不同pH和腐殖酸对饮用水中吲哚类嗅味物质的氧化效果影响研究

Effects of pH and humic acid on indoles oxidation in drinking water

近年来饮用水嗅味事件频发,化学类嗅味问题已不容忽视.本研究以吲哚(Indole)和3-甲基吲哚(3-MI)两种化学类嗅味物质为研究对象,探究不同pH与腐殖酸(HA)浓度对NaClO和KMnO_(4)氧化效果的影响,并在实际水体中加以验证.结果表明,不同pH下(pH=5、7、9)NaClO均可高效氧化Indole和3-MI,去除率达95%以上,但pH=9时氧化速率明显降低;HA对NaClO氧化Indole和3-MI的效果有一定的抑制作用(<10%).KMnO_(4)对Indole的氧化去除效果不明显(<10%),而KMnO_(4)对3-MI的去除率却可达88.90%以上.不同pH对KMnO_(4)氧化Indole和3-MI影响不大,但HA可以明显提高KMnO_(4)对Indole和3-MI的去除率(>86%,>96%).实际水体的实验结果表明,虽然NaClO对Indole和3-MI的氧化效果较纯水体系中略有降低,但依然明显高于KMnO_(4).当水体中Indole、3-MI的浓度较高时,使用KMnO_(4)氧化时会提高水体的色度,严重时可能会产生其他异味.因此,当实际水体中出现吲哚类嗅味问题时,NaClO氧化是有效的处理方法之一.

In recent years,frequent odor problems have been induced by chemical odorants.This study investigated the oxidation effects of NaClO and KMnO_(4)at different pH and humic acid(HA)on two chemical odorants(indole and 3-methylindole(3-MI))in both pure water and raw water.Results showed that,NaClO had high removal efficiencies(higher than 95%)at different pH(5,7 and 9)on the two odorants,while the oxidation rate decreased significantly at pH 9.However,HA inhibited the oxidation of NaClO on the odorants,and removal efficiencies were lower than 10%.KMnO_(4)oxidation was lower(less than 10%)for indole,but over 88.90%for 3-MI.The pH had slight effects on KMnO_(4)oxidation,but HA induced significant increase in KMnO_(4)oxidation on Indole and 3-MI,>86%and>96%,respectively.In raw water,the NaClO oxidation of the two odorants was lower than the pure water system,but still much higher than KMnO_(4).Moreover,the use of KMnO_(4)induced unpleasant color,especially odor byproducts when the concentration of Indole and 3-MI was relatively high in the water.Therefore,NaClO oxidation is the better treatment option for indole-induced odor problems in raw waters.