Hafnium - Hf

Hafnium — chemical properties and water context

Hafnium is a dense, silvery transition metal known for its corrosion resistance and high melting point. It is mainly relevant to water professionals when a process stream is associated with hafnium-bearing materials or manufacturing.

Atomic number	72
Standard atomic weight	178.486 g/mol
Density	13.3 g/cm3
Melting point	2233 °C
Boiling point	4600 °C
Electron configuration	[Xe] 4f14 5d2 6s2

Chemical properties

Hafnium is in Group 4 and Period 6. It commonly occurs with zirconium in minerals and has a similar chemistry. Hafnium forms a stable oxide layer in air and is used in applications requiring heat and corrosion resistance. Its principal oxidation state is +4.

Uses and applications

Hafnium is used in control rods because it absorbs neutrons, in high-temperature alloys and in plasma-welding equipment. Hafnium oxide is also used in electronic materials. These applications can create specialized process streams containing dissolved or particulate hafnium-bearing material.

Hafnium in water treatment

Hafnium is not commonly treated as a routine drinking-water parameter. Where it is present in an industrial process stream, treatment design should begin with source identification and characterization of total and dissolved hafnium, pH, suspended solids and co-contaminants. The appropriate separation method depends on the chemical form and the full water matrix; site-specific testing is needed before selecting a treatment process.

Environmental and health context

Because hafnium is strongly associated with mineral phases and corrosion-resistant materials, its occurrence in water is expected to be linked to particular geological or industrial sources. Avoid inferring dissolved concentration from total-metal results alone; sampling and analytical methods should match the question being assessed.

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