Magnesium is primarily removed from water using a water softener employing ion exchange. This process effectively replaces magnesium ions with less problematic ions, such as sodium or potassium.
The Ion Exchange Process
Water softeners are the most common method for removing magnesium (and calcium, which causes hardness) from water. Here's a breakdown:
- The Resin Bed: Water softeners contain a resin bed made of small, plastic beads. These beads are negatively charged and initially coated with sodium or potassium ions.
- Ion Exchange Occurs: As hard water (containing magnesium and calcium ions, which are positively charged) flows through the resin bed, the magnesium and calcium ions are attracted to the negatively charged resin beads. They displace the sodium or potassium ions, which are then released into the water.
- Softened Water: The water exiting the softener now has a lower concentration of magnesium and calcium, and a higher concentration of sodium or potassium, thus becoming "softened."
Regeneration
Eventually, the resin beads become saturated with magnesium and calcium and need to be regenerated. This involves flushing the resin bed with a concentrated brine solution (sodium chloride or potassium chloride).
- Brine Flush: The high concentration of sodium or potassium in the brine solution forces the magnesium and calcium ions off the resin beads, replacing them with sodium or potassium.
- Wastewater Disposal: The wastewater, containing the displaced magnesium and calcium, is flushed away.
- Ready for Softening: The resin bed is now ready to soften more water.
Benefits of Removing Magnesium
Removing magnesium from water offers several benefits:
- Prevents Scale Buildup: Magnesium contributes to scale formation in pipes, water heaters, and appliances, reducing their efficiency and lifespan.
- Improved Soap and Detergent Performance: Soft water allows soaps and detergents to lather more effectively, requiring less product for cleaning.
- Softer Skin and Hair: Hard water can leave skin feeling dry and hair feeling dull. Soft water can improve the feeling of skin and hair.
- Smoother Feeling Water: As the short answer states, softened water has a smoother feeling.
Other Methods (Less Common)
While water softeners are the most common method, other methods exist, although they're typically used in industrial settings or for specific research purposes:
- Chemical Precipitation: Adding chemicals like lime (calcium hydroxide) or soda ash (sodium carbonate) can cause magnesium to precipitate out of the water as a solid. This solid can then be removed through filtration.
- Reverse Osmosis: Although primarily used for desalination, reverse osmosis can also remove magnesium ions. However, it's a more expensive and energy-intensive process compared to ion exchange.
- Electrodialysis: This process uses an electric field to separate ions from the water. It can be used to remove magnesium, but it's less common than other methods.
