STUDY OF ELECTROCHEMISTRY BEHAVIOUR AND DEPOSIT MORPHOLOGY IN COPPER ELECTROREFINING WITH ADDITIVE CONCENTRATION VARIATIONS OF THIOUREA AND LIGNIN-BASED BIOPOLYMER

• Main Author: SAIFUDIN , MUHAMMAD
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/29344
• Institution: Institut Teknologi Bandung

<p align="justify">In copper electrorefining process, in addition to the product purity, other parameters that measure the success of this process are the morphology and appearance of the cathode surface. To keep a smooth copper deposit on the cathode surface and to prevent the formation of nodules and dendrites, a smal amount of additives are used in electrolytes during electrorefining process. The additives which are commonly used in copper electrorefining plants are a combination of glue, thiourea and chloride ions. There is a problem on the use of glue as additif additive due to degradation of this additive at high acid concentration and temperature of the electrolyte of copper electrorefining. In this research, the effectiveness of new additives received from Borregard company, Norway was investigated by means of electrochemical behaviour of the cathode and the deposit morphology. The additives used were four types of biopoymer with the names of DP-2782, DP-3355, DP-3356 dan DP-3357. The experimental results were compared with those by using glue and thiourea additives. <br /> <br /> The effect of additive on the electrochemical behaviour of cathodic deposition was investigated by conducting potentiodynamic and galvanostatic polarization tests under variations of additive dosages by using a potensiostat. Morphology of the copper deposit after galvanostatic scan was examined by SEM analysis. Series of degradation experiments by aging electrolytes which contains various of additives until 24h at 65oC followed by galvanostatic measurements were performed to evaluate the degradation behavior of the additives. Potential additive were then tested with long-term electrolysis for 48 hours to see morphology of deposits. Long term electrolysis experiments of 48h under variations of DP 2782 and DP 3356 were also carried out to study the quality of copper deposit under variations of the additives. <br /> <br /> Based on the results of potentiodynamic and galvanostatic measurements, DP 2782 (single or combined with thiourea) and DP 3356 (combined with thiourea) gave polarizing effect on cathodic deposition of copper. From degradation experiments, glue was proven to be degraded at high acid and high temperature condition of the electrolyte, while thiourea and all lignin-based biopolymers were not degraded. Thiourea and biopolymers retain the polarization effect after aging. Through the galvanostatic test and morphological observations the deposits, DP 2782 2.5 mg/L + thiourea and DP 3356 2.5 mg/L + thiourea gave good quality of copper deposit. Results of 48h electrolysis experiments, demonstrated that DP 3356 gave better deposits at all concentrations than DP 2782 in which the best cathode quality was obtained at 10 mg/L DP 3356 + thiourea 3.5 mg/L with current efficiency of >99% and specific energy consumption in the range of 0,20-0,27 kWh/kg of deposit.<p align="justify">