Electrochemical Accumulators

Moller, P. Kersten, G. 1994. Electrochemical accumulation of visible gold on pyrite and arsenopyrites surfaces. Mineralium Deposita, 29, 404-413. 

Voltammetric measurements confirm that Hg-modified carbon electrodes are suitable for sensitive electrochemical detection of ODN compared to mercury electrodes. In the presence of the copper ions, these electrodes modified by a mercury layer were used for the detection of a picomolar quantity of ODN. The electrochemical step includes a potential-controlled reduction of the copper ions Cu(II) and accumulation of the Cu(I)-purine base residue complex on the Hg-modified carbon surface. The proposed electrochemical method can be used for the determination of different ODN lengths because the stripping current peak of the electrochemically accumulated Cu(I]-purine complex increased linearly with the length of ODN. The optical microscope images were used for the visualization of the surface morphology of the bare and Hg-modified carbon electrodes [64]. 

A comprehensive overview of preconcentration techniques for uranium (VI) and thorium (IV) prior to analysis was published (Prasada Rao et al. 2006). The multitude of off-line techniques that were reviewed includes liquid-liquid extraction, liquid membranes, ion exchange, extraction chromatography, flotation, absorptive electrochemical accumulation, solid-phase extraction (SPE), and ion imprinting polymers. In addition, online preconcentration methods for uranium, thorium, and mixtures of the two are also briefly surveyed. This overview includes over 100 references and is a good source for finding a suitable preconcentration technique with regard to the enrichment factor, retention and sorption capacity, method validation, and types of real samples. The review article focused on samples in which the uranium was already in solution so that digestion procedures for solid samples were not discussed (Prasada Rao et al. 2006). 

The stripping techniques are so-called multistage combined procedures, with the characteristic that the voltammetric or chronopotentiometric determination is preceded by an electrochemical accumulation of analyte. The accumulation occurs on the surface of a stationary working electrode and leads to considerably improved performance. The methods enable analytical studies in the pico-trace range [ 11 ] - [ 13]. 

The aim of this chapter is to give a brief overview of the main technologies used for electrochemical accumulators. A more in-depth study is presented in [GLA 12 GLA 13],... 

Figure 6.7 shows the radar charts thus obtained for the three electricity storage devices studied in this book batteries, electrolyzer/fuel cell assemblies and supercapacitors. However, in order to illustrate the diversity of the performances achieved by electrochemical accumulators, we shall also discuss the results for a lead-acid battery and for a LiFeP04 battery. 

While the storage systems touched upon in these three chapters (hydrogen batteries and supercapacitors) both exhibit potentially advantageous characteristics, which vindicate their usage in hybrid electrical systems, at present they are still relatively costly. In fact, the days of the electrochemical accumulator by no means appear to be numbered just yet. This will therefore be the topic of Chapter 5. 

Batteries for this field of application are presently without exception electrochemical accumulators. As the demand situation differs with varying solar electric systems, it is advisable to analyze the demands closely before choosing a battery system. These subjects are explicitly treated in two separate chapters. 

The application of gold amalgam-alloy electrode (AuAE) for a sensitive voltammetric detection of different oligodeoxynucleotides (ODNs) containing the purine units within the ODN-chains in the presence of copper is described by Hason et al. [44].The analysis of the ahODNs was based on the cathodic stripping of the electrochemically accumulated complex... 

---