铁-谷氨酸-硅钨酸三元配合物作为高活性非均相类Fenton催化剂降解4-氯酚

doi:10.1016/S1872-2067(15)61011-7

摘要/Abstract

摘要：

Fenton氧化法通过Fe²⁺离子催化分解H₂O₂产生羟基自由基,能够氧化降解绝大多数有机污染物.但是传统的均相Fenton氧化法使用高浓度二价铁盐作为催化剂,催化剂不便于回收利用,而且还会引发新的环境问题.另外,均相Fenton氧化法通常需要在pH约为3的酸性条件下进行,在较高pH条件下,有机物氧化降解速率降低,同时铁盐水解产生铁泥.文献报道了一些含铁固体材料作为非均相类Fenton催化剂,能够解决催化剂回收和重复利用问题,但是许多固体催化剂仍然只在酸性条件下表现出较高催化活性.多金属氧簇是除过渡金属氧化物之外的一类光催化剂.近年来,多金属氧簇在Fenton氧化过程中的应用开始受到关注.可以预计,含铁的多金属氧簇固体化合物有可能同时具有类Fenton催化活性和光催化活性.
本文以三价铁盐(Fe^III)、谷氨酸(Glu)和硅钨酸(SiW)为原料在水溶液中合成了一种不溶性的三元固体配合物Fe^ШGluSiW,并用电感耦合等离子体原子发射光谱(ICP-AES)、热重分析(TG)、傅里叶变换红外光谱(FT-IR)、紫外-可见漫反射光谱(UV-vis DRS)、X射线衍射(XRD)和场发射扫描电镜(FE-SEM)对Fe^ШGluSiW进行了表征.根据ICP-AES,TG和FT-IR结果推断,Fe^ШGluSiW可能的化学组成为[Fe(C₅H₈NO₄)(H₂O)]₂SiW₁₂O₄₀·13H₂O,其中含有铁、谷氨酸根单元和Keggin结构的SiW₁₂O₄₀^4-阴离子.FE-SEM和XRD测试结果表明,Fe^ШGluSiW是由结晶度较低、尺寸为100-200nm的无规则颗粒组成,并含有无定形相.
通过考察在自然初始pH6.5条件下100mg/L4-氯酚(4-CP)在Fe^ШGluSiW(1.0g/L)/H₂O₂(20mmol/L)体系中的氧化降解反应,我们发现在暗态和光照条件下,4-CP完全降解所需时间分别为40和15min,延长反应时间至2h,总有机碳(TOC)去除率分别达到27%和72%.结果表明,Fe^ШGluSiW具有很高的催化活性,而且在光照条件下活性更高.进一步研究发现,Fe^ШGluSiW在pH3-6.5范围内均表现出高的催化活性,而且在酸性条件下活性更高.用ICP-AES测定Fe元素在溶液中的析出量,证实4-CP氧化降解主要发生在固体催化剂表面.在反应体系中加入正丁醇能显著抑制4-CP降解,说明4-CP降解反应涉及羟基自由基的氧化作用.在光照反应条件下,催化剂颜色明显变深,表明光照条件下的反应机理涉及催化剂中SiW₁₂O₄₀^4-阴离子的还原.考虑到催化剂中含有谷氨酸根和SiW₁₂O₄₀^4-杂多阴离子,推测H₂O₂有可能通过氢键吸附于催化剂表面,这可能是Fe^ШGluSiW表现出高催化活性的重要原因.结合文献报道的含铁固体材料类Fenton催化机理和多金属氧簇光催化机理,可以很好地解释4-CP降解反应实验结果.在暗态条件下,Fe^ШGluSiW的催化机理归因于催化剂表面Fe^III的氧化还原循环Fe^III?Fe^II,即H₂O₂分子在催化剂表面分解产生羟基自由基,从而导致4-CP氧化;而在光照条件下,除了催化剂中Fe^III的类Fenton催化作用之外,催化剂中SiW₁₂O₄₀^4-杂多阴离子的光催化作用同时发生,导致4-CP降解速率加快.在光催化过程中,4-CP可以被激发态SiW₁₂O₄₀^4-直接氧化,也可以被激发态SiW₁₂O₄₀^4-与H₂O相互作用产生的羟基自由基氧化.被还原的杂多阴离子可以被O₂氧化,也可以被H₂O₂氧化,因而H₂O₂的存在也促进了Fe^ШGluSiW的光催化作用.

