Unimpregnated carbons

Arsine (AsHs) is a gas so, like other highly volatile materials, it is hardly retained by unimpregnated carbon. Fortunately it is quite easily oxidised by the catalytic action of copper. According to some sources [40], however, this catalytic activity decreases with increasing air stream humidity. At high humidities silver takes over as the main catalyst. Different oxidation states of arsenic are possible, so the arsenic is mostly converted to a solid mixture of oxides and elemental As which tend to shield tlie catalysts and reduces their effectiveness. 

Adib, F., Bagreev, A. and Bandosz, T.J., Analysis of the relationship between H2S removal capacity and sur ce properties of unimpregnated activated carbons. Environ Sci. Technol. 34 (2000) 686. 

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