载体材料在光催化技术中的应用研究进展

海泡石、活性炭以及高岭土等材料具有较大的比表面积、良好的稳定性及可塑性,可作为载体应用于光催化技术中,提高吸附性能和光催化效果.介绍了海泡石、活性炭以及高岭土作为载体在光催化技术中的应用以及改性的研究进展,并对载体材料在光催化剂中的应用进行了展望.     

海泡石/TiO2的制备及对甲苯废水的催化降解研究

采用溶胶-凝胶法制备海泡石/TiO2光催化材料,并且在模拟废水甲苯溶液处理中,对材料的催化降解性能进行了研究。结果表明:复合材料的最佳配比为3 g酸化海泡石与10 mL钛酸四丁酯溶胶反应,经450℃煅烧4 h处理后具有较大的光催化活性;海泡石/TiO2对初始浓度为50 mg/L甲苯溶液在pH为9的条件下投加4 g/L催化剂时,甲苯溶液的降解率可达到85.3%。     

Co~(2+)/AgNbO_3复合海泡石材料的制备及对甲苯的光催化性能研究

AgNbO_3是一种可见光光催化剂,将其掺杂一定量的Co~(2+),可显著提高其光催化效率。Co~(2+)/AgNbO_3与海泡石复合制备新型复合光催化材料,并利用扫描电镜(SEM)和傅里叶红外光谱(IR)对Co~(2+)/AgNbO_3/海泡石纤维复合材料的结构及活性进行表征分析,研究其复合机理。通过气相甲苯去除实验,验证其光催化-吸附性能。研究表明:可见光(400~760 nm)照射下,当甲苯初始质量分数为50μg/g,投加1 g复合材料,Co~(2+)/AgNbO_3质量比为30%时,对甲苯的去除效果最佳,2.5 h时反应完成后,去除率高达87.876%。     

海泡石的酸处理和有机海泡石的制备

用热酸法对海泡石样品进行提纯和改性,然后用十六烷基三甲基溴化铵(CTAB)对热酸活化的海泡石进行有机化改性,制备有机海泡石.采用X射线衍射分析(XRD)、傅立叶红外光谱分析(TFIR)和扫描电镜显微分析(SEM)等测试手段分别对酸化海泡石和有机海泡石进行分析.结果表明:酸活化能有效除去样品中的方解石等杂质,海泡石中部分的Mg被H取代,同时失去端位上与Mg配位的结构水.提高固液比、延长时间、升高温度可促进海泡石的酸化效果,改变酸浓度对海泡石酸化效果影响不明显.有机化处理后海泡石层间距由12.16 nm增加到12.30nm,且有机化有利于海泡石纤维解束.     

有机海泡石的制备及其结构性能的研究

以十六烷基三甲基溴化铵(CTMAB)为改性剂,采用机械化学改性工艺对江西乐平天然海泡石进行有机改性.运用正交实验,优化出海泡石改性的最佳工艺参数.通过BET、XRD、FT-IR和TEM的测试手段对改性海泡石进行了结构表征,研究表明,海泡石改性后纯度得到提高,其比表面积为410m2/g,是原矿的4.5倍;改性样品的红外图谱表明有机改性剂(CTMAB)进入了海泡石晶体层间,引起了晶层间距的增大,从而提高了海泡石的吸附活性.TEM表明,改性海泡石的形貌呈纤维束状集合体,结构较疏松,纤维束较分散,并保持了晶体结构形态.     

花状微球结构MoS2的制备及其光催化性能研究

采用简单的水热溶剂法,以钼酸钠(Na2MoO4·2H2O)为钼源,硫脲(CS(NH2)2)为硫源,通过调控反应温度、反应时间等合成工艺参数,成功制备了花状微球结构的二硫化钼(MoS2)粉末.采用X射线衍射仪(XRD)、扫描电镜(SEM)等对MoS2粉末的结构和形貌进行了表征.结果表明:当反应温度为220℃,反应时间为24 h,反应环境pH=1时,可制备出花状微球结构的MoS2粉末.通过分析MoS2粉末对罗丹明B的光催化降解率研究其光催化性能,对罗丹明B的降解率达到93.83％,是一种理想的光催化材料.     

