近单分散介孔SiO2/Fe3O4/SiO2微球的制备及漆酶固定化

以自制近单分散、平均粒径约为250 nm的SiO2亚微球为核心,采用液相沉积法得到β-FeOOH/SiO2微球,再通过溶胶-凝胶法以β-FeOOH/SiO2微球为内核,十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸乙酯(TEOS)为硅源,经水解缩聚反应,焙烧后得到近单分散介孔SiO2/Fe3O4/SiO2微球,以复合微球为载体,对漆酶进行固定。结果表明,近单分散介孔SiO2/Fe3O4/SiO2复合微球的介孔层厚约40 nm,具有较大的饱和磁化强度(14.715 emu/g),较小的剩余矫顽力(约为109Oe),其比表面积为391.067 m2/g,孔容为0.53 cm3/g,孔径分别在5.43 nm和20～80 nm,呈现双孔径分布。复合微球吸附漆酶后,介孔材料的比表面积与孔容分别减小为103 m2/g和0.37 cm3/g,复合微球对漆酶的吸附量为202.6 mg/g。     

酚醛树脂辅助合成SiO2/TiO2介孔复合微球及其光催化

利用Stber法合成的纳米SiO2为前体,在酚醛树脂和十六烷基三甲基溴化铵(CTAB)辅助下制备SiO2/TiO2介孔复合微球,并利用XRD、SEM、EDS、BET、BJH以及FTIR对材料的晶型、形貌以及结构进行了表征,以罗丹明B为目标降解物评价样品的光催化性能。结果表明,SiO2/TiO2介孔复合微球是由TiO2和SiO2组成,直径约300 nm,TiO2以纳米薄层方式均匀地沉积在SiO2表面,界面之间存在Si—O—Ti键;SiO2/TiO2介孔复合微球的比表面积为92.3 m2/g,较P25提高了约3倍。光催化评价表明,SiO2/TiO2介孔复合微球对罗丹明B的降解率达98%,较P25光催化降解率有明显提高。     

微乳液法制备Fe3O4/TiO2磁性纳米粒子

采用多元醇还原法制备出平均粒径为6.0 nm的Fe3O4磁性纳米粒子,以此磁性纳米粒子为核,在OP-10/正丁醇/环己烷/浓氨水反向微乳体系中制备出Fe3O4/TiO2磁性纳米复合粒子,通过XRD,TEM,VSM对复合粒子进行性能表征。结果表明,采用微乳液法能够制备出Fe3O4/TiO2磁性纳米复合粒子,并且包覆后比饱和磁化强度有所下降,但矫顽力仍趋近于0,显示超顺磁性。     

正交试验优化核壳型Fe3O4@SiO2磁性复合微球的制备工艺

采用共沉淀法和溶胶-凝胶法制备了磁性Fe3O4纳米粒子及核壳型Fe3O4@SiO2复合微球,利用红外光谱(FTIR)技术测定了微球表面基团,证明了SiO2确实在Fe3O4纳米粒子的表面形成了包覆层。通过正交试验设计,利用激光粒度仪测量的微球粒径为指标,考察TEOS与磁性微球的体积比、反应温度、反应时间和乙醇浓度四因素对微球粒径的影响。结果表明TEOS与磁性微球的体积比为2、反应温度为80℃、反应时间为4 h,乙醇浓度为80%是制备大粒径Fe3O4@SiO2磁性复合微球的适宜条件。     

Fe_3O_4/SiO_2核壳复合磁性微球的制备和表征

以溶剂热法制备的高磁饱和强度Fe3O4纳米颗粒为核,正硅酸乙酯(TEOS)为前驱体,采用Stber方法,在乙醇/水溶液中,通过氨水催化水解硅醇盐,制得核壳结构的Fe3O4/SiO2复合磁性微球。对制备的样品的物相结构、形貌和磁性能进行了测试表征。结果表明:制备的Fe3O4/SiO2磁性微球呈球形,粒径分布均一,SiO2壳层圆整光滑,厚度为40~70nm。X射线衍射分析显示,Fe3O4/SiO2磁性微球具有尖锐的Fe3O4特征衍射峰,表明包覆过程没有破坏Fe3O4的晶体结构,其室温下的磁滞回线呈顺磁性,且比饱和磁化强度为30A·m2/kg。此外,对SiO2壳层的包覆机理进行了探究。     

磁性纳米光催化剂TiO2/SiO2/CoFe2O4的制备与结构性能的研究

用层状前体法制备了尖晶石铁氧体CoFeO4.在其表面依次包覆SiO2和具有光催化活性的TiO2,制备出磁性纳米光催化剂TiO2/SiO2/CoFe2O4.用XRD、FT-IR和VSM等表征技术研究了磁核CoFe2O4和磁性光催化剂的结构与性能.利用催化剂光降解甲基橙评价了催化剂的活性.     

