Sharif Digital Repository

Graphene oxide was an effective supporting material for immobilizing a dioxomolybdenum Schiff base complex via covalent interaction. The large surface of graphene oxide plays important roles to obtain a good degree of catalytic reaction. Catalytic capacity of the graphene-bound dioxomolybdenum Schiff base complex was investigated for the oxidation of various sulfides to sulfoxide compounds using hydrogen peroxide urea as an oxidant. The catalyst was characterized by various techniques including XRD, FTIR, TGA, SEM, UV–vis, and ICP-AES. The immobilized complex was very efficient with the extra benefits of easy recovery and recycling of the heterogeneous catalyst. The graphene oxide bound... 

In this study, chalcopyrite concentrate produced in Sarcheshmeh copper plant was subjected to oxidative leaching investigation by cupric ion to determine the effect of several parameters on the copper and iron dissolution, including temperature of leaching, time of holding and cupric concentration as oxidant agent in a range of 38–97 °C, 1.5–8.5 h and 0.2–0.8 M, respectively. The leaching media was chloride providing with 3 M HCl 37% and CuCl2. The experiments were designed by central composite design method. The dissolution of copper and iron was examined. The maximum dissolution of copper 62.64%, was obtained at 85 °C, 7 h and oxidant concentration of 0.7 M. The kinetics model of... 

The effect of CoSALEN on anti-oxidative properties of fullerene C60 in the presence of O2 in cumene was investigated. A comparison was made between the role of the CoSALEN as a catalyst in the C60 oxidation and oxidation in the presence of an initiator, i.e., AIBN. A mechanism is proposed for the catalytic role of CoSALEN in oxidation of C60. Oxidation of octadecylaminofullerene C60 at the same conditions reveals that oxidation could be a result of hydroperoxidation of the unreacted sites of C60. We conclude that C60 as well as its aminoderivatives enhance the efficiency of CoSALEN in the oxidation of cumene due to their radical scavenging property of their unreacted double-bond sites. ©... 

Equilibrium constants for formation of a cobalt(II) complex with the bidentate ligand dopamine have been studied with spectrophotometric methods in water + ethanol cosolvent systems at 15, 25, and 35 (±0.1)∈°C and an ionic strength of 0.2 mol·dm-3. The ionic strength was maintained using sodium chloride and a phosphate buffer. The stability constants of the complex and the resulting Gibbs energy changes are obtained. The results are discussed in terms of the effect of solvent on protonation and complexation. © Springer Science+Business Media, LLC 2007  

A sample of Tabas coal from Iran was oxidized using air, peroxyacetic acid (PAA), and PAA+air as a pretreatment for desulfurization with sodium butoxide in a batch reactor. The effects of air oxidation temperature, PAA oxidation time, sodium butoxide reaction time and temperature, solvent concentration and particle size on the reduction of sulfur were investigated. The PAA+air oxidation pretreatment was the most effective method for enhancing sulfur removal. This procedure increased pyritic sulfur removal by approximately 15% and organic sulfur removal by 20% in leaching with sodium butoxide. Increasing the temperature from 25 (unoxidized) to 100 °C on air oxidized samples, increased sulfur... 

Electrospinning is a simple and cheap process for forming one-dimensional (1D) nanofibers with controllable size, morphology, and chemistry. Besides these, the ultrahigh surface area with industrialization capability has attracted extensive interest in the research community. On the other hand, a photocatalytic process is a promising method for degrading organic pollutants that cannot be removed by conventional wastewater treatment. This review focuses on the recent progress of electrospun nanofibers for the photocatalytic degradation of water pollutants. The linkage between the electrospinning technique and the photocatalytic process is classified into two main categories: (1) polymeric... 

