Hello, I have some potassium bisulfate (KHSO4) that I obtained as a by product by making nitric acid (HNO3) from sulfuric acid (H2SO4) and potassium nitrate (KNO3). I'm pretty sure that all the nitric acid is gone (I distilled it until the mixture reached 130°C). But there is probably either an excess of KNO3 or an excess of H2SO4.

In either case, how can I purify my KHSO4?

My video of the experiment is here: https://youtu.be/dIWXU520vnE