刘丹丹，周雪飞

(同济大学 长江水环境教育部重点实验室，上海 200092)

1 引言

2 硫酸自由基的产生机理

2.1 能量活化

能量活化主要通过外界提供足够的能量促使过硫酸盐中的化学键发生断裂，从而形成硫酸自由基，其反应过程可用式(1)和式(2)表示：

(1)

(2)

目前使用最多的是高温和紫外照射两种方法。

2.2 过渡金属离子活化

相对于使用高温或UV 活化过硫酸盐，使用过渡金属活化具有高效、低成本的优点，越来越多的应用于实践中。在不同价态的过渡金属离子的催化下，PMS和PS通过下列方程式生成硫酸自由基和其他的一些物质：

(3)

(4)

(5)

(6)

(7)

(8)

金属离子与氧化剂的反应原理上主要是金属离子与氧化剂之间的电子转移过程。Anipsitakis等研究发现，Co(Ⅱ)和Ru(Ⅲ)活化KHSO5效果最好，Ag(Ⅰ)活化K2S2O8效果最好，而Fe(Ⅱ)、Fe(Ⅲ)活化H2O2效果最好[2]。

3 硫酸自由基对污染物的去除研究

4 水中离子对硫酸自由基的影响

4.1 氯离子对硫酸自由基的影响

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

(20)

4.2 溴离子对硫酸自由基的影响

(21)

(22)

4.3 水中碳酸盐对硫酸自由基的影响

(23)

(24)

同样的，人们发现在基于硫酸自由基的高级氧化体系中，通常会发生式(25)、(26)、(27)、(28)和(29)的反应过程。

(25)

(26)

(28)

(29)

5 水中有机质对硫酸自由基的影响

(28)

(29)

(30)

6 总结与展望

基于过硫酸盐的高级氧化技术在环境领域取到了快速的发展，人们越来越关注其在实际应用中环境基质的影响，相信随着研究的不断深入，更准确、更全面的过硫酸盐降解机理将会得到有效的解读。与其他高级氧化体系相比，基于过硫酸盐的高级氧化技术在实际应用中还存在着效率不高、使用范围有限等问题，如何根据硫酸自由基的特异性和其与环境基质物质的反应机理来提高过硫酸盐的去除有机物的效率是今后研究的一个重要方向。

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