符合饮用水标准，40%的水源已不能饮用。根据最近几年的中国环境统计年报，全国废水排放总量589.7亿吨，比上年增加3.1%。其中，工业废水排放量234.5亿吨，城镇生活污水排放量355.2亿吨。导致湖泊、海洋的各种环境污染问题出现，且地下水氨氮、氯化物含量普遍升高。因此,环境保护与实现可持续发展,是两个首要任务。自20世纪以来，人类水污染问题日益突出，特别是生活在水污染近距离进行操作的工人和生活在附近的居民，糟糕的生活环境以及污水产生的恶臭会使人们产生负面情绪，从而影响人们的工作学习与生活，利于社会和谐发展[1]。