The adsorptive stripping voltammetric detection of nickel and cobalt in water samples at metal film electrodes has been extensively studied. In this work, a novel, environmentally friendly, metal-free electrochemical probe was constructed for the ultra-trace determination of Ni2+ in water samples by Adsorptive Cathodic Stripping Voltammetry (AdCSV). The electrochemical platform is based on the adsorptive accumulation of Ni2+ ions directly onto a glassy carbon electrode (GCE) modified with dimethylglyoxime (DMG) as chelating agent and a Nafion-graphene (NGr) nanocomposite to enhance electrode sensitivity. The nafion-graphene dimethylglyoxime modified glassy carbon electrode (NGr-DMG-GCE) shows superior detection capabilities as a result of the improved surface-area-to-volume ratio and enhanced electron transfer kinetics following the incorporation of single layer graphene, while limiting the toxic effects of the sensor by removal of the more common mercury, bismuth and lead films. Furthermore, for the first time the NGr-DMG-GCE, in the presence of common interfering metal ions of Co2+ and Zn2+ demonstrates good selectivity and preferential binding towards the detection of Ni2+ in water samples. Structural and morphological characterisation of the synthesised single layer graphene sheets was conducted by Raman spectrometry, HRTEM and HRSEM analysis. The instrumental parameters associated with the electrochemical response, including accumulation potential and accumulation time were investigated and optimised in addition to the influence of DMG and graphene concentrations. The NGr-DMG-GCE demonstrated well resolved, reproducible peaks, with RSD (%) below 5% and a detection limit of 1.5 µg L-1 for Ni2+ reduction at an accumulation time of 120 s., the prepared electrochemical sensor exhibited good detection and quantitation towards Ni2+ detection in tap water samples, well below 0.1 mg L-1 set by the WHO and EPA standards. This comparable to the South African drinking water guidelines of 0.15 mg L-1.

https://www.mdpi.com/1424-8220/17/8/1711/pdf

Complexation-Based Detection of Nickel(II) at a Graphene-Chelate Probe in the Presence of Cobalt and Zinc by Adsorptive Stripping Voltammetry

New Mn(II), Ni(II), Cd(II), Pb(II) complexes with 2-methylbenzimidazole and other ligands. Synthesis, spectroscopic characterization, crystal structure, magnetic susceptibility and biological activity studies

New Azo ligands HL1 [2-Hydroxy-3-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)-1naphth aldehyde] and HL2 [3-((1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1Hpyrazol-4-yl)diazenyl)-2-hydroxy-1-naphthaldehyde] have been synthesized from reaction (2-hydroxy-1-naphthaldehyde) and (5-amino-1,3,4-thiadiazole-2-thiol) for HL1 and (4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one) for HL2. Then, its metal ions complexes are synthesized with the general formula; [CrHL1Cl3(H2O)], [VOHL1(SO4)] [ML1Cl(H2O)] where M = Mn(II), Co(II), Ni(II) and Cu(II), and general formula; [Cr(L2)2 ]Cl and [M(L2)2] where M = VO(II), Mn(II), Co(II), Ni(II) and Cu(II) are reported. The ligands and their metal complexes are characterized by phiscochemical spectroscopic techniques (FT.IR, Mass, UV-Vis, 1 H and 13 C-NMR, TGA, (C.H.N.), molar conductivity, Atomic Absorbance, Chloride containing magnetic susceptibility). The spectral data suggest that the (HL1) behaves as a bidentate ligand in all complexes, whereas (HL2) behaves as a tridentate ligand for all complexes; bidentate ligand in Vanadium complex is coordinated with the metal ions through azo nitrogen and oxygen atoms. Theoretical studies of these ligands and their metal complexes in gas phase using Hyper chem.8. Studies of these compounds are prepared for their bacterial activity

Spectroscopic Studies and Thermal Analysis of New Azo Dyes Ligands and their Complexes with some Transition of Metal Ions

Some Pb(II) complexes of dibasic tridentate Schiff base ligands derived from aldehydes/ketones and benzoylhydrazine have been synthesized and characterized by some physico-chemical studies; elemental, spectral (IR, UV, NMR, Mass), magnetic, and conductance analyses. The CHN elemental analysis data showed the formation of 1:1 [M:L] complexes. The obtained molar conductance values revealed non-electrolytic nature. The results of magnetic moment measurements supported diamagnetic phenomenon for the complexes. The infrared spectral data displayed the main coordination sites of ligands towards Pb2+ ions. The electronic spectral results of the complexes showed π→π* (phenyl ring), n→π* (HC=N), CT transition. Based on analytical data trigonal pyramidal geometry for the prepared complexes has been proposed. The antibacterial activity of the prepared complexes was also studied against some gram positive and gram negative bacteria. It is found that some of the complexes are quite effective against tested bacteria.

