浓硝酸处理前后多壁碳纳米管的荧光特性研究

对浓硝酸处理前后多壁碳纳米管的荧光特性进行了研究,结果发现多壁碳纳米管在浓硝酸处理前后都能产生荧光;与浓硝酸处理前相比,浓硝酸处理后的多壁碳纳米管的荧光有所增强,且荧光谱峰向短波长方向发生蓝移。碳纳米管产生的荧光与碳纳米管在其缺陷处捕获激发光的能量以及最低空轨道和最高占有轨道之间的能隙有关。多壁碳纳米管在浓硝酸处理前后都有缺陷,因而都能在其缺陷处捕获激发光能量而产生荧光;浓硝酸处理引起多壁碳纳米管的缺陷增多、捕获激发光能量增加因而荧光也随之增强。碳纳米管的最低空轨道和最高占有轨道之间的能隙随其长度减小而增大,浓硝酸处理引起多壁碳纳米管被削短导致其最低空轨道和最高占有轨道之间的能隙增大,因而引起多壁碳纳米管的荧光谱峰向短波方向蓝移。     

浓硝酸处理碳纳米管对4-硝基苯酚的吸附性能研究

本文采用浓硝酸氧化法来改性多壁碳纳米管,用Raman光谱、SEM和分光光度计对改性前后的多壁碳纳米管对4-硝基苯酚溶液的吸附能力进行了比较研究。Raman光谱和SEM分析表明浓硝酸处理使碳纳米管端口打开,管变短,并且在表面引入了羟基、羧基等酸性官能团。采用分光光度计测定溶液浓度,计算出浓硝酸处理前后多壁碳纳米管对不同浓度4-硝基苯酚的吸附效率,实验结果表明经浓硝酸处理后的多壁碳纳米管的吸附效率有较大的提高。     

磁性碳纳米管吸附去除水中甲基橙的研究

采用高温催化裂解法制备碳纳米管,对其用浓硝酸氧化法进行纯化处理,并用化学共沉淀方法制备了磁性碳纳米管(简称磁性管)。利用场发射扫描电子显微镜对磁性管进行了表征。将磁分离技术应用于碳纳米管吸附性能研究,探索碳纳米管负载磁性颗粒后对甲基橙的吸附性能,寻找最佳实验条件,对吸附质溶液进行紫外-可见吸收光谱分析。同时,进行了磁性管的脱附和再吸附性能研究。     

基于磷酸三丁酯的超浓盐酸的研究

利用磷酸三丁酯形成的反胶束在常温常压下制备出一种超浓盐酸,其酸水摩尔比（n_HCl/n_H2O）在0.50～1.50之间,高于常温常压下饱和浓盐酸的酸水摩尔比（0.28）。红外光谱的研究结果表明超浓盐酸中部分氯化氢未发生电离,而是以分子形式存在。同时HCl参与了体系内氢键网络的形成。超浓盐酸体系提供了一个特殊的物理化学环境,使得溶于其中的铜离子呈红棕色。采用FTIR及UV-Vis对含铜离子的超浓酸体系进行了表征。结果表明,超浓酸中,铜离子的d—d跃迁和电荷迁移跃迁谱带都发生了明显的变化。铜离子的加入对超浓盐酸体系中未电离的HCl分子的氢键体系产生明显影响。     

温控电弧放电法大量制备单壁碳纳米管

采用可以控制真空室温度的改进型直流电弧炉，在氮气和氦气(1∶1)混合气氛下，使用Co-Ni(1∶1wt%)合金催化剂，通过控制温度等工艺条件，在容器内壁生成了大量单壁碳纳米管，尤其在阴极与阳极之间有大量的宏观网状薄膜.通过两步纯化方法：在500℃空气中烘烧30min；再用37%盐酸浸泡72h，用去离子水过滤至中性烘干.经SEM，HRTEM，XRD，Raman观察分析，纯化后其纯度高(>95％)、管径均匀(1.24—1.38nm).实验结果表明：温度强烈影响单壁碳纳米管的产量，不同温度下管子的纯度、产量都有差异，在温度为600℃时，其纯度达到70％，产量为12g/h. 关键词： 单壁碳纳米管 电弧法 温度影响     