海泡石液相原位负载金红石型TiO2研究

以四氯化钛为原料,天然矿物海泡石为载体,沸腾回流分别制备了TiO2及TiO2/海泡石复合材料.X射线衍射分析发现:相同工艺制备的TiO2为金红石与锐钛矿型的混晶,而复合TiO2为金红石型.在扫描电子显微镜下观察到复合粉体中TiO2球主要生长在海泡石的纤维端口.透射电镜观察发现TiO2颗粒呈均匀的短轴型.用电子自旋共振对样品产生羟基自由基(·OH)的能力进行了表征,通过样品对甲基橙溶液的降解评价了样品的催化性能.结果发现:自然光照射下TiO2/海泡石复合材料可产生较强的·OH自由基信号,且具有比TiO2更高的光催化活性.     

光催化涂层/薄膜材料的制备工艺及其结构调控研究进展

光催化涂层/薄膜的材料体系包括氧化物、硫化物、氮化物、磷化物及其表面改性和新兴的材料体系。光催化涂层/薄膜的制备工艺主要包括液相法、气相法和电化学法等,指出各工艺利弊和制备工艺对薄膜光催化性能的影响。介绍了光催化涂层/薄膜材料的某些特殊微纳结构(核壳结构及中空结构、介孔结构、碳包覆结构)及其结构调控的方法;总结展望了光催化涂层/薄膜材料在制备、结构调控及其应用方面存在的问题及未来的发展趋势。通过对制备工艺和材料体系的研究设计,提高光利用率,实现光催化薄膜的结构和性能等方面的调控,未来光催化涂层/薄膜材料应向着可持续的产业化方向不断发展。     

改性海泡石对聚丙烯复合材料性能的影响

制备了聚丙烯(PP)/改性海泡石复合材料,采用SEM、XRD、DSC、TG等测试方法对该复合材料的结构和性能进行了研究。结果表明:改性处理的海泡石在PP基材中分散均匀;少量改性海泡石的引入增大了PP的结晶度以及微晶尺寸,并且提高了PP材料的热稳定性和力学性能。     

C-N掺杂TiO_2/海泡石复合材料光催化性能研究

二氧化钛(TiO_2)由于具有化学性质稳定、抗光腐蚀、无毒和成本低等优点,在光电转化和光催化领域具有广阔的应用前景。然而,TiO_2的禁带宽度较大(3.0～3.2 eV),只能被波长小于387 nm的紫外光激发,且光生电子和空穴易复合,因此限制了其在光催化领域的广泛应用。海泡石作为一种多孔型无机高分子物质,具有较大的比表面能,可以吸附或覆盖多种催化剂单质或化合物。为了增强TiO_2可见光吸收和提高TiO_2光催化效率,笔者采用溶胶-凝胶法制备了一系列C-N掺杂TiO_2/海泡石复合材料。通过XRD、SEM、XPS和紫外光谱等手段来考察非金属掺杂TiO_2/海泡石复合材料的组成和结构,并研究了其光催化特性。实验结果表明:二氧化钛小颗粒负载到了海泡石表面;N原子取代了TiO_2晶格中的氧原子而形成了少量Ti-N键,制备出了C、N共掺杂的TiO_2/海泡石复合材料;随着N掺杂量的增加,复合材料的可见光吸收能力提高;随着N掺杂量的增加可见光光催化效率略微增加。另外,对海泡石进行了酸化提纯处理后,纯度得到提高,分散度变得更好。     

制备工艺对La改性的Ca3Co4O9基陶瓷热电性能的影响

利用常压烧结、冷等静压成型后常压烧结及热等静压烧结3种不同制备工艺,合成了(Ca0.9La0.1)3Co4O9热电材料。XRD分析表明：不同工艺制备的样品均为Ca3Co4O9相。样品的SEM照片显示：晶粒为片状结构;热等静压烧结制备的样品,其片状结构不明显,但致密度较之另外两种工艺大幅度提高,其相对密度为95％。制备工艺对(Ca0.9La0.1)3Co4O9热电材料Seebeck系数影响不大,但热压烧结样品能大幅度提高(Ca0.9La0.1)3Co4O9电导率。在一定温度范围内,随温度升高,功率因子大幅度增加,对于热压烧结的样品尤为显著。     

