Magnesium hydride is not typically used as an electrode material in standard water electrolysis for purification. Instead, it is used in a hydrolysis reaction with water to produce hydrogen gas and magnesium hydroxide, which can be part of a water treatment system. The resultant magnesium hydroxide can then be used in water purification to treat acidic wastewater and remove heavy metals.
Role in Water Purification
The primary use of magnesium compounds in water treatment is related to the resulting magnesium hydroxide byproduct of the hydrolysis reaction:
pH Adjustment: Magnesium hydroxide is a weak alkali used to neutralize acidic wastewater.
Contaminant Removal: It helps precipitate heavy metals (e.g., copper, lead, cadmium) as insoluble hydroxides, which can then be removed.
Flocculation: The particles help clump together suspended solids, making them easier to filter out.
Electrolysis Context
In a conventional water electrolysis system, electrodes are used to split water molecules.
Cathode: Hydrogen gas is produced at the cathode (negatively charged electrode).
Anode: Oxygen gas is produced at the anode (positively charged electrode).
If metallic magnesium or magnesium-based materials are used as anodes in an aqueous electrolyte, they suffer from surface passivation due to the formation of an
layer, which is highly insoluble and impedes the electrochemical reaction.