Modification of the surfaces of Wyoming montmorillonite by the cationic surfactants alkyl trimethyl, dialkyl dimethyl, and trialkyl methyl ammonium bromides

Surfaces of a Wyoming SWy-2 sodium montmorillonite were modified using microwave radiation through intercalation with the cationic surfactants octadecyl-trimethyl ammonium bromide, dimethyldioctadecylammonium bromide, and methyl-tri-octadecyl ammonium bromide by an ion exchange mechanism. Changes in the surfaces and structure were characterized using X-ray diffraction (XRD), thermal analysis (TG) and infrared (IR) spectroscopy. Different configurations of surfactants within montmorillonite interlayer are proposed based on d(001) basal spacings. A range of surfactant molecular environments within the surface-modified montmorillonite are proposed based upon their thermal decomposition. IR spectroscopy using a smart endurance single bounce diamond attenuated total reflection (ATR) cell has been used to study the changes in the spectra of CH asymmetric and symmetric stretching modes of the surfactants to provide more information of the surfactant molecular configurations.     

Characterisation of organoclays and adsorption of p-nitrophenol: environmental application

Organoclays were synthesised through ion exchange of a single surfactant for sodium ions, and characterised by a range of method including X-ray diffraction (XRD), BET, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). The change in surface properties of montmorillonite and organoclays intercalated with the surfactant, tetradecyltrimethylammonium bromide (TDTMA) were determined using XRD through the change in basal spacing and the expansion occurred by the adsorbed p-nitrophenol. The changes of interlayer spacing were observed in TEM. In addition, the surface measurement such as specific surface area and pore volume was measured and calculated using BET method, this suggested the loaded surfactant is highly important to determine the sorption mechanism onto organoclays. The collected results of XPS provided the chemical composition of montmorillonite and organoclays, and the high-resolution XPS spectra offered the chemical states of prepared organoclays with binding energy. Using TGA and FT-IR, the confirmation of intercalated surfactant was investigated. The collected data from various techniques enable an understanding of the changes in structure and surface properties. This study is of importance to provide mechanisms for the adsorption of organic molecules, especially in contaminated environmental sites and polluted waters.     

可见光响应Cu-Cu2+1O复合材料的水热法一步合成

采用水热合成法, 以Cu(NO3)2为原料, 乙二醇为溶剂和还原剂, 聚乙烯吡咯烷酮k30(PVP)为表面活性剂, 一步合成可见光响应Cu-Cu2+1O 金属-半导体复合材料. 采用X射线衍射(XRD)、透射电子显微镜(TEM)和紫外-可见漫反射光谱(DRS)观测复合材料的相结构、表观形貌、粒子尺寸和光谱特征. 以苯酚为模型物, 氙灯照射下测试催化剂活性. 结果显示表面活性剂PVP的加入对产物晶相结构不产生影响, 但促进Cu2+1O还原, 并影响Cu和Cu2+1O两种粒子的尺寸分布和界面结合, 进而影响产物的催化性能. 活性测试结果表明, Cu-Cu2+1O金属-半导体复合材料具有可见光催化活性, 其对苯酚降解符合一级反应动力学.     

Physicochemical study of novel organoclays as heavy metal ion adsorbents for environmental remediation

Four organic-modified clays based on a SWy-2 montmorillonite were prepared by embedding ammonium organic derivatives with different chelating functionalities (NH(2), COOH, SH or CS(2)) in the interlayer space of montmorillonite. Organic molecules such as (a) hexamethylenediamine, (b) 2-(dimethylamino)ethenethiol, (c) 5-aminovaleric acid and (d) hexamethylenediamine-dithiocarbamate were used for the clay modification in order to study the effect of the chelating functionality on heavy metal ions binding from aqueous solutions. The organoclays were characterized by powder X-ray diffraction (XRD), infrared (FTIR) and NMR spectroscopies. The experimental data showed that the organic molecules are intercalated into the interlamelar space with the long dimension parallel to the clay sheets. Their sorbing properties were evaluated for the removal of heavy metals, Pb, Cd and Zn, from aqueous solutions as a function of the pH. When compared with the unmodified SWy-2 montmorillonite, the modified clays show significant improvement in terms of sorbing selectivity as well as of metal loading capacity. The fit to adsorption data by a Surface Complexation Model shows that the intercalated molecules act as specific binding sites in the clay. These contribute additional sorption capacity which is additive to the variable charge edge-sites of the clay in competition with the permanent charge sites.     

