零价铁活化过硫酸钾降解对氯苯酚废水特性及机理研究

发布时间：2018-08-30 09:15

【摘要】：作为一种重要化工原料,氯酚类物质已被广泛应用于日常生产和生活,由此产生的环境问题也日益严重。本文以对氯苯酚(4-CP)作为目标污染物,采用零价铁活化过硫酸钾高级氧化技术处理对氯苯酚模拟废水,并对4-CP去除效率的主要影响因素及体系的降解机理进行了研究。本文考察了反应温度、初始pH、目标污染物浓度、零价铁投加量等因素对体系去除4-CP的影响。结果表明,零价铁/过硫酸钾体系能够有效去除废水中对氯苯酚且最佳反应条件为:反应温度为30℃、体系初始pH值为5、目标污染物初始浓度为20mg/L、零价铁投加量为0.3g/L、过硫酸钾浓度为1.6mmol/L。最佳实验条件下,60分钟时4-CP去除率可达90%以上。进一步的实验表明,过硫酸钾的分批投加也可以提高4-CP去除率。通过降解动力学模拟可知,对氯苯酚的降解反应符合准一级反应动力学。过硫酸钾/零价铁体系在降解过程中的特性研究表明,溶液的pH值会随着反应的进行而逐渐降低,证明体系中有酸性物质产生。二价铁离子浓度变化与4-CP去除率关系显示,亚铁离子浓度直接决定4-CP去除率的高低。由不同体系的对照实验可知,单独零价铁体系和单独过硫酸钾体系对4-CP的去除率较低,表明4-CP的降解是体系联合作用的结果。自由基清除剂实验显示,添加甲醇和叔丁醇后,体系4-CP去除率分别降低了70%和30%。结果表明,体系中生成了硫酸根自由基和羟基自由基,而且硫酸根自由基对4-CP的降解起着主要作用。羟基自由基产生量检测的实验数据进一步证实了这一结论。TOC测定结果显示,体系的矿化率远远低于同时刻4-CP的去除率,矿化过程进行得比较缓慢。离子色谱法捕捉到体系中氯离子浓度逐渐增加,表明体系中发生了脱氯反应。结合之前分析结果,4-CP的降解过程大致可推测如下:首先4-CP发生脱氯反应和氧化反应生成中间产物对苯二酚和对苯醌,然后中间产物被硫酸根自由基攻击,发生开环氧化生成小分子酸,最后转化为二氧化碳和水而除去。
[Abstract]:As an important chemical raw material, chlorophenols have been widely used in daily production and daily life, resulting in increasingly serious environmental problems. In this paper, p-chlorophenol (4-CP) was used as the target pollutant to treat the simulated wastewater of p-chlorophenol by using zero-valent iron activated potassium persulfate advanced oxidation technology. The main factors affecting the removal efficiency of 4-CP and the degradation mechanism of the system were studied. In this paper, the effects of reaction temperature, initial pH, concentration and zero valent iron dosage on the removal of 4-CP from the system were investigated. The results show that the zero-valent iron / potassium persulfate system can effectively remove p-chlorophenol from wastewater. The optimum reaction conditions are as follows: reaction temperature is 30 鈩，

本文编号：2212642