HZSM-5分子筛负载SrTiO_3光催化降解活性艳红X-3B

采用溶胶-凝胶法制备HZSM-5分子筛负载SrTiO_3,对其进行XRD、FTIR和N2吸附-脱附表征,研究负载对活性艳红X-3B光催化降解过程的影响。通过分析降解液的FTIR谱图、紫外-可见光谱和总有机碳(TOC)数据,对活性艳红X-3B的光催化降解过程进行了探讨。结果表明:催化剂的主要成分为钙钛矿结构SrTiO_3,负载对SrTiO_3晶粒尺寸几乎没有影响。纯SrTiO_3没有明显的孔结构,负载后样品的比表面积和孔隙主要由HZSM-5提供。负载之后催化剂的降解活性显著提高,30%SrTiO_3/HZSM-5对活性艳红X-3B染料溶液的脱色和TOC去除速率最快。     

磷酸处理HZSM-5负载TiO2光催化降解活性艳红X-3B

以磷酸改性的HZSM-5分子筛为载体,采用溶胶-凝胶法制备TiO2/HZSM-5光催化剂,通过XRD,SEM,BET,FT-IR和XPS进行表征。结果表明:TiO2均匀地分散在HZSM-5表面,没有发生TiO2颗粒的聚集。负载后的TiO2保持了锐钛矿晶体结构,TiO2的晶粒尺寸在负载后有所减小。TiO2/0.5HZSM-5的比表面积和对活性艳红X-3B的吸附量都随HZSM-5含量的增加而增加。负载后的TiO2光催化活性均高于纯TiO2,50%(质量分数)TiO2/0.5HZSM-5具有最高的活性,经紫外光照射2h可使活性艳红X-3B降解93.4%,而染料在纯TiO2上的降解率只有61.0%。     

NaZSM-5分子筛磷酸改性对TiO2/ZSM-5光催化剂的影响

以不同浓度磷酸改性的HZSM-5为载体,采用溶胶-凝胶法制备得到TiO2/HZSM-5光催化剂,通过XRD、SEM、BET、FT-IR和XPS进行表征。结果表明,磷酸处理没有改变分子筛的晶体结构,对分子筛的表面形貌改变不大,负载后的TiO2包覆在分子筛表面。负载前后的TiO2表现为锐钛矿晶型,钛以四价钛的形式存在,氧化物的组成为TiO2。TiO2与HZSM-5没有发生化学键合作用,负载型光催化剂的比表面积随着磷酸浓度的增加而显著提高。活性艳红X-3B的降解率随磷酸浓度的增加而变化,最佳磷酸处理浓度为0.5mol/L。50%TiO2/0.5HZSM-5较TiO2有更高的光催化活性,紫外光照射2h可使活性艳红X-3B降解93.4%,而染料在TiO2上的降解率只有61.0%。     

溶胶-凝胶法制备La_2Ti_2O_7/HZSM-5及其光催化活性

采用溶胶-凝胶法制备La_2Ti_2O_7/HZSM-5光催化剂,并对其光催化活性进行研究。结果表明:La_2Ti_2O_7经HZSM-5分子筛负载后,并未改变原有晶相,仍为单斜晶系钙钛矿结构。负载后的La_2Ti_2O_7分散在分子筛表面,催化剂的比表面积大幅增加并形成新的中孔结构。HZSM-5制约了La_2Ti_2O_7的生长,导致晶粒尺寸减小。材料的光谱吸收边界随负载量的减小而发生蓝移,禁带宽度增大。负载样品中La3d和O1s的电子结合能增大。La_2Ti_2O_7/HZSM-5比纯La_2Ti_2O_7具有更高的光催化活性。经紫外光照120min后,活性艳红X-3B在70%La_2Ti_2O_7/HZSM-5上的总脱色率为91.8%,而在La_2Ti_2O_7上仅为31.7%。     

磁性活性碳负载F掺杂纳米二氧化钛的光催化性质研究

通过溶胶-凝胶法制备F掺杂纳米TiO₂ (F-TiO₂), 将其负载到磁性活性碳(MAC)上, 制得易回收分离的高效催化剂(F-TMAC)。通过XRD、SEM、UV-Vis、XPS、VSM对样品进行表征。以合成样品为催化剂降解模拟废水活性染料艳红(X-3B), 结果表明该负载型催化剂在紫外光和可见光照射下光催化效果均优于P25催化剂。0.2 g负载型催化剂分别在紫外光和可见光照射下降解200 mL浓度为100 mg/L的X-3B溶液, 90 min后经18?W紫外光照射X-3B去除率达到99.8%; 250 W可见光照射X-3B去除率为83.1%。溶液中的复合催化剂可以用磁铁很容易分离, 具有优良的重复利用性能。经5次重复试验, 复合催化剂F-TMAC对X-3B的降解率仅下降了约6.0%。     

