The Effect of pH and Temperature During Carbonation Process on Spent Die Cleaning Solution from Aluminium Extrusion Industry

Abstract

Spent die cleaning solution from Aluminium extrusion industry is a harmful waste which affects the environment and the sewage pipes due to the presence of caustic sodium hydroxide and sodium aluminate solutions. An experiment carried out to study the effect of pH and temperature in the conversion of that waste to useful materials used in other industries by carbonation of spent die cleaning solution which has known content of free OH− % and CO 3 −2 %. The pH and Temperature are controlled and measured by HANNA INSTRUMENTS.HI 9219 during the carbonation process time which takes 2 h with CO2 gas pressure less than 0.1 psi which induces the best economic benefits when this research applied industrially. It is observed that the pH increases from ambient temperature 25.6–45.3 °C and then decreases to 41.4 °C, then starts to increase again till the end of the 2 h time to reach 42.2 °C. During the carbonation process it is observed the formation of white flakes suspended in the solution, the solution then settled for 24 h where the white precipitate then formed, dried and examined by XRD instrument, ICP-VISTA MPX, LECO CS-244, FT/IR 4100 JASCO and JEOL JSM-5500 LV Scanning Electron Microscope (JEOL, Japan), to detect the type of the precipitate, which is Al(OH)3 in three different forms fresh forming Gibbsite, Aging Gibbsite and Bayerite, which are useful materials in various industries.