Electrokinetic studies of magnesium hydroxide

Area of Science:

• Colloid and Surface Science
• Materials Science

Background:

• Magnesium hydroxide (Mg(OH)2) is a key material in various industrial applications.
• Understanding its surface charge properties is crucial for controlling its behavior in suspensions.

Purpose of the Study:

• To determine the electrophoretic mobility of magnesium hydroxide.
• To investigate the influence of potential-determining ions (Mg2+ and OH-) on its surface charge.
• To identify the zero point of charge (ZPC) and zeta-potential behavior across different pH values.

Main Methods:

• Electrophoretic mobility measurements of magnesium hydroxide suspensions.
• Controlled variation of magnesium ion and hydroxide ion concentrations (pH).
• Addition of magnesium nitrate to observe effects on zeta-potential and pH.

Main Results:

• The zero point of charge for magnesium hydroxide was found to be approximately pH 10.8.
• Below pH 10.8, magnesium hydroxide exhibited a positive zeta-potential, which increased with magnesium nitrate addition.
• Above pH 10.8, charge inversion occurred, with the largest negative zeta-potential observed at pH 11.5.

Conclusions:

• The surface charge of magnesium hydroxide is highly dependent on pH and ion concentration.
• Magnesium hydroxide exhibits amphoteric behavior with a distinct zero point of charge.
• The low solubility of Mg(OH)2 influences the achievable ion concentrations and surface charge characteristics.