【作者】 王东亮；

【导师】 武福平；

【作者基本信息】 兰州交通大学 ， 市政工程， 2008， 硕士

【摘要】 本文采用真空蒸发镀膜法在几种不同基材上制备了二氧化钛光催化薄膜,并用扫描电镜和能量色散谱仪对其进行了表征与分析;在自制的光催化和电助光催化反应器中对难降解苯环类物质的典型代表—苯酚进行了降解实验,对所制备的二氧化钛薄膜的光催化活性和稳定性进行了评价,考察了几种主要影响因素对苯酚的光催化降解和电助光催化降解的影响,结果表明:采用真空蒸发镀膜法制备的二氧化钛光催化薄膜致密、连续无裂缝,二氧化钛颗粒在薄膜表面分布均匀,可以有效降解苯酚,光催化活性和稳定性良好。以不同基材制备的二氧化钛薄膜的光催化活性有所不同,二氧化钛/不锈钢板、二氧化钛/玻璃板和二氧化钛/钛板薄膜对苯酚均有较高的降解率,而二氧化钛/铜板薄膜对苯酚的降解率几乎只有前三者的一半。二氧化钛薄膜的光催化活性较镀膜所使用的商品二氧化钛粉末的活性有较大提高,二氧化钛/玻璃板薄膜对100mg/L的苯酚4小时的去除率达到57%以上,而粉末二氧化钛在相同的时间内对同等浓度的苯酚的去除率不到20%,催化剂粒度的变化是产生上述差异的主要原因。对不同苯酚浓度下的光催化降解反应作一级反应动力学分析,苯酚在二氧化钛薄膜的降解反应为准一级反应,符合Langmuir-Hinshelwood（L-H）模型,随着有机物浓度增高,降解表观速率常数逐渐下降。苯酚在二氧化钛薄膜上的电助光催化降解反应也为准一级反应,并且电助光催化降解速率大于光催化降解速率。在苯酚的电助光催化降解过程中,电压是一个重要的影响因素。在电压为1.0 V苯酚有最高的去除率;当外加电压从0V升至1.0V,苯酚降解率随电压升高而增大;当外加电压大于1.0V时,增大电压苯酚降解率反而有所下降。溶液pH值的变动对苯酚在二氧化钛薄膜上的光催化降解和电助光催化降解均产生一定影响。在酸性条件下电助光催化对苯酚去除率反而不如光催化（光催化pH=3时苯酚去除率最高）,在中性和碱性条件下电助光催化对苯酚去除率要高于光催化（光催化在碱性条件下对苯酚几乎没有降解作用）。在不同情形下光生电子能否有效去除是产生差异的主要原因。NO₃^-和SO₄^2-对苯酚的光催化降解几乎没有影响;Cl^-、SO₃^2-和C₂O₄^2-作为·OH的清除剂与苯酚竞争导致苯酚去除率下降;而CO₃^2-通过影响整个体系的pH值,导致苯酚去除率的下降。电解质种类对电助光催化降解苯酚的影响NO₃^-＜Cl^-、SO₄^2-、C₂CO₄^2-＜SO₃^2-、CO₃^2-。更多还原

【Abstract】 TiO₂ films were prepared with vacuum deposition coating on different kinds of substrates.The films were characterized by EDS and SEM.One of the most typical and difficultly degradated aromatic compounds--phenol was the objective substance.The photocatalytic and electrochemically assisted photocatalytic degradation of phenol on TiO₂ films were studied.The photocatalytic activity and stability were estimated.Also the effects of some factors were investigated.The result indicated:The surfaces of the TiO₂ films prepared with vacuum deposition are fine,without crack. The distribution of TiO₂ in the films is well-proportioned.An excellent photocatalytic property is investigated,which could degradate phenol in aqueous solution effectively.Different from substrate,the photocatalytic activity is different to some extent.TiO₂/Ti, TiO₂/steel and TiO₂/glass have almost the same activity,while the activity of TiO₂/Cu is much lower,only 1/2 of that of the formers.The TiO₂ films have higher photocatalytie activity than commodity TiO₂ power which was used as the material of the films.The degradation rate of phenol on TiO₂/glass is 57%,when C₀=100mg/L,t=4h,while that of the powered TiO₂ is just 20%.The difference of the granularity may be the reason.In the experiment conditions,the photocatalytic and electrochemically assisted photocatalytic degradations of phenol on TiO₂ films both follow apparen first-order reaction kinetics.The rate of electrochemically assisted photocatalytie quicker than that of photocatalytic.The change of pH inflences both photoeatalytic and electrochemically assisted photocatalytic.The optimal initial pH of photocatalytic is 3 while that of electrochemically assisted photocatalytic is 7.In acidic condition the rate of electrochemically assisted photocatalytic is slower than photocatalytic;In alkaline and litmuless conditions the rate of electrochemically assisted photocatalytic is quicker than photocatalytic.The phenol degradation rate gets the maximum at U=1.0 V.When U＜1.0 V,the rate of electrochemically assisted photocatalytic gets more and more quicker;When U＞1.0 V, turning up the anodic bias the rate gets slower.There is no inference to photocatalytic when the solution contains NO₃^- or SO₄^2-.While C1^-、SO₃^2-、C₂O₄^2- or CO₃^2- may cut down the rate of photocatalytic degradation.All of these ions including NO₃^- and SO₄^2-may have effect on electrochemically assisted photocatalytic,the extent was NO₃^-＜C1^-、SO₄^2-、C₂CO₄^2-＜SO₃^2-、CO₃^2-.更多还原