Oxidation of Copper Sulfides in Aqueous Ammonia. II. Electrochemical Aspects

1979 ◽  
Vol 32 (5) ◽  
pp. 975 ◽  
Author(s):  
AO Filmer ◽  
ID MacLeod ◽  
AJ Parker
Keyword(s):  
Aqueous Ammonia ◽  
Linear Sweep Voltammetry ◽  
Carbon Paste ◽  
Linear Sweep ◽  
Sulfate Ions ◽  
Copper Sulfides ◽  
Carbon Paste Electrodes ◽  
Controlled Potential Electrolysis ◽  
Controlled Potential ◽  
Equilibrium Thickness

The oxidation of covellite, CuS, to copper(II) and sulfur or sulfate ions in aqueous ammonia is slowed by the formation of an equilibrium thickness of a copper polysulfide Cuss (y < 1). The polysulfideis thermally and electrochemically unstable when in contact with CuS. A surface coating of sulfur, although formed, is not responsible for the semi-passivation of CuS during oxidation. Cyclic voltammetry, controlled potential electrolysis, linear sweep voltammetry, and various amperiometric and coulometric experiments with electrodes of pressed CuS, of carbon paste containing CuS and or a carbon ring with a CuS disc have been used to study the formation or decomposition of Cuss and its effect on rates of oxidation or CuS in aqueous ammonia. CuS-carbon paste electrodes offer some advantages over pressed discs of CuS for such studies.

Linear sweep voltammetry with carbon paste electrodes in the rat striatum

Neuroscience ◽  
1982 ◽  
Vol 7 (8) ◽  
pp. 1945-1954 ◽  
Author(s):  
R.D. O'Neill ◽  
R.A. Grünewald ◽  
M. Fillenz ◽  
W.J. Albery
Keyword(s):  
Linear Sweep Voltammetry ◽  
Rat Striatum ◽  
Carbon Paste ◽  
Linear Sweep ◽  
Carbon Paste Electrodes

Oxidation of Copper Sulfides in Aqueous Ammonia. III. Kinetic Characteristics

1979 ◽  
Vol 32 (12) ◽  
pp. 2597 ◽  
Author(s):  
AO Filmer ◽  
AJ Parker ◽  
BW Clare ◽  
LGB Wadley
Keyword(s):  
Aqueous Ammonia ◽  
Sulfide Oxidation ◽  
Metal Sulfide ◽  
Diffusion Control ◽  
Sulfate Ions ◽  
Kinetics Of Oxidation ◽  
Copper Sulfides ◽  
Shrinking Core ◽  
Kinetics Of ◽  
And Diffusion

The kinetics of oxidation with oxygen of chalcocite, Cu2S, to CuS in buffered aqueous ammonia at pH 10.5 at 30� can be modeled approximately by a shrinking core of Cu2S within a thickening shell of CuxS (x ≥ 1). The Cu2S core offers partial cathodic protection to the CuxS and diffusion of Cu+ through CuxS controls the rate of reaction. The kinetics of oxidation of covellite, CuS, to Cu2+, sulfur and sulfate ions in the same solvent can be modeled by a shrinking core of CuS surrounded by a shrinking sphere of CuyS (y < 1) which is much less effectively protected cathodically by the CuS core. Oxidation of CuS is subject to mixed chemical and diffusion control. Rates of oxidation of NiS and of CuS, in the presence and absence of tetrachloroethene and ammonium sulfate, show that, whether sulfur is a major oxidation product or not, the presence of sulfur has very little, if any, influence on the rate or mechanism of oxidation. This is contrary to current ideas on metal sulfide oxidation.