/pdf/pb-ii-complexes-of-schiff-bases-derived-from-15s99gpiy6.pdf

Pb(II) Complexes of Schiff Bases Derived from Benzoylhydrazine as the Antibacterial Agents

Zeolite Y was obtained from diatomite in a template-free system, and the product was modified by dimethylglyoxime. Characterization studies indicate that the DMG molecules were loaded onto both the exterior surfaces and channels of the zeolite Y during the modification process. Removal of Ni(II) by modified samples was investigated in batch procedure, and it was found that the modified zeolite Y has a very high capacity. The effects of various parameters such as sorbent content, contact time, concentration of nickel solution, pH and selectivity were discussed. The best removal efficiency was observed by Y-DMG at the following experimental conditions: Y-DMG dosage: 2 g L−1, CNi(II): 100 mg L−1 and contact time: 9 h. The Y-DMG sorbent shows good efficiency for the removal of nickel in the presence of different multivalent cations. Adsorption kinetics based on the pseudo-second-order rate equation indicates that the rate-limiting step involves chemical reaction. Adsorption isotherms of Ni(II) ions obey Langmuir equation which indicates the monolayer sorption of Ni(II). The results of thermodynamic parameters of Ni(II) on Y-DMG indicate the process was endothermic and spontaneous.

Synthesis of zeolite Y from diatomite and its modification by dimethylglyoxime for the removal of Ni(II) from aqueous solution

A number of mixed-ligand complexes of the general formula [M(D)(G)] where D=dimethylglyoximato monoanion, G=N-acetylglycinato and M=VO(IV), Ni(II), Zn(II), Pd(II), Cd(II) and Pb(II) were prepared. Each complex was characterized by elemental analysis, determination of metal, infrared spectra, electronic spectra, (1H and 13C) NMR spectra, conductivity and magnetic moments. All these complexes were not soluble in some of the organic solvent but highly soluble in dimethylformamide. The conductivity data showed the non-electrolytic nature of the complexes. The electronic spectra exhibited absorption bands in the visible region caused by the d-d electronic transition such as VO(IV), Ni(II) and Pd(II). The IR and (1H, 13C) NMR spectra which have indicate that the dimethylglyoxime was coordinated with the metal ions through the N and O atoms of the oxime group and N-acetylglycine was coordinated with metal ions through the N atom and terminal carboxyl oxygen atom.

/pdf/preparation-and-spectral-properties-of-mixed-ligand-23gsotmpwn.pdf

Preparation and Spectral Properties of Mixed-Ligand Complexes of VO(IV), Ni(II), Zn(II), Pd(II), Cd(II) and Pb(II) with Dimethylglyoxime and N-acetylglycine

This paper presents a new mixed-ligand complexes with the general formula [M(BT)(BI)2X2] where BT=benzotriazole, BI=benzimidazole, X=SCN and M=Mn(II), Co(II), Ni(II), Cu(II), Cd(II) and Pb(II). The reaction was carried out by using the appropriate molar ratios of metal:ligand (1:1:2:2) (M:BT:BI:X) as required. The resulting products were found to be solids, not soluble in water and in ordinary organic solvents but highly soluble in DMSO. These complexes have been studied by UV-visible, IR and (1H, 13C) NMR spectra, molar conductivity, elemental analysis of C, H, N, determination of metal and magnetic susceptibility. The result suggests that the benzimidazoleas as a monodentate was coordinated with the metal ions through the N atom. Nevertheless, the benzotriazole as bidentate was coordinated with the metal ions through the N2 and N3 atoms. SCN was coordinated with the metal ions through the nitogen atom.

https://downloads.hindawi.com/journals/jchem/2010/793261.pdf

Shayma A. Shaker

Papers

Preparation and Spectral Properties of Mixed-Ligand Complexes of VO(IV), Ni(II), Zn(II), Pd(II), Cd(II) and Pb(II) with Dimethylglyoxime and N-acetylglycine

Preparation and Study of Some Mn(II), Co(II), Ni(II), Cu(II), Cd(II) and Pb(II) Complexes Containing Heterocyclic Nitrogen Donor Ligands