Nowadays cobalt is mostly produced through the electrowinning process of sulfate solutions. Regarding to the competition between the precipitation of cobalt ions and evolution of hydrogen gas on the cathode surface during the reduction process in a sulfate bath, investigation on the mechanism of metal precipitation is of great importance. In the present work, study on the kinetics of cobalt electrowinning and the mechanism of the involved reactions have been carried out. The obtained results, confirm the mechanism of cobalt precipitation by depletion of hydroxides. The effects of temperature and scan rate parameters were studied on electrowinning of cobalt by CYCLIC VOLTAMMETRY technique. The diffusion coefficient and rate constant of the reactions were measured and calculated by performed experiments.

The assembly of phosphomolybdic acid of Keggin-type polyoxoanion, [(PO4)Mo12O36]3-, and [La(DMF)8]3+ fragments via layer method under mild condition led to the formation of a new hybrid inorganic-organic compound with formula [La(DMF)8][(PO4)Mo12O36] (1) (DMF = N,N- dimethylformamide). The hybrid is characterized by using elemental analysis, IR spectroscopy, Energy Dispersive X-ray Spectroscopy analysis (EDS), CYCLIC VOLTAMMETRY, and single crystal X-ray diffraction. This compound crystallizes in the orthorhombic system, space group Pna21 with four molecules per unit cell. The unit cell parameters are: a = 27.1550 (5) A,b =18.5111 (4) A, c = 13.5055 (3) A, and a = b= γ =90o. The final R value was 0.0424 for 65109 observed reflections. The crystal structure is stabilized by non-covalent interactions of type C-H···O, linking the various components into a three-dimensional framework, which results in the formation of a supramolecular structure. Redox activities for the molybdenum centers of 1 have been observed using CYCLIC VOLTAMMETRY.

Many applications of polypyrrole conducting polymers based on their interesting and unique electroactivity properties (e.g., sensors) may demand possessing high thermal stability in solutions. So, thermal stability of electroactivity of polypyrrole conducting electroactive polymers (CEP) is very important. In this research, in order to investigate the thermal stability of the electroactivity in solutions, a series of polypyrrole (PPy) films doped with different dopants coated on glassy carbon electrodes were prepared electrochemically. Electroactivity stability of polymers in different solution temperatures was then investigated using CYCLIC VOLTAMMETRY(CV) technique. It was found that the electroactivity of the PPy is strongly dependent on the kind of the counterion. PPy/PTS was found to be more thermally stable in aqueous solution than other inorganic ions such as chlorides. Chemically, electrochemically stable as well as large size counterions (dopants) show higher stability at elevated solution temperatures. The nature of counterion, the preparation conditions (physical, chemical and electrochemical) and the nature of supporting electrolytes in which the polymer is switched, not only affect electroactivity of PPy films but also affect the thermal stability of these polymers in aqueous solutions

The electrochemical oxidation behavior of m-nitrophenol (m-NP) was studied comparatively on glassy carbon electrode, Pt electrode, PbO2 electrode, SnO2 electrode, and graphite electrode using CYCLIC VOLTAMMETRY. The CYCLIC VOLTAMMETRY measurements were performed in acidic (1 M H2SO4, pH 0. 4), neutral (1 M Na2SO4, pH 6. 8), and alkaline (1 M NaOH, pH 12. 0) media to investigate the effect of pH value on the oxidation of m-NP. The fouling of electrodes was also studied during CYCLIC VOLTAMMETRY measurements. The results indicate that both of the electrode material and the pH value of supporting electrolyte had significantly influence on the oxidation of m-NP. In acidic medium, m-NP was irreversibly oxidized on glassy carbon electrode, Pt electrode, SnO2 electrode, and graphite electrode at 1. 23, 1. 26, 1. 26 and 1. 27 V, respectively, while there was no any oxidation peak for PbO2 electrode. In a neutral medium, m-NP yielded well-defined oxidation peaks on all electrodes, although the height and potential of the peaks depended on the material of electrodes. In the alkaline medium, the m-NP could be directly oxidized only on glassy carbon electrode and graphite electrode, but their peaks were not well defined because the oxidation of m-NP occurs closer to oxygen evolution potential region. In addition, the oxidation peaks appeared at the lower potential value in the alkaline medium than in neutral and acidic media. Under all conditions, except in the alkaline solution and on glassy carbon electrode, the passivation of electrodes occurred during continual scans.

Ajwain is one of the medicinal plants, which the highest composition is thymol, as a strong antioxidant respect to the obtained chromatograms of GC/MS. The antioxidant activity of the Ajwain is measured by square wave VOLTAMMETRY method and CYCLIC VOLTAMMETRY method and 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) method in at the specific concentrations of 1%, 1. 5%, 2% and 2. 5% and constant pH. The results of the present study indicated that the antioxidant activity of Ajwain obtained from CYCLIC VOLTAMMETRY and square wave is almost equal to the results of the DPPH method, which can be used to measure the antioxidant activity. Compared to DPPH method, electrochemical method involves a number of advantages such as simplicity, cheap operating costs, fastness, low amount of solvent, and no need for chemical reagents. Furthermore, based on the results obtained, the square wave method includes a higher sensitivity and accuracy than CYCLIC VOLTAMMETRY method and DPPH method.