Do you know what kind of wood it is? I have leached mopani driftwood. What I did with mine is I soaked it in a big trash can. I bought a Seachem Purigen filter pad dropped it in the bottom of the trash can. I soaked it in warm dechlorinated water, changing the water everyday. I did that for almost 2 weeks if not longer. But I had several big pieces. I stopped when the water was a faint tea color.
...I'm sure someone else might be able to give more advice.