PHOTOCATALYTIC OXIDATION OF ALDEHYDES/PCE USING POROUS ANATASE TITANIA AND VISIBLE-LIGHT-RESPONSIVE BROOKITE TITANIA

We have synthesized an annealed porous aerogel titania (LUAG2), which demonstrates a very high photocatalytic activity for aldehydes and perchloroethylene (PCE) photocatalytic oxidation (PCO) in gas phase under blacklight and fluorescent light irradiation. LUAG2 has a BET surface area of 237 m²/g and a porosity of 0.31 (volume fraction). X-ray diffraction (XRD) analysis shows LUAG2 is nearly pure anatase. It has improved the destruction of PCE and aldehydes as a group by 10-34% with black light compared to Degussa P-25. The optimum water vapor to butyraldehyde molar ratio is around 1/3. LUAG2 also shows better mineralization to CO₂ than Degussa P-25 TiO₂ does. Under irradiation of a 4 W fluorescent lamp LUAG2 gives a consistently higher conversion than that of Degussa P-25. The highly active photocatalyst indicates potential applications in indoor and outdoor environmental pollution control. A visible-light-responsive TiO₂, NTB 200, is also investigated for comparison purposes.     

An improved method for preparing monolithic aerogels based on methyltrimethoxysilane at ambient pressure Part II: Microstructure and performance of the aerogels

The microstructures, physical properties and mechanical properties of the methyltrimethoxysilane (MTMS) derived aerogels, prepared at ambient pressure using an improved method reported in Part I, have been comprehensively characterised in this paper, as Part II. The study has revealed sophisticated pore structures and morphologies of the aerogels produced, and demonstrated the relationships between the key processing conditions and microstructures of the resultant aerogels. The results of the study also help to further understand the effect of microstructure changes on the macrostructure, volume shrinkage and performances of the aerogels, and provide a general guide on how to manipulate the processing conditions to produce monolithic MTMS based aerogels with desirable structure and properties by ambient pressure drying.     

淀粉基气凝胶的制备及其表征方法研究进展

淀粉基气凝胶是一种新型生物可降解材料,用于食品配料、营养素、药品的包埋与输送、包装、隔热等。淀粉基气凝胶具有高比表面积、高孔隙率、优良生物活性及可降解性等特点,是优良的载体材料。根据淀粉基气凝胶的形状不同,可分为淀粉基微球气凝胶和淀粉基块状气凝胶,淀粉基微球气凝胶应用范围较广,但其制备工艺较为复杂,本文主要对其制备及影响因素进行综述,分析其特性与结构表征,为淀粉基气凝胶的高效制备、有效表征、拓展应用提供参考。     

Design, simulation, and performance of a draft tube spout fluid bed coating system for aerogel particles

A draft tube spout fluid bed coating system was designed to coat porous aerogel particles in a size range from 0.1 to 2 mm in diameter. Its primary objective was to insure that just the outer surface of the particles was coated. The inner, pore surface area of the particles needed to remain open to preserve their insulating properties. This paper discusses the design, simulation, and experimental results we obtained on the actual coating of 1-3 mm particles. A conventional, pharmaceutical coating, Surelease®, was used as the coating material and the system successfully coated the particles without penetration of the coating material into the particles. The apparatus can be used to coat friable, low density particles as well as those of high density and is well suited for other coating applications including those in the pharmaceutical industry.     

淀粉微球气凝胶的制备及吸附性能与形态研究

以木薯淀粉为原料,利用乳化-凝胶法结合冷冻干燥制备淀粉微球气凝胶,研究加热温度、时间、淀粉乳浓度及油乳比对淀粉微球气凝胶吸附性能的影响。利用响应面法优化工艺,制备淀粉微球气凝胶,以其对亚甲基蓝的吸附力作为评价指标。研究表明：淀粉微球气凝胶吸附性能受温度影响大,温度85℃、加热时间90 min、淀粉乳质量分数为15%,其吸附力为(0.928±0.008)mg/g,较原淀粉的吸附力增69.8%;粒度分布测量及扫描电镜分析结果显示：温度升高,淀粉颗粒膨胀,淀粉微球气凝胶的粒径逐渐增大,当温度升高至100℃时,气凝胶珊瑚状表面形成,表面变粗糙,粒径趋于稳定。     

