How can I purify ethanol from formic / boric / salicylic acid?

I need some ethanol pure and strong enough for technical purposes (fuel, solvent, cleaning agent, dissolving rosin for soldering flux, etc.). Food quality is not required though, denaturated one is fine too. Distilling cheap vodka is possible, but even cheap vodka is expensive because of high tax on food ethanol; also now I don't have a distiller and want to try getting ethanol without building one. Pure denaturated ethanol is sold mostly in huge industrial bulks only. But we have extremely affordable 70% ethanol-based solutions in medicine stores - they are several-percent solutions of boric, formic and salicylic acids respectively. So, my question is: how can I turn these acids into precipitate or gas for easy removal, using not so exotic reagents and conditions?


UPD: I have realized my question may be ambiguous. Every substance I'm speaking about consists of alcohol + ONE of the three mentioned acids, not all of them together. I have a choice which acid I will be getting rid of. 


