Electrodeposition of Silicon from Fluorosilicic Acid Produced in Iraqi Phosphate Fertilizer Plant

Abbar, Ali H.; Kareem, Sameer H.; Alsaady, Fouad A.

doi:2011.2.3.168

J. Electrochem. Sci. Technol > Volume 2(3); 2011 > Article

Article

Journal of Electrochemical Science and Technology 2011;2(3):168-173.
DOI: https://doi.org/10.5229/JECST.2011.2.3.168

Electrodeposition of Silicon from Fluorosilicic Acid Produced in Iraqi Phosphate Fertilizer Plant

Ali H. Abbar, Sameer H. Kareem, Fouad A. Alsaady

Chemical Engineering Department, College of Engineering Al-Qadisiyah University;College of science for Women, Baghdad University;College of Pharmacy, Kufa University;

Abstract

The availability, low toxicity, and high degree of technological development make silicon the most likely material to be used in solar cells, the cost of solar cells depends entirely on cost of high purity silicon production. The present work was conducted to electrodeposite of silicon from $K_2SiF_6$, an inexpensive raw material prepared from fluorosilicic acid ($H_2SiF_6$) produced in Iraqi Fertilizer plants, and using inexpensive graphite material as cathode electrode. The preparation of potassium fluorosilicate was performed at ($60^{circ}C$) in a three necks flask provided with a stirrer, while the electro deposition was performed at $750^{circ}C$ in a three-electrodes configuration with melt containing in graphite pot. High purity potassium fluorosilicate (99.25%) was obtained at temperature ($60^{circ}C$), molar ratio-KCl/$H_2SiF_6$(1.4) and agitation (600 rpm). Spongy compact deposits were obtained for silicon with purity not less than (99.97%) at cathode potential (-0.8 V vs. Pt), $K_2SiF_6$ concentration (14% mole percent) with grain size (130 ${mu}m$) and level of impurities (Cu, Fe and Ni) less than (0.02%).

Keywords: Silicon, Potassium fluorosilicate, Flourosilicic acid, Electrodeposition, Molten salt