不同有机离子表面活性剂改性蒙脱土结构与性能比较

分别用阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）、阴离子表面活性剂十二烷基磺酸钠(SDS)以及二者混合物(CTAB-SDS)的水溶液处理天然蒙脱土。 用红外光谱和X射线衍射比较了它们对蒙脱土结构的影响。 证明CTAB及CTAB-SDS处理蒙脱土的层间距分别由1.5420 nm增大至2.1946和1.8935 nm。 表明CTAB插入蒙脱土层间,且CTAB及CTAB-SDS处理蒙脱土在苯乙烯中分散性能明显提高,对有机物表现出良好的吸附性;而阴离子表面活性剂未进入蒙脱土层间,蒙脱土的结构和性能几乎未变。     

Stabilization of hydroxyl-group-terminated SERS-marker molecules on microAg particles by silanization

Surfactant modified montmorillonitic clays synthesized by ion exchange using the hydrothermal reaction method have been compared using XRD and thermal analysis. X-ray diffraction (XRD) shows the changes in the surface properties of organoclays through expansion with surfactant loading. A polynomial relationship exists between the basal spacing and the CEC loading described by the equation y=0.3232x(2) + 0.2052x+1.2834 with R(2)=0.9955. Different arrangements of the surfactant molecules in the organoclays are inferred from the changes in basal spacings. para-Nitrophenol also causes the expansion of the montmorillonite clay and affects the arrangements of the surfactant molecules within the clay layers. Changes in the surfactant molecular arrangements were analyzed by thermogravimetry. Additional thermal decomposition steps were observed when para-nitrophenol is adsorbed on the organoclay.     

Electrospinning and characterization of poly(vinyl alcohol)/chitosan oligosaccharide/clay nanocomposite nanofibers in aqueous solutions

Submicron fibers of the composite of poly(vinyl alcohol) (PVA), chitosan oligosaccharide [COS, (1→4)2-amino-2-deoxy-β-d-glucose], and montmorillonite clay (MMT) were prepared using electrospinning method with aqueous solutions. Scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal gravimetric analyzer, and tensile strength testing machine (Zwick) were utilized to characterize the PVA/COS/MMT nanofiber mats morphology and properties. The PVA/COS ratio and MMT concentration play important roles in nanofiber mat properties. XRD and TEM data demonstrated that exfoliated MMT layers were well-distributed within nanofiber. It was also found that the mechanical property and thermal stability were increased with COS and MMT contents.     

阴离子氨基酸表面活性剂调控下水热合成羟基磷灰石纳米片

利用水热合成方法, 在含有氨基酸结构的阴离子表面活性剂N-酰基十二烷基肌氨酸钠(Sar-Na)的控制下, 合成具有较大长径比(aspect ratio)的片状纳米羟基磷灰石晶体. 采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)和傅立叶变换红外(FTIR)光谱表征, 并分析了合成产物的形貌、结构和组成. 结果表明, 在Sar-Na的调控下合成了长度0.5-1.0 μm、宽约30 nm的片状羟基磷灰石晶体, 其长径比约为20:1. 考察了表面活性剂Sar-Na的用量对羟基磷灰石形貌的影响. 随着Sar-Na的添加及用量的增加, 羟基磷灰石由椭圆形变为长片状, 并且片的两端逐渐变尖. 结果显示了Sar-Na对羟基磷灰石形貌的控制作用, 为合成具有较大长径比的羟基磷灰石纳米片提供了一个新的途径.     

CdS纳米粒子的水热微乳法制备

0引言CdS是一种重要的Ⅱ-Ⅵ族半导体,其独特的光电化学性能引起人们的广泛关注,而其性能与晶粒尺寸、晶体结构等密切相关,因而CdS的纳米结构的研究备受关注[1￣3]。目前,制备CdS纳米粒子的主要方法有溶剂热法[4],化学浴沉积法[5],微乳液法[6]等。微乳液是合成球形纳米粒子的良好介质,具有实验装置简单,操作方便,应用领域广并且有可控制微粒的粒度等优点[7]。但其在室温条件下合成的CdS粒子的结晶性较差,严重影响其光电性能。Gan和Liu等[8]曾在NP5-NP9/PE/SOL微乳液中,在室温及水热条件下合成ZnS:Mn发光纳米材料,来提高在微乳液中制…     

Effect of pullulan/poly(vinyl alcohol) blend system on the montmorillonite structure with property characterization of electrospun pullulan/poly(vinyl alcohol)/montmorillonite nanofibers

