Possibly the best thing to do with xylene is to couple it with the FASA approach as long as you can get hold of acetone and fumaric acid.

Alternatively, xylene really needs to be evaporated ( cannot go freeze-precipitation). This takes some time and will result in residue that is smokeable but possibly quite harsh to do so (loads of plant oils). but the resudue can be washed with warm naphtha to pick up the spice and then freeze-precipitate.