Novel reactivation allows effective reuse of Nafion® super-acid nano-catalyst

•Alternative mild regeneration method to calcination for superacid resin-catalysts.•Fenton and non-Fenton oxidation remove organics after reaction.•Superb reactivation efficiency on the esterification of octanoic acid with methanol.•Cleaner process than hot-water extraction in terms of residual liquids’ TOC.