Photocatalytic activity of bauxite-tailings supported nano-TiO2

TiO₂/bauxite-tailings (TiO₂/BTs) composites were prepared via a chemical liquid deposition method and characterized by X-ray diffractometry (XRD), scanning electronic microscopy (SEM) and N₂ adsorption analysis. The photocatalytic performance of TiO₂/BTs composites was evaluated with UV-Vis spectrophotometer following the changes of phenol concentration under different illumination time. Effects of the calcination temperature, the pH and the cycles on the photocatalytic activity of TiO₂/BTs composites were investigated. The composites calcined at 500 and 600 °C exhibit the best photocatalytic performance, and the phenol degradation ratios reacting for 40 and 160 min reach 35% and 78% respectively under the same conditions, higher than those of 29% and 76% of the Degussa P25(TiO₂). The ability of TiO₂/BTs₅₀₀ (BTs₅₀₀ represents bauxite-tailings calcined at 500 °C) composites to degrade phenol increases with decreasing pH.     

稀土离子掺杂TiO2纳米晶光催化性能研究

摘要：以柠檬酸作为一种还原剂和燃料、硝酸根作为氧化剂,用柠檬酸溶胶一凝胶燃烧法制备了稀土离子（Ce3^＋,Dy^3＋,Eu^3＋）掺杂的Ti02,研究了改性Ti02的光催化活性及稀土离子的最佳掺杂浓度。     

微波辐射制备TiO2薄膜光催化性能研究

采用微波辐射法由溶胶制备出TiO2薄膜,用XRD和TEM对催化剂进行了表征。以甲基橙为模拟污染物,考察了微波功率和膜层厚度对TiO2光催化活性的影响,并实际考察了TiO2薄膜对啤酒废水的降解效果。结果表明：制备的TiO2薄膜具有较高光催化活性,微波功率300W时光催化活性最大,对啤酒废水具有良好的处理效果。     

微波辐射制备TiO_2薄膜光催化性能研究

采用微波辐射法由溶胶制备出TiO2薄膜,用XRD和TEM对催化剂进行了表征。以甲基橙为模拟污染物,考察了微波功率和膜层厚度对TiO2光催化活性的影响,并实际考察了TiO2薄膜对啤酒废水的降解效果。结果表明:制备的TiO2薄膜具有较高光催化活性,微波功率300 W时光催化活性最大,对啤酒废水具有良好的处理效果。     

油田管道用纳米TiO_2改性防腐涂料的研究

制备了TiO2:改性防腐涂料,并对其性能进行了实验研究.结果表明,当纳米粒子添加量为3%时,防腐材料的常规性能、耐磨擦性及耐腐蚀性都得到了较大的提高.说明纳米TiO2对改善石油管道防腐涂料的性能具有重要作用.     

可见光照射下纳晶TiO_2电极对染料污染物的光电催化降解研究

为揭示TiO2光催化降解染料的反应机理,研究了可见光照射下各种染料污染物在正、负不同偏压下的降解情况.以溶胶-凝胶结合水热法制备的TiO2薄膜为光电极,通过检测反应过程中染料溶液的紫外-可见吸收光谱及总有机碳变化情况,深入探讨了外加电压在光电催化降解染料中的作用.同时,通过电子自旋共振技术检测了染料降解过程中活性自由基的生成情况.实验结果表明,在可见光照射下,外加正偏压时,阳离子染料如罗丹明B和孔雀绿虽也褪色,但矿化率比较低;而负偏压作用时,阳离子型染料在可见光与偏压的共同作用下,以分子中共轭结构的破环为主,产生较高的矿化率.     

水热法制备海绵钛负载二氧化钛膜及性能研究

以多孔海绵钛为载体,2 mol/L H2O2为氧化剂,0.15 mol/L KOH为矿化剂,在水热条件下一步合成了颗粒大小约为0.5 μm的四方状锐钛矿海绵钛负载TiO2膜.以XRD、SEM观察海绵钛负载TiO2膜晶型、形貌,以亚甲基蓝为目标降解物研究了其光化性能催化,并探讨了水热时间对产物TiO2膜晶型、形貌及光催化性能的影响.结果表明,12 h为最佳水热时间,海绵钛负载TiO2膜有着最佳的光催化性能:光催化反应60 min,亚甲基蓝溶液的降解率达99%.采用该法制备的TiO2光催化剂回收简单,反复利用后,其光催化性能无明显下降.     

