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Graphene is mostly grown from methane on copper foils at a high temperature about 1000°C. In this research, a commercial ethylene-acetylene-ethane mixture was used as a clean precursor for graphene synthesis on nickel foils in a chemical vapor deposition reactor at 750°C. Furthermore, controlled functionalization of graphene sheets was achieved via hydrothermal oxidation at moderate pressure and temperature using nitric acid. Broadened 2D band and G band frequencies in Raman spectra indicated that pristine graphene (PG) was of high quality with low defects. X-ray diffraction results confirmed that PG has five layers. Transmission electron microscopy and N2adsorption-desorption analyses affirmed that the graphene is of a good quality, large surface area (562 m2/g) and small pore size. Fourier transform infrared spectroscopy confirmed functionalization process performance. Thermogravimetric analysis affirmed that the thermal stability of PG was drastically decreased after the functionalization process. [ABSTRACT FROM AUTHOR]

Nanoporous activated carbons, as adsorbent for CO storage, were prepared from walnut shells via two chemical processes including phosphoric acid treatment and KOH activation at high temperature. Specific surface area and porosities were controlled by KOH concentration and activation temperature. The obtained adsorbents were characterized by N2 adsorption at 77.3 K. Their carbon dioxide adsorption capacities were measured at different pressures at 290 K by using volumetric adsorption equipment. The KOH-treated nanoporous carbons typically led to the production of high specific surface areas and high micropore volumes and showed better performance for CO adsorptions. The maximum experimental value for adsorption capacity happened when pressure increased from 5 to 10 bar (1.861-2.873mmol·g). It was found that in order to improve the highest capacity of CO adsorption for KOH-modified carbon (9.830-18.208mmol·g), a KOH: C weight ratio of 3.5 and activation temperature of 973 K were more suitable for pore development and micro-mesopore volume enhancement. [ABSTRACT FROM AUTHOR]

In this study, to remove CO 2 and H 2 S from a natural gas stream through some absorption experiments, a nanofluid containing SiO 2 and Al 2 O 3 nanoparticles in Diethanolamine was used. We employed a wetted wall column system in a laboratory scale. Some quantities including the nanoparticle dosage, the liquid, and gas flow rates were adjusted to the best removal percent. The range of nanoparticle concentration varied from 0.005 to 0.5 wt. % in our experiments. The nanofluids were prepared by ultrasonic treatment and showed acceptable stability. In addition, a parametric analysis was performed to explore the effects of particle types, as well as concentrations on absorption of H 2 S and CO 2 . The results showed up to 33% improvement of CO 2 absorption at 0.05 wt. % of Al 2 O 3 /DEA nanofluids, and also 40% at 0.05 wt.% of SiO 2 /DEA nanofluids for sample no.1 (feed gas mixture composition: 50 ppm H 2 S and 3% CO 2 in balance of CH 4 ). Moreover, adding silica nanoparticles to DEA deteriorated the absorption of H 2 S; whereas using Al 2 O 3 /DEA nanofluid with 0.1wt.% Al 2 O 3 enhanced the absorption by 14%. [ABSTRACT FROM AUTHOR]

In this research, UiO-66-NH 2 was synthesized with solvothermal method and analyzed by XRD, SEM, BET, TGA and IR spectroscopy to understand its crystalline structure, morphology, thermal stability, and porous structure. Mass fraction of 0.1% of UiO-66-NH 2 added to aqueous solution of mass fraction of 40% N-Methyldiethanolamine (MDEA). Measurement of zeta potential showed that UiO-66-NH 2 particles are stable in aqueous mass fraction of 40% MDEA. The solubility of carbon dioxide investigated in aqueous solution of mass fraction of 40% MDEA and the prepared mixture of mass fraction of 0.1% of UiO-66-NH 2 nanofluid in aqueous solution of mass fraction of 40% MDEA at temperatures of 303.15, 313.15, 323.15, and 333.15 K, and carbon dioxide pressures up to 2300 kPa. Results showed that addition of UiO-66-NH 2 nanoparticles to the MDEA solution, increased capacity of CO 2 absorption of solution up to 10%. The solubility of CO 2 increased with increasing partial pressure and decreased with increasing temperature for both systems. [ABSTRACT FROM AUTHOR]

A carbon nanotube-supported metallo carboxyporphyrin has been synthesized and characterized by X-ray diffraction (XRD), field-emission scanning electronic microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The prepared catalyst has been evaluated for the removal of mercaptan from gas stream in a fixed bed reactor. The effect of important operating parameters including temperature, gas hourly space velocity (GHSV), and loading (%) was investigated on the mercaptan removal. The results confirmed that the mercaptan concentration could be reduced from 16,800 ppm to less than 10 ppm under optimized conditions by (Fe)TCPP-MWCNTs-NH 2 as nanocatalyst. [ABSTRACT FROM AUTHOR]

