纳米TiO2光催化降解含油污水中HPAM的研究

用溶胶-凝胶法制备了锐钛矿型纳米TiO2,研究了合成催化剂反应条件对光催化降解含油废水中聚丙烯酰胺(HPAM)的影响。确定了最佳反应条件分别为:煅烧温度在500℃时,光催化活性达到最高,随着煅烧温度的升高,催化剂晶型从锐钛矿向金红石型转化,转型温度为600℃,有金红石型晶体出现时催化活性降低;最佳老化时间约为1 d;随着醇用量的增加,制备出来的TiO2其光催化活性也逐渐升高,当V(钛酸丁酯)∶V(醇)=10:80时,催化剂活性最高,继续增加,催化活性降低;随着水量的增加催化活性增强,当V(钛酸丁酯)∶V(水)=100:40时,制备出的TiO2催化活性最大,继续增加催化活性下降。     

纳米TiO2中试生产工艺的研究

以硫酸法钛白生产的中间产品钛液(TiOSO4)为原料，以工业尿素为沉淀剂，生成偏钛酸沉淀，再加入0．01mol／LH2SO4和去离子水、溶胶剂、表面活性剂，然后絮凝分离、喷雾干燥、回转窑煅烧，获得纳米TiO2粒子；其中550℃煅烧产物为锐钛矿晶型，大于750℃煅烧为金红石型，得到的纳米TiO2粒径为20～50nm，收率达92％。     

纳米TiO_2-WO_3的制备及对甲醛的光催化降解

采用溶胶-凝胶法制备TiO2 WO3纳米复合催化剂,对浓度为3 3×10-3mol/L的甲醛溶液进行光催化,考察了不同条件对其光催化降解的影响。结果表明,相同的焙烧温度下,WO3掺杂能抑制粒径的长大;焙烧温度升高,TiO2金红石相质量分数增加,粒径变大;WO3掺杂量为w(WO3)=3%、600℃焙烧时,金红石相质量分数为13 5%,光催化活性最高,甲醛光催化1 5h后降解率达到64%,比纯TiO2光催化活性高出79 4%。     

纳米TiO2薄膜中锐钛矿晶型的稳定性研究

采用溶胶—凝胶法制备钛溶液 ,将钛溶胶涂敷在玻璃和陶瓷基片上 ,干燥后进行煅烧 ,形成具有亲水 亲油作用、抗菌自清洁作用和防雾作用的纳米TiO2 薄膜。实验展示了与文献所述不同的结果。涂敷 1层— 7层的薄膜 ,其亲水性随层数增加而增大 ,未发现最大值 ;热处理温度为 65 0 -670℃ ,反复涂层反复煅烧保温条件下 ,仍未发现显著的金红石量生成。研究认为涂敷层数的增加不应降低光催化效率 ,影响纳米TiO2 薄膜光催化性质的主要因素是纳米粒子的表面密度和晶粒尺寸 ;纳米尺度下锐钛矿向金红石的转变温度并非固定 ,条件适宜时 ,可在较高温度下保持纳米锐钛矿的晶型稳定 ;影响纳米薄膜中TiO2 锐钛矿向金红石转变的因素主要与工艺条件、基材性质及基材与薄膜在高温下的相互作用方式有关     

50t/a纳米TiO2工业化生产工艺条件的研究

以钛液(TiOSO4)为原料,尿素为沉淀剂,生成偏钛酸沉淀;再加入0.01MH2SO4和去离子水、溶胶剂、表面活性剂,然后絮凝分离、喷雾干燥、回转窑煅烧,获得纳米TiO2粒子;其中550℃煅烧产物为锐钛矿晶型,大于750℃煅烧为金红石型;50t/a纳米TiO2粉体工业化生产的最佳工艺条件为:反应温度98±2℃,反应时间2—3.5h,反应物摩尔比TiOSO4:CO(NH2)2=2:1,溶胶剂与偏钛酸浓度之比4:1,絮凝剂用量9.5mgL;得到的纳米TiO2粒径为20—50nm,收率达92％。     

明胶对纳米二氧化钛相变和光催化活性的影响

以明胶为分散剂采用溶胶-凝胶法制备了纳米晶TiO2粉末.通过XRD、TG-DTA、AFM、N2吸附-解吸等手段,考察了明胶对TiO2煅烧过程中相变和平均粒径的影响;用光催化降解甲基橙检测了明胶用量对样品光催化活性的影响.结果表明：明胶的存在抑制了TiO2由无定形向锐钛矿的相变,降低了锐钛矿向金红石的相变温度;同时,TiO2纳米晶的平均粒径也随明胶用量的增加而减小.600℃煅烧样品的光催化活性随明胶用量的增加而提高;800℃煅烧样品在mG：mTBOT（明胶与钛酸四丁酯的质量比）=1：8时,具有最高的光催化活性.     

