Journal of Nanoanalysis

6

Authors: Hamid Shirkhanloo, Ali Akbar Miran Beigi, Amir Vahid, Nasrin Shirkhanloo, Behzad Kalantri and Hossein Ali Ghadirian

On-line solid phase extraction (SPE) based on nano adsorbent for pre-concentration of inorganic arsenic in water and waste water samples was developed prior to determine by hydride generation atomic absorption spectrometry (HG-AAS). By hydride generation simulation system (HGSS), the inorganic arsenic in liquid samples changed to hydride form and pass through nano platinum multi wall carbon nanotube (3 wt % Pt, NPt-MWCNT,). The hydride form of arsenic (AsH3), pre-concentrated on NPt-MWCNTs and then completely desorption by electric heater accessory at 200oC for determining. The detection limit (LOD) and linear range of perposed method were obtained 0.4 ng L-1 and 6 –410 ng L-1 respectively(R2 = 0.9988). The relative standard deviations (%RSD) at 100 ng L-1 of analyte were found less than 5%. The capacity and efficiency of nano adsorbent were 75 mg g-1 and 96% at argon flow rate less than 100 ml min-1. The developed method was applied successfully to determination of ultra trace of inorganic arsenic in environmental samples by HG-AAS.

6

Authors: Mohsen Asadi Asadabad, Mohammad Jafari Eskandari, Reza Tafrishi, Mojtaba Bagherzadeh

The cross-rolling is a new process that results in significant evolutions in microstructure of the metallic sheets. In this study, an aluminium 1050 sheet was rolled up to 95% reduction in cross directions for ten passes. The rolled samples were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The rolled samples possess a high dislocation density and ultra-fine crystallite structure. In addition, an anisotropic texture was formed in the structure of material. In fact, the intensity of {220} planes of Al was extremely increased about 7500 counts per second (CPS) in cross-rolling process. In this research a new method called selected area electron diffraction (SAED) was used to determine the direction of planes. In cross-rolled samples, the rolling texture component {110} [001] was created that are known as brass texture (Bs). A regular geometric structure accompanied by ultrafine-grained observed in TEM micrographs. Ultra-fine crystalline structure is proved by rings which were obtained from SAEDs. The results show that the grain sizes are about 200 nm and 300 nm in cross-rolling and straight rolling, respectively.

11

Authors: Ali Karimi, Ahmad Tavasoli, Maryam Davari, Ali Mohajeri

Functionalization of carbon nanotube (CNT) was performed, during preparation of Fischer–Tropsch synthesis (FTS) via cobalt nanocatalysts, to modify the surface properties of CNT support. Common and functionalized CNT supported cobalt nanocatalysts were prepared using impregnation wetness method with cobalt loading of 15 wt.%. The catalysts were characterized by Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), temperature program reduction (TPR), H2 chemisorption, and transmission electron microscopy (TEM) technique. Most of the cobalt particles were homogeneously distributed inside the tubes and the rest on the outer surface of the functionalized CNT. Functionalization of CNT shifted the TPR reduction peaks to lower temperatures, improved the reduction degree, and increased the dispersion of cobalt particles and stability of catalysts. The proposed cobalt catalyst supported on functionalized CNT- (N-doped functionalized CNT) increased the FTS rate (g HC/gcat./hr), and CO conversion (%) from 0.1347, and 30 to 0.235, and 47 respectively, compared to that of the catalyst prepared by impregnation wetness method on common CNT. Catalysts supported on functionalized CNT also showed better stability.