Evolution of PZC with thermal transformation of Tunisian kaolinite

The purpose of this paper is to study the thermal behaviour of Na + -saturated Tunisian kaolinite (ka-Tab) with the evolution of its point of zero charge (PZC). The Fourier Transform Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA), Cation Exchange Capacity (CEC) and specific surface area (SSA) were used to characterize the kaolinite sample. In the present investigation, the focus was on the surface charge characteristics of kaolinite at different temperature of heating. The results show that the formation of new phases in the kaolinite structure at temperature >500–600°C, shifts the PZC value towards 8 which approximately PZC value of α-Al 2 O 3 .