蔬菜中铁含量的测定及方法比较

用分光光度法直接测定蔬菜中铁的含量,方法简便、快速、准确.分别采用浓盐酸和浓硫酸两种消解方法对样品进行处理,并对其测定结果进行比较,实验结果表明,浓硫酸消解法消解能力更强,测定更为准确.5种蔬菜中木耳铁含量最高,对指导人们合理食用蔬菜进行补铁及进一步开发蔬菜产品提供了可靠的理论依据.     

多巴胺功能化碳纳米管的制备及其性能

将浓硝酸氧化后得到的碳纳米管(MWNT-COOH)酰氯化,将活化后的MWNT-COCl与生物药物分子多巴胺(Dopa)继续发生反应,得到Dopa功能化的碳纳米管MWNT-Dopa.采用傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)对功能化的碳纳米管进行表征分析,进一步对MWNT-Dopa进行分散稳定性分析和生物矿化实验.结果表明,Dopa通过酰胺键共价接枝在MWNT上,且Dopa的功能化修饰有效提高了碳纳米管在水和乙醇中的分散稳定性及生物矿化活性.     

等离子体处理碳纳米管的研究现状及展望

采用等离子体处理技术对碳纳米管进行表面处理是一项新兴的技术,本文对在碳纳米管处理过程中,等离子体处理工艺参数的选择,以及处理前后表面结构变化、形貌变化、场发射效应等进行了综述,并对等离子体处理技术在碳纳米管表面修饰中的应用前景进行了展望.     

等离子体处理碳纳米管的研究现状及展望

采用等离子体处理技术对碳纳米管进行表面处理是一项新兴的技术,本文对在碳纳米管处理过程中,等离子体处理工艺参数的选择,以及处理前后表面结构变化、形貌变化、场发射效应等进行了综述,并对等离子体处理技术在碳纳米管表面修饰中的应用前景进行了展望。     

原子荧光光谱法同时测定水中痕量砷和硒

用浓盐酸和5%硫脲-5%抗坏血酸混合试剂处理样品,并以2%硼氢化钾和0.5%氢氧化钾为还原剂,在5%的盐酸介质中用原子荧光光谱法同时测定水中砷和硒.对原子化器的高度、灯电流、负高压等实验条件进行了优化选择,确立了最佳分析条件.砷和硒的检出限分别为As:0.5μg/L,Se:0.1μg/L.     

地球化学样品中有机碳的光谱分析

有机碳已成为多目标地球化学调查、土地质量地球化学调查等项目研究的必测指标,对有机碳的准确定量是地球化学调查工作的重要内容,准确测定有机碳含量具有重要意义。然而传统的重量法、容量法流程长、速度慢,已经不能满足大批量及快速测定地球化学样品的要求。采用稀盐酸去除样品中的无机碳,应用高频红外碳硫分析仪对不同类型地球化学样品中有机碳的测定进行了研究,着重从称样量、酸的选择、最佳浓度及用量、助熔剂的选择和最佳加入量进行对比实验,优化出适合分析地球化学样品中有机碳含量的条件,并采用国家一级地球化学标准物质建立校准曲线,建立盐酸预处理-红外吸收光谱法测定地球化学样品中有机碳含量的分析方法。结果表明：陶瓷坩埚经1 200 ℃灼烧处理可以有效降低碳空白,减小对分析结果的影响;选择50.0～70.0 mg称样量,测试准确度高且样品熔融时不易喷溅;0.40～0.60 mL稀盐酸（1+7）除尽样品中的无机碳同时减少有机碳流失损失;0.40～0.50 g纯铁屑和1.50～1.70 g钨粒作为助熔剂,助熔效果稳定;采用国家一级地球化学标准物质建立校准曲线,校准曲线线性良好（R2=0.998 5）。该方法的检出限为69 μg·g-1,测定结果的相对标准偏差（RSD,n=12）均小于8%。经63个不同类型国家一级地球化学标准物质（土壤、岩石、水系沉积物）验证,测定结果与标准值相符。本方法操作简便,检出限低,灵敏度高,结果准确可靠,适用于地球化学样品中有机碳含量的测定。     