TiO_2/HZSM-5的制备及光催化性能的表征

以钛酸四丁酯为钛源,采用溶胶-凝胶法在HZSM-5分子筛表面合成TiO2前驱体,程序升温处理制得TiO2/HZSM-5负载型光催化剂。采用X射线衍射、扫描电镜、傅里叶变换红外光谱、X射线光电子能谱对光催化剂晶相结构、表面形貌及化学组成进行了表征。结果表明,HZSM-5可提高TiO2分散性能,降低TiO2晶粒的尺寸。TiO2/HZSM-5中的Ti都以TiO2形式存在,没有Ti—O—Si键生成。甲基橙溶液的光催化降解结果表明,负载后提高了TiO2对甲基橙溶液的光催化降解活性。TiO2的质量分数为30%,400℃下煅烧2h时的催化剂光催化性能最好。     

加压溶氧光催化反应器中降解活性艳红X-3B的研究

首次探讨加压溶氧条件下pH值、TiO2投加量及温度等对活性艳红X-3B的降解和脱色的影响,结果表明,加压条件与常压条件下变化趋势基本一致,加压充氧相比加压充N2更有助于活性艳红X-3B的降解与脱色,其中,加压使溶液中溶解氧增加是导致活性艳红X-3B的降解与脱色的主要原因。COD的降解与色度的褪除成正相关,脱色率越高COD的降解率越高。     

超声波-Fe3＋掺杂TiO2纳米管光催化降解活性艳红X-3B的研究

以超声波作用制备的Fe3＋掺杂TiO2纳米管作为光催化剂,氙灯模拟紫外光为光源,降解活性艳红X-3B,探讨了超声预处理时间、催化剂煅烧温度、pH值、催化剂加入量等因素对活性艳红X-3B降解率的影响,结果表明,超声波预处理时间为20min,催化剂煅烧温度为400℃,pH为强酸或强碱,催化剂加入量为1.0g/L时对活性艳红X-3B处理效果较好。     

溶胶-凝胶法制备Bi_4Ti_3O_(12)/SiO_2及其光催化性能

采用溶胶-凝胶法制备石英砂负载Bi_4Ti_3O_(12)/SiO_2光催化材料,研究负载对Bi_4Ti_3O_(12)的物理性质和光催化活性的影响。结果表明,负载后的层状钙钛矿结构Bi_4Ti_3O_(12)包覆在非晶态石英砂球体表面,Bi_4Ti_3O_(12)中各元素的电子结合能没有发生改变。活性艳红X-3B在纯Bi_4Ti_3O_(12)和不同负载量x Bi_4Ti_3O_(12)/SiO_2上的吸附率不超过3%。负载后Bi_4Ti_3O_(12)的光催化活性均有提高,其中质量分数为50%负载量的Bi_4Ti_3O_(12)/SiO_2具有最高的活性。在Bi_4Ti_3O_(12)和质量分数为50%负载量的Bi_4Ti_3O_(12)/SiO_2上的光催化反应速率常数分别为0.021 s-1和0.027 s-1。     

PVA/PA6/TiO_2复合纳米纤维膜制备及光催化性能

通过静电纺丝技术制备聚乙烯醇/聚酰胺/纳米二氧化钛(PVA/PA6/TiO_2)复合纳米纤维,并考察了复合纳米纤维对模拟染料(亚甲基蓝和活性红X-3B)的光催化降解性能。利用扫描电子显微镜(SEM)、透射电镜(TEM)、能谱分析(EDX)、热重分析(TG)、X射线衍射分析(XRD)等表征测试对复合纳米纤维的形貌结构、表面元素分布进行分析。结果表明,用50 mg PVA/PA6/TiO_2复合纳米纤维膜(其中TiO_2含量是PVA/PA6质量的3%的)光催化降解50 mL浓度为5 mg/L亚甲基蓝溶液和50 mg/L活性红X-3B溶液,反应时间为120 min时,降解率分别为92.8%和87.5%。纳米纤维膜重复使用4次后,其亚甲基蓝降解率为86.6%,活性红X-3B降解率为66.9%,其依然保持良好的光催化性能。说明制备的复合纳米纤维膜具备优异的光催化性能及重复使用性。     

Synergistic effects of hollow structure and surface fluorination on the photocatalytic activity of titania

To study the synergistic effects of hollow structure and surface fluorination on the photoactivity of TiO₂, TiO₂ hollow microspheres were synthesized by a hydrolysis–precipitate method using sulfonated polystyrene (PS) as templates and tetrabutylorthotitanate (TBOT) as precursor, and then calcined at 500 °C for 2 h. The calcined samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N₂ sorption. Photocatalytic activity was evaluated using reactive brilliant red X3B, an anionic organic dye, as a model pollutant in water. The results show that the photocatalytic activity of TiO₂ hollow microspheres is significantly higher than that of TiO₂ nanoparticles prepared in the same experimental conditions. At pH 7 and 3, the apparent rate constants of the former exceed that of the latter by a factor of 3.38 and 3.15, respectively. After surface fluorination at pH 3, the photoactivity of hollow microspheres and nanoparticles further increases for another 1.61 and 2.19 times, respectively. The synergistic effect of surface fluorination and hollow structure can also be used to prepare other highly efficient photocatalyst.     

