Optimization of the solvent-exchange process for high-yield synthesis of aqueous fullerene dispersions

The ultrasound-assisted solvent-exchange technique for aqueous fullerene dispersions (AFD) of C$_{60}$ (10$^{-4}$ – 10$^{-6}$ M) have been improved for high-yield synthesis, thereby achieving AFDs with total recovery over 90 %. Using ICP-AES, HPL-CUV, HGC-MS, the elemental and residual organic compounds have been estimated as not exceeding 3 ppm. The possible structure of fullerene clusters in AFD was assumed as $\{n[\mathrm{C}_{60}]m\mathrm{C}_6\mathrm{H}_5\mathrm{COO}^-(m-x)\mathrm{Na}^+\}x\mathrm{Na}^+$.