混晶结构纳米TiO2粉体的制备与性能表征

以钛酸丁酯为前驱体,采用溶胶-凝胶法制备了具有混晶结构的二氧化钛纳米粉体材料.研究了煅烧温度、pH值对二氧化钛晶型的影响,并用X射线衍射(XRD)、场发射扫描电镜(SEM)、分光光度计等对其进行测试表征.光催化降解性能测试表明:同一pH值下,随着温度的升高,金红石型TiO2的含量增加,锐钛矿型TiO2的含量减少.随着溶胶pH值的减小,TiO2由锐钛矿相向金红石相的转变温度也随之降低.光催化降解亚甲基兰实验表明,锐钛矿含量为76.12%、金红石含量为23.88%时1h内光降解率达98%.     

掺Fe3+纳米TiO2晶体结构及光催化性能研究

采用溶胶-凝胶法制备了纯的和Fe3+掺杂的TiO2纳米粒子,对样品进行了XRD分析,并以甲基橙的光催化降解研究了样品的光催化性能.结果发现Fe3+的掺杂抑制了TiO2粒径的长大,细化了晶粒;Fe3+掺入到TiO2的晶格中,引起了晶格的畸变和膨胀;Fe3+的掺杂促进了TiO2由锐钛矿向金红石的转变;Fe3+的掺杂量和煅烧温度对其光催化性能影响较大,在本实验的条件下,Fe3+的最佳掺杂量为0.05%,最佳煅烧温度为600℃.     

纳米二氧化钛纤维的制备及其光催化活性

以钛酸丁酯为钛源,用溶胶-乳化-凝胶技术合成了纳米TiO2粉末,将其置入碱溶液中进行回流处理得到了纳米TiO2纤维.用X射线衍射和透射电镜对纳米TiO2的晶型和表面形貌进行表征.结果表明:当氢氧化钠溶液的浓度为10 mol/L时,所制备的纳米TiO2纤维直径为10～15 nm,纤维长径比为20～25.TiO2纤维在750℃热处理后发生由锐钛矿相向金红石相的转变.光催化降解亚甲基蓝的实验显示:未经热处理的TiO2纤维的光催化活性比纳米TiO2粉末的差,而经500℃热处理后的TiO2纤维光催化活性最强,在紫外光照射4 h后,亚甲基蓝降解率达92%.当热处理温度进-步升高后,TiO2纤维光催化活性反而降低.     

纳米TiO2粉体晶型转化问题的研究

用一种纳米ＴｉＯ２低温实现由锐钛矿转化为金红石型的方法,采用加入煅烧晶种和复合促进剂,在７００℃时直接煅烧,制得粒径约３０￣６０ｎｍ的金红石型二氧化钛粉体,并利用ＴＥＭ、ＸＲＤ、ＢＥＴ对粉体粒子的形貌、大小、晶型及比表面积进行了分析。     

低温制备纳米TiO2及其可见光光催化活性

对TiO2纳米晶进行了研究。采用”低温水热法”在室温附近的低温下处理无定型的TiO2前驱体制备出了纳米TiO2,制备温度比传统的水热法和溶胶一凝胶法要低很多,在低于50℃的温度下即可得到金红石型TiO2。研究了TiO2的相组成与温度的关系以及TiO2的形貌。实验表明,在波长大于400nm的可见光照射下,棒状的金红石型TiO2具有良好的可见光光催化性能。     

Effect of pressure on TiO2 crystallization kinetics using in‐situ high‐temperature synchrotron radiation diffraction

