Study on K+/H+ Exchange for K2O·4TiO2

Potassium tetratitanate (K₂O·4TiO₂) is an artificial mineral whisker with the diameter of 0.5-1 μm and the length 5-20 μm. The interlayered potassium ion exchange reaction for the K₂O·4TiO₂ whisker results in the appearance of many new nonstoichiometric metal titanate whiskers M₂O·nTiO₂ (M are K, H, Na, Cs, Ba, Ru, Co or Pb, etc.). Through the K⁺-H₃O⁺ exchange in solutions,TiO₂ and K₂O·6TiO₂ whiskers were synthesized. Generally, the target product quality and yield are greatly affected by the ion exchange conditions. The optimal synthetic conditions are difficult to obtain. In this paper, a new method was proposed to control the ion-exchange process by applying the ion-exchange reaction thermodynamics and combining with monitoring the multi-ions concentrations with ISE. Ion-exchange thermodynamic model for potassium tetratitanate whisker (K₂O·4TiO₂) was established, and model parameters were calculated through the existent experimental equilibrium data. Ion selective electrode achieved the on-line monitor for K⁺/H⁺ exchange and the equilibrium point was judged. The calculation for the accurate ion concentration was done through the Pitzer equation. Based on the proposed method, the ion-exchange process was controlled and the optimal synthesis conditions could be obtained.