Breakthrough behavior of sulphur mustard vapor on whetlerite carbon

Sulphur mustard vapor breakthrough behavior on whetlerite carbon has been studied by using modified Wheeler equation. The values of pseudo-first-order rate constant (k(v)) and kinetic saturation capacity (W(e)) were calculated and the effects of various parameters such as bed height, air flow rate, concentration and temperature on the above parameters have also been studied. Rate constant is found to be increasing with air flow rate, while W(e) is found to be invariable. Both k(v) and W(e) decrease with the increase of temperature, however, no significant effect on W(e) and k(v) is observed due to concentration change. The values of kinetic saturation capacity are used to predict the service lives/breakthrough times of carbon beds (when used in filtration systems).     

Electrodialysis with bipolar membrane for regeneration of a spent activated carbon

The main purpose of the present work was to develop a treatment method to regenerate granular adsorbent beds saturated with H₂S by utilizing three electrodialysis compartments equipped with a cation or an anion exchange membrane or a bipolar membrane. Three electrodialysis compartments were utilized under various experimental parameters to determine the optimum conditions for the recovery of column particles saturated by H₂S. The desulphurization operation is achieved with the extent of extraction close to 90% and an electric current density of about 30%.Use of the bipolar membrane makes it possible to regenerate the saturated adsorbent granules without adding chemical products. Since the only reagent was electricity, the projected economics are very attractive.     

Chemical vapor deposition of amorphous molybdenum sulphide on black phosphorus for photoelectrochemical water splitting

Non-precious metal electrocatalyst molybdenum sulphide(MoS) and black phosphorus(BP) are highly promising catalysts for H₂ evolution reaction(HER).However,BP is environmentally unstable and the basal planes of crystal MoS₂ are inactive toward HER.Herein,amorphous molybdenum sulphide(MoSx)directly on BP/BiVO4 film dramatically improves the performance of photoelectrochemical water splitting compared with pure BiVO4.Additionally,we demonstrate that a BP layer,inserted between the MoSx and BiVO4,can enhance the photoelectrochemical performance and improve the stability of the electrodes.Finally,MoS_x/B P/BVO electrode shows the excellent current density of 2.1 mA/cm² at the potential of 1.2 V(vs Ag/AgCl),which is twice higher than that of pure BVO electrode.Our novel nanostructure materials will lead to a new class of non-precious metal photocatalysts for hydrogen production.     

活性碳纤维制品的研究与应用

介绍了聚丙烯腈基活性碳纤维的制备工艺和其制品开发的技术措施 ,并论述了活性碳纤维在医药及食品工业方面的应用。     

Optical properties of silver sulphide thin films formed on evaporated Ag by a simple sulphurization method

Silver sulphide (Ag₂S) thin films were grown on the surface of silver films (Ag) deposited on glass substrate by using a simple chemical sulphurization method. According to X-ray diffraction analysis, the Ag₂S thin films display low intensity peaks at 34.48°, 36.56°, and 44.28°, corresponding to diffraction from (100), (112) and (103) planes of the acanthite phase (monoclinic). A model of the type Ag₂S/Ag/glass was deduced from spectroscopic ellipsometric measurements. Also, the optical constants (n, k) of the system were determined. Furthermore, the optical properties as solar selective absorber for collector applications were assessed. The optical reflectance of the Ag₂S/Ag thin film systems exhibits the expected behavior for an ideal selective absorber, showing a low reflectance in the wavelength range below 2 µm and a high reflectance for wavelengths higher than that value. An absorptance about 70% and an emittance about 3% or less were calculated for several samples.     

改进化学气相沉积法在炭纤维表面生长碳纳米管(英文)

采用一种改进的化学气相沉积法在炭纤维表面制备碳纳米管。为了提高炭纤维表面的润湿性能,炭纤维在浸渍之前先在CVD设备中在真空下973 K的高温处理,然后在硝酸和浓硫酸体积比为3∶1的混合酸中酸处理30 min。而改进的化学气相沉积法关键在于让催化剂的还原步骤和碳纳米管的生长步骤同时进行。这样通过减小过渡金属元素与炭纤维之间的接触时间从而降低了它们之间的相互扩散,在确保了炭纤维本身的力学性能下降程度明显小于用普通化学气相法制备的情况下生长出长且茂密的碳纳米管阵列。另外,经过对工艺参数的优化发现当用乙醇作溶剂,Fe(NO3)3.9H2O溶度为100 mmol/L,氢气和碳源气体比值为4/1,而生长时间为30 min时得到最好的碳纳米管阵列。     

