【作者】 李松田；

【导师】 吴春笃；

【作者基本信息】 江苏大学 ， 环境工程， 2008， 博士

【摘要】 染料废水是工业废水的主要来源,其水量大,浓度高,成分复杂,色度深,盐度高,毒性强,难生化降解,治理合格率低,是国内外公认的难处理的工业废水,也是目前人们研究的热点之一。光催化氧化是一种绿色高效的高级氧化技术。非均相光催化常用的催化剂是纳米二氧化钛,可用于染料废水的处理。但是,基于纳米TiO₂的光催化作用一般在液-固相和气-固相进行,存在催化剂的流失和难以回收的问题,TiO₂的固载化是解决催化剂分离回收以及气相夹带的有效途径。纳米TiO₂固载主要包括催化剂载体的选择和固载技术的研究。由于TiO₂对光的吸收仅限于紫外光区,对于可见光或太阳光的吸收利用率很低。提高光能利用效率的关键在于突破催化剂的禁带宽度,使其响应光谱向可见光扩展。对TiO₂的光敏化是延伸其激发波长的一个重要手段。课题选用钛酸盐晶须、凹凸棒土、空心微珠、漂珠等材料为载体,以锐钛型纳米TiO₂作为基体,依托TiO₂高强机械性能、热稳定性能、小尺寸效应、紫外光响应及高吸附性能的优点,结合杂多酸具有紫外光响应特性以及酞菁配合物的Q带光吸收性质,将杂多酸或金属酞菁配合物修饰于TiO₂表面,对TiO₂进行负载和光敏化改性,制备多元复合型光催化材料,实现新材料对光谱响应的红移,拓展材料对光吸收的范围和应用空间。利用X-射线衍射光谱、扫描电子显微镜、X-射线能量色散光谱、紫外-可见漫反射等手段进行产品性能表征。在光化学反应仪中,用若干种染料为底物考察产品的光催化性能。主要内容包括:（1）纳米二氧化钛的固载化研究以四钛酸钾晶须为载体,用溶胶-凝胶法制备负载型光催化剂TiO₂/K₂Ti₄O₉。能量色散谱图显示,钛酸钾晶须的能谱峰以Ti、O、K为主,而包覆后则以Ti、O为主,K的谱峰已消失,说明晶须表面已被包覆上TiO₂。XRD图谱中出现了与锐钛型TiO₂的特征峰相吻合的衍射峰。在紫外光照射下,当罗丹明B浓度为8mg·L^-1时,加入0.01g·L^-1的TiO₂/K₂Ti₄O₉,在160min之内,TiO₂/K₂Ti₄O₉对罗丹明B的脱色率达到95%以上,比TiO₂单独处理提高了0.50倍以上。以凹凸棒土为载体,用溶胶-凝胶法制备负载型光催化剂TiO₂/凹凸棒土。X-射线衍射谱图显示,产品表面的衍射峰与锐钛型TiO₂的特征峰相吻合。EDS图谱显示,其表面包覆良好。在紫外光照射下,在30min之内,TiO₂/凹凸棒土对亚甲基蓝的脱色率达到90%以上。以空心微珠为载体,用溶胶-凝胶法制备负载型光催化剂TiO₂/空心微珠。在紫外光照射下,以孔雀绿为底物进行光催化性能研究。空心微珠经二氧化钛负载后对紫外光有较强响应,有较好的紫外光催化效果。实验条件下,TiO₂/空心微珠对底物的脱色率达70%以上。以上实验表明,用钛酸盐晶须、凹凸棒土、空心微珠作为催化剂载体对TiO₂进行固载化是可行的。（2）二氧化钛紫外光敏化作用研究以六钛酸钾晶须为载体,以硅钨酸为修饰剂,用溶胶-凝胶-浸渍法制备修饰型复合光催化剂H₄SiW₁₂O₄₀/TiO₂/K₂Ti₆O₁₃。UV-vis漫反射图谱显示H₄SiW₁₂O₄₀/TiO₂/K₂Ti₆O₁₃对紫外光的响应增强,有较高的光催化活性,实验条件下对孔雀绿的脱色率达80%以上。以三钛酸钠晶须为载体,以磷钨酸为修饰剂,用溶胶-凝胶-浸渍法制备复合光催化剂H₃PW₁₂O₄₀/TiO₂Na₂Ti₃O₇。XRD谱图表明产品的包覆情况良好,TiO₂为锐钛晶型,磷钨酸为Keggin结构。UV-Vis光谱显示产品的紫外光响应增强。与TiO₂/Na₂Ti₃O₇相比,H₃PW₁₂O₄₀TiO₂/Na₂Ti₃O₇对底物的脱色率提高了18.3%（10min时）至33.4%（50min时）。以漂珠为载体,以磷钨酸为修饰剂,用溶胶-凝胶-浸渍法制备轻质修饰型复合光催化剂H₃PW₁₂O₄₀/TiO₂/漂珠。结果表明,复合光催化剂H₃PW₁₂O₄₀/TiO₂/漂珠对紫外光的响应增强,光催化活性提高。以刚果红为底物进行光解催化实验,反应70 min后刚果红的降解率达到90%。（3）二氧化钛可见光敏化作用研究以四钛酸钾晶须为载体,以磺化酞菁钴为修饰剂,用溶胶-凝胶-浸渍法制备修饰型复合光催化剂CoPcS/TiO₂/K₂Ti₄O₉。结果表明在423K灼烧所得样品的光吸收发生显著红移,特别是在600-680nm之间有强的吸收。X-射线衍射图谱表明,样品中TiO₂依然保持锐钛晶型。在可见光照射下,以活性艳红X-3B为模拟污染物进行光催化降解试验,与TiO₂/K₂Ti₄O₉相比,CoPcS/TiO₂/K₂Ti₄O₉对底物的脱色率大幅提高,在5小时之内达到85%。以三钛酸钠晶须为载体,以三核酞菁钴磺酸盐为修饰剂,用溶胶-凝胶-浸渍法制备修饰型复合光催化剂tri-CoSPc/TiO₂/Na₂Ti₃O₇。UV-vis漫反射光谱表明,tri-CoSPc/TiO₂/Na₂Ti₃O₇的吸收光谱发生了红移,光响应范围扩展至400nm以上的可见光区,尤其在600-700nm之间有强的吸收。以孔雀绿为底物,以tri-CoSPc/TiO₂/Na₂Ti₃O₇为催化剂,进行染料污染物光催化降解试验。在1小时之内,孔雀绿脱色率为42.9%,6小时之内脱色率达到90.3%。研究表明,采用四钛酸钾晶须、六钛酸钾晶须、三钛酸钠晶须、凹凸棒土、空心微珠、漂珠作催化剂的载体是可行的。用溶胶-凝胶法制备负载型光催化剂,用溶胶-凝胶-浸渍法制备光敏型多元复合光催化剂的方法是成功的。以二氧化钛为基础的负载型催化剂、光敏型多元复合光催化剂处理多数的染料底物是有效的。更多还原

【Abstract】 Dye wastewater is the main source of industrial effluent.It is recognized as a kind of unmanageable industrial effluent,which can be ascribed to its large quantum,high concentration,complex component,dark chroma,high salinity,strong toxicity,and difficulty by biochemical degradation.Currently,more and more researchers become interested in this issue.Photocatalysis-oxidation is a senior oxidation technology with high efficiency.The commonly used catalyst in heterogeneous photocatalysis is nanometer titanium dioxide, which can be used for the treatment of dye wastewater.But the photocatalysis based on nanometer titanium dioxide usually proceed in liquid-solid phase and gas-solid phase. So the catalyst is easy to run off and hard to recycle.Load of titanium dioxide is an efficient approach for the separation and recycle of catalyst.It can also solve the problem of gas carry secretly.The loading technique for nanometer titanium dioxide mainly includes the selection of catalyst carrier and the