The electro-catalytic behavior of Pt-CoO x /MWCNTs in methanol electro-oxidation reaction (MOR) is investigated and compared to that of Pt/MWCNTs. The electro-catalysts were synthesized by an impregnation method using NaBH 4 as the reducing agent. The morphological and physical characteristics of samples are examined by XRD, TEM, ICP and EDS techniques. In the presence of CoO x , Pt nanoparticles were highly distributed on the support with an average particle size of 2 nm, an obvious decrease from 5.1 nm for Pt/MWCNTs. Cyclic voltammetry, CO-stripping, Chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements are used to study the electrochemical behavior of the electro-catalysts. The results revealed a considerable enhancement in the oxidation kinetics of CO ads on Pt active sites by the participation of CoO x . Compared to Pt/MWCNTs, Pt-CoO x /MWCNTs sample has a larger electrochemical active surface area (ECSA) and higher electro-catalytic activity and stability toward methanol electro-oxidation. According to the results of cyclic voltammetry, the forward anodic peak current density enhances more than 89% at the optimum atomic ratio of Pt:Co = 2:1. Furthermore, inclusion of cobalt oxide species causes the onset potential of methanol electro-oxidation reaction to shift 84 mV to negative values compared to that on Pt/MWCNTs. Based on EIS data, dehydrogenation of methanol is the rate-determining step of MOR on both Pt/MWCNTs and Pt-CoO x /MWCNTs, at small overpotentials. However, at higher overpotentials, the oxidation of adsorbed oxygen-containing groups controls the total rate of MOR process. [ABSTRACT FROM AUTHOR]

In this study, graphene oxide (GO) nanosheets were synthesized by the modified Hummers method. GO structure was estimated by XRD, UV–vis-spectrophotometer and SEM imaging. Then homogeneous and stable GO/water nanofluid was prepared. The effects of GO concentration and temperature on the thermal conductivity were investigated. The measurements of thermal conductivity indicate that the nanofluids have substantially higher thermal conductivities than the base fluid. The thermal conductivity enhancement depends strongly on the concentration of GO and increases with the increasing loading. When the nanosheet loading is 0.25 wt.%, the enhancement ratio is 33.9% at 20 °C and when the temperature increased to 40 °C the enhancement is up to 47.5%. Therefore the level of enhancement is dependent of temperature in the measured temperature range. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the preparation of highly stable nano-porous Ni–Cu catalysts for simultaneous production of CO x –free hydrogen and carbon nano-fibers. The main features of this work focuses on the optimization, methods of catalyst preparation and application of an experimental model for deactivation. The fresh catalysts and the deposited carbon were characterized by SEM, TEM, XRD and Raman spectroscopy. Whatever to be the preparation methods, performance tests showed that the presence of Cu as promoter in Ni–Cu–MgO catalysts, enhanced the catalytic activity, substantially at higher temperatures with the best result obtained for Ni–Cu–MgO catalyst prepared by one step sol- gel method, reaching a hydrogen concentration of 70 vol% (160.51 mol H2/mol Ni-1 h) and a smaller value of ID/IG (less imperfection) for produced carbon nano-fibers at 670 °C. Detailed rate-based model for deactivation of catalyst was found to be dependent on the time, reaction temperature and partial pressure of methane and indicated that the reaction of deactivation could be modeled by a simple hyperbolic model. [Copyright &y& Elsevier]

Abstract: In the present work, effects of different surface modification methods (surfactant, acid, base, amide, sulfate) on multi walled carbon nanotubes (CNTs) are studied. The dispersion stability of CNTs in aqueous media was confirmed and the effects of the type of treatment on the thermal conductivity of CNT/water nanofluids were investigated. The surface of the CNTs was modified with acid mixtures (H2SO4–HNO3), potassium persulfate (KPS), tetrahydrofuran (THF), octadecylamine and sodium dodecyl sulfate (SDS). UV–visible spectral data indicate that the CNTs treated first with the acid mixture and then with KPS show the best dispersion stability. The basic treatment and SDS treated CNT/water nanofluids (SDS-KCNT/water) showed the highest conductivity of 0.765W/mK which increases 24.9% of water as a base fluid conductor. [Copyright &y& Elsevier]

Abstract: The synthesis of carbon nanotubes with a cobalt phthalocyanine (CoPc) complex has been described. The removal of mercaptan from gas stream in the present MWCNT-COOH-CoPc nanocatalyst was tested in a fixed bed reactor. For synthesizing this catalyst, multi-walled carbon nanotubes (MWCNTs) were used as support and MWCNT-COOH-CoPc nanocatalyst with loadings of 10 wt% of cobalt phthalocyanine organometal were prepared using the incipient wetness impregnation method. Nanocatalysts were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The effect of important operating parameters including temperature and Gas Hour Space Velocity (GHSV) was investigated. The results confirmed that the best condition can be achieved by setting the temperature at 200 °C and GHSV at 2000 h−1 with maximum mercaptan conversion of 99.99%. [Copyright &y& Elsevier]

Background: Anxiety is a special kind of anxiety that athletes competing in major competitions threshold to do so. The physical dimensions of anxiety symptoms such as tremor, palpitations, shortness of breath and symptoms such as cognitive symptoms include fear of failure and fear of poor performance, will occur. One of the psychological skills that are thought to be effective in reducing and controlling athletes' competitive anxiety, relaxation techniques are. It generally consists of two methods based on relaxation and cognitive. In this way, progressive muscle relaxation, has been used. Methods: This study consisted of 30 players, club Zob Ahan, randomly assigned to experimental and control groups. First of all players by anxiety questionnaires - Competitive CSAI-2 pre-test was performed. The players were in the experimental group received 20 sessions of relaxation, then step test was performed. Findings: The results were statistically analyzed using one-way ANOVA with post hoc test , the paired t test, t- test for independent groups, respectively (P = 0.05), showed a progressive muscle relaxation rate reduce anxiety 's physical , cognitive anxiety brought down close to the border between the players resting heart rate is significantly reduced. Conclusion: The results showed that the goalkeepers and defenders, midfielders had significantly more cognitive anxiety but is not significant in comparison to the quarterback .have. And the native players one of the three subscales of cognitive anxiety, somatic anxiety and self-esteem were not significantly different. [ABSTRACT FROM AUTHOR]