Electrophoretic study of the SnO2/aqueous solution interface up to 260 degrees C

Area of Science:

• Surface Chemistry
• Electrochemistry
• Materials Science

Background:

• Understanding the surface properties of metal oxides like tin oxide (SnO(2)) is crucial for various applications.
• Zeta potential measurements provide key insights into surface charge and stability in aqueous solutions.
• Limited data exists on SnO(2) surface behavior at elevated temperatures.

Purpose of the Study:

• To determine the zeta potential of the SnO(2)/aqueous solution interface across a wide temperature range (25–260°C).
• To calculate the isoelectric points (IEPs) of SnO(2) at different temperatures for the first time.
• To compute standard thermodynamic functions for surface protonation-deprotonation equilibria.

Main Methods:

• Utilized a custom-developed electrophoresis cell for high-temperature zeta potential measurements.
• Employed experimental techniques and calculation methods suitable for elevated temperatures.
• Applied the 1-pK surface complexation model to analyze IEP data.

Main Results:

• Successfully measured zeta potential of SnO(2) in a 10⁻³ mol kg⁻¹ NaCl solution from 25 to 260°C.
• Determined the isoelectric points (IEPs) of SnO(2) as a function of temperature.
• Observed a decrease in SnO(2) IEP values with increasing temperature.

Conclusions:

• The temperature dependence of SnO(2) IEP was characterized for the first time.
• Calculated thermodynamic functions provide insights into surface complexation mechanisms.
• Experimental results show excellent agreement with predictions from the multisite complexation (MUSIC) model.