真空烧结对SrTiO3功能陶瓷性能的影响

采用真空烧结替代气氛烧结制备SrTiO3陶瓷材料,获得了既具有电容效应又具有良好压敏效应性能的SrTiO3复合功能陶瓷元件.在此基础上探讨了Nb2O5和La2赴O3作为单、双施主掺杂对SrTiO3功能陶瓷半导化、电性能及显微结构的影响.研究结果表明,双施主掺杂不仅可以促进SrTiO3功能陶瓷半导化,而且对显微结构有重要的影响.在x(Nb2O5);x(La2O3)0.6:0.2时可获得性能较好的半导体材料.相比于气氛烧结工艺,真空烧结同样可以得到性能优良的SrTiO3功能陶瓷材料.     

Pt纳米颗粒负载SrTiO3/TiO2异质结结构制备及制氢性能

本文以固定n(Sr)/n(Ti)摩尔比0.4的SrTiO_3/TiO_2(金红石相)异质结纳米颗粒,通过"光催化还原沉积方法"制备不同质量分数的纳米铂颗粒(0、1%、2%、5%),探究其催化活性的变化,采用XRD、SEM、UV-vis、XPS方法对其进行表征,并做了相关光催化分解水产氢性能测试.结果表明:负载贵金属Pt纳米颗粒量越大,对应的Pt晶粒平均尺寸为40.8 nm,1%Pt纳米颗粒SrTiO_3/TiO_2异质结构的BET比表面积在23.195 m~2/g处最高,并且介孔材料的特征是平均Barrett-Joyner-Halenda(BJH)孔径为13.60 nm,总孔体积为0.079 cm~3/g;高BET表面积和大的总孔体积强烈地支持SrTiO_3/TiO_2具有介孔结构的事实;相应的催化剂催化活性越高,其中负载5%Pt纳米颗粒的SrTiO_3/TiO_2纳米颗粒光催化8 h产氢量为3.574 mmol,平均产氢效率为0.447 mmol/(gcat·h),但从性价比的角度来考虑,其催化效率远不及负载1%Pt纳米颗粒的SrTiO_3/TiO_2纳米颗粒催化效率的5倍,因此负载5%Pt的SrTiO_3/TiO_2纳米颗粒光催化效率最高.     

Treatment of wastewater containing azo dye reactive brilliant red X-3B using sequential ozonation and upflow biological aerated filter process

In this work, the treatment of wastewater containing azo dye reactive brilliant red X-3B using sequential ozonation and upflow biological aerated filter process has been studied. Decolorization was almost complete after 120min with an ozone concentration of 34.08mg/L, the biological oxygen demand for 5 days (BOD5)/chemical oxygen demand (COD) ratio increased from 0.102 to 0.406, which was more effective for the subsequent upflow biological aerated filter (UBAF) to reduce COD concentration. Under the conditions of gas/liquid=3, hydraulic load=4.8m3/m3.d, T=20-25 degrees C, the mass ratio of ozone to dye=4.5, pH 11, the COD and color of the effluent were less than 40mg/L and 20 Pt-Co units, respectively, and the average decolorization and COD removal efficiency were 97% and 90%, respectively. The experimental results showed that the combination of ozone oxidation and upflow biological aerated filter was a promising technique to treat wastewater containing azo dye.     

Synthesis and characterization of highly dispersed TiO2 nanocrystal colloids by microwave-assisted hydrothermal method

Anatase TiO₂ nanocrystal colloids with high dispersion and photocatalytic activity were rapidly synthesized from peroxo-titanium-acid precursor by microwave-assisted hydrothermal method within 30?min at low temperature (120–180?°C). The transmission electron microscopy results indicate that the as-prepared TiO₂ have a narrow particle size distribution (25–29?nm) and high dispersion. The crystal structure of all these products are pure anatase phase (XRD, Raman), and they show good crystallinity and large surface area (N₂ adsorption–desorption measurements BET). The results of the UV–Visible absorbance and Fourier transform infrared spectra indicate that the surface peroxo group Ti(O₂) still remains in TiO₂ nanoparticles prepared by microwave-assisted hydrothermal method at 120?°C, and this surface peroxo group can be decomposed effectively by drying at 140?°C. The photocatalytic activity of the as-prepared TiO₂ were evaluated by the degradation of reactive brilliant red X-3B, it is found that the as-prepared TiO₂ exhibited good photocatalytic performance. Moreover, the existence of surface peroxo group greatly suppressed the photocatalytic activity of the TiO₂ nanoparticles.