Electrosynthesis of cobalt – hydroxyapatite nanoparticles

Cobalt is one of the potential candidates that exhibit good catalyst properties. The catalyst support is needed to increase the dispersion of the catalyst and to prevent the catalyst loss. Hydroxyapatite (HA) is one of the good catalyst support for transition metal catalyst. The electrochemical synthesis to HA supported cobalt catalyst has the advantages of being easy, inexpensive, controlled, and producing metal that is perfectly dispersed at its support. The novelty of this work is the synthesis of hydroxyapatite that supports cobalt in one step by the electrochemical method. In this paper, we demonstrate the effects of current density to the particle Co-HA produced. The solution for cobalt-HA synthesis by electrochemical method is calcium chloride, potassium dihydrogen phosphate and EDTA in molar ratio 0.25/0.15/0.25 M 250 mL solution. The initial concentration of cobalt were 0.2 and 0.5 M. The cell of electrolysis consists of two carbon plates. The bipolar membrane was used to separate the electrolysis cell. The electrolysis cell had a size of (3×10×10)cm and was constructed from the acrylic box. Both carbon plates were 2.5×5 cm and placed in the electrolyte a depth of 2.5 cm. The electrolysis cell was placed in ultrasonic. The current density was various at 80, 160, and 240 mA/cm². The pH of the solution in the anode chamber decreased as the electrolysis time increased while in the cathode chamber increased. In the anode chamber, the higher the current density, the faster the pH of the solution decreases. In the cathode chamber, the higher the current density, the faster the pH of solution increases. The pink particles were resulted by electrolysis in the cathode chamber while no particles in the anode chamber. In the low current density, the particle products are HA and brushite while the higher current density the particle product is pure HA. The higher the current density the bigger the crystallite size of the particles.