Microstructure,phase, magnetic properties,and electromagnetic wave absorption of graphene oxide – Ni0.7Zn0.3Fe2O4 – Al2O3 aerogel

In this work, an ultralight nanocomposite of graphene oxide aerogels as a matrix and nickel-zinc ferrite (Ni_0.7Zn_0.3Fe₂O₄) nanoparticles as a second phase for the absorption of electromagnetic waves in the frequency of 1–18 GHz were fabricated by the hydrothermal - freeze-drying method. α-Al₂O₃ nanoparticles were used for further impedance matching for applications in electromagnetic wave absorption. XRD, SEM, EDS, and VNA analyses were used to characterize the sample. The effects of the amount of Ni_0.7Zn_0.3Fe₂O₄ (NZF) nanoparticles (GO: NZF volume percent ratio = 5:1 and 2:1) on the absorption of electromagnetic waves were investigated.     

The production of rGO/ RuO2 aerogel supercapacitor and analysis of its electrochemical performances

In this study, ruthenium was bonded to the reduced graphene oxide in an ultrasonic bath. The aerogel of the mixture was produced at −78 °C. Structural characterization of aerogels was done with XRD and FTIR, surface characterization was performed with STEM, and elemental analysis was conducted by EDX analysis. The produced aerogel composites were transformed into electrodes on conductive Nickel foam. IviumStat, a potentiostat/galvanostat device, was used for the electrochemical characterization of the symmetrical supercapacitors. According to CV voltammograms, rGO/RuO₂ aerogels' highest specific capacitance was calculated as 328.6 F g⁻¹ at a potential scan rate of 5 mV s⁻¹. The assembled rGO/RuO₂ aerogel-based supercapacitor cell offered a high energy density value of 31.1 W h kg⁻¹ even at the power density of 8.365 kW kg⁻¹; this is comparable to that of lead-acid and nickel-metal hybrid batteries.     

Functional nanostructured materials: Aerosol,aerogel, and de novo synthesis to emerging energy and environmental applications

In this review, we introduce advanced synthetic methods for functional nanostructured materials (in powder form) bridging to the development in emerging energy and environmental applications. Three types of synthetic methods (aerosol-based, aerogel-based, and de novo methods) are introduced, all of which have shown to be extensively investigated as novel routes to create nanostructured materials with designed material properties (i.e., controlled size, shape, porosity, and chemical composition are to be achievable). The typical experimental setup and the general experimental procedure for material preparation via the above three synthesis routes are discussed. Complementary characterization approaches are employed to study material properties of the synthesized nanostructured materials via the three synthesis routes. Here we investigate: (1) Cu_xO-CeO₂, Ni-CeO₂, and Cu_xO nanoparticle-encapsulating metal–organic framework (MOF) hybrid nanoparticles synthesized via the aerosol-based method; (2) Cr-encapsulating MOF (Cr-MOF-199), Au-encapsulating MOF (Au@ZIF-8), and MOF-derived nanocomposites (CuO/CuCr₂O₄) produced via the de novo route; (3) a variety of aerogels (carbon, metal oxide, polymer) with high porosity created by the aerogel-based approach. Finally, several examples of emerging energy and environmental applications are introduced using these functional nanostructured materials, including (1) catalytic transformation to chemicals by using precious metal nanoparticles-embedded MOFs and the MOF-derived nanocomposites as the catalysts; (2) methane combustion using Cu_xO-CeO₂ hybrid nanoparticles as catalyst, (3) methane dry reforming with CO₂ using Ni-CeO₂ hybrid nanoparticles as catalyst; (4) CO₂ capture by fluoroalkyl silane-modified mesoporous silica and polymethylsilsesquioxane (PMSQ) aerogel membranes; (5) adsorption of organic solvent, dye, and oil by cetyltrimethylammonium bromide-modified PMSQ aerogel.     

溶胶—凝胶成膜过程Monte Carlo模拟软件的设计与应用

在扩散限制集团凝聚（ＤＬＣＡ）模型的基础上，考虑溶胶粒子的密度和能量分布对溶胶－－凝腕过程初始状态的影响，编制了溶胶－凝胶成膜过程的Ｍｏｎｔｅ Ｃａｒｌｏ模拟软件，利用该软件对硅气凝胶膜的凝胶化过程进行了模拟，得到了薄膜生长阶段的分形图象，计算了分形并讨论了硅气凝胶的生长机制。