Pity the freezing didn't work, but cold and freeze drying is hit and miss, it's just the least destructive option, and great for drying wet paper too. I think Charcoal, baking soda, and UV all got borught up last time. Chlorine dioxide... they sell a lot of chlorine dioxide mouthwashes and breath sprays now, I'd bet that's probably about the right dilution and would be at most drug stores. They have uses it in libraries with success, and it does absolutely kill mold.