Authors: Bongiwe Silwana, Charlton van der Horst, Emmanuel Iheanyichukwu Iwuoha, Vernon Somerset
Abstract: Electrochemical kinetics of Platinum Group Metals was studied by cyclic voltammetry and the concentration of these metal ions was successfully detected by adsorptive differential pulse cathodic stripping voltammetry using a GCE/rGO-SbNPs sensor. The sensor constructed in this work consisted of a reduced graphene oxide film that was impregnated with antimony nanoparticles. The constructed nanosensor provided an excellent platform for the simultaneous determination of Pd (II), Pt (II) and Rh (III) metal ions. The analytical curve was linear in the concentration range from 0 - 0.40 ng L-1, and 0 - 0.56 ng L-1 for Pd (II)-Rh (III) and Pt (II)-Rh (III), respectively. The detection limits of Pd (II) and Rh (III) were found to be 0.46 ng L-1and 0.55 ng L-1, respectively while for Pt (II) and Rh (III) it was 0.52 ng L-1and 0.48 ng L-1, respectively. The relative standard deviation from 5 measurements for 0.4 ng L-1 Pd (II)-Rh (III) and Pt (II)-Rh (III) by using the GCE/rGO-SbNPs sensor was found to be 6.21% and 3.96%, respectively. Interferences by other metal ions were also studied.
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Authors: Charlton van der Horst, Bongiwe Silwana, Emmanuel Iheanyichukwu Iwuoha, Vernon Somerset
Abstract: The present work describes the development of an electrochemical sensor for the simultaneous determination of Pd-Rh and Pt-Rh complexes using a bismuth-silver bimetallic nanofilm modified glassy carbon electrode. The electrochemical sensor was prepared by drop-casting bismuth-silver bimetallic nanoparticles on to glassy carbon electrode surfaces. The HRTEM microscopy and UV-Vis spectroscopy results of the bismuth-silver nanoparticles were compared with other work in literature. The developed nanosensor exhibited a linear working range of 0.4 - 1.4 ng/L for Pd-Rh and 0.8-1.2 ng/L for Pt-Rh DMG complexes, respectively. Very low detection limits (S/N = 3) of 0.19 ng/L for Pd (II), 0.2 ng/L Pt (II) and 0.22 ng/L for Rh (III) were obtained and the sensor was successfully applied to environmental samples.
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Authors: Xuan Wen Liu, Bing Wen Zhong, Yue Hong Zhang, Rui Guo
Abstract: A new complex crystal [Co2(Hdmg)2(dien)2](ClO4)24.5(H2O) (H2dmg= dimethylglyoxime, dien = diethylenetriamine) had been synthesised in aqueous solution and was characterized by X-ray diffraction and IR spectrum. The complex crystallizes in monoclinic space group C2/c with cell constants =20.868(7)Å, =11.408(4)Å, =15.816(4)Å, =90.00°, =116.97(2)°, =90.00°, =3355.8(17)Å3, =4, (000)=1732. The cobalt atom lies in a distorted octahedron environment and coordinates with one oxygen atom from neighbour Hdmg and five nitrogen atoms from bidentate chelate Hdmg and tridentate chelate dien. The two Hdmgs bridge two cobalt atoms to form a six-number Co2O2N2 ring.
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Authors: Xuan Wen Liu, Shi Hua Yuan, Ting Ting Lin
Abstract: A New Complex Crystal [Co(Hdmg)2(Him)2]·(ClO4) (H2dmg = Dimethylglyoxime,Him = Imidazole) Had Been Synthesised in Aqueous Solution and Was Characterized by X-ray Diffraction and IR Spectrum. the Complex Crystallizes in Triclinic Space Group with Cell Constants a= 20.868(7)Å, B=11.408(4)Å, C=15.816(4)Å, α=90.00°, β=116.97(2)°, γ= 90.00°, V= 3355.8(17) Å3, Z=4, F(000)=1732. the Coordination Environment of Cobalt Atom Is a Slightly Distorted Octahedron. the Four Equatorial Donors Are Four Nitrogen Atoms from Two Bidentate Chelate Hdmg Anion Ligands. the Apex Points Are Occupied by Two Nitrogen Atoms from him Ligands. the Co-N(Him) Distance Is 1.930Å, and the Co-N(dmg) Distances Are Varying in the Range from 1.886Å to 1.993Å which Are in Agreement with Corresponding Reported in a Number of other Structurally Related Copper(II) Complexes.
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Abstract: A preconcentration method based on the adsorption of palladium-dimethylglyoxime -anchored organobentonite (DMG-bentonite) for the determination of palladium at trace levels by flame atomic absorption spectrometry (AAS) has been developed. The optimum experimental parameters for the adsorption and preconcentration of the palladium, such as pH value of medium, contact time, eluent and coexisting ion, have been investigated. The results showed that the palladium ion could be quantitatively retained by the DMG-bentonite in the pH range of 3–5 using citric acid/citrate buffer, the adsorption time was 20 min, and capability of adsorption was 8.73 mg•g-1. The palladium ion adsorbed on the DMG-bentonite could be completely eluated by using 1 mol•L-1 HCl. The detection limits of this method for palladium was 1.02µg•L-1 with an enrichment factor of 60. The method has been applied to the determination of trace amounts of palladium ion in street dust and environmental water with satisfactory results.
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