Abstract
摘要
将亚砜作为指示化合物，利用亚砜类物质与Fe(IV)反应生成相应的砜类物质而与•OH反应不生成砜这一反应产物的差别，已经证实了Fenton试剂在酸性条件下主要产生•OH，而在近中性条件下产生Fe(IV)。近年来，过硫酸盐（过一硫酸盐HSO5−，过二硫酸盐S2O82−）被视作可替代H2O2的新型绿氧化剂，在高级氧化领域得到广泛应用。与Fe(II) / H2O2体系类似，Fe(II)活化过硫酸盐体系被认为是基于产生自由基（SO4•-或•OH）的高级氧化技术。令人疑惑的是，在Fe(II) / S2O82−和Fe(II) / HSO5−体系的相关研究中，从未将Fe(IV)作为一种可能存在的活性中间物种考虑在内。本研究探讨了Fe(II) / S2O82−和Fe(II) / HSO5−体系及其还原剂强化体系中产生Fe(IV)的可能性。
借助LC – MS / MS技术，研究发现亚砜与SO4•-的产物中没有砜类物质产生，说明亚砜同样可以作为区分Fe(IV)与SO4•-的指示化合物。本研究还以甲基苯基亚砜（PMSO）为例研究了SO4•-、•OH氧化亚砜的主要产物种类，并推测出可能的反应路径。同时，利用竞争动力学方法计算了SO4•-、•OH分别氧化PMSO和甲基苯基砜（PMSO2）的二级反应速率常数，建立起完善的亚砜鉴别Fe(IV)与自由基的研究方法。
利用PMSO作为指示化合物，发现酸性条件下Fe(II) / S2O82−和Fe(II) / HSO5−体系中降解的PMSO全部转化为PMSO2，即PMSO2的生成率（η (PMSO2)）达到100 %，说明Fe(II)活化S2O82−和HSO5−产生的活
性中间物种均为Fe(IV)，并非自由基，这与其它研究者的结论完全不同。在Fe(II) / S2O82−体系中，Fe(II)引起的Fe(IV)的消耗是主要的副反应，PDS对Fe(IV)的消耗可以忽略不计。而在Fe(II) / HSO5−体系中，Fe(II)和PMS均会竞争消耗Fe(IV)。在近中性条件下，活性物种的产生量急剧下降，PMSO的降解量很小，难以准确计算PMSO2的生成率，但是仍可观察到PMSO2的生成，说明Fe(II) / S2O82−和Fe(II) / HSO5−体系在中性条件下仍有Fe(IV)生成。
研究了四类铁还原剂分别强化Fe(II) / S2O82−和Fe(II) / HSO5−体系中活性氧化剂的生成规律。在Fe(II) / S2O82−体系中，羟胺类无机还原剂使PMSO2生成率下降到70 %，酚、醌类有机还原剂对PMSO2生成率无影响，酚酸类有机还原剂和氨基酸类有机还原剂均使PMSO2生成率下降，并且PMSO2生成率还随反应进行不断变化。在Fe(II) / HSO5−体系中，硫酸羟胺对PMSO2生成率无影响，而盐酸羟胺因引入了Cl−致使产生部分自由基，致使PMSO2生成率下降；酚、醌、酚酸类有机还原剂强化体系中PMSO2生成率均稳定在100 %；半胱氨酸使PMSO2生成率下降至80 %。某些还原剂强化体系中PMSO2生成率下降，说明一些还原剂可以改变反应路径，使Fe(II)活化过硫酸盐体系产生部分自由基。
关键词：过渡金属铁；过一硫酸盐；过二硫酸盐；铁还原剂；亚砜；高活性中间价态铁
Abstract
Abstract
In previous studies, researchers have demonstrated that Fenton reagents produce hydroxyl radicals under acidic condition while the dominant reactive oxidant convert to ferryl ion (Fe(IV)) species at near-neutral pH by using sulfoxides which produce corresponding sulfones with Fe(IV) species, which differ markedly from their hydroxyl radical-induced products, as probe compounds. Recently, persulfate (i.e., peroxymonosulfate (HSO5−) and peroxydisulfate (S2O82−)) has been widely used as an environmental friendly alternative oxidant in advanced oxidation processes (AOP). It is recognized that a conventional advanced oxidation processes (AOP) by combining peroxymonosulfate (PMS) or peroxydisulfate (PDS) and Fe(II) based on the generation of sulfate radical or hydroxyl radical, similar to H2O2 / Fe(II) system. It is puzzling that Fe(IV) species were not taken into account as potential active oxidants when utilize Fe(II) to active PDS or PMS in any previous studies. The purpose of this study was to explore the possibility of the produce of Fe(IV) species in Fe(II) / S2O82− and Fe(II) / HSO5−system and the system enhanced by iron reducing agents.