Surface treatment of barium gallogermanate laser glass

The surface of barium gallogermanate glass is modified through HCl solution etching to remove the surface defects and contaminations. The etching process and mechanism for barium gallogermanate glass in hydrochloric acid are investigated, and its optimum conditions are determined. However, the HCl etching induces the insoluble etch product containing minute crystal particles on glass surface. By heating BGG glass at the optical fiber drawing temperature, the deposited surface layer turned to be amorphous again and results in the increase of the transmittance of glass. The results indicated that the HCl etching combined with subsequent high-temperature heat treatment is an effective approach to improve the surface quality of barium gallogermanate glass, which would reduce the optical loss of the final optical fiber.     

Surface cleaning procedures for thin films of indium gallium nitride grown on sapphire

Surface preparation procedures for indium gallium nitride (InGaN) thin films were analyzed for their effectiveness for carbon and oxide removal as well as for the resulting surface roughness. Aqua regia (3:1 mixture of concentrated hydrochloric acid and concentrated nitric acid, AR), hydrofluoric acid (HF), hydrochloric acid (HCl), piranha solution (1:1 mixture of sulfuric acid and 30% H₂O₂) and 1:9 ammonium sulfide:tert-butanol were all used along with high temperature anneals to remove surface contamination. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were utilized to study the extent of surface contamination and surface roughness, respectively. The ammonium sulfide treatment provided the best overall removal of oxygen and carbon. Annealing over 700 °C after a treatment showed an even further improvement in surface contamination removal. The piranha treatment resulted in the lowest residual carbon, while the ammonium sulfide treatment leads to the lowest residual oxygen. AFM data showed that all the treatments decreased the surface roughness (with respect to as-grown specimens) with HCl, HF, (NH₄)₂S and RCA procedures giving the best RMS values (∼0.5-0.8 nm).     

Differences in the catalyst removal from single- and double-walled carbon nanotubes

Single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) synthesized by a catalytic chemical vapor deposition method showed partially incorporated metal catalysts inside the graphene walls. In order to remove the metal catalysts, acid and thermal treatments were successively carried out. The methods for effective catalyst removal in SWCNTs and DWCNTs were examined by means of thermogravimetric analysis, electron microscopy, and electron paramagnetic resonance. The DWCNTs showed distinctly different metal catalyst removal behavior from that of SWCNTs due to the double-wall structure. The acid treatment is less efficient for catalyst removal from DWCNTs, while catalysts in SWCNTs are effectively removed by acid treatment. Additional thermal treatment is quite effective to remove metal catalysts from DWCNTs.     

A new method for deaggregation of nanodiamond from explosive detonation: Graphitization-oxidation method

In this communication, a new method for the deaggregation of detonation nanodiamond (ND) and some preliminary results using this method are presented. ND is firstly graphitized in nitrogen at 1000°C and then oxidized by air at 450°C to remove the surface graphite layer formed. The sample after such treatment was suspended in water by ultrasonics, and the particle-size distributions were measured. It has been found that the diameters of more than 50% of the ND particles can be reduced to less than 50 nm.     

Xenogenic bone matrix treated with supercritical carbon dioxide as a potential osteoplastic material

A multistage environmentally safe method for processing xenogenic bone matrix using suband supercritical media has been developed. This method provides fast matrix delipidization in a medium of supercritical carbon dioxide and deproteinization by treatment with a 3% hydrogen peroxide solution followed by washing with subcritical water for removal of polar substances. The final treatment with supercritical carbon dioxide serves to remove residual nonpolar components. A method to control the porosity of xenogenic bone matrix at different stages of its purification has been suggested. Preliminary data indicate that a cellular test system based on an allogenic osteoid cell line Th-1 could be used for evaluation of primary adhesion and proliferation of cells on the surface of purified bone matrix.     

