Electrosynthesis of Al(OH)3 by Al(s)|KCl(aq)||KCl(s)|C(s) system

13th Joint Conference on Chemistry

Suyati, Linda^1 ; Fadilah Nur, Intan Dian^1 ; Widodo, Didik Setiyo^1 ; Gunawan^1 ; Rahmanto, W.H.^1

Chemistry Department, Faculty of Sciences and Mathematics, Diponegoro University, Semarang, Indonesia^1

关键词: Absorbed energy;    Aluminium plates;    Carbon electrode;    Electrolysis process;    Electrolyte concentration;    Electrolyte solutions;    Endothermic peaks;    Mass reduction;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/509/1/012066/pdf
DOI  :  10.1088/1757-899X/509/1/012066

来源: IOP

【 摘 要 】

Electrosynthesis of Al(OH)3 by using Al(s)|KCl(aq)||KC(aq)l|C(s) system had been done.The presence of electrolyte was much influenced to the electrolysis result. The purpose of this work was to investigate the purity of Al(OH)3 compound with the presence of KCl concentration using XRD characterization. Electrolysis process was done in 2-compartment system, by using aluminium plate electrode as anode, carbon electrode as cathode, and electrolyte solutions of KCl were varied at the concentrations of 0.25; 0.30; 0.35; 0.40; 0.45 M. The electrolysis process was done at room temperature and potential of 12 V for 6 h.The electrolysis products were characterized using XRD and the the best electrolysis result was determined its thermal property by using TGA-DSC.The result showed that electrolysis of Al(s)|KCl(aq)||KC(aq)l|C(s) system with the variation of electrolyte concentration solutions gave white precipitations with the masses of 50.6; 51.8; 56.1; 64.9; 97.2 mg, respectively. The XRD characterization of the electrolysis product precipitates gave the best product as Al(OH)3 when using KCl concentration of 0.3 M, while at KCl concentration of 0.45 M was resulted KAlOCl2, and another variation KCl concentration gave a mixture product of Al(OH)3and KAlOCl2. Thermal analysis result of the best electrolysis product using TGA-DSC showed the reduced total sample mass of 45.47 % and two endothermic peaks at 270.08°C as the transformation of Al(OH)3 to AlOOH (boehmite) with the absorbed energy of 2.47 kJ/mol. At temperature of 660.28°C was the phase change of AlOOH (boehmite) to y-Al2O3 with absorbed energy of 0.23 kJ/mol. Then, at temperature above 800°C there was no mass reduction, that meant it formed stable phase of Al2O3. To sum up, the purity of Al(OH)3 compound was much influenced by KCl concentration and the increase of temperature transformed the Al(OH)3 sample to AlOOH (boehmite) and γ-Al2O3.