A practical way of removing the volatile matter would be to boil it off at reduced pressure i.e. put a vacuum on the carbon black,while stirring it and remove the gasses that are produced.

One can add heat, but one will definitely want to keep oxygen away - so vacuum it anyway.

low temp oxidation; meaning at a temp less than ~350 C. This is ASTM prescription

1 vacum + heat,

2 an opportune solvent as the molecules are low weight, then stripping of the solvent in vacuum + heat (treatment repeated 2 or 3 times) 

Apart from vacuum and heat there is a different avenue, i.e. solvent extraction using a volatile solvent, such as pentane or methylchloride. This road will, however, always leave traces of solvent.