Preparation and characterization of surface bond-conjugated TiO2/SiO2 and photocatalysis for azo dyes

Surface bond-conjugated TiO₂/SiO₂ was prepared by means of the impregnation method. Based on the results of XRD, FTIR, XPS and BET measurements, the growth of titania (predominantly anatase) on the silica substrate seems to occur by anchoring of the TiO₂ phase through Ti–O–Si cross-linking bonds. The structure model of TiO₂/SiO₂ was proposed. Compared to B–TiO₂, the most efficient catalyst is 30 wt.% TiO₂/SiO₂ (Ims30), which showed three times higher photoactivity for the degradation of reactive 15 (R15). In addition, the catalyst had a higher photoactivity on a silica of smaller particle size than on the silica of larger particles. Silica gel plays the basic role of dispersion and support for power TiO₂. The isoelectric point of the catalyst was 3.0 pH units by the measurement of zeta-potential, indicating the presence of the surface acidity of the catalyst. The photodegradation and the adsorption of R15 and cationic blue X-GRL (CBX) were investigated with the change of initial aqueous pH.     

Dependence of the properties of compositionally graded Pb(Zr,Ti)O3 ferroelectric films of the bottom electrode

Compositionally graded Pb(Zr_,Ti)O₃ thin films were prepared on the Pt(1 1 1)/Ti/SiO₂/Si, LNO/Si(1 0 0) and LNO/Pt(1 1 1)/Ti/SiO₂/Si substrates by a modified sol–gel method and rapid heat-treatment. The composition depth profile of a typical up-graded film was determined using a combination of auger electron spectroscopy and Ar-ion etching. The crystallographic orientation and the microstructure of the resulting graded PZT thin films on the different substrates were characterized by XRD. The dielectric and ferroelectric properties of the graded PZT films were discussed. The graded PZT films on LNO/Pt/Ti/SiO₂/Si and LNO/Si(1 0 0) substrates have larger dielectric constant and remnant polarizations compared to that grown on Pt/Ti/SiO₂/Si substrates.     

Ruthenium as oxidation catalyst: bridging the pressure and material gaps between ideal and real systems in heterogeneous catalysis by applying DRIFT spectroscopy and the TAP reactor

Two supported Ru catalysts were prepared by the chemical vapor deposition of Ru₃(CO)₁₂ on MgO and SiO₂ (MOCVD). TEM, XRD, and static H₂ chemisorption measurements confirmed that the Ru particle size was about 2 nm on both supports. Using in situ DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy at atmospheric pressure it was found that the adsorption of CO on the reduced samples is clearly influenced by the supports whereas the adsorption of CO on the oxidized Ru catalysts is essentially independent of the support. O₂ chemisorption measurements showed that a thin RuO₂ surface layer was formed on both catalysts under oxidizing conditions at room temperature. The observed C–O stretching frequencies were found to be in good agreement with HREELS and LEED data reported for the RuO₂(1 1 0) single crystal surface. The catalytic activity was assessed under high-vacuum conditions using the TAP (temporal analysis of products) reactor by co-feeding CO and O₂. These conditions ensured that heat and mass transfer limitations were absent. Both supported Ru catalysts were found to be highly active and stable under the CO oxidation conditions even down to room temperature. The deactivation of the catalysts observed at room temperature was reversible and independent of the support. The turnover frequencies (number of CO₂ molecules per metal surface site per second) derived from steady-state measurements are in good agreement with data reported for the RuO₂(1 1 0) single crystal surface under UHV conditions. Based on the results of the DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) and the kinetic measurements supported RuO₂ is identified as the catalytically active phase. In addition, the turnover frequencies are in good agreement with data reported for Ru/SiO₂ at atmospheric pressure. Thus, both the materials and the pressure gap were bridged successfully.     

