  The accretion of phantom fields by black holes within a thermodynamic context
is addressed. For a fluid violating the dominant energy condition, case of a
phantom fluid, the Euler and Gibbs relations permit two different possibilities
for the entropy and temperature: a situation in which the entropy is negative
and the temperature is positive or vice-versa. In the former case, if the
generalized second law (GSL) is valid, then the accretion process is not
allowed whereas in the latter, there is a critical black hole mass below which
the accretion process occurs. In a universe dominated by a phantom field, the
critical mass drops quite rapidly with the cosmic expansion and black holes are
only slightly affected by accretion. All black holes disappear near the big
rip, as suggested by previous investigations, if the GSL is violated.
