Accelerated Life Testing of a Palladium-Doped Tin Oxide Electrode for Zn Electrowinning

Abstract

Electrowinning is a technique that can be used to obtain high-purity elements through electrolysis. The degradation of accelerated life testing for Pd-based electrodes is discussed in this study. The lifetime of the electrodes was examined by multiplying the acceleration rate with the current to measure the voltage of the electrodes. The acceleration rate was set to 10, 20, and 30 times. Four components were deposited on the TiO 2 plate. The ratio of Ir to Sn was fixed at 1:1, while Ta was deposited at 10 wt.%. Pd was deposited at 2, 4, 8 and 10 wt.% to create Pd-Ir/Sn-Ta. The initial voltage decreased as the Pd deposition amount increased irrespective of the acceleration rate. The lower the acceleration rate, the lower the voltage. An increase in the Pd content caused the initial voltage to be low. The multiple of the acceleration rate slightly increased for all cases of life testing for one year. When the test was conducted by increasing the current density by 20 times, the increase in voltage was proportional to the Pd deposition amount. However, for the 30 times acceleration rate, the lifetime of the electrodes was shortened as the Pd content increased. It can be inferred that the content of Pd and the ratio of Ir to Sn can influence the lifetime of the electrodes. According to these results, if the multiple of the acceleration rate is too extreme, the lifetime of the electrodes cannot be evaluated because they are damaged in an extreme situation.feasibility. In particular, many studies have been conducted on metal compositions; however, most of these investigations focus on simple compositions or characteristics of the electrodes [15,16].Electrowinning is typically conducted within 48 h when considering the current efficiency and zinc recovery efficiency, in which the electrodes are reused several times. These electrodes, with a high rate of reusability, are provided with a low power consumption in the electrowinning process. When a purified solution undergoes direct electrowinning, the purity of zinc ingot, which is the final product, may be reduced due to various metal substances (excluding zinc) in the purified solution. Therefore, the process of extracting zinc alone from a purified solution and then proceeding with electrowinning is gaining attention. Zinc is then dissolved in sulfuric acid. If the electrodes are exposed to highly concentrated sulfuric acid for an extended period of time, substances coated on the electrodes detach, and zinc recovery is hindered. In addition, the power consumption is increased due to the increased voltage. Thus, the lifetime of electrodes is very important in the electrowinning process [17][18][19].For electro refining, an excellent electrode must be able to work efficiently for several years. However, testing the electrode stability under normal conditions is time consuming. The lifetime of the electrode is one of the most important factors for the stability of the electrode [20]. Generally, the researcher compared the service life with different compositions of electro...