The chemical working principles in Water Filter

Water filters work through a combination of physical, chemical, and biological processes. Focusing on the chemical working principles, here are the primary mechanisms involved:

1. Adsorption (Activated Carbon)

Principle: Contaminants adhere to the surface of activated carbon.

Chemistry: Activated carbon has a very high surface area due to its porous structure. Organic molecules, chlorine, and some heavy metals are attracted and held by van der Waals forces and chemical bonding.

Used for: Chlorine, VOCs (volatile organic compounds), pesticides, herbicides, bad tastes, and odors.

2. Ion Exchange

Principle: Ions in the water are exchanged with ions on a resin or other material.

Chemistry:

Cation exchange: e.g., Ca²⁺ or Mg²⁺ (hardness ions) are replaced with Na⁺ or H⁺.

Anion exchange: e.g., NO₃⁻ or SO₄²⁻ can be removed by replacing them with OH⁻ or Cl⁻.

Used for: Water softening (removing hardness), nitrate removal, heavy metal removal.

3. Chemical Precipitation

Principle: Soluble contaminants are converted into insoluble compounds that can be filtered out.

Chemistry: Adding chemicals like lime (Ca(OH)₂) or alum (Al₂(SO₄)₃) causes precipitation reactions. For example:

Calcium hardness: Ca²⁺ + CO₃²⁻ → CaCO₃↓

Phosphate removal: PO₄³⁻ + Al³⁺ → AlPO₄↓

Used for: Removing heavy metals, phosphates, and hardness.

4. Redox Reactions

Principle: Contaminants are chemically transformed through oxidation or reduction.

Chemistry:

Using KDF (Kinetic Degradation Fluxion) media, copper-zinc granules can reduce:

Chlorine to chloride: Cl₂ + 2e⁻ → 2Cl⁻

Heavy metals like lead to an insoluble form

Used for: Chlorine, iron, hydrogen sulfide, and heavy metals.

5. pH Adjustment and Neutralization

Principle: Chemicals are added to correct pH imbalances.

Chemistry:

Acidic water is neutralized using calcite (CaCO₃) or magnesium oxide.

Basic water may be treated with acids or acid-forming salts.

Used for: Corrosion control, improving taste, preventing pipe damage.

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