Pd–WO3 nanostructures were incorporated on graphene oxide (GO) and partially reduced graphene oxide (PRGO) sheets using a controlled hydrothermal process to fabricate effective hydrogen gas sensors. Pd–WO3 nanostructures showed ribbon-like morphologies and Pd–WO3/GO presented an irregular nanostructured form, while Pd–WO3/PRGO exhibited a hierarchical nanostructure with a high surface area. Gas sensing properties of thin films of these materials were studied for different hydrogen concentrations (from 20 to 10,000 ppm) at various temperatures (from room temperature to 250 °C). Although adding GO in the Pd–WO3, after hydrothermal process could increase the film conductivity, gas sensitivity... 

The dearth of efficient, robust, and economical electrocatalysts for water oxidation is dubiously the key obstacle for renewable energy devices, so synthesis of efficient, and cost-effective metal-based water oxidation catalysts is vital. Herein, Co3O4, Co9S8 catalysts and their heterostructure Co3O4/Co9S8 were synthesized and evaluated as water oxidation electrocatalysts. The characterization of Co3O4, Co9S8, and Co3O4/Co9S8 electrocatalysts was performed using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques. The heterostructure Co3O4/Co9S8 (1.46 V) exhibited water oxidation electrocatalysis at extremely low onset potential compared to... 

The polymer supported hypochlorite ion is a facile selective oxidizing agent for the oxidation of various alcohols to aldehydes and ketones. Similarly it successfully oxidizes various Hantzsch type 1,4 - dihydropyridines to corresponding pyridines  

Nanoparticles for biomedical use must be cytocompatible with the biological environment that they are exposed to. Current research has focused on the surface functionalization of nanoparticles by using proteins, polymers, thiols and other organic compounds. Here we show that inorganic nanoparticles such as titanium oxide can be coated by pyrolytic carbon (PyC) and that the coating has cytocompatible properties. Pyrolization and condensation of methane formed a thin layer of pyrolytic carbon on the titanium oxide core. The formation of the PyC shell retards coalescence and sintering of the ceramic phase. Our MTT assay shows that the PyC-coated particles are cytocompatible at employed doses  

Electrochemical oxidation of acetaminophen (N-acetyl-p-aminophenol) (1) has been studied in the presence of dimethylamine (2) as a nucleophile in aqueous solution, by means of cyclic voltammetry and controlled-potential coulometry. The results indicate the participation of electrochemically generated N-acetyl-p-quinoneimine (1a) in Michael reaction with dimethylamine (2). Based on ECE mechanism, the observed homogeneous rate constant (kobs) of the above mentioned reaction is estimated by comparing the experimental cyclic voltammograms with the digital simulated results. Further more; kinetics and mechanism of the reaction were studied with ab initio calculation, Monte Carlo and QM/MM... 

Sodium hypochlorite adsorbed on montmorillonite K10 is a useful oxidant for the oxidation of thiols to disulfides under the room temperature. © 2005 Bentham Science Publishers Ltd  

Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. ©2005 Sociedade Brasileira de Química  

A remarkably fast microwave assisted selective oxidation of benzylic alcohols with calcium hypochlorite under solvent-free conditions is described  

A density functional theory (DFT) study of graphene synthesis from graphite oxidation and exfoliation is presented. The calculated DFT results for O adsorption predict CO as a most stable bond on the graphene oxide (GO) sheet. The obtained exfoliation energy for the graphene and the GO are 143 and ∼70 mJ/m2 that verify easier exfoliation of the graphite oxide compared with the graphite. Furthermore, the DFT results show that for decreasing the exfoliation energy of the GO at least two layers of the graphite should be oxidized during the oxidation process  

The electro-catalytic oxidation of methanol on a Ni-Cu alloy (NCA) with atomic ratio of 60/40 having previously undergone 50 potential sweep cycles in the range 0-600 mV vs. (Ag/AgCl) in 1 m NaOH was studied by cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS). The electro-oxidation was observed as large anodic peaks both in the anodic and early stages of the cathodic direction of potential sweep around 420 mV vs. (Ag/AgCl). The electro-catalytic surface was at least an order of magnitude superior to a pure nickel electrode for methanol oxidation. The diffusion coefficient and apparent rate constant of methanol oxidation were found to be 2.16 × 10-4 cm2 s-1 and...