苯酚在氨氮体系中的氧化降解研究

研究了氨氮存在下次氯酸钠处理苯酚模拟废水的氧化特性,探讨了苯酚在氨氮体系中的反应途径。实验结果表明:在含氨氮的苯酚废水中加入次氯酸钠,氨氮将与苯酚发生竞争反应。折点加氯曲线表现为当氯与氨氮质量比由5.35上升到27.67时,氨氮去除率的变化趋势滞后;而余氯量则不断减小,没有折点出现。随着氨氮浓度增加,苯酚的氧化降解受到抑制:一方面,苯酚的去除率不断下降;另一方面,体系中检测到一系列氯酚中间产物,其生成量和种类先增加后减少。HPLC分析结果显示体系中生成的氯酚中间产物至少有2种(2-氯酚和4-氯酚),至多有5种(2-氯酚、4-氯酚、2,6-二氯酚、2,4-二氯酚和2,4,6-三氯酚)。其中,2-氯酚和4-氯酚是导致三卤甲烷产生的最有效前体物质,而2,6-二氯酚、2,4-二氯酚和2,4,6-三氯酚则是生成卤乙酸的高活性物质。实验结果对次氯酸钠处理含氨氮的难生化或有毒有机废水具有一定的参考价值。

Oxidation of Phenol by Sodium Hypochlorite in Ammonia Nitrogen System

Degradation of phenol by oxidation using sodium hypochlorite in ammonia nitrogen system was investigated.Reaction pathway during oxidation process was discussed.Results showed that there was a competition between ammonia and phenol after sodium hypochlorite was added to wastewater.Breakpoint chlorination curve indicated that when chlorine/ammonia weight ratio rose from 5.35 to 27.67,trend of ammonia nitrogen removal lagged behind and residual chlorine continuously decreased with no discount point.With increasing ammonia nitrogen concentration,degradation of phenol was inhibited,with removal rate of phenol declining,and a series of chlorophenols whose amount and sort showed an increase before decreasing were detected.Analysis of products by HPLC revealed that chlorophenols were only two kinds including 2-monchlorohenol and 4-monchlorophenol at least and five kinds at most including 2-monchlorohenol,4-monchlorophenol,2,6-dichlorohenol,2,4-monchlorophenol and 2,4,6-trichlorophenol.2-monchlorophenol and 4-monchlorophenol were the highest activity of forming trihalomethanes,while 2,6-dichlorohenol,2,4-monchlorophenol and 2,4,6-trichlorophenol were the highest activity of forming haloacetic acids.Experimental results provided certain reference for dealing with organic wastewater with low biodegradability or toxicity by sodium hypochlorite in ammonia nitrogen system.