loading technology.Because titanium dioxide can only adsorb the ultraviolet light,the adsorption rate for visible light or sun’s rays is quite low.The key for the improvement of light using efficiency lies in the breakthrough of the forbidden band width of catalyst and the expansion of the response spectrum to visible light.The photosensitization of titanium dioxide is an important means to extend the excitation wavelength.Titanate whisker,attapulgite clay,cenosphere and float beads were selected as the carrier,and anatase nanometer titanium dioxide as the substrate in our research.The high mechanism performance,thermal stability,small size effect,ultraviolet response and high adsorption properties of titanium dioxide was integrated with the ultraviolet response of heteropoly acid and the Q band adsorption behavior of phthalocyanine compound.Heteropoly acid or phthalocyanine compound was decorated on the surface of titanium dioxide,and the compound photocatalyst was prepared through loading and photosensitive modification of titanium dioxide.The adsorption range and application field of the novel material were extended because the light response area of novel material had red shift.The photocatalysis performence was investigated with different dyes as the substrates in the photochemical appearance.The main conclusions included the following items: （1）Study on solid-supported of nanometer titanium dioxideWith potassium titanate（Ⅳ）as carder,TiO₂/potassium titanate photocatalyst was prepared with sol-gel method.With rhodamine B as substrate,the photocatalytic performance of TiO₂/potassium titanate was investigated under ultraviolet illumination. The product was characterized by X-ray diffraction and SEM.From the EDS,the main energy spectrum included Ti,O and K peaks in potassium titanate whisker.The Ti and O peaks stayed after the whisker was covered by TiO₂.The disappearance of K peak indicated that the surface of potassium titanate whisker had already covered by TiO₂.As shown in XRD,the diffraction peak corresponded to the characteristic peak of anatase TiO₂.Under irradiation of ultraviolet light,when the concentration of rhodamine B was 8 mg·L^-1,0.01 g·L^-1of TiO₂/potassium titanate was added.The decolorization rate for rhodamine B was over 95%in 160 min,which was 0.50 times higher than that with pure TiO₂.With attapulgite clay was carrier,TiO₂/attapulgite clay photocatalyst was prepared by sol-gel method.With methylene blue as substrate,the photocatalysis performance of TiO₂/attapulgite clay was investigated under ultraviolet illumination.Results from X-ray diffraction indicated that the diffraction peaks on its surface corresponded to the characteristic peaks of TiO₂.As shown in Energy Dispersive Spectroscopy（EDS）,A1, Mg,Fe,K and Si peaks generated by attapulgite clay disappeared or weaken to some extent after loading process.Ti and O peaks were the main peaks,which indicated that attapulgite clay was covered well by TiO₂.Under irradiation of ultraviolet light,the decolorization rate of TiO₂/attapulgite clay for methylene blue was more than 90%in 30 min.With cenosphere as carrier,TiO₂/cenosphere photocatalyst was prepared by sol-gel method.The photocatalysis performance was studied by degradation of malachite green under ultraviolet illumination.The cenosphere loaded by titanium dioxide had strong ultraviolet response and excellent photocatalysis effect for ultraviolet light.Under the experimental conditions,the decolorization rate for malachite green was over 70%.Above experiments showed it was feasible with potassium titanate whisker, attapulgite clay or cenosphere as the photocatalyst carrier.