690环境化学34卷
[18]2+
其在酸性条件下活性较差,性的配位体被广泛用于金属络合剂,却不能消耗PS产生能与Fe络合,
2+2+
且能消耗PS产生硫酸自由基.结合图4中的Fe硫酸自由基;而在中性和碱性条件下,能与Fe络合,
2+
不同pH条件下,当体系中加入BPY时,溶液中的Fe浓度维持在一个相对稳定的范围,浓度可知,在酸2+2+
Fe2+浓度要大,相对于未添加BPY而言,性条件下,使但BPY与Fe络合后将屏蔽体系中游离的Fe,
2+
Fe2+难以释放出来活化PS,降低了体系中的硫酸自由基的含量,相当于添加BPY体系中游离的Fe浓度小于未添加BPY体系中的浓度,添加BPY未能促进PCA的降解;在中性和碱性条件下,添加BPY促
2+
进了Fe的溶出,提高了PS的活化效率,进而促进了过量的BPY能消耗体系中的PS产生硫酸自由基,
PCA的降解.上述结果更进一步说明螯合剂是通过调节溶液中Fe2+的浓度而影响PS的活化效率,为在中性和碱性条件下获得较高效能的过硫酸盐活化体系提供了可能性.
图6Fig.6
5.0、7.0、9.0、11.0时添加与未加2,2-联吡啶体系中PCA的降解在pH值为3.0、
ComparisonofPCAdegradationwithandwithoutBPYatpH3.0,5.0,7.0,9.0,11.0
(20℃,[ZVI]=0.1g[PCA]=0.1mmol[PS]=2.5mmol[BPY]=1.0mmol·L-1,·L-1,·L-1,·L-1)
3结论
CA、OA、BPY后零价铁活化过硫酸盐体系中对氯苯胺污染物氧化降解的本文对添加螯合剂EDTA、
EDTA、CA、OA抑制了PCA的影响进行研究,重点研究BPY对其的影响.研究结果表明,在中性条件下,BPY的浓度和PCA的降解曲线符合拟准一级反应降解,而BPY促进了PCA的降解.在pH值为7.0时,
PS体系的作用机制,BPY是一种Fe2+中性配位体,动力学方程.进一步考察了BPY对ZVI-结果表明,通过调节溶液中Fe
2+
2+
BPY由的浓度而影响ZVI中Fe的溶出,进而影响PS的活化效率.在酸性条件下,
2+
BPY的螯合作用促进于减少了溶液中游离的Fe浓度,表现出对PCA的降解抑制;在中性和碱性条件,
2+
PS非均相体了ZVI中Fe的溶出,提高了PS的活化效率,从而促进了PCA的降解.进一步证明了ZVI-Fe2+活化PS的作用机制.ZVI是作为Fe2+的来源、系中,
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