蒙脱土负载ZnCl2催化剂的烷基化反应活性研究

研究了一种以酸化蒙脱土为载体,负载ZnCl2的新型固体酸催化剂,测试了在烷基化反应中的催化活性,通过对催化剂的XRD、TG－DTG测试表征,结果表明制备中酸化时间、活化温度对催化剂结构和活性显著影响。     

金属酞菁负载分子筛对孔雀石绿的降解

采用浸渍法制备了4种负载型金属酞菁催化剂：MCM-41-a-（GH11O）4PeCo（Ⅱ）[Ni（Ⅱ）、Cu（Ⅱ）、Zn（Ⅱ）]。并在室温（25±1℃）中性以及可见光条件下,考察了上述催化剂中心金属、催化剂用量、H2O2浓度以及重复利用方面对孔雀石绿降解速率的影响。研究结果表明：4种催化剂均具有良好的催化性能,在相同条件下,MCM-41-a-（C3H11O）4PcCo的催化效果最好,并且其浓度在0．7g／L（质量为20mg）,H2O2浓度为10mmol／L条件下,孔雀石绿在10min内降解率可达92％。对重复性的研究表明该种负载催化剂具有良好的重复利用性。     

煅烧和水热法制备纳米TiO2及其光催化性能

用微乳液法制备出纳米TiO_2前驱体,通过煅烧和水热法两种后处理方式制备了纳米TiO_2,用TG-DSC,XRD和SEM等对纳米TiO_2进行表征分析。结果表明,煅烧法和水热法获得的锐钛矿型纳米TiO_2的晶粒尺寸分别为14～23 nm和4.4～5.3 nm。在紫外光照射下测试两种方法制备的锐钛矿型纳米TiO_2的光催化性能。通过比较,煅烧法后处理制备的纳米TiO_2在90 min内对亚甲基橙溶液的降解率98.36%。在相同测试条件下,水热法后处理获得的纳米TiO_2在90 min内对亚甲基橙溶液的降解率达到99.9%。     

Photocatalytic H2 evolution activity of CuO/ZrO2 composite catalyst under simulated sunlight irradiation

Zirconia-supported CuO (CuO/ZrO₂) composite photocatalysts were successfully synthesized via citric acid-assisted sol-gel technique. For comparison, CuO/ZrO₂ materials were also prepared by solid state reaction and co-precipitation method. The as-prepared powders were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), and thermogravimetric-differential thermal analysis (TG-DTA). The photocatalytic activity of CuO/ZrO₂ catalyst was investigated based on the H₂ evolution from oxalic acid solution under simulated sunlight irradiation. The effects of molar ratio of CuO to ZrO₂, preparation method, phase change with the calcination temperature and the durability on the photocatalytic activity of the photocatalyst were investigated in detail. It is found that the optimal activity of photocatalytic H₂ evolution (2.41 mmol·h⁻¹μ⁻¹) can be obtained when CuO/ZrO₂ composite photocatalyst is synthesized by sol-gel technique and the mole ratio of CuO to ZrO₂ is 40%. The activity of copper oxide supported on monoclinic ZrO₂ calcined at higher temperature is much higher than that on tetragonal ZrO₂ calcined at lower temperature, and the best calcination temperature is 900 °C.     

钠钙玻璃负载TiO_2薄膜光催化性能影响因素研究

以普通钠钙玻璃片为载体,采用溶胶—凝胶法,经胶液配制、膜的涂覆与焙烧等工序,制备TiO2催化膜。通过正交实验,考察胶液配比、涂覆次数、升温程序等因素对TiO2薄膜光催化降解苯酚性能的影响,在选定个因素各水平下,在普通钠钙玻璃片上负载TiO2催化膜的影响因素主次顺序为:硝酸体积涂覆次数焙烧温度V乙醇∶V酞酸丁酯,最优条件为:涂覆次数=4次;焙烧温度=450℃;V乙醇∶V酞酸丁酯∶V硝酸(1∶4)∶V水=400∶40∶1∶4。通过扫描电子显微镜(SEM)可以观察到玻璃片表面明显负载着厚实的薄膜,最优条件下制备的TiO2颗粒粒径在100nm左右。     

Comparison of chemical reactivity of bauxite-tailings pre- and post-calcinations and whitening bauxite-tailing

Bauxite-tailings is aluminosilicate wastes and is used in polymer as fillers. But its intrinsic low-whiteness has limited its large-scale application in polymeric materials. Conventional methods for whitening bauxite-tailings were ineffective. A new method, which involved reactions with phosphoric acid and calcinations, was proposed to whiten bauxite-tailings. Two process routes were employed to whiten bauxitetailings, which were pre- and post-reaction calcination. While the process of pre-reaction calcination was able to achieve a whiteness of 87% from bauxite-tailings, it required high-energy post-treatment processes such as washing, milling and drying. The process of post-reaction calcination, on the other hand, resulted in an increase in whiteness of bauxite-tailings from 19% to 73%. This was achieved using 4.5% of added phosphorous, 40% acid concentration, reaction time of 2.5 hours and a calcination temperature of 600 ℃. The resultant did not require any further processing, and was therefore industrially feasible. The whitened tailings consisted of corundum, anatase, and quartz. When compared to calcined tailings, whitened tailings possessed a higher content of amorphous material, the disappearance of red iron minerals, and the emergence of a new phase of AlPO 4.     

