The core criteria for determining whether magnesium oxide has been successfully activated are whether the active magnesium oxide content has recovered to ≥60%, the moisture content ≤1.5%, and the physical state is a loose white powder. This can be verified by combining chemical detection with physical observation.
1. Chemical Detection Method (Most Accurate)
(1) Hydration Method (Recommended Standard: HG/T 3928-2012)
Principle: Active magnesium oxide reacts with water to produce magnesium hydroxide. The active content is calculated by measuring the increase in mass.
Simplified Operation: Weigh 100g of sample and add 400g of purified water and stir.
Pre-dry in a 110℃ oven for 2 hours, then raise the temperature to 150℃ and dry to constant weight.
This method is widely used in the industry, the results are reliable, and it is suitable for industrial acceptance.
(2) Citric Acid Method or Iodine Adsorption Method
Suitable for rapid screening, indirectly reflecting activity through reaction rate.
Requires titration with a standard solution, the operation is more complex, but quantitative comparison is possible.
2. Physical and Sensory Judgment (Auxiliary Methods)
|
Judgment Indicators |
Signs of Successful Activation |
Explanation |
|
Color |
White or off-white powder |
Grayish or dark color indicates incomplete decomposition or secondary moisture absorption |
|
Appearance |
Loose, no lumps |
Still clumpy indicates insufficient internal dehydration |
|
Flowability |
Smooth pouring, no stickiness |
Poor flowability indicates residual moisture or sintering |
|
Feel |
Dry, smooth, non-sticky |
Dampness indicates moisture absorption during cooling or packaging |
Appearance alone cannot provide a precise judgment; it can only serve as a preliminary screening.
3. Laboratory Validation Recommendations
|
Test Item |
Success Criteria |
Recommended Method |
|
Active Magnesium Oxide Content |
≥60% |
Hydration Method (HG/T 3928-2012) |
|
Moisture Content |
≤1.5% |
Loss on Drying Method or Karl Fischer Method |
|
Specific Surface Area |
Significantly Increased |
BET Method (Highly active MgO is typically >30 m²/g) |
For applications in critical fields such as rubber and electronics, it is recommended to submit samples to a CNAS-accredited laboratory for an authoritative report.
