【作者】 杨祝红；

【导师】 陆小华； 冯新；

【作者基本信息】 南京工业大学 ， 化学工程， 2003， 博士

【摘要】 以二氧化钛为代表的纳米半导体光催化处理废水技术，尤其是在处理水中痕量难降解有机污染物方面已为世人所公认。但是要真正大规模应用还存在以下主要问题：1)TiO₂纳米颗粒的高活性与分离回收问题；2)大规模低成本的光催化剂制备问题；3)产业化过程的放大问题及处理废水的成本问题等，这些问题使得光催化技术在废水处理方面的应用一直停滞不前。 从四钛酸钾晶须前驱体出发，利用离子交换法得到的既具有微米级尺寸的形貌，又具有纳米结构的TiO₂晶须有望成为解决以上问题的新型光催化剂。 本文的主要工作是探索适合于大规模制备高质量TiO₂晶须的方法及其在光催化降解含有机污染物废水中的应用。 在TiO₂晶须制备方面，本文提出了适合于大规模生产的离子交换热力学模型，即只要控制物料的初始水合比和溶液的pH值就可达到控制固相中钾含量的目的，保证了TiO₂晶须的质量，同时解决了原模型需要在线测定溶液中K⁺浓度的问题。通过模型分析和实验验证获得的结果为，平衡时固相中钛钾摩尔比随初始水合比及溶液酸性的增强而增加，提出了采用多级水合定向控制和合成TiO₂晶须的最优生产工艺。当溶液的pH值为2时，经过初始水合比分别为10倍、20倍、30倍的水三次水合后，可得到钾含量低于0.5 wt％的高质量TiO₂晶须；而原模型采用一次水合工艺，需用大约1000倍的水稀释，才能使溶液中m_K⁺的浓度符合制备上述要求的TiO₂晶须。 在将TiO₂晶须用于废水处理方面，分别以甲基橙和氯仿作为模型代表物，研究了改性TiO₂晶须在印染废水和饮用水净化处理方面的光催化活性。 研究结果表明，经过150℃甘油热处理后TiO₂晶须的主晶相为H₂Ti₈O₁₇，比表面积为127 m²／g，其中小于1 nm的微孔的比表面积为79 m²／g，其光催化降解甲基橙的活性优于P25（TiO₂，Degussa公司），但是该TiO₂晶须的光催化活性 摘 要 不能持久稳定，使用两次即失活。 TIO。晶须经铂掺杂表面改性后，光催化活性和稳定性都得到了大幅度的提 高，同时发现氧气作为反应中的电子受体，对光催化降解氯仿的效率有着极其重 要的影响。如果降解过程中没有氧气的参与，掺铂量为0．5 Wt％的TIOZ晶须对 氟仿的价解率不足25％；W同川的光训化剂，在血气气预分你听，对凤仙的！耶 价率机离达98．叩％，从汕省人勺4．5估。仆仆J条件卜止复攸川八次后，该催化剂 对氯仿的降解率仍能维持在90％以上。 发明了基于TIOZ晶须的连续光催化反应装置，并建立了相应的废水处理技 术，其特点是：废水在光反应管中以平推流方式流动，取代了传统的反应效率低 下的全混流方式，因此具有较高的反应器效率。在相同条件下，与小试装置相比， 处理废水效率提高 5倍以上。在此基础上完成了日处理 200吨印染废水处理装置 的初步设计。更多还原

【Abstract】 It is well-known that photocatalytic technique of nano-semiconductor is suitable to degrade organic pollutants. However, there are many problems in large-scale application, which make photocatalytic technique in wastewater application stagnant. Three main possible reasons could account for this phenomenon. One possible reason is that it is hard to separate TiO2 nanoparticle with high photocatalytic activity from the system. Another possible reason is that it is hard to prepare the photocatalyst cheaply in large scale. The third possible reason is that it is hard to solve the problem about magnification in industrialization process and to reduce the cost of purifying wastewater.In order to solve the above problems, our research group did a lot of research. Firstly, the K2Ti4O9 whisker was taken as the precursor and TiO2 whisker was obtained by ion-exchange method. The size of the TiO2 whisker is about micron and it has nanostructures. The main purpose of this thesis is to investigate the method for large-scale production of high quality TiO2 whisker and its applications in photocatalytic degradation of organic substances in wastewater.For the improvement of titanium dioxide whisker preparation method, a new hydration kinetics model, which is suit for large-scale production, is proposed. The control variables in the new model are the initial hydration ratio and pH value of solution. Therefore, we could avoid measuring the concentration of K+ ion by ISE with certain amount of KC1 added in the solution. Finally a controllable and optimal approach for the synthesis of TiO2 whisker was presented. The concentration of HCl acid is lmol/l. Ilydratcd 3 times, the amount of water 10 times, 20 times, 30 times. Then the high quality TiO2 whisker was obtained, among which the content of K element is less than 0.5% (wt%).In application about the objective the printing and dyeing wastewater and drinking water purifying were mainly studied. Methyl orange and chloroform were taken as the study objectives for printing and dyeing wastewater and drinking water, respectively. The photocatalytic activity of glycerine modified TiO2 whisker to degrade methyl orange is prior to P25. However, the stability of the photocatalyst decreases after two degradation times. Modified by Pt doping, TiO2 whisker’s both photocatalytic activity and stability were improved. Ninety eight percent chloroform could be degraded by the 0.5% Pt doped TiO2 whisker which was prepared using light reduction deposition. After the catalyst was repeated to use 8 times, above 90% chloroform could still be degraded. So, the modified TiO2 whisker will be promisingdealing with wastewater in real practice.A flow photocatalytic reactor based on TiO2 whisker is established, which is above 5 times efficiency than a batch one in the same conditions. Furthermore an apparatus dealing with 200 tons wastewater per day was designed and the capacity to deal with waste water and the degradation could be automatically controlled using series connection and parallel connection reactors.更多还原