Study on effect of oxygen adsorption on characteristics of field electron emission from aligned carbon nanotubes grown by plasma-enhanced hot filament chemical vapor deposition

The characteristics of field electron emission (FE) from aligned carbon nanotubes (ACNTs) in a form of film, which were catalytically grown by plasma-enhanced hot filament chemical vapor deposition, were measured for many cycles. The results indicate that the FE characteristic for every measurement cycle is different and it follows the Fowler–Nordheim model in the low field region, but it deviates from the model in the high field region. The ACNTs were investigated by energy dispersive X-ray (EDX) and the EDX spectrum shows that oxygen is adsorbed on the ACNTs. The theory related to adsorption and space-charge effect was applied to analyze the experimental results.     

TiO2/活性炭复合体的制备及其表征

以活性炭(AC)为载体,采用溶胶-凝胶法制备纳米TiO2/AC复合型催化剂.利用SEM,TG-DTA,XRD,等手段对其组成、结构、尺寸等进行分析和表征,结果表明,该复合材料由碳、钛、氧等3种元素组成,其中TiO2纳米粒子尺寸在2O-50nm之间,比本体TiO2纳米粒子尺寸小;在该纳米复合材料中,活性炭作为载体与TiO2结合牢固,存在着某种化学键,TiO2纳米颗粒间不发生团聚,并且活性炭载体的比表面积变化不大.     

脉冲FCVI制备炭/炭复合材料的微观结构及力学性能

采用脉冲强制流动热梯度化学气相渗透（IFCVI）法制备了毡基炭／炭复合材料。借助偏光显微镜及扫描电子显微镜观察了基体热解炭的微观组织结构及断口形貌特征；用弯曲实验测定了材料的力学性能。结果表明：采用脉冲FCVI，经1000℃～1250℃，100h致密化，2300℃热处理后，炭／炭复合材料的密度可达1．7g／cm^3，弯曲强度为125．4MPa，挠度为0．61mm。该工艺致密化速率快，所制备材料的密度分布均匀、力学性能好。研究表明，温度是影响材料组织结构的主要因素，高温条件下有利于粗糙层热解炭组织的生成，而低温有利于光滑层热解炭组织的生成，一般因沉积环境复杂多变，常得到混合型组织。     

基于微波等离子体方法生长的纳米碳对碳纤维/环氧树脂复合材料界面性能的影响

为了提高复合材料的界面性能,采用微波等离子体（MPECVD）方法,通过控制工艺参数,在碳纤维（CF）表面生长结构形貌各异的纳米碳,将其引入CF/环氧树脂（EP）复合材料界面微区。采用FESEM研究了不同MPECVD工艺参数对沉积纳米碳结构形貌的影响,采用单纤维破碎实验研究了纳米碳形貌对CF/EP复合材料的界面性能影响,探讨了纳米碳-CF/EP复合材料界面微观结构与其界面性能之间的关系。结果表明：随着MPECVD沉积功率的变化,沉积的纳米碳结构形貌变化较大。当沉积功率为700 W时,制备得到的多尺度纳米碳-CF/EP复合材料界面性能最高,界面剪切强度（IFSS）达到112.38 MPa,提高了118.85%。     

多壁碳纳米管吸附异甘草苷的热力学研究

多壁碳纳米管可选择性地吸附结构相似的两种黄酮类化合物甘草苷和异甘草苷,研究了异甘草苷被多壁碳纳米管吸附的吸附热力学特征。结果表明:多壁碳纳米管吸附异甘草苷的量随着异甘草苷浓度的增加而增加,随着温度升高而降低。异甘草苷的吸附过程符合Freundlich方程。其ΔH0和ΔG0值表明该吸附反应是自发进行的放热反应。     

Electrochemical properties of ferrocene adsorbed on multi-walled carbon nanotubes electrode

The adsorbed process of ferrocene on a glassy carbon (GC) electrode modified by multi-walled carbon nanotubes (MWNTs) and electrochemical properties of the adsorbed layers are investigated. It is found that the redox process of ferrocene in solution is controlled by diffusion and surface electrochemical steps on the MWNT/GC electrode in contrast to the diffusion-controlled process of ferrocene on the GC electrode. The adsorbed ferrocene exhibits a pair of well-defined redox waves in the potential range from − 0.2 V to 0.6 V. Interestingly, two pairs of obvious redox waves for the adsorbed ferrocene are observed at the switching potential over 0.8 V and the peak current values of redox waves in more positive potential increase with the enlarging switching potential. The electrochemical reaction model of ferrocene adsorbed on the MWNT/GC electrode is proposed.     