新型磁性可分离TiO2的制备及其催化臭氧化苯酚

以磁性纳米材料Fe3O4为核心,外面包覆SiO2作为阻隔保护层,形成球状SiO2/Fe3O4磁核(SF),再以TiO2为活性物质,包覆于磁核外,制备出磁性可分离的TiO2包覆SiO2/Fe3O4臭氧催化剂(TSF)。采用X射线衍射(XRD)和振动样品磁强计(VSM)对其表征,并以苯酚为模型污染物,考察了催化剂的催化臭氧化活性。实验结果表明,所制备的催化剂具有良好的催化臭氧化去除苯酚的能力,苯酚初始浓度20 mg/L、反应温度为20℃、O3/O2投加量50 mL/min、TSF投加量1.0 g/L时,反应120 min后苯酚去除率可达82%,并且具有良好的磁分离效应。     

微乳液法制备Fe3O4/TiO2磁性纳米粒子

采用多元醇还原法制备出平均粒径为6.0 nm的Fe3O4磁性纳米粒子,以此磁性纳米粒子为核,在OP-10/正丁醇/环己烷/浓氨水反向微乳体系中制备出Fe3O4/TiO2磁性纳米复合粒子,通过XRD,TEM,VSM对复合粒子进行性能表征。结果表明,采用微乳液法能够制备出Fe3O4/TiO2磁性纳米复合粒子,并且包覆后比饱和磁化强度有所下降,但矫顽力仍趋近于0,显示超顺磁性。     

多孔Fe2O3/SiO2复合磁性微球的合成

采用分散聚合法制备了单分散脲醛树脂／Fe2O3／SiO2的复合微球,研究了不同的反应条件对于复合微球的分散状况和粒径大小的影响。该微球在马弗炉内灼烧后,脲醛树脂成分被除去,得到Fe2O3／SiO2的复合微球,其中的Fe2O3组分一部分转化为磁性γ—Fe2O3。由脲醛树脂／Fe2O3／SiO2复合微球的电镜(SEM)图、Fe2O3／SiO2复合微球的XRD衍射图得知该微球为多孔的磁性复合微球,且具有单分散性。     

超亲水性介孔SiO2/Bi2O3/TiO2分层薄膜的制备及其自洁净性能研究

采用溶胶-凝胶/旋转涂覆法在玻璃基板表面制备介孔SiO2/Bi2 O3/TiO2分层薄膜.采用XRD、UV-vis及表面接触角测量仪对薄膜的结构、透光性及超亲水性进行分析.结果表明,介孔SiO2/Bi2 O3/TiO2分层薄膜仍然保持了表面SiO2的介孔结构,在无光照条件下仍具有超亲水性.涂有硬脂酸的薄膜在紫外光照射后恢复了其超亲水性,具有良好的自洁净性能.且SiO2/Bi2 O3/TiO2分层薄膜表现出比单独的SiO2/TiO2和SiO2/Bi2O3分层薄膜更高的光催化活性.     

Self-organized nano-crystallisation of BaF2 from Na2O/K2O/BaF2/Al2O3/SiO2 glasses

In glasses with the compositions (100 ? x)(2Na₂O·16K₂O·8Al₂O₃·74SiO₂)xBaF₂ (with x = 0 to 6), the glass transition temperature decreases with increasing BaF₂-concentration. Samples with x = 6 were thermally treated at temperatures in the range from 500 to 600 °C for 5–160 h. This leads to the crystallisation of BaF₂. The quantity of crystalline BaF₂ increases with increasing time of thermal treatment, while the mean crystallite size remains constant within the limits of error. The glass transformation temperature of partially crystallised samples increases with increasing crystallisation time and approaches a value equal to the temperature, at which the samples were treated. This is explained by the formation of a highly viscous layer enriched in SiO₂ which is formed during crystallisation. This layer acts as a diffusion barrier and hinders further crystal growth.     

Prediction of Immiscibility Boundaries of the Systems K2O-SiO2, K2O-Li20-SiO2, K20-Na2O-Si02, and K2O-BaO-SiO2

In earlier work, a prediction method of the immiscibility boundary of a ternary silicate glass system was developed involving two known binary immiscibility boundaries and a measured immiscibility temperature of one ternary glass composition. In the present work, the method is extended to the case where one of the two binary immiscibility boundaries is not known and is applied as an example to ternary silicate systems containing K₂O. First, the immiscibility boundary of the system K₂O-SiO₂ is estimated by measuring the immiscibility temperatures of three glasses in the system K₂O-Li₂O (or Na₂O)-SiO₂. Using this result the immiscibility boundaries of the systems K₂O-Li₂O-SiO₂, K₂O-Na₂O-SiO₂, and K₂O-BaO-SiO₂ are estimated. The results agree reasonably well with the experimentally determined immiscibility temperatures at selected compositions.     

