热解活化法制备椰壳活性炭的方法和机理研究(摘要)

研究了一种制备活性炭的新方法,在不添加任何活化气体或化学试剂的情况下,依靠原料自身热解产生的气体作为活化剂,原料吸附的空气以及反应器内部自带的空气作为活化助剂,自活化造孔.意在研究一种绿色环保,工艺简单,清洁节能的制备活性炭的快速制备方法.     

折边锥形壳体壁厚确定的简易方法

通过对各计算公式及相关图表进行分析和比较,总结出一种简单易行的折边锥形壳体壁厚确定方法。此方法不需要把折边锥形壳体的中间锥体和两端过渡区3部分的厚度都计算出来,而是先进行简单地比较,再选其中的一个公式计算就可得到满意的结果。     

Measuring Permeability of Rigid Materials by a Beam-Bending Method: II, Porous Glass

It has been shown in a companion paper that the permeability of a porous body can be found from a three-point bending experiment. When the sample is bent, a pressure gradient is created in the liquid within the pores; as the liquid flows in response to the gradient, the force that must be applied to the rod to sustain a fixed deflection decreases with time. By fitting the force decay curve to the predicted shape, the permeability is obtained, along with the elastic modulus. In this paper, that theory is tested using porous Vycor® glass saturated with various solvents, including several normal alcohols, water, and glycerol. The shape of the measured decay is in excellent agreement with the prediction. Consistent with observations of previous workers, we find that the permeability is influenced by the size of the solvent molecule; by assuming that the pore surfaces are covered with a monolayer of immobile solvent, the observed variation can be explained. The advantage of the beam-bending method is that the results are obtained in a few minutes; moreover, there is no problem with leaks or need for high pressures, as there is in conventional measurements of low permeabilities.     

Synthesis of Titanium Carbide Nanoparticles with a High Specific Surface Area from a TiO2 Core–Sucrose Shell Precursor

By carbothermally reducing a TiO₂ core–sucrose shell precursor, titanium carbide mesoporous nanoparticles with a very high specific surface area (147 m²/g at 1500°C) have been prepared. The high specific surface area results from the mesoporous nature of the produced nanoparticles with two types of pores: the one with a pore diameter of about 20 nm and the other with <4 nm.     

A Facile Strategy to Prepare Small Water Clusters via Interacting with Functional Molecules

Although small water clusters (SWCs) are important in many research fields, efficient methods of preparing SWCs are still rarely reported, which is mainly due to the lack of related materials and understanding of the molecular interaction mechanisms. In this study, a series of functional molecules were added in water to obtain small water cluster systems. The decreasing rate of the half-peak width in a sodium dodecyl sulfate (SDS)–water system reaches ≈20% at 0.05 mM from ¹⁷O nuclear magnetic resonance (NMR) results. Based on density functional theory (DFT) and molecular dynamics (MD) simulation calculation, it can be concluded that functional molecules with stronger negative electrostatic potential (ESP) and higher hydrophilicity have a stronger ability to destroy big water clusters. Notably, the concentrations of our selected molecule systems are one to two magnitudes lower than that of previous reports. This study provides a promising way to optimize aqueous systems in various fields such as oilfield development, protein stability, and metal anti-corrosion.     

Direct Formation of Mg–Al-Layered Double-Hydroxide Films on Glass Substrate by the Sol–Gel Method With Hot Water Treatment

Amorphous Al₂O₃–MgO thin films with an Mg/Al ratio of unity were prepared on glass substrates by the sol–gel method with a heat treatment at 300°C for 30 min. By immersing the films in water containing sodium hydroxide (pH 10–13) at 100°C, nano-crystals of Mg–Al-layered double hydroxide (LDH) with a hexagonal structure, which is called hydrotalcite and the most basic composition of LDH, were precipitated on the amorphous Al₂O₃–MgO films. The maximum amount of Mg–Al nanocrystals was obtained when the film was immersed in basic solution of pH 12.     

水玻璃组成快速测定方法改进

水玻璃的用途十分广泛,几乎遍及到国民经济的各个行业。不同模数的硅酸钠有着不同的用处,而模数作为水玻璃的重要参数,目前其测量的通常方法是分别测出Na2O和SiO2的质量分数然后算出其模数。文章介绍了以溴百里酚蓝指示剂部分取代甲基红指示剂,实现快速测定水玻璃模数的一种新方法,该方法省去了氢氧化钠标准溶液的返滴过程,更加简便、快捷,并详细阐述了该方法的基本原理和实验步骤,计算方法以及相关数据。     

