We have discovered that size dependent solubility of large fullerenes in strong acids is dependent on acid strength. This provides a scalable method for separating large fullerenes by size. According to some embodiments, a method for processing a fullerene starting material comprises large fullerenes comprises mixing the starting material with a first concentrated sulfuric acid solution so as to obtain a first dispersion comprising a first portion of the large fullerenes solubilized in the first concentrated sulfuric acid solution.