改性纳米TiO₂的研究及在光催化处理矿井水中的应用

【作者】 姚恩亲；

【导师】 桂和荣；

【作者基本信息】 安徽理工大学 ， 环境工程， 2008， 博士

【摘要】 纳米TiO₂光催化技术作为一种高级氧化技术,在污染物降解方面具有降解效率高、无二次污染等优点。但是,纯的纳米TiO₂光催化性能不强,限制了它的应用。为了提高纳米TiO₂的光催化活性,必须对其进行改性。矿井水是一种可重复利用的水资源。将改性纳米TiO₂应用于矿井水处理中,对缓解我国水资源紧张,实现矿区经济可持续发展具有重要意义。采用溶胶-凝胶技术合成WO₃掺杂改性纳米TiO₂和改性聚乙二醇（PEG）的TiO₂。运用XRD、SEM、XPS、IR、TG-DTA等测试手段,研究了改性二氧化钛的物理化学性质。考察了改性纳米TiO₂对甲基橙的光催化降解情况和动力学:研究了催化剂投加量、溶液初始浓度、反应时间、反应温度、pH对甲基橙降解的影响,优选出最佳掺杂量的改性TiO₂。比较了在光催化和光氧化两种作用下甲基橙降解的动力学。考察了7种无机离子对改性TiO₂光催化降解矿井水中COD的影响,HCO₃^-、SO₄^2-、Cl^-和Ca²⁺,在矿井水中的实际浓度时对两种光催化剂（PEG400-TiO₂和TiO₂）的性能均有抑制作用,抑制作用大小为HCO₃^-＞SO₄^2-＞Cl^-＞Ca²⁺;Cl^-在相对低浓度范围时（0.9～8.9mmol/l）,对两种光催化剂的性能有促进作用;Mn²⁺在矿井水中实际浓度时（0.0013mmol/L）,对光催化性能没有影响,当Mn²⁺浓度＞0.013mmol/L就对TiO₂光催化性能有抑制,当Mn²⁺浓度＞0.039mmol/L才对PEG400-TiO₂光催化性能有抑制。Cu²⁺在其浓度为0.008～0.072mmol/L对两种光催化剂性能有促进作用,其浓度＞0.072mmol/L对光催化性能有抑制作用;和Mn²⁺、Cu²⁺一样Fe³⁺在矿井水中实际浓度时（0.0457mmol/L）,对两种光催化剂没有影响,但在浓度（0.2～0.7mmol/L）对光催化剂的性能均有显著促进作用,但浓度＞0.8 mmol/L对光催化性能有抑制作用。通过两因子方差分析,各离子浓度均与实际矿井水中离子浓度相近条件下,HCO₃^-和SO₄^2-,HCO₃^-和Cl^-,SO₄^2-和Cl^-对两种光催化剂均降解率均有显著影响;Mn²⁺和Cu²⁺对两种光催化剂均降解率均没有显著影响;Mn²⁺和Ca²⁺,Cu²⁺和Ca²⁺中的Ca²⁺对两种光催化剂的降解率均有显著影响,而Mn²⁺和Cu²⁺没有影响。研究了活性炭负载改性TiO₂处理矿井水的中试试验,针对超标严重的指标,氟化物、浊度、色度、Hg²⁺、Cr⁶⁺、大肠菌群、细菌总数等参数进行5d的试验,结果良好。并对其稳定性和工艺的经济效益进行了初步分析。更多还原

【Abstract】 As an advanced oxidation technology,the nano-TiO₂ photocatalytic technology can degrade the pollutants effectively without secondary pollution.But the photocatalytic performance of pure nano-TiO₂ is not good, so its application is limited.In order to improve the photocatalytic activity,modification of pure nano-TiO₂ is an effective way.While the mine water is a kind of reusable water,in this way,using the nano-TiO₂ in the treatment of mine water will be significant to alleviate the shortage of water resources and achieve sustainable economic development of the mining areas.The WO₃ modified and the PEG modified nano-TiO₂ were prepared with the sol-gel technology.Both were characterized or tested with XRD,SEM,XPS, IR,TG-DTA,etc.Research of the degradation of methyl orange caused by the photocatalysis of modified nano-TiO₂.The kinetics of photocatalysis in methyl orange were studied.The influence factors such as the amount of photocatalyst,initial concentration of the solution,reaction time, temperature and the pH on the degradation of methyl orange were also investigated and the optimum amount of WO₃ and PEG were determined.The dynamics of the degradation of methyl orange under photo-oxidation and photo-catalyze was compared.The influences of 7 kinds of inorganic ions to the activity of the modified TiO₂ on catalyzing and degrading the COD in the water were studied. It is found that HCO₃^-,SO₄^2-,Cl^-and Ca²⁺ all can restrain the two photocatalysts PEG400-TiO₂ and TiO₂ when they reach the actual concentration in the coal mine water,and the order of their restraining capacities is HCO₃^-＞SO₄^2-＞Cl^-＞Ca²⁺.The Cl^- can improve the performances of the two photocatalysts when its concentration is low（0.9～8.9mmol/l）; Mn²⁺ has no influence on the photocatalysts when it reaches the actual concentration（0.0013mol/L）,while when its concentration is more than 0.013mol/L,it could restrain the photocatalytic performance of TiO₂,and it can restrain the catalytic performance of PEG400-TiO₂ only when its concentration is more than 0.039mmol/L.The Cu²⁺ can improve the performances of the two photocatalysts when its concentration is 0.008～0.072mmol/L,while when its concentration is more than 0.072mol/L,it can restrain the photocatalytic performance;Like Mn²⁺ and Cu²⁺,Fe³⁺ has no influence on the photocatalysts when it reaches the actual concentration （0.0457mmol/L）,and it can greatly improve the performances of the two photocatalysts when its concentration is 0.2～0.7mmol/L,but it can restrain the photocatalytic performance when its concentration is more than 0.8mmol/L.When the concentration of each ion is very close to the one in the actual mine water,it shows that HCO₃^- and SO₄^2-,HCO₃^- and Cl^-,SO₄^2- and Cl^- all have obvious influences on the degradation rate of the two photocatalysts through the two-factor analysis of variance;Both Mn²⁺ and Cu²⁺ have no influence on the degradation rate of the two photocatalysts;When the Mn²⁺ and Ca²⁺ coexist or Cu²⁺ and Ca²⁺ coexists,it is Ca²⁺ that influences the degradation rate of the both photocatalysts.Experimentation of the activated carbon load modified Ti₂ on the coal mine water has been researched.5d experiment on the serious against standard indicators,such as fluoride,nephelometer,chroma,Hg²⁺,Cr⁶⁺, coliform bacteria and parameters of the total number of the bacteria has been carried out.The results are satisfying and its stability and the economic benefits are preliminarily analyzed.更多还原