An approach for the in-situ specific surface area assessment of aqueous oxide particles

作者：Hanaor Dorian A H^*; Chrzanowski Wojciech; Gan Yixiang

来源：Journal of the Australian Ceramic Society, 2015, 51(2): 88-93.

• Alumina
• surface area measurement
• adsorption
• electrokinetic
• electrochemical

Ceramic particles tend to exhibit hierarchical surface structures, with measurable surface-area varying with analysis scale, in resemblance to the coastline paradox. Specific surface area for ceramic materials is most often reported as the gas-accessible area, conventionally measured by N-2 adsorption at 77K with BET isotherm interpretation. However, the adsorption of nitrogen at low temperatures may not give a relevant indicator of effective surface area for various applications, particularly those involving aqueous suspensions. Here we examine the use of electrokinetic analysis of ionic adsorption at aqueous particle surfaces to gauge the surface structure of suspended alumina. We establish a numerical framework on the basis of the Grahame equation for modelling the change in electric-potential with Stern layer modification, and the Langmuir model to describe monolayer ligation of ionic species at particle surfaces. This framework is applied for the analysis of surface structure in aluminium oxide. We explore the use of in-situ zeta potential analysis of the adsorption of oxalate anions in aqueous suspension to assess the specific surface area of Al2O3 powders with varying morphologies. By parameter fitting of acquired zeta-potential data with a Grahame-Langmuir type relationship it is shown that for a given system, the shift in electrokinetic behaviour with adsorbate concentration can be used for the scalable assessment of available surface area in ceramic powders.

• 出版日期2015