（SBA-15）-ZnO的制备和发光性质

采用液相介质微波法和固相微波法制备了（SBA-15）-ZnO主一客体纳米复合材料样品。采用X射线衍射、红外光谱和透射电子显微镜对所制备（SBA-15）-ZnO样品的性质进行了表征。结果显示：在制备的（SBA-15）-ZnO主一客体纳米复合材料样品中,SBA-15分子筛的骨架保存完好,结构仍然具有很高的有序性。用激发光谱...     

Effects of monomer composition on the mechanical and machinability properties of gel-cast alumina green compacts

In the present work, machinable green gel-cast alumina compacts were prepared by using polyethyleneglycol (400) diacrylate (P4) and polyethyleneglycol (600) dimethacrylate (P6) together with the acrylamide (AAm) comonomer. The glass transition temperatures of copolymers decreased with the increasing of P4 or P6 amount in total copolymer. The green samples obtained in an aqueous system were mechanically analyzed by means of three-point bending. Flexural strength values increased, from 2 MPa to 25 MPa, as the weight ratio of P4 or P6 in total copolymer (AAm-P4 or AAm-P6) decreased from 90% to 3.5%, respectively. The green gel-cast samples prepared by using P4 or P6 were machined easily by using a lathe, drill and milling machine without damaging the samples, which have good surface finish. The binder removal was achieved at lower temperatures than those samples prepared by using only AAm.     

Sol derived gold–palladium bimetallic nanoparticles on TiO2: structure and catalytic activity in CO oxidation

Bimetallic AuPd catalysts were prepared by deposition of bimetallic aqueous sols formed in different ways: (i) co-reduction of the precursor Au and Pd ions by Na-citrate/tannic acid mixture, (ii) reduction of Au(III) ions onto preformed Pd sol, and (iii) reduction of Pd(II) ions onto a preformed Au sol. The Au/TiO₂ and Pd/TiO₂ samples as references were prepared from their respective sols. The structure of the samples was characterized by XRF, XRD, XPS, TEM and CO chemisorption both in the as-prepared state and after calcination and reduction. The catalytic activities of the calcined/reduced catalysts in the CO oxidation were compared. The presence of bimetallic crystalline phases was evidenced in all three samples both in the as prepared and calcined/reduced states, however, various extents of Pd surface enrichment were determined. The catalytic activity of the bimetallic samples regardless of the preparation method, is about the same as that of the mixture of the monometallic samples. No significant synergism is suggested in the present bimetallic samples.     

静电纺丝制备TiO2纳米纤维的光催化性能

纳米TiO2材料在光催化、抗菌等方面有着广泛应用。采用尺寸为20～30nm的TiO2颗粒与聚乙烯吡咯烷酮（PVP）的醇溶液混合制得纺丝液,通过静电纺丝技术与烧结工艺,制得TiO2纳米纤维。采用能谱仪、X射线衍射、扫描电子显微镜和投射电子显微镜等分析手段对样品进行了表征,与采用溶胶–凝胶结合静电纺丝技术得到的TiO2纳米纤维进行了形貌对比,并通过亚甲基蓝降解实验研究其光催化性能。结果表明：以TiO2纳米颗粒为原料通过静电纺丝技术制备的TiO2纳米纤维,主要为多晶相的锐钛矿结构,直径为150～250 nm,长度大于20μm,与溶胶–凝胶结合静电纺丝技术制得的TiO2纳米纤维相比,直径分布更为均匀。在紫外光照射90min时,对浓度为4mg/L的亚甲基蓝溶液的分解率为72%,具有较好的光催化效率。     

Effect of Cold Pressing on Dielectric Properties of (Sr0.8Pb0.2)TiO3-MgO Composites