关键词: 多金属氧簇, 硅钨酸, 非均相催化, Fenton氧化, 4-氯酚降解

Abstract:

A novel iron-glutamate-silicotungstate ternary complex (Fe^ШGluSiW) was synthesized from ferric chloride (Fe^III), glutamic acid (Glu), and silicotungstic acid (SiW), and used as a heterogeneous Fenton-like catalyst for 4-chlorophenol (4-CP) degradation at neutral pH value. The prepared Fe^ШGluSiW was characterized using inductively coupled plasma atomic emission spectroscopy, thermogravimetry, Fourier-transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, X-ray diffraction, and field-emission scanning electron microscopy. The results showed that Fe^ШGluSiW has the formula [Fe(C₅H₈NO₄)(H₂O)]₂SiW₁₂O₄₀·13H₂O, with glutamate moiety and Keggin-structured SiW₁₂O₄₀^4- heteropolyanion. The catalyst showed high catalytic activity in 4-CP degradation in the dark and under irradiation. Under the conditions of 4-CP 100 mg/L, Fe^ШGluSiW 1.0 g/L, H₂O₂ 20 mmol/L, and pH = 6.5, 4-CP was completely decomposed in 40 min in the dark and in 15 min under irradiation. When the reaction time was prolonged to 2 h, the corresponding total organic carbon removals under dark and irradiated conditions were ca. 27% and 72%, respectively. The high catalytic activity of Fe^IIIGluSiW is resulted from hydrogen bonding of H₂O₂ on the Fe^IIIGluSiW surface. The enhanced degradation of 4-CP under irradiation arises from simultaneous oxidation of 4-CP through Fenton-like and photocatalytic processes respectively catalyzed by ferric iron and the SiW₁₂O₄₀^4- hetropolyanion in Fe^ШGluSiW.

Key words: Polyoxometalate, Silicotungstate, Heterogeneous catalysis, Fenton oxidation, 4-Chlorophenol degradation

尹冬菊, 张立忠, 赵秀峰, 陈汉, 翟倩. 铁-谷氨酸-硅钨酸三元配合物作为高活性非均相类Fenton催化剂降解4-氯酚[J]. 催化学报, 2015, 36(12): 2203-2210.

Dongju Yin, Lizhong Zhang, Xiufeng Zhao, Han Chen, Qian Zhai. Iron-glutamate-silicotungstate ternary complex as highly active heterogeneous Fenton-like catalyst for 4-chlorophenol degradation[J]. Chinese Journal of Catalysis, 2015, 36(12): 2203-2210.

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https://www.cjcatal.com/CN/Y2015/V36/I12/2203