（2）Study on visible light photosensitization of titanium dioxideWith potassium titanate（Ⅵ）whisker as carrier,and silicotungstic acid (H₄SiW₁₂O₄₀)as modified reagent,the compound photocatalyst H₄SiW₁₂O₄₀/TiO₂/K₂Ti₆O₁₃was prepared by sol-gel-dipping method.UV-vis spectra showed that the compound photocatalyst possessed stronger light response and higher photocatalysis activity.Under the experimental conditions,the decolorization rate for malachite green reached over 80%.With natrium titanate（Ⅲ）whisker（Na₂Ti₃O₇）as carrier and phosphotungstic acid (H₃PW₁₂O₄₀)as modified reagent,the compound photocatalyst H₃PW₁₂O₄₀/TiO₂/Na₂Ti₃O₇ was prepared by sol-gel-dipping method.The XRD results indicated that the product was well covered by anatase TiO₂ and phosphotungstic acid was Keggin structure.UV-vis spectra showed its light response was enhanced. Compared with TiO₂/Na₂Ti₃O₇,the decolorization rate increased by 18.3%for 10 min and 33.4%for 50 min with H₃PW₁₂O₄₀/TiO₂/Na₂Ti₃O₇ as photocatalyst.With float beads as carrier and phosphotungstic acid as modified reagent,the compound photocatalyst H₃PW₁₂O₄₀/TiO₂/float beads was prepared by sol-gel-dipping method.The prepared compound photocatalyst had stronger light response and higher photocatalysis activity for congo red degradation.With congo red as substrate,the degradation rate reached 90%after 70 min.（3）Study on ultraviolet light photosensitization of titanium dioxideWith potassium titanate（Ⅳ）whisker as carder and cobalt sulfophthalocyanine as modified reagent,the compound photocatalyst cobalt sulfophalocyanine/titanium dioxide/potassium titanate（Ⅳ）（CoPcS/TiO₂/K₂Ti₄O₉）was prepared by sol-gel-dipping method.The results indicated that the adsorption obtained by baking at 423K had obvious red shift,and adsorption between 600 and 680 nm was especially strong.The XRD results showed that the titanium dioxide was still anatase type.Under the visible light irradiation,the decolorization rate of X-3B reached 85%in 5 h.Compared with TiO₂/K₂Ti₄O₉,the decolorization rate of substrate was remarkably enhanced with CoPcS/TiO₂/K₂Ti₄O₉ as photocatalyst.With Na₂Ti₃O₇ whisker as carrier and tri-CoSPc as modified reagent,the compound photocatalyst tri-CoSPc/TiO₂/Na₂Ti₃O₇ was prepared by sol-gel-dipping method.UV-vis spectra indicated that the adsorption spectra of tri-CoSPc/TiO₂/Na₂Ti₃O₇ had red shift,and the light response area had extended to visible light（above 400 nm）.There existed especially strong adsorption between 600 and 700 nm.With malachite green as the simulate contamination and tri-CoSPc/TiO₂/Na₂Ti₃O₇ as photocatalyst,the decolorization rate of malachite green reached 42.9%in 1 h and 90.3%in 6 h.The results indicated that titanate whisker,attapulgite clay,cenosphere and float beads could be used as the carrier for photocatalysts.Sol-gel method was developed to prepare loaded photocatalyst and sol-gel-dipping method was established to prepare photosensitive compound photocatalyst.The loaded photocatalyst and photosensitive compound photocatalyst based on titanium dioxide were effective for the treatment of various dye wastewater.更多还原