Nanofibers of the composite of pullulan (PULL), poly(vinyl alcohol) (PVA), and montmorillonite clay (MMT) were prepared using electrospinning method in aqueous solutions. Pullulan is an interesting natural polymer for many of its merits and good properties. Because of biocompatibility and non-toxicity of PVA, it could be used in numerous fields. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were done to characterize the PULL/PVA/MMT nanofibers morphology and properties. XRD patterns and FTIR data demonstrated that there were good interactions between PULL and PVA caused by possibly hydrogen bonds. Moreover, XRD data and TEM images indicated that intercalated and exfoliated MMT nanoplatelets can be obtained within the PULL/PVA/MMT nanofibers depending on the PULL/PVA blend ratios. Furthermore, the thermal stability and mechanical property (tensile strength) of PULL/PVA/MMT nanofibers could be enhanced more by exfoliated MMT nanoplatelets than intercalated structures of that nanoplatelets.     

表面活性剂辅助水热合成氧化钛纳米针溶胶

TiO₂ nanoneedles sol with particle size of 10～15 nanometer was synthesized by hydrothermal method using peroxo titanic acid as the precursor, cetyltrimethyl ammonium bromide(CTAB) as the surfactant. The product was characterized by XRD, TEM, HRTEM and selected area electron diffraction(SAED). The results show that the as-prepared products have high crystallinity and grow along the c-axis, with homogeneous morphology and good monodispersity. In addition, TiO₂ hydrosol possessed good photocatalytic activity for the photocatalytic degradation of methyl orange aqueous solution under the sunlight illumination.     

CdS纳米球的水热制备及性质表征

采用水热方法制备了CdS纳米球.通过扫描电镜和透射电镜可以看出:该方法可直接获得具有较好结构的纳米球,比较不同溶剂中得到产品的SEM,发现甘油对CdS纳米球的形成起到了重要的作用.X射线粉末衍射图谱中无杂质衍射峰出现,表明样品为纯的六方相CdS.CdS纳米球的室温光致发光光谱中有2个不同的峰.     

Key factor affecting the basicity of mesoporous silicas MCM-41: effect of surfactant extraction time and Si/Al ratio

Mesoporous silica Si-MCM-41 was prepared by hydrothermal method using TEOS and CTAB as the source of silica and structuring agent, respectively. The surface of the as-synthesized material was treated using HCl/ETOH solvent to remove the CTA surfactant instead of using the calcination. Characterization of the catalysts was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen sorption at 77 K, scanning and transmission electronic microscopy (SEM, TEM), and thermogravimetric analysis TGA. The catalytic properties of the prepared materials in the condensation of acetophenone with ethyl cyanoacetate were studied. The effects of the catalyst type, Si/Al ratio, reaction kinetics, and reaction temperature were also investigated to find an optimal parameter. The results show that an interesting yield was obtained (about 96%) in a short reaction time; it is found that the yields of products depend not only on the amount of surfactant inside the mesopores but also on the Si/Al ratio. The catalyst reuse shows that this catalyst can be used up to five cycles, and at temperatures higher than 50 °C, the yield of products decreases due to the slight destruction of the catalyst as confirmed by the XRD analysis. Based on the results obtained, a possible mechanism of the condensation reaction of acetophenone was proposed.     

Preparation of CdS nanoparticles by hydrothermal method in microemulsion

CdS nanoparticles with good crystallinity were prepared by hydrothermal method in microemulsion composed of polyoxyethylene laurylether/water/cyclohexane/butanol. The structure and the size of the CdS nanoparticles were analyzed by TEM and XRD. The UV-Vis optical absorption of the samples was also investigated. The results show that hydrothermal treatment is an effective method to prepare CdS nanoparticles of hexagonal structure at lower temperature. The particles were in dimensional uniformity. The diameter of the CdS nanoparticles decreased with the increase of the molar ratio of water to surfactant. The minimum diameter of the CdS nanoparticles prepared in this work was about 10 nm. Obvious blue shift appeared in the UV-Vis absorption spectra. Translated from Chinese Journal of Inorganic Chemistry, 2006, 22(5): (in Chinese)     

Influence of different substrates on ZnO nanorod arrays properties

Zinc Oxide (ZnO) nanorod arrays were grown on different substrates by hydrothermal method. The crystallinity of ZnO nanorod was regularly investigated by X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine morphology of the ZnO nanorods. The results indicate that the nanorods grow along [002] orientation. SEM and TEM images and XRD patterns show that the growth of ZnO nanorods on graphene/Quartz substrate is better than the other substrates due to the number and size of the nanorods which are highly affected through the properties of ZnO seed layers and it has lower defects than the other substrates. PL spectra ZnO would have a higher concentration of oxygen vacancy.     

