ABSTRACT
Since graphene was first isolated in 2004, it has become an attractive material on electrochemical energy storage devices. The purpose of this study is to compare Mg/graphite and Mg/graphene electrodes to commercial primary battery cathodes. This research is an experimental laboratory research. Graphene was synthesized with Hummer's method modified. Electrodes cathode of primary battery (Mg/graphite and Mg/graphene) were prepared using impregnation method. Graphene and electrodes cathode were analyzed with X-Ray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX) and conductivity, respectively. The XRD data of graphene show that there is a weak and sharp peak on 2θ = 26,5o, indicating graphene is formed. The peaks shape of 2θ = 35o are totally different for Mg/graphite and Mg/graphene. At Mg/graphite, the sharp and narrow peak appears on 2θ = 35o. It means Mg is well deposited on graphite. Interestingly, Mg/graphene has narrow and weak peak on 2θ = 35o, indicating the Mg was deposited on graphene and properties of Mg has been changed by graphene. This data is also well confirmed by EDX data. Mg atoms exist on graphene (1.47 wt%) (EDX data). SEM images of Mg/graphite and Mg/graphene are significantly different, probably support material effect. The properties of Mg/graphite and Mg/graphene comparing to commercial primary battery cathode were evaluated using conductivity. The conductivity of Mg/graphene (1080 µS/cm) is highest among Mg/graphite (90 µS/cm) and commercial battery cathode (10 µS/cm). All of data show that the Mg/graphene is potentially used as a primary battery cathode.
ABSTRACT
Differential pulse polarography is used in a rapid-flow analysis system for automated determination of lead, zinc and ascorbic acid in acetate-buffered sample solutions, without the need for sample deaeration. By use of a nitrogen-segmented buffer stream at high flow-rates, high-speed sampling at up to 180 samples/hr can be obtained at a flow-rate of 22.8 ml/min through a polarographic flow-cell fitted to the dropping mercury electrode. A linear calibration range of approx. 0.1 x 10(-4)-1.0 x 10(-3)M is found for lead, zinc and ascorbic acid, with respective detection limits of 4.0, 0.8 and 0.2 x 10(-6)M, limited by the high base-line current and high noise-level. Vitamin C tablets can be routinely analysed without prior separation steps, provided the sample and wash solutions are matched in electrolyte composition. A precision of better than 1% RSD is obtained at a sampling rate of 120/hr.