Sharif Digital Repository

Single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were synthesized in aqueous solutions containing FeCl2, FeCl3, FeSO4 and Fe2(SO4)3. The effects of iron charge and the counter ions on the formation of carbon nanotubes (CNTs) were investigated. Thermogravimetric (TG) analysis indicated that carbon multilayer structures including CNTs and multishell graphite particles were formed in deionized (DI) water without the iron precursor. SWCNTs were also synthesized in the presence of the iron ions. It was also found that the mole ratio of [Fe2+]/[Fe3+] in the solution has a significant influence on the purity of CNTs and the process yield. The highest yield was... 

In copper electrorefining process, some additives are added to the electrolyte to improve the morphology of cathode deposits as well as the quality of products. In the present investigation, the effects of thiourea, glue and chloride ions (as additives) on the passivation of industrial copper anodes under high current densities have been reported. Experiments were conducted at 65 °C; using a synthetic electrolyte containing 40 g/l Cu2+ and 160 g/l H2SO4. Results obtained from chronopotentiometry experiments showed that increasing the concentration of chloride ion leads to increase in passivation time. The results also indicated that from a certain level on, namely 2 ppm, the increase in... 

Single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were synthesized in aqueous solutions containing FeCl2, FeCl3, FeSO4 and Fe2(SO4) 3. The effects of iron charge and the counter ions on the formation of carbon nanotubes (CNTs) were investigated. Thermogravimetric (TG) analysis indicated that carbon multilayer structures including CNTs and multishell graphite particles were formed in deionized (DI) water without the iron precursor. SWCNTs were also synthesized in the presence of the iron ions. It was also found that the mole ratio of [Fe2+]/[Fe3+] in the solution has a significant influence on the purity of CNTs and the process yield. The highest yield was... 

Natural and synthetic anion receptors are extensively employed, but the structures of their bound complexes are difficult to determine in the liquid phase. Infrared spectroscopy is used in this work to characterize the solution structures of bound anion receptors for the first time, and surprisingly only two of three hydroxyl groups of the neutral aliphatic triols are found to directly interact with Cl-. The binding constants of these triols with zero to three CF3 groups were measured in a polar environment, and KCD3CN(Cl-) = 1.1 × 106 M-1 for the tris(trifluoromethyl) derivative. This is a remarkably large value, and high selectivity with respect to interfering anions such as, Br-, NO3 -... 

The formation of multi-walled carbon nanotubes (MWCNTs) during arc discharge in aqueous solutions of Fe2(SO4)3 and FeCl3 was studied. The concentration of iron ions changed from zero (deionized water) to 0.25 M and the cathodic products were examined by transmission electron microscopy, Raman spectrometry, and thermal gravimetric analysis. The experimental results showed that the crystallinity of MWCNTs is improved by increasing the concentration of iron ions. Nevertheless, the process yield and overall quality of the produced CNTs were significantly affected by iron concentration in the aqueous solution. This observation suggested that there should be an optimum iron concentration at which... 

We have compared the gas phase thermochemical properties of aspartame (artificial sweetener) and α- and β-glucose. These parameters include metal ion affinities with Li+-, Na+-, K+-, Mg+2-, Ca+2-, Fe+2-, Zn+2-ions, and chloride ion affinity by using DFT calculations. For example, for aspartame, the affinity values for the above described metal ions are, respectively, 86.5, 63.2, 44.2, 255.4, 178.4, 235.4, and 300.4, and for β-glucose are 65.2, 47.3 32.9, 212.9, 140.2, 190.1, and 250.0 kcal mol-1, respectively. The study shows differences between the intrinsic chemistry of aspartame and glucose. © 2008 Elsevier Ltd. All rights reserved  

Because of the recent frequent observations of major dust storms in southwestern cities in Iran such as Ahvaz, and the importance of the ionic composition of particulate matters regarding their health effects, source apportionment, etc., the present work was conducted aiming at characterizing the ionic composition of total suspended particles (TSP) and particles on the order of ∼10 μm or less (PM10) during dust storms in Ahvaz in April-September 2010. TSP and PM10 samples were collected and their ionic compositions were determined using an ion chromatography. Mean concentrations of TSP and PM10 were 1,481.5 and 1,072.9 μg/m 3, respectively. Particle concentrations during the Middle Eastern...