羧基化磁性Fe3O4复合材料的制备及其对水体中Pb2+的吸附研究

以采用共沉淀法制备的磁性Fe₃O₄为核,通过硅烷化及酰胺化反应,制备了羧基化磁性Fe₃O₄复合材料（Fe₃O₄?SiO₂?NH?COOH）,通过红外光谱仪（FTIR）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、磁强度计（VSM）和X射线衍射仪（XRD）等对复合材料的结构进行了表征,并对不同作用条件下Fe₃O₄?SiO₂?NH?COOH吸附Pb²⁺的效果及Fe₃O₄?SiO₂?NH?COOH的重复使用效能进行了研究。结果表明,具有Fe₃O₄?SiO₂?NH?COOH结构的复合材料已被成功被制备,且该材料仍然能够实现快速磁性分离;Fe₃O₄?SiO₂?NH?COOH对Pb²⁺的静态吸附动力学数据更符合准二阶动力学,吸附时间为100 min、pH=4.5、Fe₃O₄?SiO₂?NH?COOH用量为1.0 g/L时,Fe₃O₄?SiO₂?NH?COOH对Pb²⁺的最大吸附容量为208.7 mg/g,且Langmuir方程更能描述该吸附等温过程;Fe₃O₄?SiO₂?NH?COOH对Pb²⁺的吸附是吸热过程;Fe₃O₄?SiO₂?NH?COOH对Pb²⁺的吸附量随时间延长先增加后趋于稳定,随pH值的增加先增加后减小;相比于一价阳离子,溶液中二价Ca²⁺、Mg²⁺的存在对吸附反应具有一定抑制作用;Fe₃O₄?SiO₂?NH?COOH吸附Pb²⁺后可洗脱再生,连续重复使用6次后对Pb²⁺的去除率仍大于50 %。     

SiO2/还原氧化石墨烯复合材料的简易制备及对罗丹明B的吸附

以正硅酸乙酯（TEOS）为硅源,氧化石墨烯（GO）为载体,在不添加任何还原剂的情况下,通过水热法简易制备SiO₂/还原氧化石墨烯（SiO₂/RGO）复合材料。采用TEM、FTIR、XRD、TG-DSC、N₂-吸附对复合材料的微观结构进行表征,分析表明：负载量为76.60%（质量分数）的SiO₂纳米颗粒均匀分散在RGO表面上,且部分以Si-O-C键进行配位;具有多级孔结构的SiO₂/RGO复合材料孔径主要分布在1~7nm,比表面积高达676m²/g。以罗丹明B为目标污染物,考察了pH、投入量、温度和接触时间等因素对复合材料吸附性能的影响,结果表明：在pH为2、35℃时,复合材料具有最佳的吸附效果,吸附量为127.8mg/g。动力学分析表明吸附过程符合准二级动力学模型,热力学参数揭示吸附过程为自发吸热过程。     

Solubility of silica-alumina gels in different pH solutions Discussion on the hydration of slags and fly ashes in cement

The solubility of silica-alumina gels with different compositions were measured in different pH solutions. The solubilities of a silica-alumina gel is remarkably affected by its composition and the pH of the solution. There is a gel with a composition of Si/Al atomic ratio of about 7/3. When the Al/(Si+Al) ratio of silica-alumina gel is less than 0.7, the composition of the liquid phase is more rich in Al₂O₃ than that of the gel, that is, the surface of gel becomes rich in SiO₂. Conversely, when the Al/(Si+Al) ratio of gel is more than 0.7, the composition of the liquid phase is more rich in SiO₂ than that of the gel, and the surface of gel becomes rich in Al₂O₃. In the hydration of silica-alumina glasses such as slag and fly ash, the reason why the hydration proceeds or not, is whether the surface of reacting glass becomes rich in Al₂O₃ or not.     

SiO2表面原位接枝聚环氧丙烷高分子刷的制备及表征

通过“Stober”法制备出单分散球形SiO₂粒子,并采用3-缩水甘油醚氧基丙基三甲氧基硅烷对其表面进行功能化修饰,然后,利用异丙醇铝作为多相催化剂,原位引发环氧丙烷（PO）单体开环聚合,制得了聚环氧丙烷（PPO）高分子刷接枝改性的SiO₂（PPO-g-SiO₂）。研究了单体添加量、反应温度及反应时间等因素对聚环氧丙烷高分子刷接枝量的影响规律。采用红外光谱（FT-IR）、X射线光电子能谱（XPS）、透射电子显微镜（TEM）、扫描电子显微镜（SEM）及热重分析（TGA）等分析方法对制备的PPO-g-SiO₂的化学结构、微观形貌以及接枝量进行了表征。结果显示,当单体添加量为2.38 mol·L^-1,反应温度为80℃,反应时间为24 h时,PPO在SiO₂表面的接枝量可达23.56%（质量分数）;其厚度约为15 nm。     

Oxidative dehydrogenation of methanol over a ruthenium-containing polyoxomolybdate supported on metal oxides chemically modified with silane coupling agent

A salt of ruthenium-containing polyoxomolybdate anion ([Ru₂Mo₁₄O₅₀]¹⁰⁻ or [Ru₂Mo₁₄O₅₂]¹⁴⁻; Ru₂Mo₁₄) was synthesized by mixing ruthenium chloride and sodium molybdate in a buffer solution (acetic acid–ammonium acetate) at pH 5. The polyanion, Ru₂Mo₁₄, was loaded on a silica carrier chemically modified with a silane coupling agent having a 1,2-diaminoethyl group (DAPS–SiO₂). X-ray diffraction, FT-IR and surface area measurements revealed that Ru₂Mo₁₄ was highly dispersed on DAPS–SiO₂ up to 20 wt.% loading. The highly dispersed Ru₂Mo₁₄ exhibited a high level of activity for oxidative dehydrogenation of methanol to formaldehyde with a high selectivity, whereas combustion of methanol occurred on the bulky salt of Ru₂Mo₁₄ and ruthenium catalyst supported on a SiO₂ carrier.     

