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首页> 外文学位 >Developing an efficient nanocatalyst system for enhanced photocatalytic degradation of toxic aqueous contaminants.
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Developing an efficient nanocatalyst system for enhanced photocatalytic degradation of toxic aqueous contaminants.

机译：开发有效的纳米催化剂体系，以增强有毒水性污染物的光催化降解。

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摘要

Heterogeneous photocatalysis is an emerging treatment option for degrading phenolic contaminants. This dissertation focused on using Titanium dioxide (TiO2) nanomaterials as a potential heterogeneous photocatalyst. The various factors affecting the TiO2 nanoparticle catalyzed photo-degradation process were discussed and the photocatalysis of phenol using TiO2 nanoparticles was evaluated. A statistical model was developed to consolidate the factors based on the Box-Benkhen statistical design (BBD) technique. The degradation rate constant was considered as the model response, and expressed as a function of the independent variables for the photocatalysis. The independent variables considered for developing the BBD based model were as follows: TiO 2 nanoparticle size and concentration, dissolved oxygen (DO) concentration, and substrate concentration. The model-predicted phenol photocatalytic rates were in agreement with the experimental rates for all four variables under consideration. The model developed for phenol degradation was later used to predict the photocatalytic degradation rate of p-cresol, a substituted phenol. Except at high DO concentration and low p-cresol concentration, the model-predicted rates were in close agreement with the experimental degradation rate for p-cresol. A comparison of quantum yield and activation energy for phenol and p-cresol revealed that the latter degraded faster than the former.;The practical limitations associated with the use of TiO2 nanoparticle slurry in photocatalytic process, and the challenges in immobilizing TiO2nanoparticles onto a solid catalyst support were discussed. A study on fabrication of immobilized TiO2 nanofiber using sol-gel electrospinning was presented in the later chapters of this dissertation. The characterization procedures followed to fabricate the immobilized TiO 2 nanofiber catalyst was presented. Literature suggested that stability of the immobilized nanofiber catalyst was an issue. A surface treated catalyst support material was used to improve the stability of the immobilized nanofiber catalyst. The optimum process variable settings of sol-gel electrospinning for minimum nanofiber diameter were identified using the BBD procedure. The diameter of the TiO2 nanofiber generated from the BBD optimization was significantly lower than that reported in the literature. Other than the electrospinning variables, the calcination condition and catalyst loading on the support affected the specific surface area (SSA) of the immobilized catalyst. The immobilized TiO2 nanofiber catalyst fabricated by sol-gel electrospinning under optimum process conditions had high SSA and improved catalytic property. A comparison of phenol photocatalytic rates of TiO2 nanoparticle slurries against the immobilized TiO2 nanofiber demonstrated that the latter had higher (approximately twice) catalytic activity than that of the former at comparable SSA.
机译：非均相光催化是用于降解酚类污染物的新兴处理选择。本文主要研究使用二氧化钛（TiO2）纳米材料作为潜在的多相光催化剂。讨论了影响TiO2纳米粒子催化光降解过程的各种因素，并评价了TiO2纳米粒子对苯酚的光催化性能。基于Box-Benkhen统计设计（BBD）技术，开发了一个统计模型来合并这些因素。降解速率常数被认为是模型响应，并表示为光催化自变量的函数。考虑用于开发基于BBD的模型的独立变量如下：TiO 2纳米粒子的大小和浓度，溶解氧（DO）浓度以及底物浓度。对于所有四个变量，模型预测的苯酚​​光催化速率与实验速率一致。为苯酚降解开发的模型随后用于预测对甲酚（一种取代的苯酚）的光催化降解速率。除了在高溶解氧浓度和低对甲酚浓度下，模型预测的速率与对甲酚的实验降解速率非常吻合。对苯酚和对甲酚的量子产率和活化能的比较表明，对甲酚和对甲酚的降解速度快于对甲酚。;在光催化过程中使用TiO2纳米颗粒浆料的实际限制，以及将TiO2纳米颗粒固定到固体催化剂上的挑战支持进行了讨论。在本文的后续章节中，将对利用溶胶-凝胶电纺丝法制备固定化的TiO2纳米纤维进行研究。介绍了制备固定化TiO 2纳米纤维催化剂的表征程序。文献表明固定化纳米纤维催化剂的稳定性是一个问题。使用表面处理过的催化剂载体材料可提高固定化纳米纤维催化剂的稳定性。使用BBD方法确定了最小纳米纤维直径的溶胶-凝胶静电纺丝的最佳工艺变量设置。由BBD优化产生的TiO2纳米纤维的直径显着低于文献报道的直径。除了静电纺丝变量以外，煅烧条件和催化剂在载体上的负载影响固定化催化剂的比表面积（SSA）。在最佳工艺条件下通过溶胶-凝胶电纺丝法制得的TiO2纳米纤维固定化催化剂具有较高的SSA值和改善的催化性能。 TiO2纳米颗粒浆料与固定化TiO2纳米纤维的苯酚光催化速率的比较表明，在可比的SSA中，后者具有比前者更高的催化活性（大约两倍）。

著录项

  • 作者

    Ray, Srimanta.;

  • 作者单位

    University of Windsor (Canada).;

  • 授予单位 University of Windsor (Canada).;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 196 p.
  • 总页数 196
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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