微生物铁载体调控铁离子活化过硫酸盐降解药物类有机污染物的效能和机理研究

The sulfate radical produced by persulfate activation was widely used in water pollution control and groundwater remediation because of its strong oxidizing ability. It is a emerging development direction of advanced oxidation technologies in recent years. Persulfate activation by ferrous ion was efficient, simple and energy-saving. The activation methods had been recognized by many environmental scientists. However, the main disadvantage of this system was that pH value had restricted the ferrous ion concentration obviously. The applicant of this research had concluded in previous study that Fe(III)-complex was stable in a wide pH range. It could work as the generating source of ferrous ion and significantly improve the efficiency of persulfate activation. In this research, three kinds of natural microbial siderophores were introduced to complex ferric ion in activating persulfate with photoreduction assist. The characteristics and mechanism of the complex reaction between microbial siderophores and ferric ion would be studied. The mechanism of persulfate activation by Fe(III)-siderophores would also be studied. Atenolol, as a typical pharmaceutical pollutant, was chosen as the target pollutant. The effect of different reaction parameters on persulfate activation and atenolol degradation would be investigated. The oxidation pathway of atenolol would be explored by the analysis of byproducts. The implementation of this research would provide the theoretical basis for the development of emerging advanced oxidation processes which based on sulfate radical.

通过活化过硫酸盐产生强氧化性硫酸根自由基并用水污染控制和地下水修复，是近年来高级氧化技术的新兴发展方向。在活化过硫酸盐的诸多途径中，亚铁离子活化法由于效率高、体系简单、无需外加热源光源、能耗少等特点受到了环境学家广泛的关注；可是该体系的主要弱点是溶解态亚铁离子的浓度受到pH条件的苛刻限制。申请人前期研究发现三价铁配合物能够在较宽的pH值范围内稳定存在并能作为亚铁离子的产生源，能明显提高过硫酸盐的活化效率。本项目将利用自然界中存在的三类典型微生物铁载体络合三价铁离子，在光还原的作用下活化过硫酸盐，研究不同类型的微生物铁载体调控铁离子浓度的配位反应特征和活化过硫酸盐的机理；选择药物阿替洛尔作为目标污染物，研究不同pH值等反应条件对铁载体配合物活化过硫酸盐效率和机理的影响；通过产物分析来探索硫酸根自由基氧化降解阿替洛尔的转化路径。本研究将为基于硫酸根自由基的新兴高级氧化技术的发展提供理论依据。

利用微生物铁载体调控铁离子浓度来提高过硫酸盐(PS)的活化效率，是近年来较为新颖的一种活化PS的途径。本项目按照计划，研究了四种含不同官能团的铁载体在有光和无光的作用下，活化PS产生硫酸根自由基(SO4•-)，降解有机污染物（阿替洛尔、萘普生、双酚A）的过程。主要包括以下几个部分：(1)初探了结构较为简单的异羟肟酸型的铁络合剂—乙酰氧肟酸(AHA)引入后，对活化PS降解阿替洛尔(ATL)的影响。实验结果表明，光照下Fe(III)-AHA配合物能够产生Fe(II)，Fe(II)活化PS产生SO4•-和HO•，最终达到ATL降解的目的；但是在中性pH值条件下，反应速率仍然受到抑制。(2)研究了真菌分泌的铁载体去铁胺Desferrioxamine B（DFOB）与Fe(III)络合后，活化PS的过程。研究结果表明，Fe(III)与DFOB形成的配合物能在pH值2-11范围内稳定存在；在模拟太阳光照射下，Fe(III)-DFOB能够产生Fe(II)和HO•；Fe(III)-DFOB能够活化PS降解ATL，并且在pH值2-8的范围内保持相对稳定的降解效率，在一定程度上克服了传统类芬顿反应受pH限制的缺点；但是由于DFOB本身也是一种有机物，会与污染物竞争消耗自由基，因此ATL的降解速率还不够理想。(3)研究了铜绿假单胞菌产生的铁载体Pyoverdine(Pyd)，它同时含有铁载体的三种特征官能团：异羟肟酸、羧基和儿茶酚官能团，结构非常复杂，分子量上千；由于它本身与自由基反应的速率非常快，即使Fe(III)-Pyd在光照下能够产生Fe(II)来活化PS，但目标污染物仍然未能有效降解。(4)重点研究了儿茶素Catechin (CAT)这种绿茶中提取的儿茶酚类型的铁载体对铁离子的调控机制。研究结果表明，CAT不同于前3种螯合剂，CAT与Fe(III)不能形成稳定的络合物，它们之间形成的是寿命仅为几秒的瞬态配体物种，随后迅速反应生成大量的Fe(II)；在无光的条件下，亦可同样高效地产生Fe(II)；Fe(II)的大量产生能够强化PS的活化，产生大量的自由基，大大提高了目标污染物的降解速率；ATL、萘普生(NPX)、双酚A(BPA)做为目标污染物，均得到了高效的降解；同时还研究了Fe(III)/CAT对H2O2的活化效果；分析了污染物转化途径并对产物毒性进行了鉴定。