The System Na2O-CaO-SiO2-H2O

A portion of the quaternary phase diagram for Na₂O-CaO-SiO₂-H₂O has been constructed. Plotting concentrations as their 10th roots allows compounds having solubilities which differ by several orders of magnitude to be represented on a single diagram. The compositional relationships among sodium-substituted calcium silicate hydrate, calcium-substituted sodium silicate hydrate, calcium bydroxide, a quaternary compound of approximate composition 0.25Na₂O · CaO · SiO₂· 3H₂O, sodium hydroxide monohydrate, and miscellaneous sodium silicate hydrates are presented. The quaternary diagram constructed shows the quaternary compound to exist in equilibrium with sodium-substituted calcium silicate hydrate and calcium hydroxide. Conditions in concrete pore solutions which favor the formation of this quaternary compound may also favor the occurrence of the alkali-silica reaction.     

复合固体超强酸SO42-/ZrO2-Al2O3催化合成乳酸正丁酯的研究

合成了几种不同Zr、Al原子比的SO42-/ZrO2-Al2O3复合固体超强酸,将其用于催化乳酸与正丁醇的酯化反应,均有较好的催化活性,尤以ZrAl=12的催化效果最好,经济性优于ZrO2超强酸催化剂.其最佳反应条件为酸醇摩尔比为13,催化剂用量为乳酸质量的10%,反应时间2～2.5h,酯化率达96.9%.该催化剂具有制备容易、催化活性高、不污染环境、可重复使用的优点.     

Some Properties of the System Na2O-NaF-B2O2-H2O

It was first shown that the enamel slips which have the best suspnding characteristics contain equal amounts of Na₂O and B₂O₃ and at least a moderate amount of NaF. The solubilities of mixtures of Na₂O, NaF, and B₂O₃ were then investigated. The pH of these solutions and the primary crystalline phases separating on evaporation also were determined. The solubility data obtained at room temperature were summarized. When the solutions were evaporated, NaF was the first crystalline phase to separate from a large proportion of the mixtures investigated. It was concluded that the desirable handling characteristics of enamels whose mill liquors contain the proper proportion of Na₂O, NaF, and B₂O₃ are not due to the formation of complex salts but to the following combination of properties: (1) the presence of salts with a moderate solubility which changes very slightly with temperature, (2) a moderate pH of about 10 in a probably well-buffered solution, (3) a relatively stable crystalline material, NaF, as a primary phase, and (4) a secondary phase which crystallizes slowly with relatively little shrinkage.     

固体超强酸SO^2—4／TiO2催化合成尿囊素的研究

用固体超强酸SO42/TiO2为催化剂,以尿素和乙醛酸为原料合成了尿囊素。得到最佳条件为TiO2在1mo1·L-1H2SO4溶液中浸渍12h,再在600℃焙烧3h;尿素与乙醛酸摩尔比3.51,催化剂9％,时间3h,温度72℃～75℃,产率达57.4％。     

Photocatalytic activity of Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions

Cu₂O/TiO₂, Bi₂O₃/TiO₂ and ZnMn₂O₄/TiO₂ heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu₂O, Bi₂O₃ and ZnMn₂O₄ are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu₂O/TiO₂ and Bi₂O₃/TiO₂ by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed.     

Phase Diagrams for the Systems MgCl2-MgF2, CaCl2-MgF2, and NaCl-MgF2

Equilibrium phase diagrams for the systems MgCl₂-MgF₂, CaCl₂-MgF₂ and NaCl-MgF₂ were determined by differential thermal analysis, thermal analysis, and temperature-composition equilibrium techniques. Simple eutectics were observed at 78.0±0.5 mol% MgCl₂ and 628°±2°C in the MgCl₂-MgF₂ system, at 87.5±0.5 mol% CaCl₂ and 694°±2°C in the CaCl₂-MgF₂ system, and at 95.5±0.5 mol% NaCl and 786°±3°C in the NaCl-MgF₂ system. The phase diagrams determined for these systems were compared with phase diagrams that were computed using Temkin's model. The phase diagrams of the CaCl₂-MgF₂ and NaCl-MgF₂ systems were also compared with diagrams that were computed using the expression suggested by Flood et al. for reciprocal systems. The experimentally determined and computed phase diagrams agreed for the MgCl₂-MgF₂ system but not for the CaCl₂-MgF₂ and NaCl-MgF₂ systems.     

Crystallization of zeolite L from Na2O-K2O-Al2O3-SiO2-H2O system

Zeolite L powder was prepared from the substrate mixture of Na₂O-K₂O-Al₂O₃-SiO₂-H₂O system at temperatures of 373-443 K. In order to investigate the factors which influence the synthesis outcome, a reference system which yields zeolite L in a reproducible manner was chosen and subjected to controlled changes in synthesis parameters. The crystalline zeolite L samples obtained were characterized by elemental chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). It was established that phase purity, morphology, and the size of crystals of crystalline product were affected by molar ratios of the substrate, such as SiO₂/Al₂O₃, (K₂O+Na₂O)/SiO₂, Na₂O/(K₂O+Na₂O), and H₂O/(K₂O+Na₂O). Amorphous silica powder (Zeosil) was the preferred silica source, and the crystallization rate was promoted by introducing gel aging, seeding, and rapid heating rate.