A new Methimazole sensor based on nanocomposite of CdS NPs–RGO/IL–carbon paste electrode using differential FFT continuous linear sweep voltammetry

Talanta ◽  
2014 ◽  
Vol 127 ◽  
pp. 94-99 ◽  
Author(s):  
Parviz Norouzi ◽  
Vinod Kumar Gupta ◽  
Bagher Larijani ◽  
Mohammad Reza Ganjali ◽  
Farnoush Faridbod
Keyword(s):  
Carbon Paste Electrode ◽  
Linear Sweep Voltammetry ◽  
Continuous Linear ◽  
Carbon Paste ◽  
Linear Sweep ◽  
Paste Electrode

Determination of Levodopa in Pharmaceuticals Using a Disposable Electrochemically Activated Carbon-Paste Electrode by Linear Sweep Voltammetry

2018 ◽  
Vol 51 (10) ◽  
pp. 1520-1528 ◽  
Author(s):  
Alexander Chebotarev ◽  
Konstantin Pliuta ◽  
Anastasiya Koicheva ◽  
Kateryna Bevziuk ◽  
Denys Snigur
Keyword(s):  
Activated Carbon ◽  
Carbon Paste Electrode ◽  
Linear Sweep Voltammetry ◽  
Carbon Paste ◽  
Linear Sweep ◽  
Paste Electrode

Comparative Electrochemical Study of Some Phenothiazines with Carbon Paste, Solid Carbon Paste and Glass-Like Carbon Electrodes

2000 ◽  
Vol 65 (6) ◽  
pp. 1014-1028 ◽  
Author(s):  
Robert V. Sandulescu ◽  
Simona M. Mirel ◽  
Radu N. Oprean ◽  
Simion Lotrean
Keyword(s):  
Modified Electrodes ◽  
Linear Sweep Voltammetry ◽  
Pharmaceutical Formulations ◽  
Oxidation Potential ◽  
Electrochemical Study ◽  
Carbon Electrodes ◽  
Potential Range ◽  
Solid Carbon ◽  
Carbon Paste ◽  
Linear Sweep

In order to obtain modified electrodes with phenothiazines and to develop electrochemical methods for their determination in pharmaceutical formulations, promazine maleate, promethazine maleate and levomepromazine, were studied by linear sweep voltammetry using different types of working electrodes: carbon paste, solid carbon paste and glass-like carbon electrodes. A comparative electrochemical study of the above mentioned pheno- thiazines was performed in aqueous-alcoholic solutions, investigating the influence of pH, ionic strength and concentration on the current-potential curves. Linear sweep voltammetry in potential range from -0.1 to +1.3 V revealed that the oxidation potential and the current, strongly depend on the type of electrode and pH, the best results being obtained in acid buffer (pH 1.0). The current intensity depending linearly on the concentration in the range of 2.5·10-5-5·10-4 M promazine maleate, 2.5·10-5-2.5·10-4 M promethazine maleate and 6.2·10-5-1.2·10-3 M levomepromazine permits the development of electroanalytical methods to determine these phenothiazines in pharmaceuticals. The electrochemical determination yielded results comparable with spectrophotometric methods. Linear sweep voltammetry of carbon paste electrodes modified by incorporation of phenothiazines opens the possibility to use them as mediators in the design of some enzyme selective electrodes.

Effect of cetyltrimethylammonium bromide on the electrochemiluminiscence and electrooxidation of luminol

1983 ◽  
Vol 48 (2) ◽  
pp. 477-483 ◽  
Author(s):  
Jan Lasovský ◽  
František Grambal
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Linear Sweep Voltammetry ◽  
Critical Micellar Concentration ◽  
Peak Height ◽  
Anodic Peak ◽  
Alkaline Solutions ◽  
Platinum Electrodes ◽  
Micellar Solutions ◽  
Linear Sweep ◽  
Low Concentrations

The electrooxidation of luminol in alkaline solutions in the presence of cetyltrimethylammonium bromide (I) was studied by linear sweep voltammetry on fixed and vibrating platinum electrodes. The presence of I in low concentrations (below the critical micellar concentration) brings about aggregation of the luminol, which is manifested by an increase in the anodic peak height and its shift towards lower potentials. In micellar solutions the peak height decreases owing to the slower diffusion of the bulkier micelles, the shift to lower potentials being preserved. The light-voltage curves correspond with the voltammetric curves, exhibiting identical shifts of the peak potentials in dependence on the concentration of the surfactant.

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