Surface characterization and nanomechanical properties of diamond-like carbon films synthesized by RF plasma enhanced chemical vapor deposition

Diamond-like carbon (DLC) films were synthesized by RF plasma enhanced chemical vapor deposition using acetylene as the carbon source and the effects of acetylene/nitrogen ratio in the reaction atmosphere, deposition pressure, and plasma post-treatment using different atmospheres on the surface roughness and mechanical properties of DLC films were investigated. Although the surface roughness, characterized by AFM, decreased as the acetylene/nitrogen ratio in the reaction atmosphere decreased, the hardness of DLC films measured by nanoindentation also decreased with the decrease of the acetylene/nitrogen ratio, which is consistent with the Raman results of the I_D/I_G ratio. Rougher films with higher residual stress were obtained when using a deposition pressure higher than 40.0 Pa (0.3 torr). For the effect of plasma post-treatment using different atmospheres, surface smoothing was found for the hydrogen plasma post-treatment, whereas nitrogen and argon plasma post-treatments resulted in surface roughening. Hydrogen plasma post-treatment was found to lower the surface roughness without significantly sacrificing the hardness.     

高温热处理对活性炭纤维微孔及表面性能的影响

研究了1173K高温改性处理对沥青基活性炭纤维吸附性能、孔径分布、微孔结构和表面化学的影响。低温(77K)N2吸附结果表明热处理后活性炭纤维比表面积略有下降，通过密度函数理论解析活性炭纤维全孔范围的孔分布得出活性炭纤维表面孔径大于1．0nm的微孔明显减少，微孔孔径更加集中于0．5nm～1．0nm，从而提高了活性炭纤维的碘吸附值。X射线衍射分析表明活性炭纤维是乱层石墨结构，热处理使活性炭纤维类石墨微晶碳层面的层间距下降，X光电子能谱分析表明热处理后活性炭纤维表面的含氧官能团C=O和COOH的含量变化不大，而呈碱性酚羟基C—OH含量的明显下降使活性炭纤维表面碱性降低。     

Adherent amorphous hydrogenated carbon films on metals deposited by plasma enhanced chemical vapor deposition

This paper reports the findings of a study of the structural, mechanical, and tribological properties of amorphous hydrogenated carbon (a-C:H) coatings for industrial applications. These thin films have proven quite advantageous in many tribological applications, but for others, thicker films are required. In this study, in order to overcome the high residual stress and low adherence of a-C:H films on metal substrates, a thin amorphous silicon interlayer was deposited as an interface. Amorphous silicon and a-C:H films were grown by using a radio frequency plasma enhanced chemical vapor deposition system at 13.56 MHz in silane and methane atmospheres, respectively. The X-ray photoelectron spectroscopy technique was employed to analyze the chemical bonding within the interfaces. The chemical composition and atomic density of the a-C:H films were determined by ion beam analysis. The film microstructure was studied by means of Raman scattering spectroscopy. The total stress was determined through the measurement of the substrate curvature, using a profilometer, while micro-indentation experiments helped determine the films' hardness. The friction coefficient and critical load were evaluated by using a tribometer. The results showed that the use of the amorphous silicon interlayer improved the a-C:H film deposition onto metal substrates, producing good adhesion, low compressive stress, and a high degree of hardness. SiC was observed in the interface between the amorphous silicon and a-C:H films. The composition, the microstructure, the mechanical and tribological properties of the films were strongly dependent on the self-bias voltages. The tests confirmed the importance of the intensity of ion bombardment during film growth on the mechanical and tribological properties of the films.     

Influence of carboxyl group formation on ammonia adsorption of NiO-templated nanoporous carbon surfaces

The scope of this work was to control the surface functional groups of nanoporous carbons (NPs) by oxidizing agents (nitric acid and hydrogen peroxide) treatments and to investigate the relation between carboxyl group and ammonia removal efficiency. The NPs were directly prepared from a cation exchange resin by the carbonization of a mixture with Ni acetate at 900 °C. N₂/-196 °C adsorption, Boehm's titrations, and X-ray photoelectron spectroscopy (XPS) analyzes were employed to confirm the physicochemical properties of NPs. The ammonia removal efficiency was confirmed by temperature programmed desorption (TPD) technique. In the result, the oxygen content of NPs increased after various treatments and the highest content of carboxyl group formation appeared at a 2:3 volume ratio of HNO₃/H₂O₂. It was also found that the oxidation treatment led to an increase in ammonia removal efficiency of NPs, mainly due to an increase of acid oxygen functional groups (such as carboxyl) on NPs surfaces.     

