Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 18 No. 5 October 2008|
（School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract:Acid/basic potentiometric titration can be used to quantify the red mud surface charge properties. The amount of surface active —OH groups and surface charge density on the red mud particles generated from Chinese diaspore bauxite were evaluated from the acid/basic potentiometric titration data in 0.1 mol/L or 0.5 mol/L NaCl solution. The results show that the adsorption of sodium polyacrylate(SPA) on the red mud surface causes the increase of the surface active —OH groups, which makes the point of zero charge(PZC) shift to a lower pH value. However, the adsorption of polyacrylamide(PAM) causes little change. As the concentration of NaCl solution increases, the surface charge becomes more positive in acidic solution and more negative in alkaline solution, which can be attributed to the presence of a porous surface gel coating on the red mud particles.
Key words: red mud; surface charge; point of zero charge; potentiometric titration; bauxite