We investigated the removal of bacteriophages by adsorption on commercially available powdered activated carbon (N-PAC, median diameter >10 mu m) and super-powdered activated carbon (S-PAC, median diameter 0.7-2.8 mu m). N-PACs failed to remove the virus in Milli-Q water buffered with 100 mu M Ca2+, but some S-PACs successfully removed it under the same condition. Three factors contributed substantially to virus removal: a smaller electrophoretic repulsive force between the virus and the PAC particles, a large proportion of pores 20-50 nm in diameter, and a greater hydrophobicity of the virus surface. (C) 2013 Published by Elsevier B.V.