In this work, we used liquid chromatography-mass spectrometry identified that, sulfoxides would not be oxidized to sulfones by sulfate radicals, so that sulfoxides can be introduced as probe compounds to distinguish SO4•- with Fe(IV). Represented by methyl phenyl sulfoxide (PMSO), we investigated the main products of sulfoxides oxidized by SO4•-and •OH respectively and analyzed the possible reaction
routes. Meanwhlie, the second-order rate constants of the selected sulfoxides (PMSO) and sulfones (PMSO2) with •OH and SO4•-was determined by a competition kinetic method. Depending on all above studies, we established a method which can be used to distinguish Fe(IV) with free radicals.
Utlizing PMSO as probe compounds, the results shown that the prevalence rate of PMSO2 (e.g. η (PMSO2)) in Fe(II) / S2O82− and Fe(II) / HSO5− system are 100 % under acid conditions, indicating that the reactive oxidant in these two systems is Fe(IV) species rather than free radicals, which stand in sharp contrast with previous studies. In Fe(II) / S2O82− system, the consumption of Fe(IV) by Fe(II)was the main side reactions and the the consumption of Fe(IV) by S2O82− was negligible. While in Fe(II) / HSO5− system, the side reactions induced by Fe(II) and HSO5− were all strong. At near-neutral pH, the degradation amount of PMSO was too small to be calculated exactly for the generation amount of reactive intermediates decreased sharply with the rise of pH. However, the generation of PMSO2 was observed too, suggesting that Fe(II) / S2O82−and Fe(II) / HSO5−system also produce Fe(IV) under near-neutral
Abstract
conditions.
Four species of iron reducing agents were used to accelerate Fe(II) / S2O82− and Fe(II) / HSO5−system and the generation of reactive oxidants were researched. Compared to Fe(II) / S2O82−system, in which η(PMSO2) reached to 100 %, hydroxylamine led to η (PMSO2) decline to 70 %; polyphenols and benzoquinone have no effects on η (PMSO2); phenolic acids and amino acids led to the decrease and fluctuation during reaction time of η (PMSO2). In Fe(II) / HSO5−system, hydroxylamine sulfate have no effects on η (PMSO2), while hydroxylamine hydrochloride made η (PMSO2) decreased to 70 % for the interference of Cl−. The η (PMSO2) in the Fe(II) / HSO5− system enhanced by polyphenols, benzoquinone and phenolic acids compounds were fairly constant and approached to 100 %. The addition of L-Cysteine made the η (PMSO2) of Fe(II) / HSO5− system decreased to 80 %. The results shown that some iron reducing agents change the rection route of Fe(II) with HSO5−, which led to the generation of free radicals and the decrease of η (PMSO2).