Characterization and photocatalytic activity of transition-metal-supported surface bond-conjugated TiO2/SiO2

TM/TiO₂/SiO₂ photocatalysts were prepared by the photodeposition method using transition metal salts (TM=Fe³⁺, Co²⁺, Ni²⁺ and Cu²⁺) as precursors and the surface bond-conjugated TiO₂/SiO₂ as supporter in N₂ atmosphere, and were characterized by XRD, XPS, UV-Vis diffuse reflection and zeta-potential. Their photocatalytic activities were evaluated using reactive brilliant red K-2G (K-2G) and cationic blue X-GRL (CBX) showing different adsorption behavior on the oxides. Fe, Cu supported TiO₂/SiO₂ can efficiently extend the light absorption to the visible region. XPS analysis verified that the introduction of transition metal lead to the changes of the electronic environmental of Ti cations and the zeta-potential of oxides. As a result, K-2G has higher adsorption on the modified TiO₂/SiO₂ than that on the baked one, while the adsorption of CBX has a little change on the both oxides. At the same time, for the photodegradation of K-2G, Fe³⁺, Co²⁺, Ni²⁺-modified catalysts show that their photoactivities are 3.3–2.2 times higher than the bare one. On the contrast, all transition-metal-supported catalysts have no significant activity improvement except that Fe/TiO₂/SiO₂ shows 1.68 times higher activity for the photodegradation of CBX. The results indicate that the photoactivity could be increased in photodegradation of dyes by changing the performances of adsorption to dyes and absorption to light of photocatalyst.     

二氧化硅/聚噻吩复合吸附剂处理Pb2+和Cd2+

绿色环保、高效等特点是吸附剂发展的趋势。以溶胶-溶剂热法合成了SiO₂,再与聚噻吩反应合成了SiO₂/聚噻吩复合材料。采用扫描电镜(SEM)、傅里叶红外光谱(FT-IR)以及Zeta电位对复合材料进行了表征分析。SiO₂/聚噻吩是表面粗糙的球形,且表面带有负电荷。SiO₂/聚噻吩复合材料用于吸附Pb²⁺和Cd²⁺离子,改变吸附过程中的变量来研究吸附过程的影响因素,通过探讨动力学和等温线模型来研究其吸附机理。研究结果表明,pH通过改变SiO₂/聚噻吩表面的电荷数来影响吸附性能,吸附容量与吸附剂的量不呈正相关。同时得知,SiO₂/聚噻吩吸附剂吸附Pb²⁺和Cd²⁺的过程符合拟二级动力学模型及Langmuir等温线模型。根据研究结果提出吸附机理:SiO₂/聚噻吩表面的负电荷吸引带有正电荷的重金属离子,以单分层的化学吸附为主吸附过程。     

自组装法制备PVDF-SiO2/PVSQ超疏水复合膜及膜蒸馏抗污染性能

采用乙烯基三甲氧基硅烷(VTMOS)对SiO₂疏水改性,通过自组装法,将改性SiO₂接枝在商业PVDF(聚偏氟乙烯)膜表面,使其表面达到超疏水。利用场发射电子显微镜、红外光谱仪、接触角测量仪及毛细流孔径分析仪等仪器对改性前后膜的表面形貌、化学组成、接触角及孔径变化等性能参数进行表征。结果表明,VTMOS不仅对SiO₂疏水改性,还通过自身的水解缩聚反应,生成了规整圆球状的聚乙烯基倍半硅氧烷(PVSQ)微粒,纳米级SiO₂分布于微米级PVSQ表面,在改性膜表面构造了多层次微/纳米粗糙表面,在低表面能疏水基团乙烯基和甲氧基的共同作用下,成功实现了超疏水改性,改性膜水接触角达到159.5°,滚动角降至8.1°。以NaCl、HA和CaCl₂混合溶液为进料液,对商业PVDF膜和改性膜进行了长期直接接触式膜蒸馏(DCMD)实验,探究其抗污染性能。结果表明,改性膜适用于长期DCMD实验,并表现出比商业PVDF膜更稳定的通量,截盐率始终大于99.99%,具有良好的稳定性和抗污染性能。     