蒙脱土负载ZnCl2催化剂的烷基化反应活性研究

研究了一种以酸化蒙脱土为载体,负载ZnCl2的新型固体酸催化剂,测试了在烷基化反应中的催化活性,通过对催化剂的XRD、TG-DTG测试表征,结果表明制备中酸化时间、活化温度对催化剂结构和活性显著影响。     

溶胶—凝胶法TiO2光催化膜的制备与研究

本文论述了用溶胶-凝胶法制备TiO2光催化膜的工艺过程;研究了热处理过程中TiO2膜结构转化过程;探讨了影响成膜过程的各种因素及工艺参数。结果表明：适当选择涂液成分、热处理温度,可在普通玻璃基片上制备出性能优良的膜层,其透过率高耐磨并且具有明显的光催化性能。     

纳米二氧化钛光催化薄膜的研制

采用溶胶-凝胶法(Sol-gel)制备了二氧化钛光催化薄膜，利用原子力显微镜(AFM)对薄膜表面结构进行观测．薄膜中二氧化钛粒子以纳米级分布，薄膜均匀、连续无龟裂．分别测试了纳米二氧化钛薄膜和普通二氧化钛颗粒在紫外灯照射下对CHCl3的催化降解速率．实验分析结果表明具有表面效应，量子尺寸效应的纳米二氧化钛薄膜有着更高的光催化活性和降解速率．     

TiO2光催化降解含氯有机废气实验研究

利用TiO2作为光催化剂,采用功率15 W,波长253.7 nm的医用紫外荧光灯作为光源,在圆筒型光催化反应器中,对模拟二氯甲烷和三氯乙烯废气的去除效果进行了实验研究.实验考察了有机物浓度和气体停留时间等操作条件对去除率的影响.研究结果表明,对于三种不同温度(250℃,400℃和550℃)下焙烧的TiO2光催化剂,在550℃灼烧3 h的催化剂(锐钛矿型和金红石型混合物)的降解效果最佳.对于流量为160 mL/min,初始浓度为1.23×10-5mol/L的二氯甲烷和三氯乙烯的去除率都达到70%以上.     

溶胶凝胶法制备纳米TiO2薄膜及其性能的研究

目的 制备纳米TiO2薄膜并研究涂膜层数与催化性能的关系.方法 采用溶胶凝胶法并利用提拉技术制备纳米TiO2薄膜.应用朗伯-比尔定律分析其光催化活性,利用金相显微镜观察单层和多层薄膜的表面形貌,用红外光谱和XRD分析所制备薄膜材料的结构,利用甲基橙溶液研究该薄膜的光催化性能.结果 溶胶凝胶法在500℃的热处理温度制备了结晶良好的锐钛矿相结构的纳米TiO2薄膜材料,晶粒尺寸为40～80 nm;控制提拉速度和加入乙酰丙酮,能使薄膜的缺陷减少;涂膜层数为5层时光催化性能比1层到4层时好,这是由于5层时薄膜表面更均匀、更致密,但是层数增加也使薄膜的内应力增加,致使表面产生裂纹.结论 涂膜层数增加均使TiO2光催化性能得到提高,镀膜层数较少时,膜层较好,5层镀膜时膜层产生了裂纹.     

TiO_2光催化还原CO_2技术的研究进展

介绍了TiO_2的结构和性质,以及其催化还原CO_2的反应机理。分析了非金属沉积、贵金属沉积、半导体复合和有机光敏剂改性等4类Ti基催化剂光催化还原CO_2的性能。     

不同载体负载ZnCl2催化2-甲基吲哚合成的研究

以苯肼和丙酮为原料,采用Fischer吲哚合成法,制备了2-甲基吲哚.考察了ZnCl2,ZnCl2/HZSM-5,ZnCl2/MCM-41,ZnCl2/3A,ZnCl2/γ-Al2O3和ZnCl2/硅胶等催化剂对反应的选择性和收率的影响.结果表明:ZnCl2/MCM-41的催化性能最好,当ZnCl2在MCM-41上的负载量为4 mmol/g时,产物的选择性和收率达到最高,分别为77.0%和76.2%,同时,该催化剂经过4次回收后使用,产物的收率仍高达70.4%,重复使用效果较好,实验显示,ZnCl2/MCM-41可以完全替代ZnCl2用于2-甲基吲哚的制备,是一种清洁、绿色环保的环境友好催化剂.