A nutshell-based activated carbon was treated with hydrochloric acid to par
tially de-ash it. The de-ashed sample was then treated with bromine water a
nd subsequently hydrogenated. The base sample was also treated with bromine
water and then hydrogenated. The surface areas and pore volumes available
to water vapour were unchanged by these treatments, although the polar surf
ace area was considerably reduced in each case. The sample with the lowest
surface polarity had the worst performance (shortest penetration time) when
pre-humidified at 80% RH and tested with hexane. Examination of the humidi
ty leaving the bed during the adsorption of hexane vapour suggested that th
e rate-determining step was the surface transport of displaced water and th
at removing the ash content hindered this transport considerably. Brominati
on followed by hydrogenation, although reducing the polarity, did not remov
e the ash content and may even have improved its ability to transport displ
aced water.