Evaluation of Intrinsic Ionization and Complexation Constants of TiO2 and Mg‐Fe Hydrotalcite‐like Compounds

Abstract

AbstractThe intrinsic surface reaction constants, pKinta1, pKinta2, p*KintC and p*KintA, were evaluated by a modified double extrapolation (MDE) for TiO2 without structural charge and Mg‐Fe hydrotalcite‐like compounds (HTlc) with structural charge, respectively. The results of intrinsic surface reaction constants for TiO2 were compared with those obtained by class double extrapolation (CDE) in literature. Furthermore, the values of intrinsic surface reaction constants obtained by MDE were used to simulate the charging behaviors of the materials. The following conclusions were obtained. For TiO2 without structural charge, the pKinta1 and pKinta2 evaluated by MDE are equal to those by CDE, however the p*KintC and p*KintA evaluated by MDE are much different from those by CDE. In principle, the results of the p*KintC and p*KintA evaluated by MDE are more accurate than those by CDE. The values of intrinsic surface reaction constants obtained by MDE can excellently simulate the charging curves for TiO2 with the triple layer model (TLM). For HTlc with positive structural charge, the results of *KintC=0 and *KintA→∞ were obtained by MDE, which means the inert electrolyte chemical binding does not exist; the point of zero net charge (PZNC) of c‐independence also exist as the same as solid without structural charge, and the pHPZNC obtained by the acid‐base titration can excellently be simulated and the surface charging tendency can be simulated to a great extent using the pKinta1 and pKinta2 evaluated by MDE and the diffuse layer model (DLM).