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电催化氧化技术(ECOP)广泛应用于难生化废水的处理,具有处理效率高、占地面积小、无药剂添加和易于管理等优点,ECOP可以将大分子污染物以及难生化有毒污染物分解成羧酸、丙酮等小分子物质,进而可以缓慢地将这些小分子有机物进一步氧化分解成CO2。在ECOP中起到主导作用的是阳极材料,钛基氧化物涂层电极(DSA)[1]是目前常用的阳极材料,其中Ti/SnO2-Sb电极被认为是DSA电极中氧化效率较高的电极。目前,钛基锡锑电极(Ti/SnO2-Sb)存在的主要问题是电极催化效率偏低和催化层容易脱落[2]。Ti/SnO2电极改性的研究很多都集中在掺杂稀土元素[3-6]以及使用新型的双向脉冲式电沉积工艺优化,以此提高电催化氧化效果[7-8],通过钛基底改性进而提高催化效率的研究[9-10]较少。为了提高Ti/SnO2-Sb电极的催化效率,本研究采用阳极氧化法[11],在钛板上制备垂直生长的空心二氧化钛纳米管(TiO2-NTs),并以此为基底,制备纳米管修饰的锡锑电极(TiO2-NTs/SnO2-Sb),进而通过与Pt、TiO2-NTs和Ti/SnO2-Sb电极对比研究,阐明其高效降解有机物的主要机制。
目前,对于锡锑电极的处理研究多停留在实验室处理模拟污染物,而对于实际工业废水的处理研究较少。有研究[12]指出,钻井废水中含有较多的高分子聚合物和丙烯腈等有害物质,具有色度深、高COD值和难生化处理的特点。国内对于钻井废水的处理技术主要有混凝法、臭氧氧化法、Fenton试剂氧化法和生物法等[13-16],但是这些方法单一使用存在处理效果差、易产生二次污染的缺点。本研究以制备出的高效TiO2-NTs/SnO2-Sb电极作为阳极材料处理实际钻井废水,考察TiO2-NTs/SnO2-Sb电极对于实际钻井废水的处理效果,这对该电极应用于难生化降解有机废水的ECOP处理有着重要的现实意义。
修饰型TiO2锡锑电极的制备及其在钻井废水处理中的应用
Preparation of Sb-doped SnO2 electrode with titanium dioxide nanotubes on Ti substrate and its application in drilling wastewater treatment
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摘要: 为了解决传统锡锑电极电催化氧化效果偏低、涂层易脱落的问题,使用阳极氧化法,在钛基底表面制备垂直生长的二氧化钛纳米管(TiO2-NTs), 然后在此基底上采用电沉积法制备出锡锑电极(TiO2-NTs/SnO2-Sb)。结果表明,相比没有二氧化钛纳米管的锡锑电极(Ti/SnO2-Sb),TiO2-NTs/SnO2-Sb 电极的析氧电位从1.9 V 增加到2.03 V,电极具有较高的羟基自由基生成能力和更高的电流效率,促进了苯酚的矿化。TiO2-NTs/SnO2-Sb 电极对实际钻井废水具有较好的脱色效果,COD去除率高达81.4%,且能够有效地改善阳极的“中毒效应”。Abstract: This study aimed to address the low electro-catalytic oxidation effect and coating falling off easily of traditional Sb-doped SnO2 electrode. The vertically grown titanium dioxide nanotubes (TiO2-NTs) structure was first formed on the Ti plate by anodization, then the Sb-doped SnO2 electrode (TiO2-NTs/SnO2-Sb) was prepared on this modified Ti plate by electrodeposition. The results showed that compared to the Sb-doped SnO2 electrode without titanium dioxide nanotubes (Ti/SnO2-Sb) on the Ti plate, the oxygen evolution potential of TiO2-NTs/SnO2-Sb electrode increased from 1.9 V to 2.03 V, which contributed to the phenol mineralization enhancement due to its high capacity for hydroxyl radicals generation and higher current efficiency. The TiO2-NTs/SnO2-Sb electrode can completely remove the color of the drilling wastewater, and the COD removal rate was as high as 81.4%. In addition, the “Poisoning effect” of the anode was alleviated during the treatment of drilling wastewater.
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Key words:
- electrochemical oxidation /
- TiO2 nanotube /
- SnO2 electrode /
- hydroxyl radical
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表 1 不同阳极条件下钻井废水色度变化
Table 1. Color variation of the drilling wastewater with different anodes
反应时间/h 色度/倍 TiO2-NTs Pt Ti/SnO2-Sb TiO2-NTs/SnO2-Sb 0 2 750 2 750 2 750 2 750 6 2 600 2 000 1 500 1 500 12 1 000 600 400 400 24 800 50 0 0 表 2 不同电极电催化钻井液过程Tafel拟合动力学参数
Table 2. Tafel fitting kinetic parameters of anodes during the drilling wastewater treatment
电极材料 a/V b/V R2 Pt(0 h) 2.57 0.45 0.992 Pt(6 h) 2.70 0.49 0.995 Pt(24 h) 2.85 0.56 0.984 Ti/SnO2-Sb(0 h) 2.66 0.43 0.998 Ti/SnO2-Sb(6 h) 3.79 0.81 0.993 Ti/SnO2-Sb(24 h) 4.01 0.76 0.997 TiO2-NTs/SnO2-Sb(0 h) 4.13 0.83 0.999 TiO2-NTs/SnO2-Sb(6 h) 3.97 0.76 0.998 TiO2-NTs/SnO2-Sb(24 h) 3.11 0.56 0.960 -
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