活性炭纤维对铂(Ⅳ)的还原吸附及其影响因素的研究

载铂活性炭纤维在燃料电池催化材料的制备等方面具有重要的应用前景.本文比较了水蒸汽活化和磷酸或氯化锌活化活性炭纤维对水溶液中铂离子的还原吸附性能,并研究了影响活性炭纤维对铂的还原吸附的几种因素.结果表明,不同工艺制备的活性炭纤维,由于其电极电位的差异,其对铂离子的吸附容量也不同;水蒸汽活化和氯化锌活化活性炭纤维由于具有低的电极电位,因而表现出对铂离子更大的还原倾向,在吸附的初期,表现出更快的吸附速度.纤维状的活性炭纤维比颗粒状的活性炭具有更快的吸附速度.溶液的酸度也显著影响活性炭纤维对铂离子的还原吸附能力;低的pH下,活性炭纤维对铂一般具有更强的还原吸附容量.     

碳纤维/环氧预浸布耐折叠性能研究

针对碳纤维/环氧预浸布复合材料的耐折叠性能特点,进行了不同折叠半径和不同折叠时间力学性能的对比实验.选定折叠时间为4h,折叠半径取0-4mm.再以折叠半径0.5mm为条件,取折叠时间为1-4h.对不同折叠条件下的试件进行拉伸性能试验、从而得出不同折叠半径,不同折叠时间对复合材料预浸布性能的影响.实验结果表明:折叠造成了复合材料增强纤维的损伤和树脂的堆积,引起了拉伸性能的下降,折叠半径越小、折叠时间越长,碳纤维/环氧预浸布薄膜复合材料强度下降越严重.     

Adsorption of ionizable organic contaminants on multi-walled carbon nanotubes with different oxygen contents

Multi-walled carbon nanotubes (MWNTs), which are considered to be promising candidates for the adsorption of toxic organics, are released into aqueous environment with their increasing production and application. In this study, the adsorption behaviors of five structurally related ionizable organic contaminants namely perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonamide (PFOSA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-n-nonylphenol (4-NP) onto MWNTs with different oxygen contents (3.84-22.85%) were investigated. The adsorption kinetics was investigated and simulated with pseudo-second-order model. The adsorption isotherms were found to be fitted with Freundlich model and influenced by both the properties of organic chemicals and the oxygen contents of MWNTs. As adsorption capacity decreases dramatically with the increasing of oxygen contents, the MWNTs with the lowest oxygen contents possess the highest adsorption capacity among four MWNTs. For the MWNTs with the oxygen contents of 3.84%, the adsorption affinity related with hydrophobic interaction and π-electron polarizability decreased in the order of 4-NP>PFOSA>PFOS>2,4-D>PFOA. Furthermore, the adsorption characters of five contaminants were affected by solution pH and solute pK(a) considering electrostatic repulse force and hydrogen bonding, which showed the adsorption of MWNTs with lower oxygen content is much sensitive to solution chemistry.     

Adsorption equilibrium of hydrogen on graphene sheets and activated carbon

For obtaining the technical data to evaluate the performance of hydrogen storage by adsorption on graphene sheets (GS), analysis of adsorption equilibrium of hydrogen on the GS and the activated carbon were carried out based on the hydrogen adsorption data covering a wide temperature range. The GS and SAC-02 activated carbon, which respectively had a specific surface area about 300 m²/g and 2074 m²/g, were selected as adsorbents. Six adsorption isotherms of excess amounts of high purity hydrogen were measured at temperature from 77.15 K to 293.15 K and pressure up to 6 MPa. Parameters of Langmuir, Langmuir–Freundlich and Toth equations were set by non-linear fit against adsorption data, predicting accuracy of the equations was then evaluated by the accumulated relative errors between experimental data and those from the equations under different pressure regions. Absolute adsorption amounts determined by the modified equation were used to calculate the isosteric heat of adsorption.It shows that both adsorption isotherms of hydrogen on the GS and the activated carbon have the features of Type I, but the trend of isotherms varying over the pressure is different within the lower temperature region. Results from Langmuir equation have the largest error. Toth equation can much accurately predict the adsorption data with an overall accumulated relative error less than 4%. The value of the isosteric heat of hydrogen adsorption on the GS is about 5.06–6.37 kJ/mol, which is much higher than 4.05–5.52 kJ/mol for hydrogen on the SAC-02 activated carbon under the whole experimental condition. It reveals that interaction between hydrogen molecules and the graphene layer is stronger than that of hydrogen and carbon surface, and Toth equation could be appropriate to analyzing adsorption equilibrium for hydrogen on carbon based adsorbents.