Photoelectrocatalytic humic acid degradation kinetics and effect of pH,applied potential and inorganic ions

This study addresses the removal of humic acid (HA) dissolved in an aqueous medium by a photoelectrocatalytic process. UV₂₅₄ removal and the degradation of color (Vis₄₀₀) followed pseudo‐first order kinetics. Rate constants were 1.1 × 10^?1 min^?1, 8.3 × 10^?2 min^?1 and 2.49 × 10^?2 min^?1 (R² > 0.97) for UV₂₅₄ degradation and 1.7 × 10^?1 min^?1, 6.5 × 10^?2 min^?1 and 2.0 × 10^?2 min^?1 for color removal from 5 mg dm^?3, 10 mg dm^?3 and 25 mg dm^?3 HA respectively. Following a 2 h irradiation time, 96% of the color, 98% of the humic acid and 85% of the total organic carbon (TOC) was removed from an initial 25 mg dm^?3 HA solution in the photoanode cell. Photocatalytic removal on the same photoanode was also studied in order to compare the two methods of degradation. Results showed that the photoelectrocatalytic method was much more effective than the photocatalytic method especially at high pH values and with respect to UV₂₅₄ removal. The effect of other important reaction variables, eg pH, external potential and electrolyte concentration, on the photoelectrocatalytic HA degradation was also studied. Copyright © 2003 Society of Chemical Industry     

新型Au/TiO_2纳米管的制备及其在化学需氧量测定中的应用研究

该文首次用光电催化的方法,在TiO2纳米管中嵌入金纳米粒子,新材料可以促进界面间电子的传递,有助于电子和空穴对的分离,进而提高光催化效率.对Au/TiO2纳米管进行扫描电子显微镜(SEM),色散型X射线能谱(EDX)和X射线衍射(XRD)表征,结果表明金纳米粒子被成功嵌入TiO2纳米管中,形成蜂窝状结构.将该材料首次用于光电催化法化学需氧量(COD)的测定,发现该传感器的光电流值在1～800mg/L范围内与COD值有良好的线性响应,检测限为0.3 mg/L.利用该传感器测定实际水样的COD值,结果与传统的K2Cr2O7标准方法有较好的一致性.     

Bi2MoO6@CQDs/TiO2纳米管阵列的制备与光电催化性能

为提高TiO₂的可见光光电催化活性,本文用Bi₂MoO₆和碳量子点(CQDs)对TiO₂纳米管阵列(TNA)进行了改性。以CQDs、Bi(NO₃)₃·5H₂O和Na₂MoO₄为原料,通过简单的溶剂热法,在TNA中沉积了CQDs和Bi₂MoO₆,成功制备了新型Bi₂MoO₆@CQDs/TNA。扫描电镜(SEM)和元素mapping分析结果表明,CQDs和Bi₂MoO₆成功涂覆在TNA管壁上。通过在可见光下降解甲基橙(MO)溶液,评价了所制备的光催化剂的光电催化性能。结果显示,经3 h的光电催化降解,Bi₂MoO₆@CQDs/TNA对MO的去除率比Bi₂MoO₆/TNA高32%。CQDs优异的上转换光致发光(UCPL)性能促进了TiO₂在可见光下被激发产生光生载流子,同时Bi₂MoO₆与TiO₂的耦合抑制了光生载流子的复合,从而提高了Bi₂MoO₆@CQDs/TNA的光电催化活性。     

Preparation and characterization of TiO2/Ti film electrodes by anodization at low voltage for photoelectrocatalytic application

Multiporous TiO₂/Ti film electrodes were prepared by different anodic oxidation processes at low voltage, in which the micro-structured TiO₂ thick films were prepared in H₂SO₄–H₂O₂–H₃PO₄–HF solution for 2 h and the nano-structured TiO₂ thin films were prepared in H₃PO₄–HF solution for 30 min with post-calcination. Both types of TiO₂/Ti films were characterized by scanning electron microscopy and X-ray diffraction analysis. The photocatalytic (PC) and photoelectrocatalytic (PEC) reactivity of the TiO₂/Ti electrodes were evaluated in terms of bisphenol A (BPA) degradation in aqueous solution. The experimental results demonstrated that the nano-structured TiO₂/Ti thin-film electrodes had higher reactivity in the BPA degradation reaction. The PEC degradation of BPA was further studied using different cathodes, either a reticulated vitreous carbon (RVC) electrode or a platinum (Pt) electrode. The experimental results confirmed that the efficiency of BPA degradation could be significantly enhanced in the TiO₂/Ti–RVC reaction system due to the generation of H₂O₂ on the RVC cathode. It is believed that such a H₂O₂-assisted TiO₂ PEC oxidation process may have good potential for water and wastewater treatment.     