镁皂石的水热合成与表征研究

采用优化的水热合成法,在473K反应2h合成了具有优良长程有序性的2：1型三八面体蒙皂石(皂石)。XRD分析表明合成产物具有典型的皂石层状结构。TEM测试发现,不同温度下合成的皂石具有类似的形态,但其层状片大小随着合成温度的提高而增大。不同温度(423K,473K,523K,573K)下水热合成实验结果表明,473K是合成具有良好层状有序结构皂石的临界温度。不同层电荷合成皂石对于活性染料(MB)的等温吸附实验说明吸附过程包含离子交换和絮凝机理。相对于天然蒙脱石,合成皂石对于离子性染料具有更大的吸附容量和作用力。     

Growth of carbon nanotubes on the novel FeCo-Al2O3 catalyst prepared by ultrasonic coprecipitation

FeCo-Al_2O_3 catalyst was prepared by an ultrasonic coprecipitation (UC) method for the growth of carbon nanotubes (CNTs) from catalytic decomposition of methane. Its catalytic performance was compared with that of the FeCo-Al_2O_3 catalyst counterparts prepared by stepwise impregnation (I) and conventional coprecipitation (C) methods, respectively. The structure and properties of the catalysts and the CNTs as produced thereon were investigated by means of XRD, XPS, TEM and N_2 adsorption techniques. It was found that the catalyst prepared by the ultrasonic coprecipitation method was more active, and the yield and purity of the synthesized CNTs were promoted evidently. The XPS results revealed that there were more active components on the surface of the catalyst prepared by the ultrasonic coprecipitation method. On the other hand, N_2 adsorption demonstrated that the catalyst prepared by the ultrasonic coprecipitation method conferred larger specific surface area, which was beneficial to dispersion of active components. TEM images further confirmed its higher dispersion. These factors could be responsible for its higher activity for the growth of CNTs from catalytic decomposition of methane.     

XRD,TEM and thermal analysis of Fe doped boehmite nanofibres and nanosheets

Iron doped boehmite nanofibres with varying iron content have been prepared at low temperatures using a hydrothermal treatment in the presence of poly(ethylene oxide) surfactant. The resultant nanofibres were characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM). TEM images showed the resulting nanostructures are predominantly nanofibres when Fe doping is no more than 5%; in contrast nanosheets were formed if Fe doping was above 5%. For the 10% Fe doped boehmite, a mixed morphology of nanofibres and nanosheets were obtained. Nanotubes instead of nanofibres were observed in samples with 20% added iron. The Fe doped boehmite and the subsequent nanofibres/nanotubes were analysed by thermogravimetric and differential thermogravimetric methods. Boehmite nanofibres decompose at higher temperatures than non-hydrothermally treated boehmite and nano-sheets decompose at lower temperatures than the nanofibres.     

特殊形貌GdF3:Eu3+纳米发光材料的制备及性能

以PEG-2000、柠檬酸和甘氨酸为表面活性剂,采用水热法制备出扁平纳米棒、纳米花和纳米片状的GdF3:Eu3+发光材料,并对其结构和性能进行了表征.XRD结果表明,所得样品均为正交晶系.FESEM照片表明,使用不同表面活性剂所制备的产物形貌不同.研究了以PEG-2000为表面活性剂时反应物浓度对产物形貌的影响,并对其...     

Influences of surfactant (PVA) concentration and pH on the preparation of copper nanoparticles by electron beam irradiation

Electron beam irradiation method was successfully applied to the preparation of Cu nanoparticles in aqueous solution under room temperature and ambient pressure using polyvinyl alcohol (PVA) as the surfactant. The influences of the pH on the products were studied by X-ray diffraction (XRD), and those of the surfactant PVA concentration on the particle size and agglomeration by ultraviolet–visible spectrophotometry (UV–vis) and laser scattering particle size distribution analysis (LSPSDA). The products were characterized by XRD and transmission electron microscopy (TEM). The results showed that the grain size of Cu nanoparticles, within a certain range, can decrease with increasing PVA concentration. Pure Cu nanoparticles with the grain size distribution of 5–50 nm were prepared when the pH was adjusted between 5.0 and 9.0, and the PVA concentration was 2.20 g/100 mL.