The phase transformation behavior of TiO₂ sol‐gel synthesized nanopowder heated in a sealed quartz capillary from room temperature to 800°C was studied using in‐situ synchrotron radiation diffraction (SRD). Sealing of the capillary resulted in an increase in capillary gas pressure with temperature. The pressures inside the sealed capillary were calculated using Gay‐Lussac's Law, and they reached 0.36 MPa at 800°C. The as‐synthesized material was entirely amorphous at room temperature, with crystalline anatase first appearing by 200°C (24 wt% absolute), then increasing rapidly in concentration to 89 wt% by 300°C and then increasing more slowly to 97 wt% by 800°C, with there being no indication of the anatase‐to‐rutile transformation up to 800°C. The best estimate of activation energy for the amorphous‐to‐anatase transformation from the SRD data was 10(2) kJ/mol, which is much lower than that observed when heating the material under atmospheric pressure in a laboratory XRD experiment, 38(5) kJ/mol. For the experiment under atmospheric pressure, the anatase crystallization temperature was delayed by ~200°C, first appearing after heating the sample to 400°C, after which crystalline rutile was first observed after heating to 600°C. The estimated activation energy for the anatase‐to‐rutile transformation was 120(18) kJ/mol, which agrees with estimates for titania nanofibers heated under atmospheric pressure. Thus, heating the nanopowders material under pressure promoted the amorphous‐to‐anatase transformation, but retarded the anatase‐to‐rutile transformation. This behavior is believed to occur in an oxygen‐rich environment and interstitial titanium is also expected to form when the material is heated under high gas pressure. This suggests that atmospheric oxygen appears to accelerate the amorphous‐to‐anatase transformation, whereas interstitial titanium inhibits TiO₂ structure relaxation, which is required for the anatase‐to‐rutile transformation.     

聚丙烯酸锂/锂盐聚合物电解质的研究

以丙烯酸和氢氧化锂为原料用溶液聚合法合成聚丙烯酸锂(PAALi),将其熔于低共熔盐(一定比例的LiNO3-LiOOCCH3混合物)中得到新型高分子固体电解质(SPE),用IR技术进行了表征,讨论了影响合成PAALi工艺及新型固体电解质电导率的主要因素,在Li-NO3-LiOOCCH3质量比为1∶1时,将其按质量百分比80∶20与聚丙烯酸锂混合均匀并熔融,得到的电解质其室温离子电导率可达2×10-5S.cm-1.     

金红石型云母钛珠光颜料的合成研究

采用化学诱导法合成金红石型云母钛珠光颜料 ,以SnCl4及其复配物为金红石诱导促进剂 ,在 85 0℃、0 5h的焙烧条件下合成得到了完全金红石型的云母钛珠光颜料。由正交试验得到了金红石化学诱导促进剂最佳复合配方为 :m(云母 )∶m(SnCl4)∶m(ZnO)∶m(C助剂 ) =10 0∶3∶2∶4。此方法缩短了焙烧时间 ,并使颜料表面的TiO2 相转变温度降低了约 10 0℃ ,使制得的耐候性云母钛珠光颜料具有高的珠光光泽     

溶胶-凝胶制备TiO2空气净化特性研究

利用XRD等手段对以钛酸四丁酯为原料采用溶胶-凝胶法制备的TiO₂纳米粒子的表面特性及其对空气环境中乙醛的光催化降解性能进行了测定。结果表明，乙醇与钛酸四丁酯体积比、溶胶pH、加水量和焙烧温度等对催化剂降解乙醛的活性有显著影响。在实验条件范围内，较短胶凝时间制备出的纳米粉末晶粒尺寸较小，活性较高。焙烧温度不但影响TiO₂粉末的粒径，而且对晶型的组成也有影响。锐钛矿晶型的光催化活性明显高于金红石晶型，锐钛矿型向金红石型转变的临界温度在（500～600） ℃。实验得到TiO₂最佳制备条件为：V(乙醇)∶V(钛酸四丁酯)=4、溶胶pH=3.0、加水量4 mL和焙烧温度(400～500) ℃。     

Anatase–rutile transformation in doped titania under argon and hydrogen atmospheres

