Organochlorine formation in magnesium electrowinning cells

Area of Science:

• Industrial Chemistry
• Environmental Science

Background:

• Electrolytic magnesium production can generate hazardous byproducts.
• Organochlorines are persistent organic pollutants with potential environmental impacts.

Purpose of the Study:

• To investigate the formation and characteristics of organochlorines during magnesium electrolysis.
• To quantify organochlorine output under varying operational conditions.

Main Methods:

• Laboratory-scale electrolytic cell with graphite anode and aluminum alloy cathode.
• Operation at 3000–10,000 A m⁻² and 660–750°C.
• Off-gas adsorption on silica gel, hexane extraction, and gas chromatography analysis.

Main Results:

• Identified fully chlorinated aliphatic and aromatic organochlorines, including hexachlorobutadiene, hexachlorobenzene, hexachloroethylene, and octachlorostyrene.
• Organochlorine output ranged from 5 to 20 g per tonne of magnesium.
• Formation decreased with electrolysis time and current density; increased with temperature and graphite type.

Conclusions:

• Organochlorine formation is a significant byproduct of magnesium electrolysis.
• Operational parameters and materials influence the extent of organochlorine generation.
• Further research is needed to mitigate these emissions.