Abstract: In the physical chemistry experiment “Colloid ζ potential measurement by electrophoresis”, there exist some issues affecting the effectiveness of experimental teaching, such as prolonged colloid purification time and low accuracy in interface position measurement. To address these challenges, this paper explores methods and conditions for the rapid, large-scale, and repeatable purification of Fe(OH)₃ colloids using acid and alkali ion exchange resins. Additionally, an innovative device utilizing a digital scale and a light barrier for precise measurement of colloidal interface position has been designed. This device is integrated with the electrophoresis tube holder, forming a dedicated set of instrumentation. The increased accuracy in interface position measurement allows for a reduction in electrophoresis measurement time to 5 minutes, mitigating the impact of potential gradient changes caused by prolonged electrophoresis. The application of these improved methods and instruments in experimental teaching has resulted in enhanced efficiency, reduced measurement result deviation, and improved repeatability. This lays the groundwork for incorporating some exploratory experiments into the teaching program.

Key words: ζ Potential, Electrophoresis, Ferric hydroxide colloid, Ion exchange, Instrument innovation