二氧化钛光电催化降解水中有机污染物的研究进展

光电催化可有效阻止光生载流子的简单复合,提高催化活性,是一种很有发展前途的污水处理方法。综述了TiO2光电催化原理、光电极的制备及影响光电催化降解的因素等近年来的研究进展。     

新型光电催化反应器的研制及效能提高的研究

研制了一种新型的光电催化反应器,并对0.5 g/L的聚乙二醇-2000模拟废水进行了处理研究,考察了外加阳极偏压、外加氧化剂H2O2、金属离子掺杂和硫酸酸化对光催化提高效果的影响。结果表明,在最佳阳极偏压12 V条件下COD去除率提高了18.4%,光电协同作用明显;投加30%H2O2 4.0 mL,反应3 h后COD去除率达95.4%;金属离子掺杂和H2SO4酸化改性后的TiO2膜比改性前对COD的去除率有了不同程度的提高。     

A high‐efficient rotating disk photoelectrocatalytic (PEC) reactor with macro light harvesting pyramid‐surface electrode

A series of pyramid‐surface TiO₂/Ti electrodes were proposed, fabricated, and used in a rotating disk photoelectrocatalytic (PEC) reactor to treat rhodamine B (RB) solution. Compared with conventional planar electrode, pyramid‐surface electrode exhibited much lower light reflectivity, larger photocurrent, and better treatment efficiency. For samples containing 20 to 150 mg L^?1 RB, 100– 98% color removal, and 87–30% COD removal were obtained in 150 min using 1/3 (h/w) pyramid‐surface electrode, much higher than 98–77% and 48–9% obtained by a conventional planer electrode. The excellent treatment performance attributed to two major reasons: (a) enhanced light harvest resulted from multiple reflections of irradiation light on the pyramid‐surface, and (b) enlarged electrode surface area enabling the electrode to carry more TiO₂ catalyst and pollutants for treatment. Experimental results also showed that the pyramid‐surface electrode consumed less power and exhibited superior performance when treating high concentration wastewater. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2448–2455, 2012     

泡沫镍负载二氧化钛光电协同催化氧化砷

通过化学复合镀的方法制备成催化材料,TiO2粉末与镍磷合金共沉积在泡沫镍表面上,并通过光、电催化的方法将3价砷(As(III))氧化为5价砷(As(V))进行吸附试验。结果表明,As(III)吸附在7 h后达到平衡,As(V)吸附在5 h后达到平衡;As(III)和As(V)的吸附动力学与拟2级动力学特征相一致。在光催化、电催化和光电催化3种氧化As(III)的方法中,光电催化的效果最好;当As(III)的初始质量浓度为1 mg/L时,使用光电催化方法的除砷率能达到80.76%。     

TiO2薄膜光电催化亚甲基蓝的研究

采用溶胶-凝胶-浸渍法在钛基底上制备了TiO2薄膜,以该薄膜为工作电极,石墨作对电极,饱和甘汞电极为参比电极,建立光电催化反应体系,对亚甲基蓝溶液进行了光电催化降解研究。结果表明：当外加偏压1.0 V,热处理温度500℃时,pH为10.2,TiO2薄膜光电催化活性最好,光电催化亚甲基蓝120 min可使其脱色率达64....     

光电转盘反应器处理染料废水数学模型

相较于传统的A／O法、生物处理法等水污染治理技术,光电催化降解技术在处理废水时具有处理彻底、水力停留时间短、降解完全等巨大优势。基于此提出了具有动态光阳极的转盘式光电液膜反应器（RPEC）,通过将催化剂负载在转盘上,利用转盘的转动加强废水的传质。在转盘表面形成几十微米的液膜,激发光直接透过该液膜即可照射到光阳极催化剂表面,解决了光源利用率的问题,同时可以通过外加偏压来减少光生电子与空穴的简单复合,提高了处理效率。该文在RPEC反应动力学方程的基础上,综合考虑光强、外加偏压、转盘转速、初始浓度、催化剂用量以及溶液DH值等因素对反应过程的影响,运用MAT—LAB软件对转盘转动的反应过程进行模拟迭代计算,建立迭代模型,绘制出降解曲线。试验证明计算结果与试验数据有较好吻合,从而建立了不同条件下转盘式光电催化降解废水的降解模型,为实际工业应用提供指导意义。