Mix 3 cups water with 3 cups distilled white vinegar in a large bowl. Put the curtains in the bowl and submerge them completely. The vinegar will help neutralize the smell. You may need to use more water and vinegar if your curtains are thick and absorbent.
Leave the curtains to soak for at least 20 minutes.
Remove the curtains and wring out as much of the vinegar solution as possible.
Wash and dry the curtains according to the curtain manufacturer's instructions. Curtain manufacturers will stipulate the temperature of the water you should use and how you should dry the curtains.
Lay the curtains out flat and sprinkle baking soda over them. Completely coat the curtains.
Let the baking soda sit for several hours or overnight.
Sweep off the baking soda and discard it. The baking soda will have absorbed any remnants of smoke or vinegar smell.
Shake the curtains outside to remove any remnants of baking soda. Launder them again if you prefer.