【作者】 李春；

【导师】 何杰；

【作者基本信息】 安徽理工大学 ， 应用化学， 2008， 硕士

【摘要】 近年来,铌酸盐优越的物理化学性能与光催化活性引起了人们广泛的重视。铌酸盐在光催化分解水和光催化降解有机物方面具有优越的性能。苯酚是一种较难降解的有机物,特别是在工业废水中含有的苯酚如何去除一直是研究者感兴趣的课题。本研究探讨了铌酸盐K₂Nb₄O₁₁的合成条件以及对苯酚的光催化降解性能。实验采用固相反应法制备了铌酸钾K₂Nb₄O₁₁光催化剂。并运用扫描电镜（SEM）、X—射线粉末衍射（XRD）和紫外—可见漫反射光谱（UV-vis DRS）等表征手段,研究了催化剂的晶体结构、粒子形貌以及对紫外—可见漫反射光谱的吸收特征,探讨了K₂CO₃/Nb₂O₅摩尔比、升温速率、焙烧温度、焙烧时间等因素对催化剂的结构、产品纯度等特征的影响,确定了合适的制备K₂Nb₄O₁₁工艺。并以苯酚作为目标降解物评价铌酸钾K₂Nb₄O₁₁的光催化活性,考察了铌酸钾光催化剂的制备条件对苯酚光催化降解活性的影响。研究表明,碳酸钾与五氧化二铌的摩尔比是影响产品的晶相结构和纯度的一个主要因素,随着碳酸钾与五氧化二铌的摩尔比增加（即按反应计量计算,碳酸钾过量的量增加）,产品越纯,结晶度越好,其次是焙烧温度的影响,随着焙烧温度的升高,产品纯度和结晶度都增加,升温速率也是影响产品结构与结晶度的一个因素。分析结果表明,碳酸钾过量10%,升温速率为1℃/min,焙烧温度为1100℃,焙烧时间为24h时,能制得较纯的四方晶系铌酸钾K₂Nb₄O₁₁晶体。晶体呈立方柱状,晶粒长度约为1-2μm。对K₂Nb₄O₁₁光催化活性的研究表明,在合适的条件下,该催化剂对苯酚的光催化降解具有一定的催化活性,当催化剂用量为25mg/100mL,苯酚浓度为100mg/L时,制得的铌酸钾K₂Nb₄O₁₁在实验条件下具有较好的光催化活性。更多还原

【Abstract】 Recently,the niobates have been studied extensively as its superior physico-chemical properties and photocatalytic activities.The niobates have superior photocatalytic properties in photolysis splitting water and photo-degradation of organic compounds.Phenol is a difficult degradation of organic compounds,especially the researchers have been interested in the subject that how to remove phenol in the industrial wastewater.This study investigated the synthesis conditions of the niobate K₂Nb₄O₁₁,as well as the photocatalytic properties of phenol degradation.The potassium niobate photocatalysts were synthesis by the solid-state reaction method.The samples as-synthsized were chacarterized by scan electron microscopy （SEM）,X-ray power diffraction（XRD）,Ultraviolet visible diffuse reflection spectroscopy（UV-vis DRS） and so on.The crystal structure of the catalyst,particle morphology,as well as the absorption characteristics of the UV-visible spectroscopy were investigated.Some factors on the structure of catalysts and the purity of the product were studied,such as the K₂CO₃/Nb₂O₅ molar ratio,heating rate,the calcination temperature and calcination time,and so on.And the appropriate preparation process of K₂Nb₄O₁₁ were determined.And as a target the phenol were selected,the photo-degradation activity of potassium niobate K₂Nb₄O₁₁ were evaluated.The preparation conditions on the photocatalytic activity of the degradation of phenol were investigated.The results show that the molar ratio of potassium carbonate to niobium oxide is a major factor on the crystal phase structure and the purity of products.With the molar ratio of potassium carbonate to niobium oxide increasing（that is calculated on the basis of reaction equation,the excessive amount of potassium carbonate）,the more pure product, the better crystallinity.The secondary factor is the calcination temperature,with increasing the calcination temperature,the purity of products and crystallinity increased,the heating rate is a factor that affected the structure and crystallization of the product.The results of XRD patterns and SEM confirmed that the compound K₂Nb₄O₁₁ which was synthesized at 1100℃for 24 h,and the excessive amount 10%of potassium carbonate,the heating rate of 1℃/min,assumed the pure crystal of tetragonal.The samples consisted of cubic column shape crystalline particles with the length of about 1-2μm. The photocatalytic activity for the K₂Nb₄O₁₁ as-synthesized was evaluated by the photo-degradation of phenol.The effect of experimental factors such as the amount of catalyst,phenol concentration and so on,on the photocatalytic reaction was studied.The result show that When the amount of catalyst is 25mg/100mL,and the initial concentration of phenol is 100mg/L,the photocatalytic activity of K₂Nb₄O₁₁ showed the superior activity.更多还原