A Novel Method to Prepare Nano‐sized CL‐20/NQ Co‐crystal: Vacuum Freeze Drying

Nano‐sized energetic co‐crystal consisting of the most powerful used military explosive 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20) and a typical insensitive explosive used in propellants nitroguanidine (NQ) was prepared by vacuum freeze drying method. Material studio 6.1 was used to simulate the hydrogen bonds between CL‐20 and NQ molecules. Scanning electron microscopy (SEM) was used to reveal the morphology and size of the product. Fourier Transform infrared spectroscopy (FT‐IR) and X‐ray diffraction spectrum (XRD) proved the formation of the co‐crystal at the molecular level. Differential scanning calorimetry (DSC) was employed to characterize the thermal behavior of the co‐crystal. The result of mechanical sensitivity test indicated the sensitivity was effectively reduced compared to neat CL‐20.     

Thermal Poling of Soda‐Lime Silica Glass with Nonblocking Electrodes—Part 1: Effects of Sodium Ion Migration and Water Ingress on Glass Surface Structure

It is generally well known that not only the sodium itself, but also the non‐bridging oxygen (NBO) sites associated with sodium ions are largely responsible for the surface reactivity of soda‐lime‐silica (SLS) glass. Thermal poling can modify the distribution of sodium in the subsurface region. In this work, a commercial SLS float glass was thermally poled using nonblocking electrodes in air. The Na⁺?depleted anode surface and the Na⁺?gradient cathode surface were characterized using a variety of methods to find the compositional, structural and morphological effects of thermal poling. Of particular significance is the use of nondestructive vibrational spectroscopy methods, which can lead to new and improved understanding of water interactions with sodium and its sites in the glass. It was found that during thermal poling, the Na⁺?depleted glass network on the anode side undergoes condensation reactions of NBO sites accompanied by the increase in concentrations of silanol (SiOH) groups and molecular water species. In contrast, silanol and water species do not increase and the silicate network change is negligible in the Na⁺?gradient cathode side. Vibrational sum frequency generation (SFG) spectroscopy analysis revealed the difference in distributions of hydrous species in the Na⁺?depleted and Na⁺?gradient surfaces. The structural information of the thermally‐poled surfaces provides critical insights needed to understand the mechanical and mechanochemical properties of the Na⁺?concentration modified SLS glass surfaces reported in the Part 2 companion paper.     

Prospects of a New Method for Thermal Treatment of Sheet Glass

The essence of pulse hardening of sheet glass is considered and the results of a three-stage pulse hardening of sheet glass with a shrinking polymer film, are given.     

催化亚临界水氧化法处理糖蜜酒精废液的研究

以铜、锰为活性成分和微波辐射法制备的γ-Al2O3为载体,制备了CuO/MnO2/γ-Al2O3复合催化剂,考察了成分配比、浸渍时间对催化剂催化活性的影响,研究了氧气分压、催化剂投加量、反应温度和反应时间对催化亚临界水氧化法处理糖蜜酒精废液过程的影响规律。结果表明:CuO/MnO2/γ-Al2O3催化剂是催化亚临界水氧化法处理糖蜜酒精废液的可选催化剂;当进水CODCr的质量浓度为10×104mg/L时,适宜的氧气供应量为理论需氧量的3.5～4.7倍,催化剂的投加量以10g/L为佳;在360℃下反应10min,处理水可达到《污水综合排放标准》GB9878-1996的一级标准。     

A New Process to Make a Porous PTFE Structure from Aqueous PTFE Dispersion with the Help of Hydrogel

A novel method to make a porous material having relatively large cell diameter (200–300 m), which consisted of mainly poly(tetrafluoroethylene) (PTFE), was developed from aqueous PTFE dispersion by using the characteristics of hydrogel with the addition of carbon nanofiber (CNF). The porous material was produced as follows: firstly, an aqueous agar gel containing PTFE and CNF was prepared; secondly, the gel was freeze-dried; thirdly, the dried gel was heat-treated at 400°C where the agar was almost decomposed and PTFE became molten. The porous material showed electric conductivity (about 50 ), high porosity (about 96 vol%), and relatively uniform cell structures without shrinkage during freeze drying and heat treatment. While the method without CNF resulted in large shrinkage during heat treatment, meaning that CNF prevented the shrinkage. It was explained by the idea that the existence of rigid CNF, which was dispersed in the cell wall, prohibited the shrinkage of PTFE during heat treatment. It was unexpectedly found by SEM analysis that the porous materials had another macro-porous structure inside the cell wall, suggesting that the developed materials had a double porous structure.     