(Sr_0.8Pb_0.2)TiO₃-MgO (50:50 by weight) composites are prepared and their dielectric properties are investigated. The dielectric properties of the samples prepared by using the green samples prepared under different cold pressing conditions are compared. The cylindrical samples prepared by using uniaxial pressing (UP) followed by cold isostatic pressing (CIP) show the higher quality of dielectric properties than the plate samples prepared by using only UP. It is found that the forming pressure before CIP also influences the dielectric constant of the sintered products. Furthermore, the dielectric constant of the rectangular composite samples cut out of the disk samples is direction dependent with respect to the UP direction while the tan δ of the composites is almost independent of the measurement directions.     

Beta Zeolite-Supported Iridium Catalysts by Gas Phase Deposition

In this study, H-beta zeolite-supported iridium catalysts were prepared by atomic layer deposition (ALD) and characterized as such and after different activation treatments. A reference catalyst was prepared by wet impregnation. The samples were tested in decalin ring opening reaction. ALD samples were clearly more active and selective in decalin ring opening compared to impregnated sample. The differences observed in characteristics and activities between ALD samples and impregnated sample are discussed.     

Physical and surface properties of polyurethane hydrogels in relation with their chemical structure

Polyethylene glycol (PEG)/castor oil (CO)‐based polyurethanes were prepared by one‐shot bulk polymerization method with the potential for biomedical applications. Hexamethylene diisocyanate and 1,4‐buthane diol were used as diisocyanate component and chain extender, respectively. Polyurethanes were prepared (1) with crosslinker and catalyst, (2) with crosslinker and without catalyst, and (3) without crosslinker and catalyst. The effects of the ratio of CO to PEG, and presence/absence of the crosslinker and catalyst on some physical and surface properties of the polyurethanes were investigated. The glass transition temperatures of prepared polyurethanes are below room temperature. The swelling ratio increased and the water contact angle decreased with increasing amount of PEG in polymer structure. The samples prepared with crosslinker and without catalyst showed the highest swelling ratio. Gas permeability of the samples was measured in a gas permeability system and surface roughness was determined by scanning electron microscope and atomic force microscope. Protein adsorption studies were performed for the samples synthesized without crosslinker and catalyst by using bovine serum albumin and bovine serum fibrinogen. Unexpected results were obtained for the samples which have low contact angles. They exhibited relatively high protein adsorption. POLYM. ENG. SCI., 54:1182–1191, 2014. © 2013 Society of Plastics Engineers     

Ce掺杂TiO_2纳米粒子的制备及其光催化活性研究

以钛酸四丁酯为原料,采用溶胶-凝胶法制备了纯的和掺杂铈的TiO2纳米粒子,并利用XRD和UV-VIS对其进行表征,且在紫外光下,以甲基橙的光催化降解为模型反应,考察了TiO2纳米粒子的光催化活性和不同Ce掺杂量对光催化活性的影响。结果表明,Ce的掺杂抑制了锐钛矿晶粒的生长,并使TiO2纳米粒子的光谱响应范围拓展到可见光区,掺杂Ce的摩尔分数为0.05%时,TiO2纳米粒子具有最佳的光催化活性。     

Synthesis and characterization of polyethylene modified through phase‐transfer‐catalyzed graft copolymerization

In an effort to impart biodegradability, polyethylene (PE) was modified through the graft copolymerization of vinyl monomers such as acrylamide (AAm) and acrylic acid (AAc) by a phase‐transfer‐catalyst method. The grafting percentage of AAm and AAc for PE was found to be dependent on the dibenzoyl peroxide concentration, monomer concentration, time, temperature, and concentration of the phase‐transfer catalyst. Some AAm‐ and AAc‐grafted PE samples were prepared by chemical, UV, and γ‐radiation methods. The biodegradation of samples of PE, polyethylene‐g‐polyacrylamide, and polyethylene‐g‐poly(acrylic acid) prepared by all these methods was studied. The weight loss of the samples over a period of time was observed with soil‐burial tests. The grafted samples prepared by the phase‐transfer‐catalyst method showed better biodegradation results than those prepared by other methods of grafting. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008