Dispersion of Zirconium Diboride in an Aqueous, High-Solids Paste

The dispersion of ZrB₂ particles was investigated. In aqueous systems, the surface of ZrB₂ consists of a thin layer of ZrO₂ that controls the surface chemistry and surface charge. Measurements showed that the ZrB₂ had an isoelectric point of pH=4.7 and a maximum ζ potential of −50 mV at pH=9. The addition of a dispersant, either an ionic ammonium polyacrylate or a nonionic alkoxylated polyether, increased the ζ potential of ZrB₂ by as much as 60 mV to −110 mV. Viscosity measurements were used to optimize dispersant concentrations. High-solids loading (∼45 vol.% ZrB₂) aqueous pastes were prepared with two different dispersants. The pastes had viscosities of 40–50 Pa·s which was acceptable for extrusion, and were used to fabricate three-dimensional components from ZrB₂.     

Enhanced dielectric tunability properties of Ba(ZrxTi1−x)O3 thin films using seed layers on Pt/Ti/SiO2/Si substrates

The compositionally graded and homogeneous Ba(Zr_xTi_1−x)O₃ (BZT) thin films were fabricated on LaNiO₃ (LNO) buffered Pt/Ti/SiO₂/Si and Pt/Ti/SiO₂/Si substrates by a sol–gel deposition method, respectively. These films crystallized into a single perovskite phase. The BZT thin films deposited on LaNiO₃/Pt/Ti/SiO₂/Si substrates had a highly (1 0 0) preferred orientation and exhibited a preferred (1 1 0) orientation when the thin films were deposited on Pt/Ti/SiO₂/Si substrates. The LNO and Ba(Zr_0.30Ti_0.70) served as seed layer on Pt/Ti/SiO₂/Si substrates and analyze the relationship of seed layer, microstructure and dielectric behavior of the thin films. The compositionally graded thin films from BaTiO₃ to BaZr_0.35Ti_0.65O₃ were fabricated on LNO/Pt/Ti/SiO₂/Si substrates. The tunability behavior of compositionally graded films was analyzed in order to produce optimum effective dielectric properties. The dielectric constant of BaZr_xTi_1−xO₃ compositionally graded thin films showed weak temperature dependence. This kind of thin films has a potential in a fabrication of a temperature stable tunable device.     

改性镍铁渣吸附剂对Cr(VI)吸附性能的影响及机理分析

以镍铁渣为原料,加入硝酸和表面活性剂对其矿物相改性,制备改性镍铁渣吸附剂,考察表面活性剂种类、十六烷基三甲基溴化铵(CTAB)掺量、吸附剂掺量、溶液初始pH值、Cr(VI)浓度对Cr(VI)吸附效果的影响。结果表明:镍铁渣经改性后可制得结构疏松、比表面积高达180.6 m²/g的无定形SiO₂;改性镍铁渣对Cr(VI)的吸附率在10 min内可达到90%,吸附等温线符合Langmuir模型,最大理论吸附容量为42.55 mg/g,吸附动力学符合拟二级动力学模型。改性镍铁渣吸附剂对Cr(VI)的吸附机理主要是物理吸附和氧化还原,即吸附剂表面范德华力将HCrO ^-₄吸附至吸附剂表面,CTAB提供的电子对将Cr(VI)还原为Cr(III)。对镍铁渣改性获得的高比表面积无定形SiO₂不仅可以有效吸附净化Cr(VI),同时可以实现镍铁渣资源化利用,达到以废治污的目的,具有良好的环境效应和经济效益。     

用于蛋白质BSA识别的温度/pH双敏印迹聚合物

用N-异丙基丙烯酰胺(NIPAM)和壳聚糖为功能单体,牛血清白蛋白（BSA）为模板蛋白,在改性SiO₂表面制备温度/pH双敏蛋白质印迹聚合物。TEM、FTIR和TG等结果证明印迹层已成功接枝在载体表面。系统研究了聚合物的温度/pH双敏性、吸附容量、吸附动力学、特异性、竞争吸附性及重复性。结果表明,印迹聚合物（MIP）的溶胀率和吸附容量受温度和pH影响较大,高温碱性收缩,低温酸性溶胀。在pH 4.6和35℃下,对0.6mg/mL BSA吸附4h时获得较大的吸附容量（83.74mg/g）,印迹因子为2.02。同时MIP也有较好的特异性和竞争吸附性。重复5次后,吸附容量仍能维持在88%,说明重复性良好。这种新型的温度/pH双敏蛋白质分子印迹合成方法简单,在蛋白质的分离和识别方面有较好的应用前景。     

