超声吹脱去除氨氮的机理和动力学研究
Study on mechanism and kinetics of ammonia-nitrogen removal by ultrasound stripping
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摘要: 采用超声吹脱技术对某印染厂印染废水中的氨氮进行了处理实验，探索了其反应机理并进行了动力学研究。研究表明，叔丁醇的存在没有降低废水中氨氮的去除率，证明·OH不是超声吹脱去除氨氮反应中的主导氧化物种。通过对反应产物的分析发现，超声吹脱去除氨氮的机理主要是氨氮以游离态的方式在空化效应下高温高压热解成氮气和氢气排出，同时氨气在空化效应产生的超临界状态下传质速度加快，在吹脱条件下更易于从废水中散失。动力学分析表明，印染废水中氨氮的超声去除反应属于一级反应，符合一级反应动力学。Abstract: The experiments of the removal of ammonia-nitrogen from dyeing wastewater by ultrasound stripping were carried out,the mechanism and kinetics were studied. It was found that the presence of t-butanol had no inhibitory effect on the ozonation. It was inferred that the hydroxyl radicals were not the dominating oxidative species in the ozonation process. According to the observed product, the mechanism of ammonia-nitrogen removal by ultrasound stripping was that the ammonia molecules entered into the cavitation bubbles and transformed into nitrogen molecules and hydrogen molecules via pyrolysis at high temperature and high pressure in the cavitation bubbles. Ammonia′s mass transfer speed increased under supercritical condition emerging from ultrasonic cavitation, and easier released from wastewater by stripping. The firstorder removal kinetics of ammonia nitrogen by ultrasound stripping was observed.
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Key words:
- ultrasound stripping /
- ammonia-nitrogen /
- mechanism /
- kinetics
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