Fe2+活化过硫酸钾降解2,4,6-三氯苯酚的研究*

刘姜裔，钟美娥，高　权

(1 湖南农业大学东方科技学院，湖南　长沙　410128；2 湖南农业大学理学院，湖南　长沙　410128)



Fe2+活化过硫酸钾降解2,4,6-三氯苯酚的研究*

刘姜裔1，钟美娥2，高权2

(1 湖南农业大学东方科技学院，湖南长沙410128；2 湖南农业大学理学院，湖南长沙410128)

以Fe2+为活化剂，K2S2O8为氧化剂，对水中2,4,6-三氯苯酚进行降解处理。首先研究K2S2O8浓度和FeSO4浓度等因素对2,4,6-三氯苯酚降解的影响，发现在K2S2O8浓度为3.75 mmol/L和FeSO4浓度为1.25 mmol/L，即K2S2O8/Fe2+=75:25的条件下，2,4,6-三氯苯酚的降解率达到最大值，为91%。动力学研究表明，Fe2+活化K2S2O8降解2,4,6-三氯苯酚的过程可分为两个阶段，其中第一阶段反应速度较快，第二阶段为慢速反应，并且第二阶段符合一级反应动力学规律。

2,4,6-三氯苯酚；硫酸根自由基；过硫酸钾；Fe2+

2,4,6-三氯苯酚作为染料中间体、杀菌剂、防腐剂，在染料、农药和化工等领域被广泛使用[1-2]。其化学性质稳定，自然条件下很难降解，具有脂溶性，可以通过食物链富集。据报道，2,4,6-三氯苯酚对人类神经系统、呼吸系统有不良影响，会带来许多健康问题[3]。因此，处理含2,4,6-三氯苯酚的废水和修复被其污染的土壤已成为环境领域的研究热点。

1　实　验

1.1主要试剂与仪器

试剂：2,4,6-三氯苯酚(2,4,6-TCP，江苏天容，96%)，甲纯(色谱纯)，过硫酸钾(K2S2O8，PDS)、七水合硫酸亚铁(FeSO4·7H2O)、冰乙酸均为分析纯。

仪器：HPLC高效液相色谱，Agilent1260)；SPH-2102C恒温震荡器，上海世平实验设备有限公司；FA2400精密天平，上海民桥精密科学仪器有限公司。

1.2实验方法

向25 mL的比色管中依次加入一定浓度的2,4,6-三氯苯酚溶液和PDS溶液，最后加入一定量的FeSO4溶液开始反应并计时，实验中均未调节pH值。实验在150 r/min恒温振荡箱中进行，于25 ℃振荡反应，按照一定时间间隔取样1 mL，然后加入1 mL甲醇进行淬灭，摇匀后用高效液相色谱仪测试溶液中剩余的2,4,6-三氯苯酚，流动相为甲醇和水(1%冰乙酸)(V:V=8:2)，检测波长290 nm，流动相速度为0.8 mL/min，进样量为20 μL。

2　结果与讨论

2.1Fe2+用量对2,4,6-三氯苯酚降解的影响

图1　Fe2+用量对2,4,6-三氯苯酚降解的影响

(1)

2.2K2S2O8用量对2,4,6-三氯苯酚降解的影响

氧化剂用量是影响污染物降解的重要因素，同时也是评估修复技术经济性的重要指标。使2,4,6-三氯苯酚初始浓度为0.05 mmol/L、FeSO4初始浓度为1.25 mmol/L，改变K2S2O8的用量，使溶液中K2S2O8/Fe2+的摩尔比为5:25、10:25、25:25、50:25、75:25、100:25、150:25，研究K2S2O8用量对2,4,6-三氯苯酚降解的影响，所得结果如图2所示。

图2　K2S2O8用量对2,4,6-三氯苯酚降解的影响

由图2可知，随着K2S2O8用量的增加，2,4,6-三氯苯酚的降解率也随之升高，当K2S2O8/Fe2+的摩尔比为75:25时，反应24 h后，2,4,6-三氯苯酚的降解率达到了91%。当继续增加K2S2O8用量时，2,4,6-三氯苯酚的降解率增幅较小。表明过高浓度的K2S2O8并不能显著提高2,4,6-三氯苯酚的降解率。陈晓旸等[20]认为，K2S2O8浓度过高时，反应体系中产生大量的硫酸根自由基来不及消耗，过多的硫酸根自由基之间相互反应生成过硫酸盐，从而造成K2S2O8的利用率下降。

(2)

2.3K2S2O8/Fe2+体系中2,4,6-三氯苯酚降解的动力学过程

图3　K2S2O8/Fe2+体系中2,4,6-三氯苯酚降解动力学过程

3　结　论

(1)Fe2+活化K2S2O8能够在一定程度上降解2,4,6-三氯苯酚，适当提高Fe2+和K2S2O8浓度均能促进2,4,6-三氯苯酚的降解。

(2)FeSO4活化K2S2O8降解2,4,6-三氯苯酚的过程可分为两个阶段，其中第一阶段反应速度较快，第二阶段为慢速反应，并且第二阶段符合一级反应动力学规律。

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Study on Potassium Persulfate Activated by Fe2+for Degradation of 2,4,6-Trichlorophenol*

LIU Jiang-yi1, ZHONG Mei-e2, GAO Quan2

(1 College of Orient Science & Technology, Hunan Agricultural University, Hunan Changsha 410128;2CollegeofScience,HunanAgricultureUniversity,HunanChangsha410128,China)

To investigate the degradation of 2,4,6-trichlorophenol in water, the activating agent of Fe2+and the oxidant of K2S2O8were used. The effects of the concentrations of K2S2O8and FeSO4on the degradation of 2,4,6-trichlorophenol were studied. The optimal operating conditions were obtained as follows: 3.75 mmol/L of K2S2O8and 1.25 mmol/L of FeSO4, namely, the optimal molar ratio of oxidant K2S2O8to activating agent Fe2+was 75:25. Under these conditions, the degradation rate of 2,4,6-trichlorophenol was 91%. The degradation kinetics of 2,4,6-trichloro-phenol showed that the reaction included an initial fast stage and a final slow stage. The reaction was very fast at the first stage, and became slow at the second stage which followed a first-order kinetic.

2,4,6-trichlorophenol; sulfate radical; potassium persulfate; Fe2+

湖南农业大学东方科技学院大学生研究性学习和创新实验计划项目(No.DFCXY201324)；湖南省教育厅科学研究项目(15C0653)。

钟美娥(1979-)，女，博士，讲师，主要从事环境污染物的修复治理研究。

X703.1

A

1001-9677(2016)013-0073-03