Keywords: transition metal iron, peroxymonosulfate, peroxydisulfate, iron reducing agents, sulfoxide, high reactive intermediate iron
目录
目录
摘要 .......................................................................................................................... I ABSTRACT ................................................................................................................ II 第1章绪论 (1)
1.1 课题背景 (1)
1.2 传统芬顿体系中活性组分研究现状 (1)
1.3Fe(II)活化过硫酸盐体系中活性组分研究现状 (4)
1.4 铁还原剂强化Fe(II)活化过硫酸盐体系的研究现状 (6)
1.4.1 羟胺类无机还原剂强化Fe(II) / PS体系的研究现状 (6)
1.4.2 有机还原剂强化Fe(II) / PS体系的研究现状 (7)
1.5 课题研究的目的、意义和主要内容 (11)
1.5.1 课题研究的目的和意义 (11)
1.5.2 课题研究的主要内容 (11)
第2章实验材料与方法 (13)
2.1 目标物选择 (13)
2.2 实验药品及溶液配制 (14)
2.3 实验仪器 (15)
2.4 分析方法 (16)
2.4.1 液相谱法测定有机物浓度 (16)
2.4.2 H2O2浓度与PMS浓度测定 (16)
2.4.3 PDS浓度测定 (17)
2.4.4铁浓度测定 (17)
2.5 实验方法 (17)
2.5.1•OH和SO4•-氧化PMSO主要产物鉴别实验 (17)
2.5.2 竞争动力学实验 (18)
2.5.3Fe(II)/PS体系及其还原剂强化体系中活性组分鉴别实验 (19)
第3章亚砜鉴别活性组分方法建立 (20)
3.1 引言 (20)
3.2 自由基和Fe(IV)降解亚砜产物对比 (21)
3.3 羟基自由基(•OH)氧化亚砜产物鉴别 (22)
3.4 硫酸根自由基(SO4•-)氧化亚砜产物鉴别 (25)
3.5•OH、SO4•-氧化PMSO与PMSO2的反应速率测定 (26)
3.6 本章小结 (28)
目录
第4章Fe(II)/过硫酸盐体系中活性组分的鉴别 (30)
reaction研究4.1 引言 (30)
4.2Fe(II)活化过二硫酸盐体系中活性组分的鉴别 (30)
4.2.1亚砜初始浓度的影响 (30)
4.2.2 PDS初始浓度的影响 (32)
4.2.3 Fe(II)初始浓度的影响 (33)
4.2.4 pH的影响 (34)
4.3 Fe(II)活化过一硫酸盐体系中活性组分的鉴别 (37)
4.3.1亚砜初始浓度的影响 (37)
4.3.2 PMS初始浓度的影响 (38)
4.3.3 Fe(II)初始浓度的影响 (39)
4.3.4 pH的影响 (40)
4.4 本章小结 (42)
第5章铁还原剂强化Fe(II)/过硫酸盐体系中活性组分的鉴别 (43)
5.1 引言 (43)
5.2 铁还原剂强化Fe(II) / S2O82−体系中活性组分的鉴别 (43)
5.2.1 羟胺类无机还原剂强化Fe(II) / S2O82−体系 (43)
5.2.2 酚、醌类有机还原剂强化Fe(II) / S2O82−体系 (46)
5.2.3 酚酸类有机还原剂强化Fe(II) / S2O82−体系 (47)
5.2.4 氨基酸类有机还原剂强化Fe(II) / S2O82−体系 (49)
5.3 铁还原剂强化Fe(II) / HSO5−体系中活性组分的鉴别 (51)
5.3.1 羟胺类无机还原剂强化Fe(II) / HSO5−体系 (51)
5.3.2 酚、醌类有机还原剂强化Fe(II) / HSO5−体系 (53)
5.3.3 酚酸类有机还原剂强化Fe(II) / HSO5−体系 (54)
5.3.4 氨基酸类有机还原剂强化Fe(II) / HSO5−体系 (55)
5.4 本章小结 (56)
结论 (58)
参考文献 (60)
哈尔滨工业大学学位论文原创性声明和使用权限 (66)
致谢 (67)

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