Inhibitor effect of sodium benzoate on the corrosion behavior of nanocrystalline pure iron metal in near-neutral aqueous solutions

Nanocrystalline iron coating was produced on carbon steel surface by pulse electrodeposition using citric acid bath. The grain size of a nanocrystalline surface was analyzed by X-ray diffractometry and scanning electron microscopy. The electrochemical behavior of nanocrystalline iron coating in the presence of sodium benzoate was evaluated in 30 mg l^-1 NaCl + 70 mg l^-1 Na₂SO₄ aqueous solution using potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results were compared with that of the coarse-grained iron surface. The thermodynamic properties of the inhibitor adsorption were also determined. The results indicated that corrosion inhibition of sodium benzoate in near-neutral aqueous solution was increased as the grain size of iron was decreased from micro- to nanocrystalline surface. This was reported in terms of excess free energy of nanocrystalline surface.     

Application of sulfur microparticles for solid-phase extraction of polycyclic aromatic hydrocarbons from sea water and wastewater samples

The application of sulfur microparticles as efficient adsorbents for the solid-phase extraction (SPE) and determination of trace amounts of 10 polycyclic aromatic hydrocarbons (PAHs) was investigated in sea water and wastewater samples using high performance liquid chromatography coupled with an ultraviolet detector (HPLC–UV). Parameters influencing the preconcentration of PAHs such as the amount of sulfur, solution flow rate and volume, elution solvent, type and concentration of organic modifier, and salt effect were examined. The results showed that at a flow rate of 10 mL min⁻¹ for the sample solutions (100 mL), the PAHs could be adsorbed on the sulfur microparticles and then eluted by 2.0 mL of acetonitrile. For HPLC–UV analysis of extracted PAHs, the calibration curves were linear in the range of 0.05–80.0 μg L⁻¹; the coefficients of determinations (r²) were between 0.9934 and 0.9995. The relative standard deviations (RSDs) for eight replicates at two concentration levels (0.5 and 4.0 μg L⁻¹) of PAHs were lower than 7.3%, under optimized conditions. The limits of detection (LODs, <!-- no-mfc -->S/N<!-- /no-mfc --> = 3) of the proposed method for the studied PAHs were 0.007–0.048 μg L⁻¹. The recoveries of spiked PAHs (0.5 and 4 μg L⁻¹) in the wastewater and sea water samples ranged from 78% to 108%. The simplicity of experimental procedure, high extraction efficiency, short sample analysis, and using of low cost sorbent demonstrate the potential of this approach for routine trace PAH analysis in water and wastewater samples.     

Design of ionic liquid 3-methyl-1-sulfonic acid imidazolium nitrate as reagent for the nitration of aromatic compounds by in situ generation of NO(2) in acidic media

3-Methyl-1-sulfonic acid imidazolium nitrate ([Msim]NO(3)) as a new Br?nsted acidic ionic liquid and nitrating agent was prepared and used for the efficient nitration of aromatic compounds (even aniline derivatives). The dramatic effect of this reagent by in situ generation of nitrogen dioxide as a radical on aromatic compounds to give nitroarenes has been studied.     

Trityl Chloride (TrCl): Efficient and Homogeneous Organocatalyst for the Solvent‐Free Synthesis of 14‐Aryl‐14H‐dibenzo[a,j]xanthenes by in situ Formation of Carbocationic System

Trityl chloride (triphenylmethyl chloride, TrCl, Ph₃CCl) is utilized as an efficient and homogeneous organocatalyst for the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes from β‐naphthol and arylaldehydes under solvent‐free conditions. Moreover, a plausible mechanism is suggested based on the literature and on in situ formation of trityl carbocation with inherent instability during the reaction.     

Modification of graphene/graphene oxide with polymer brushes using controlled/living radical polymerization

Graphene nanosheets possess a range of extraordinary physical and electrical properties with enormous potential for applications in microelectronics, photonic devices, and nanocomposite materials. However, single graphene platelets tend to undergo agglomeration due to strong π–π and Van der Waals interactions, which significantly compromises the final material properties. One of the strategies to overcome this problem, and to increase graphene compatibility with a receiving polymer host matrix, is to modify graphene (or graphene oxide (GO)) with polymer brushes. The research to date can be grouped into approaches involving grafting‐from and grafting‐to techniques, and further into approaches relying on covalent or noncovalent attachment of polymer chains to the suitably modified graphene/GO. The present Highlight article describes research efforts to date in this area, focusing on the use of controlled/living radical polymerization techniques. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and characterization of some organotin(IV) adducts containing a related series of pyridines: Crystal structure of [SnMe2Cl2(bu2bpy)]

Organotin(IV) complexes of [SnR_(4−n)Cl_n] (n = 2, R = Me, ⁿBu; n = 1, R = Ph) react with the bidentate pyridyl ligand 4,4′-di-tert-butyl-2,2′-bipyridine (bu₂bpy) to give hexa-coordinated adducts with the general formula [SnR_(4−n)Cl_n(bu₂bpy)]. However, the reaction of these organotin(IV) complexes with the corresponding monodentate ligand 4-tert-butylpyridine (bupy) resulted in the formation of the hexa-coordinated complex [SnMe₂Cl₂(bupy)₂] and the penta-coordinated complexes [SnR_(4−n)Cl_n(bupy)] (n = 2, R = ⁿBu; n = 1, R = Ph). Moreover, the reaction of the above organotin(IV) complexes with 4,4′-trimethylenedipyridine (tmdp) yields hexa-coordinated adducts with the general formula [SnR₂Cl₂(tmdp)] (R = Me, ⁿBu) and the penta-coordinated complex [ClPh₃Sn-μ-(tmdp)SnPh₃Cl] in the solid state. The resulting complexes have been characterized by multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and elemental analysis. NMR data shows that the triphenyltin(IV) adducts are not stable in solution and dissociate to give tetra-coordinated tin(IV) complexes. The X-ray crystal structure determination of [SnMe₂Cl₂(bu₂bpy)] reveals that the tin atom is hexa-coordinated in an octahedral geometry with a trans-[SnMe₂] configuration.