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A new approach was developed for the magnetic separation of copper(II) ions with easy operation and high efficiency. p-Mercaptobenzoic acid served as the modified tag of Fe2O3@Au nanoparticles both for the chelation ligand and Raman reporter. Through the chelation between the copper(II) ions and carboxyl groups on the gold shell, the Fe2O3@Au nanoparticles aggregated to form networks that were enriched and separated from the solution by a magnet. A significant decrease in the concentration of copper(II) ions in the supernatant solution was observed. An extremely sensitive method based on surface-enhanced Raman spectroscopy was employed to detect free copper(II) ions that remained after the magnetic separation, and thus to evaluate the separation efficiency. The results indicated the intensities of the surface-enhanced Raman spectroscopy bands from p-mercaptobenzoic acid were dependent on the concentration of copper(II) ions, and the concentration was decreased by several orders of magnitude after the magnetic separation. The present protocol effectively decreased the total amount of heavy metal ions in the solution. This approach opens a potential application in the magnetic separation and highly sensitive detection of heavy metal ions. [ABSTRACT FROM AUTHOR]

Abstract: The adsorption and reorientation behavior of benzonitrile on an electrochemical roughened Pt electrode were studied by surface-enhanced Raman spectroscopy (SERS) over a wide potential range. The results revealed that benzonitrile was adsorbed on the surface in a vertical orientation through the nitrogen atom of CN group in the relative positive potential region (>−0.6V), while the benzonitrile molecule changed its orientation with the negative movement of potential (<−0.8V). In the hydrogen evolution region, the intensity of the Raman bands from the benzene ring and CN group decreased dramatically, and the frequency of CN red-shifted about 160cm−1. It indicated that the benzonitrile was adsorbed on the Pt electrode in a flat orientation by interacting with the electrode surface via CN and/or benzene ring. A schematic model about the adsorption configurations of benzonitrile in different potential regions was proposed. [Copyright &y& Elsevier]

The adsorption behaviour and the formation of a surface complex film of benzotriazole (BTAH) on Cu electrodes have been studied by in situ surface enhanced Raman spectroscopy in acetonitrile solution. A potential-dependent Raman study revealed that the adsorption and film formation process of BTAH involves the formation of a chemisorbed adlayer and a compact polymer film in two different potential regions in the acetonitrile solution. The results showed that BTA− ion can interact with the Cu surface through the two N atoms of the triazole ring to form a surface polymer complex of [Cu(BTA)]n, which suppressed the dissolution and oxidation of Cu effectively. When triphenylphosphine (pph3) was introduced into the solution, the formation of the surface polymer complex film was suppressed due to the formation of soluble . In solution, a complex of Cu with BTA− and pph3 was formed leading to a significant decrease of the surface inhibition efficiency. These two kinds of surface complexes were prepared by the direct electrochemical synthesis technique in similar solutions, and characterized by normal Raman spectroscopy and elemental analysis. The results showed that the final complexes were insoluble [Cu(BTA)]n polymer and CunBTAm(pph3)p complex with low solubility in the acetonitrile solution. [Copyright &y& Elsevier]

Abstract: The adsorption of three cyanopyridine isomers on Pt electrodes was investigated using electrochemical surface-enhanced Raman spectroscopy (SERS) within a wide potential region. It was revealed that the adsorption configurations depend on the applied potential and on the positions of CN group. The 4-cyanopyridine (4-CP) and 3-cyanopyridine (3-CP) molecules adsorb on Pt surfaces via the N atoms of the pyridine ring, while the 2-cyanopyridine (2-CP) molecules attach to the surface with the N atoms of both the pyridine ring and the CN group. In the case of 4-CP, the tilted adsorption mode is dominant under the potential of −0.8–0V. It is converted to the vertical mode when the potential is moved to 0–0.8V. For 3-CP, the vertical adsorption mode is found to be preferential in the full potential window. The Cing vibrational band of 2-CP is absent in the observed SER spectra. This is mainly caused by the characteristic π-electron delocalization as both N atoms are anchored to the Pt surface to form a heterogeneous ring. The hydrogen atoms are co-adsorbed with the cyanopyridine isomers on the Pt surface in extremely negative potential region. [Copyright &y& Elsevier]