Synthesis of nanosized TiO2/SiO2 particles in the microemulsion and their photocatalytic activity on the decomposition of p-nitrophenol

Nanosized pure TiO₂ particles were prepared by hydrolysis of TTIP in the sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. TiO₂/SiO₂ nanoparticles were also prepared from TEOS as a silicon source and TTIP as a titanium source. These particles were characterized by TEM, XRD, FT-IR, BET, TGA and DTA. From thermal analysis and XRD analysis, the anatase structure of pure titania appeared in the 300–600 °C calcination temperature range and the rutile structure was showed above 700 °C. However, no rutile phase was observed for the TiO₂/SiO₂ particles up to 800 °C. The crystallite size decreased and the surface area of TiO₂/SiO₂ particles monotonically increased with an increase of the silica content. From FT-IR analysis, the band for Ti–O–Si vibration was observed and the band intensity for Si–O–Si vibration increased with an increase of the silica content. The micrographs of TEM showed that the TiO₂/SiO₂ nanoparticles had a spherical and a narrow size distribution. In addition, TiO₂/SiO₂ particles showed higher photocatalytic activity than pure TiO₂ and the TiO₂/SiO₂ (90/10) particles showed the highest activity on the photocatalytic decomposition of p-nitrophenol.     

PASSIVATION OF COPPER BY LOW TEMPERATURE ANNEALING OF Cu/Mg/SiO2 BILAYERS

Annealed thin films of Cu/Mg/SiO₂ are studied as possible conductors for microelectronics. Rutherford backscattering and sheet resistance measurements show that vacuum annealing at 350-400°C results in transport of Mg from the buried layer to the surface of the copper where it reacts with impurities to form a thin surface layer of MgO. Such films are then exceedingly resistant to further oxidation. These films have a resistivity of 2·μω-cm and are adherent to the SiO₂ substrate. However, at temperatures 450-500°C there is a reaction between Mg and the SiO₂ substrate releasing free Si into the copper.     

伊利石硅渣蒸汽辅助合成麦羟硅钠石及其对Cu2+的吸附研究

以伊利石硅渣为原料,采用蒸汽辅助转化法(SAC)合成了高产率、高结晶度的纯相麦羟硅钠石(Magadiite)。采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)考察了钠硅比(n(Na₂O)/n(SiO₂))、晶化温度和晶化时间对合成样品结构及形貌的影响。结果表明,该体系的初步优化合成条件为钠硅比0.15,晶化温度170 ℃,晶化时间16 h,样品形貌为玫瑰花形(尺寸约12 μm)。对合成的Magadiite进行Cu²⁺吸附性能测试,探究了吸附剂用量、pH值、吸附时间和Cu²⁺初始浓度对吸附效果的影响。在吸附剂用量为2 g/L,pH值为5,吸附时间为30 min时,Magadiite对Cu²⁺的最大吸附量为25.99 mg/g。     

New method for selective growth of diamonds by microwave plasma chemical vapour deposition

Selective nucleation and deposition of diamonds were achieved on an SiO₂-patterned Si substrate. The substrate was pre-treated with an electric field in plasma to introduce diamond nuclei. This treatment did not affect the SiO₂ area. Consequently, diamonds grew only on the area where Si was exposed under the conventional conditions of diamond growth. The maximum nucleation density on the area of SiO₂was about 5 × 10⁷ cm⁻². The ratio of the selectivity was 2 × 10² or higher. This process will be useful and very promising for manufacturing diamond electronic devices.     

疏水SiO2填充PDMS膜分离水中乙酸正丁酯的性能

以聚偏氟乙烯（PVDF）为支撑层,选用疏水性纳米SiO₂粉体作为改性剂,制备出聚二甲基硅氧烷（PDMS）复合膜材料,并用于乙酸正丁酯/水溶液的渗透汽化分离。采用SEM、FTIR、XRD、拉伸实验、接触角及正电子湮没寿命谱测定等对膜材料物理化学性能进行了表征,考察了膜材料的溶胀行为及渗透汽化性能。结果表明,SiO₂在PDMS膜中分散均匀,且没有发生化学作用,并提高了膜材料的机械强度和疏水性。随着SiO₂添加量增加,膜在乙酸正丁酯溶液中的溶胀度先升后降,渗透通量呈下降趋势,而分离因子先增大后减小。当SiO₂添加量为4%（质量）时,随进料浓度的增加,渗透通量增大,分离因子先增大后减小;随着温度升高,渗透通量增大,分离因子减小;渗透通量和分离因子最大值分别为240 g·m^-2·h^-1和542。