参考文献

[1] Ahlborg U G, Thunberg T M. Crit Rev Toxicol, 1980, 7: 1
[2] Perα-Titus M, Garcíα-Molina V, Baños M A, Giménez J, Esplugas S. Appl Catal B, 2004, 47: 219
[3] Neyens E, Baeyens J. J Hazard Mater, 2003, 98: 33
[4] Ikehata K, El-Din M G. J Environ Eng Sci, 2006, 5: 81
[5] Umar M, Aziz H A, Yusoff M S. Waste Manage, 2010, 30: 2113
[6] Kumar S M. Res J Chem Environ, 2011, 15: 96
[7] Garrido-Ramírez E G, Theng B K G, Mora M L. Appl Clay Sci, 2010, 47: 182
[8] Zhang S L, Hu X M, Wang X W, Liang S J, Wu L. Chin J Catal (张世龙, 胡小明, 王晓韡, 梁诗景, 吴棱. 催化学报), 2012, 33: 1736
[9] Valizadeh S, Rasoulifard M H, Dorraji M S S. Appl Surf Sci, 2014, 319: 358
[10] Huang Z J, Wu P X, Gong B N, Lu Y H, Zhu N W, Hu Z X. Appl Surf Sci, 2013, 286: 371
[11] Fathinia S, Fathinia M, Rahmani A A, Khataee A. Appl Surf Sci, 2015, 327: 190
[12] Gao J, Wu L, Liang S J, Zhang S L, Liu P, Fu X Z. Chin J Catal (高剑, 吴棱, 梁诗景, 张世龙, 刘平, 付贤智. 催化学报), 2010, 31: 317
[13] Zhou T, Li Y Z, Ji J, Wong F S, Lu X H. Sep Purif Technol, 2008, 62: 551
[14] Panda N, Sahoo H, Mohapatra S. J Hazard Mater, 2011, 185: 359
[15] Xu L J, Wang J L. Appl Catal B, 2012, 123-124: 117
[16] Deng J H, Wen X H, Wang Q N. Mater Res Bull, 2012, 47: 3369
[17] Amorim C C, Leão M M D, Moreira R F P M, Fabris J D, Henriques A B. Chem Eng J, 2013, 224: 59
[18] Misono M. Catal Rev-Sci Eng, 1987, 29: 269
[19] Hill C L. J Mol Catal A, 2007, 262: 2
[20] Guo Y H, Hu C W. J Mol Catal A, 2007, 262: 136
[21] Song Y F, Tsunashima R. Chem Soc Rev, 2012, 41: 7384
[22] Sivakumar R, Thomas J, Yoon M. J Photochem Photobiol C, 2012, 13: 277
[23] Lee J, Kim J, Choi W. Environ Sci Technol, 2007, 41: 3335
[24] Lee C, Sedlak D L. J Mol Catal A, 2009, 311: 1
[25] Taghdiri M, Saadatjou N, Zamani N, Farrokhi R. J Hazard Mater, 2013, 246-247: 206
[26] Zhang L Z, Zeng H H, Zeng Y M, Zhang Z H, Zhao X F. J Mol Catal A, 2014, 392: 202
[27] Chen H, Zhang L Z, Zeng H H, Yin D J, Zhai Q, Zhao X F, Li J H. J Mol Catal A, 2015, 406: 72
[28] Jin H X, Wu Q Y, Pang W Q. J Hazard Mater, 2007, 141: 123
[29] López Navarrete J T, Hernández V, Ramírez F J. J Mol Struct, 1995, 348: 249
[30] Jiang C J, Guo Y H, Hu C W, Wang C G, Li D F. Mater Res Bull, 2004, 39: 251
[31] Yue B, Zhou Y, Xu J Y, Wu Z Z, Zhang X, Zou Y F, Jin S L. Environ Sci Technol, 2002, 36: 1325
[32] Keenan C R, Sedlak D L. Environ Sci Technol, 2008, 42: 1262
[33] Guo Y H, Hu C W, Jiang S C, Guo C X, Yang Y, Wang E B. Appl Catal B, 2002, 36: 9
[34] Wang N, Zhu L H, Lei M, She Y B, Cao M J, Tang H Q. ACS Catal, 2011, 1: 1193
[35] Pignatello J J, Liu D, Huston P. Environ Sci Technol, 1999, 33: 1832
[36] Kozhevnikov I V. Chem Rev, 1998, 98: 171
[37] Troupis A, Hiskia A, Papaconstantinou E. Environ Sci Technol, 2002, 36: 5355
[38] Xu L J, Wang J L. J Hazard Mater, 2011, 186: 256
[39] Zhang S X, Zhao X L, Niu H Y, Shi Y L, Cai Y Q, Jiang G B. J Hazard Mater, 2009, 167: 560