Nickel-containing carbon nanotubes and nanoparticles prepared in a high-frequency arc plasma

This paper presents the results of an investigation of nickel-containing carbon nanostructures prepared by plasma-chemical synthesis in a carbon-helium plasma jet at atmospheric pressure with the arc fed by a high-frequency current. It is demonstrated that, under these conditions, the conversion of graphite into a carbon condensate reaches 98 wt % and the contents of carbon nanotubes and nickel in this condensate are 72 and 10 wt %, respectively. Sequential treatment with nitric and hydrochloric acids has made it possible to extract purified carbon nanotubes and nickel nanoparticles coated with a carbon shell (approximately 50 nm thick) in which the nickel content is 4 wt %. Data are presented on the diameters of the prepared nanotubes and on the state of carbon in the samples.     

A Method to Obtain a Good Infrared Spectrum of the Wet Acetone Gas Sample without Any Drying PretreatmentSCIEI北大核心CSCD

Water vapor in the beam of a Fourier transform infrared (FTIR) spectrometer or/and in a gas cell is a major source of interference in the infrared measurement of a gas sample. In general, in order to eliminate the effect of water vapor, we have to completely remove these molecules before the measurement of any spectrum. Herein, we provide an approach to collect an IR spectrum of a gas (wet acetone) sample free from water vapor interference without any drying pretreatment. After dozens of scans, the air atmosphere in the sample compartment of the FTIR spectrometer will be slightly adjusted by small amounts of dry air or wet air (room air) depending on the property of water vapor lines (absorbance> 0 or absorbance <0). Water vapor lines will then gradually disappear when the ensuing collection process is continued. The experiment results demonstrated that this method is a facile and very effective way to remove water vapor interference. Moreover, this method works still well for the measurement at 0.5 cm(-1) resolution, typically used in the gas infrared measurement.     

不需干燥预处理过程获得含水汽的丙酮气体样品的高质量红外光谱

测量气体样品的红外光谱时,红外光谱仪器内的水汽和气体样品中所含的水汽会严重干扰气体的红外光谱。为消除水汽的干扰,通常作法是测量前必须将水分子(气态)彻底排除掉,也就是使光谱仪器和气体样品保持干燥状态。该研究提供一个新测量方法,不需任何干燥预处理过程,直接获得含水汽的丙酮气体的红外光谱。经过几十次光谱扫描累加后,观察并根据水汽谱的吸收峰性质(吸光率>0或吸光率<0),向光谱仪样品室引入少量干燥氮气或少量潮湿空气,在接下来的光谱扫描累加过程中,水汽吸收峰将逐渐变小直至消失。实验结果表明该方法去除水汽干扰峰简单高效。新方法在0.5 cm-1光谱分辨率时效果非常好,为气体的高分辨分析提供了有力工具。     

微腔内气体抽离的多尺度模拟与分析

基于适用于整个克努森数范围的流动理论,建立了去除惯性约束聚变实验中靶丸内空气的理论模型,并设计实验验证了此模型的可靠性。物理实验要求靶丸内空气浓度低于10×10?6,数值模拟了去除靶丸内空气的过程,重点分析了靶丸内空气浓度、压力与除气时间的关系。计算并比较了单管路一次抽气法、单管路循环抽气法与双管路流洗法三种去除靶丸内空气方法的时间成本。数值计算结果表明:单管路一次抽气法中,靶丸上的微通道的存在对去除靶丸内空气所需时间的影响不可忽略,在考虑靶丸上微通道与充气管的情况下,需要1961.77 h才能使靶丸内的空气浓度达到标准。单管路循环抽气法中,抽气次数与单次抽气程度会影响去除靶丸内空气所需总时间,在单次抽气程度值取最优的情况下,采用充三次,抽四次的方案可使达标总时间减少至1 h左右,此方案下单次充气和抽气时间分别为6 min和10 min。而采用双管路流洗法则仅需11 min便可使靶丸内空气浓度达标。