Application of the diffusion screen technique to the determination of gaseous mercury and mercury (II) chloride in flue gases

A technique based on the use of a gold-coated diffusion screen for the collection of gaseous mercury species in flue gases is introduced. Using this technique, collection efficiencies for both metallic mercury and mercury(II)chloride are well above 90% at temperatures up to more than 100°C and at gas flow rates up to 6 1/min. SO₂, NO and H₂O do not have significant effects on the collection efficiency. The method is very convenient considering practical flue gas measurements, because the screen can be used in a compact filter holder suitable for in-stack measurements.