Abstract

Pure titania pulp containing amorphous titania was heated at different temperatures and times. Above 650°C anatase phase was evolved and between 900 and 1000°C, anatase–rutile transformation occurred. The anatase–rutile transformation in TiO₂ in the presence of different transition metal oxides, namely Fe₂O₃, Cr₂O₃, NiO, CuO and MnO₂ under argon and hydrogen atmospheres was investigated. The different phases of TiO₂ were determined using powder X-ray diffraction (XRD). The anatase–rutile transformation temperature was found to be lowered in the presence of transition metal oxides. The transformation temperature was found to vary much in argon and hydrogen atmospheres compared to air in the presence of the metal oxides. Also the method of preparation of metal oxide doped TiO₂ influences rutilation. Other methods such as chemical analysis, surface area measurements and crystallite size calculation were used for the characterisation of the samples. The surface area of heated samples was found to be decreased while crystallite size increased due to rutilation on heating. The samples were also observed under a scanning electron microscope to characterise the microstructural changes associated with each thermal treatment and atmosphere. The morphology of doped titania changes much on heating due to phase modification. The atmosphere of heating also has important effect on deciding the morphology of rutilated titania.     

锂快离子导体Li1.4Al0.1Mg0.1Ti1.8Si0.1P2.9O12和Li1.8Al0.1Mg0.1Ti1.6Si0.3P2.9O12的合成及导电性能研究

以LiTi2(PO4)3为基,用分析纯原料经高温固相反应(850、900、950℃)制得锂快离子导体材料Li1.4A l0.1Mg0.1Ti1.8Si0.1P2.9O12(以下简称TM1)和Li1.8A l0.1Mg0.3Ti1.6Si0.1P2.9O12(以下简称TM2)。用交流阻抗技术测定了合成物的电导率。反应温度为850、900和950℃合成的TM1在298 K测定的电导率分别为1.05×10-4S/cm,1.11×10-4S/cm,1.31×10-4S/cm;同样条件下合成的TM2的电导率分别为7.41×10-5S/cm,7.81×10-5S/cm,8.11×10-5S/cm。以上数据表明,TM1和TM2的离子电导率随着合成温度的升高而增大。在373、473、573和673 K测定的离子电导率也呈上述趋势。反应温度为950℃的合成物的电导率最高,反应温度为850℃的合成物的离子电导率最低,因此,TM1和TM2的最佳合成温度为950℃。T≥100℃时,TM2的离子电导率比TM1的大。X射线衍射分析结果表明,TM1和TM2在不同的反应温度(850、900、950℃)下均得到空间群为R3c的合成物。     

一种钻井液用有机高分子絮凝剂的反相乳液法制备

用环己烷作为连续相,Span80/OP10作为复合乳化剂,KPS-TMEDA作氧化还原引发剂,在室温通过反相乳液聚合法制备了黏均相对分子质量大于700万的丙烯酰胺(AM)与丙烯酸钾(AA-K)的稳定共聚物胶乳,并研究了聚合温度、引发剂浓度、单体浓度及配比对聚合物黏均相对分子质量的影响。反应条件:c(KPS)=1 7×10-3mol/L,c(monomer)=3 5～5 5mol/L,n(AA-K)/n(AM)=0 1,温度20～30℃较适宜。对聚合物胶乳的絮凝及泥浆的应用效果进行了评价,发现效果明显,应用方便。     

Porous titania microspheres with uniform wall thickness and high photoactivity

Highly porous titania particles were prepared by depositing thin films of titania, using alternating reactions of TiCl₄ and hydrogen peroxide, on poly(styrene-divinylbenzene) (PS-DVB) template particles via atomic layer deposition (ALD) at 77 °C. The composition of the titania films was verified by XPS analysis and the titania films were directly observed by TEM. TGA/DSC was used to study the thermal decomposition of the polymer template. Porous titania particles with uniform wall thicknesses were successfully obtained after the template PS-DVB was removed by oxidation in air at 400 °C for 24 h. Verification of the resulting porous structure of the titania particles was done by cross-sectional SEM and nitrogen adsorption–desorption analysis. Porous titania particles were treated at different temperatures. XRD analysis was used to determine the microstructure and phase transformation of titania at elevated temperatures. The photocatalytic activity of these porous titania particles was studied by methylene blue decomposition under UV light at room temperature and was found to be comparable to that of commercial anatase titania nanoparticles (~20 nm). Depositing Na₂SO₄ on TiO₂ retarded the TiO₂ phase transformation from anatase to rutile during calcination and, thus, greatly increased the photoactivity of the porous titania particles.