Background and Objective: Multiwall carbon nanotubes nowadays have multiple uses in the field of drug and gene delivery and other biological fields, and it is necessary to study their potential toxicity on organisms due to unique properties of these nanostructures. This study was conducted to determine the toxicity of multi-wall carbon nanotubes functionalized with carboxylic groups on the function and structure of the rats liver tissue. Methods: In this experimental study, 50 mature female Wistar Rats were randomly allocated into five groups including the control group of normal saline and Tween and treatment groups 2. 5, 5, 10, 20 mg/kg/bw concentrations of multi-wall carbon nanotubes functionalized with carboxylic group with diameter less than 8 nm and length 30 micrometers that was received in 8 steps, intraperitoneally. Blood sampling was performed in two steps (The first stage was one day after the last injection and the second stage was 20 days after the last injection). The level of activity of the aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) enzymes and the amount of malondialdehyde were measured in serum. By preparing the tissue sections of the liver, a number of rats in each group (after 20 days from the last injection) with hematoxylin-eosin staining, the tissue structure of the liver was examined by optical microscopy. Animals were weighed before and after treatment. Results: In the first stage, only the mean of AST activity at 5 mg/kg/bw concentration was significantly increased (P<0. 05). In the second stage, ALP activity was significantly reduced (P<0. 05) in all doses higher than 2. 5 mg/kg/bw and the activity of AST and ALT in doses of 5 and 10 mg/kg/bw was significantly reduced (P<0. 05) and in the dose of 2. 5 mg/kg/bw was significantly increased (P<0. 05). Histologic studies revealed disturbances such as degeneration of the vein wall of the lobular center, degeneration of the nucleus and hepatocyte lysis with severe atrophy, irregularity and dilatation of the sinusoids and accumulation of inflammatory cells in the treatment groups in dose-dependent manner. Based on the above findings the most disturbances were related to the 20 mg/kg/bw concentration. Conclusion: It seems that multi-wall carbon nanotubes functionalized with carboxylic group, even in small amounts (2. 5 and 5 mg/kg/bw) after 20 days, are toxic on the liver and cause liver tissue and function impairment.

Background and Objectives: Application of carbon nanotubes in medicine may bring about toxicity of these compounds. In the present study, the effects of carbon nanotubes were studied on liver tissue through creating oxidative stress. Methods: In this experimental study, concentrations of 10 and 20mg/kg of multiwall carbon nanotubes functionalized with carboxyl groups (10-20nm), were intraperitoneally injected into male rats in 21 stages and the control group received normal saline. Blood sampling and animal dissection were performed in two stages (24hours and 144hours after the last injection). Histological sections were prepared from the liver by hematoxylin-eosin staining and examined by optical microscopy. The concentration of thiol groups and malondialdehyde were measured and analyzed using one way ANOVA test. Results: Histological studies revealed disorders, such as hyperemia in the centrilobular vein, accumulation of inflammatory cells, abnormalities of sinusoids and vacuolation of hepatocytes, which were significantly higher with the dose of 20mg/kg and 144 hours after the treatment compared to the other groups. In the first blood collection, the plasma levels of thiol groups significantly increased with the dose of 10mg/kg (p<0. 05) compared to other groups and in the second stage, the level of malondialdehyde showed a significant increase in both doses compared to the control group (p<0. 05). Conclusion: Carbon nanotubes probably cause liver tissue disorder by aggregation and binding to various cellular components in the liver and creating oxidative stress; but, given the lack of mortality in animals, these disorders may decrease over time.

Groundwater recourses may be contaminated with trichloroethylene (TCE) which is used in electronic, electric, dry cleaning and other similar industries and often treated by air stripping, which TCE in its vapor form is stripped from groundwater by air and is emitted into the atmosphere without any additional treatments. Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. In this study adsorption of trichloroethylene on multiwall carbon nanotubes has been investigated. The effect of contact time, pH, initial concentration of trichloroethylene and temperature on its adsorption were investigated. Adsorption isotherms and related constants were also determined. Results showed that contact times to reach equilibrium changed from 30 min (for 150 mg/L initial concentration) to 10 min (for 600 mg/L concentrations) at 25oC, the equilibrium times in 40oC were 40 min and 15 min, respectively. Multi-wall carbon nanotubes showed to act as a good adsorbent for TCE in a wide range of pH=(3-9). For pH>9, adsorption decreased due to ionization of oxygen-containing groups. Adsorption test results revealed that TCE adsorption on the studied adsorbents could be better described by Freundlich isotherm.

Background and Objective: Various industries such as petrochemical, oil refinery, pharmaceutical, plastics, paper, steel and, resin produce a substantial of phenol and its derivatives. Wastewaters containing phenol need careful treatment before discharging into the environment due to their poor biodegradability and high toxicity. The objective of this study was to remove phenol by multiwall carbon nanotubes from aqueous solution.Materials and Methods: Adsorption process was implemented in a laboratory-scale batch with emphasis on the effect of various parameters such as contact time (5 to 120 minutes), pH (3, 5, 7, 9, 11), initial concentration of phenol (5, 10, 25, 50 mg/l) and the sulfate and chloride ions (20-200 mg/l) on adsorption process. To achieve a better realization of adsorption process, sorption kinetics and equilibrium isotherms were also determined.Results: The results indicated that maximum adsorption capacity occurred at concentration 50 mg/L and t=30 minutes. The uptake fluctuated very little in the pH range of 3-9, and at greater than 9 the absorption decreased suddenly. Moreover, the presence of sulfate and chloride ions had no effect on the process. It was found that adsorption kinetics and equilibrium data follow a pseudo-second-order kinetics model and a Freundlich isotherm model respectively.Conclusion: It is concluded that carbon nanotubes being effective in a wide range of pH, short time to reach equilibrium and the absence of competing ions on the absorption process can be used effectively in removing phenol from aqueous solution.

Herein, we show that amorphous carbon nanoparticles (ACNPs) can be successfully transformed into multi-walled carbon nanotubes (MWCNTs) under an annealing at temperatures (1350-1380oC), assisted by crystal defects via mechanothermal method.More importantly, the detailed observation of the morphologies and structures of the nanotubes and the related intermediate objects unveils that the transformation obeys following mechanism: nanoparticles first self-assemble into nanostructures with high-ultra crystal defects and then change into nanotubes via particle-particle coalescence and structural crystallization. Crystal phases were determined by X-ray diffraction (XRD). Scanning electron microscope (SEM) was applied to investigate the morphology. The microstructure of the CNT products were further observed by transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) with energy-dispersive X-ray spectroscopy (EDX). Raman spectra were taken at room temperature under ambient condition using an Almega Raman spectrometer with an Ar+at an excitation wavelength of 514.5 nm.As a matter of fact, the method of mechanothermal guarantees the production of multi-walled carbon nanotubes (MWCNTs) for different applications, especially reinforcement materials because of ultra-high aspect ratio.