Fe2+活化過硫酸鉀降解2,4,6-三氯苯酚的研究*

劉姜裔，鐘美娥，高　權(quán)

(1 湖南農(nóng)業(yè)大學(xué)東方科技學(xué)院，湖南　長沙　410128；2 湖南農(nóng)業(yè)大學(xué)理學(xué)院，湖南　長沙　410128)

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Fe2+活化過硫酸鉀降解2,4,6-三氯苯酚的研究*

劉姜裔1，鐘美娥2，高權(quán)2

(1 湖南農(nóng)業(yè)大學(xué)東方科技學(xué)院，湖南長沙410128；2 湖南農(nóng)業(yè)大學(xué)理學(xué)院，湖南長沙410128)

以Fe2+為活化劑，K2S2O8為氧化劑，對水中2,4,6-三氯苯酚進(jìn)行降解處理。首先研究K2S2O8濃度和FeSO4濃度等因素對2,4,6-三氯苯酚降解的影響，發(fā)現(xiàn)在K2S2O8濃度為3.75 mmol/L和FeSO4濃度為1.25 mmol/L，即K2S2O8/Fe2+=75:25的條件下，2,4,6-三氯苯酚的降解率達(dá)到最大值，為91%。動(dòng)力學(xué)研究表明，F(xiàn)e2+活化K2S2O8降解2,4,6-三氯苯酚的過程可分為兩個(gè)階段，其中第一階段反應(yīng)速度較快，第二階段為慢速反應(yīng)，并且第二階段符合一級(jí)反應(yīng)動(dòng)力學(xué)規(guī)律。

2,4,6-三氯苯酚；硫酸根自由基；過硫酸鉀；Fe2+

2,4,6-三氯苯酚作為染料中間體、殺菌劑、防腐劑，在染料、農(nóng)藥和化工等領(lǐng)域被廣泛使用[1-2]。其化學(xué)性質(zhì)穩(wěn)定，自然條件下很難降解，具有脂溶性，可以通過食物鏈富集。據(jù)報(bào)道，2,4,6-三氯苯酚對人類神經(jīng)系統(tǒng)、呼吸系統(tǒng)有不良影響，會(huì)帶來許多健康問題[3]。因此，處理含2,4,6-三氯苯酚的廢水和修復(fù)被其污染的土壤已成為環(huán)境領(lǐng)域的研究熱點(diǎn)。

1　實(shí)　驗(yàn)

1.1主要試劑與儀器

試劑：2,4,6-三氯苯酚(2,4,6-TCP，江蘇天容，96%)，甲純(色譜純)，過硫酸鉀(K2S2O8，PDS)、七水合硫酸亞鐵(FeSO4·7H2O)、冰乙酸均為分析純。

儀器：HPLC高效液相色譜，Agilent1260)；SPH-2102C恒溫震蕩器，上海世平實(shí)驗(yàn)設(shè)備有限公司；FA2400精密天平，上海民橋精密科學(xué)儀器有限公司。

1.2實(shí)驗(yàn)方法

向25 mL的比色管中依次加入一定濃度的2,4,6-三氯苯酚溶液和PDS溶液，最后加入一定量的FeSO4溶液開始反應(yīng)并計(jì)時(shí)，實(shí)驗(yàn)中均未調(diào)節(jié)pH值。實(shí)驗(yàn)在150 r/min恒溫振蕩箱中進(jìn)行，于25 ℃振蕩反應(yīng)，按照一定時(shí)間間隔取樣1 mL，然后加入1 mL甲醇進(jìn)行淬滅，搖勻后用高效液相色譜儀測試溶液中剩余的2,4,6-三氯苯酚，流動(dòng)相為甲醇和水(1%冰乙酸)(V:V=8:2)，檢測波長290 nm，流動(dòng)相速度為0.8 mL/min，進(jìn)樣量為20 μL。

2　結(jié)果與討論

2.1Fe2+用量對2,4,6-三氯苯酚降解的影響

圖1　Fe2+用量對2,4,6-三氯苯酚降解的影響

(1)

2.2K2S2O8用量對2,4,6-三氯苯酚降解的影響

氧化劑用量是影響污染物降解的重要因素，同時(shí)也是評估修復(fù)技術(shù)經(jīng)濟(jì)性的重要指標(biāo)。使2,4,6-三氯苯酚初始濃度為0.05 mmol/L、FeSO4初始濃度為1.25 mmol/L，改變K2S2O8的用量，使溶液中K2S2O8/Fe2+的摩爾比為5:25、10:25、25:25、50:25、75:25、100:25、150:25，研究K2S2O8用量對2,4,6-三氯苯酚降解的影響，所得結(jié)果如圖2所示。

圖2　K2S2O8用量對2,4,6-三氯苯酚降解的影響

由圖2可知，隨著K2S2O8用量的增加，2,4,6-三氯苯酚的降解率也隨之升高，當(dāng)K2S2O8/Fe2+的摩爾比為75:25時(shí)，反應(yīng)24 h后，2,4,6-三氯苯酚的降解率達(dá)到了91%。當(dāng)繼續(xù)增加K2S2O8用量時(shí)，2,4,6-三氯苯酚的降解率增幅較小。表明過高濃度的K2S2O8并不能顯著提高2,4,6-三氯苯酚的降解率。陳曉旸等[20]認(rèn)為，K2S2O8濃度過高時(shí)，反應(yīng)體系中產(chǎn)生大量的硫酸根自由基來不及消耗，過多的硫酸根自由基之間相互反應(yīng)生成過硫酸鹽，從而造成K2S2O8的利用率下降。

(2)

2.3K2S2O8/Fe2+體系中2,4,6-三氯苯酚降解的動(dòng)力學(xué)過程

圖3　K2S2O8/Fe2+體系中2,4,6-三氯苯酚降解動(dòng)力學(xué)過程

3　結(jié)　論

(1)Fe2+活化K2S2O8能夠在一定程度上降解2,4,6-三氯苯酚，適當(dāng)提高Fe2+和K2S2O8濃度均能促進(jìn)2,4,6-三氯苯酚的降解。

(2)FeSO4活化K2S2O8降解2,4,6-三氯苯酚的過程可分為兩個(gè)階段，其中第一階段反應(yīng)速度較快，第二階段為慢速反應(yīng)，并且第二階段符合一級(jí)反應(yīng)動(dòng)力學(xué)規(guī)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+

湖南農(nóng)業(yè)大學(xué)東方科技學(xué)院大學(xué)生研究性學(xué)習(xí)和創(chuàng)新實(shí)驗(yàn)計(jì)劃項(xiàng)目(No.DFCXY201324)；湖南省教育廳科學(xué)研究項(xiàng)目(15C0653)。

鐘美娥(1979-)，女，博士，講師，主要從事環(huán)境污染物的修復(fù)治理研究。

X703.1

A

1001-9677(2016)013-0073-03