微生物法水处理技术还原贵金属离子为单质形态的研究进展

某些工业废水中的贵金属离子具有很高的可回收价值,而微生物法还原贵金属离子为单质形态的研究成果使其成为可能。本文综述了微生物法水处理技术还原贵金属离子为单质形态的机理、影响因素、微生物种类和贵金属离子种类。另外,本文还分析了微生物法还原贵金属离子为单质形态的发展前景和存在的问题。     

Investigation of a Novel Catalyst Coated Membrane Method to Prepare Low‐Platinum‐Loading Membrane Electrode Assemblies for PEMFCs

In this work, a novel catalyst coated membrane (CCM) approach–a catalyst‐sprayed membrane under irradiation (CSMUI)–was developed to prepare MEAs for proton exchange membrane fuel cell (PEMFC) application. Catalyst ink was sprayed directly onto the membrane and an infrared light was used simultaneously to evaporate the solvents. The resultant MEAs prepared by this method yielded very high performance. Based on this approach, the preparation of low‐platinum‐content MEAs was investigated. It was found that for the anode, even if the platinum loading was decreased from 0.2 to 0.03 mg cm^–2, only a very small performance decrease was observed; for the cathode, when the platinum loading was decreased from 0.3 to 0.15 mg cm^–2, just a 5% decrease was detected at 0.7 V, but a 35% decrease was observed when the loading was decreased from 0.15 to 0.06 mg cm^–2. These results indicate that this approach is much better than the catalyst coated gas diffusion layer (GDL) method, especially for the preparation of low‐platinum‐content MEAs. SEM and EIS measurements indicated ample interfacial contact between the catalyst layer and the membrane.     

浸没燃烧蒸发(SCE)技术处理含氰含氨废水的研究

介绍采用SCE工艺,利用副产氢气做燃料,通过燃烧氧化的方法降低废水中氰根、氨氮、甲酸钠等有机物杂质的含量。经SCE方法处理后的废水有机物浓度降低,大大节约了废水处理中化学药剂的使用量。经试验表明,该工艺对废水中有机物的去除效果明显,处理结果稳定,不会引入杂质,出水经化学氧化后可以达到排放要求。     

A Quasi‐Steady State Shell and Shrinking Core Approach to the Drying of Porous Particles and an Example of Parameter Identification

A quasi‐steady state shell and shrinking core approach which recognizes heat and mass transfer resistances in both the gas and particle phases for drying of a porous particle is proposed. A mean field model (constant properties) using this approach was embedded in a spreadsheet combined with a genetic algorithm for parameter identification to provide an easy means of characterizing the drying process from drying data. In drying, assuming a mean field, four major parameters are typically unknown: two related to the process (heat and mass transfer coefficients) and two which incorporate porous particle properties (shell thermal conductivity and vapour diffusivity). It is shown how these four parameters may be determined from experimental drying data. The model was applied to data for spouted bed drying of rice. For the particular case studied, external heat transfer was found to be the controlling mode, although resistance to moisture diffusion within the particle is important. The approach presented admits of future refinements to improve its scope and utility.     

X9R BaTiO3‐Based Dielectric Ceramics with Multilayer Core–Shell Structure Produced by Polymer‐Network Gel Coating Method

The modified polymer‐network gel route has been developed to prepare a multilayer core –shell structure of BaTiO ₃‐ based dielectric ceramics. The core of particle was BaTiO₃, whereas 0.7BaTiO₃–0.3Bi(Zn_1/2Ti_1/2)O₃ (0.7BT–0.3BZT) and Nb oxides were coated as the multilayer shell compositions, which were confirmed by energy dispersive spectroscopy testing. The dielectric properties of BaTiO₃‐based samples with multilayer core–shell structure were found to meet the X9R specification. The dielectric constant was 1190 and the dielectric loss was 1.3% at room temperature.     

Hydrothermal Synthesis of Kalsilite: A Simple and Economical Method

This study reports a simple method to synthesize pure kalsilite (KAlSiO₄) using readily available precursors, kaolinite and KOH solution, after only 12 h of hydrothermal treatment in mild conditions. A structural refinement has been carried out using the Rietveld method to obtain unit cell parameters, and the ²⁹Si and ²⁷Al magic angle spinning nuclear magnetic resonance spectra have shown the purity and complete Si/Al ordering of the kalsilite structure obtained. Finally, the morphology of the particles has been analyzed by scanning electron microscopy.     

A Gravitational Procedure to Measure the Diffusion Coefficient of Water in Porous Materials: A Case Study on Concrete

A new procedure is presented with which the diffusion coefficient of water in partially saturated porous materials can be measured. The first step in the procedure is the creation of a non-equilibrium situation inside a sample by placing it into a centrifuge. In the second step, the mass of the sample is measured by hanging it from two cables, each connected to a balance. The comparison of the time evolutions of the measured masses and the masses as predicted using Fick's second law gives the diffusion coefficient.