Synthesis of microporous eskolaite from Cr(VI) using activated carbon as a reductant and template

► A technique was devised to prepare eskolaite from dichromate ions, Cr(VI). ► Activated carbon was used to reduce the Cr(VI) to amorphous Cr2O3. ► Amorphous Cr2O3 deposited in the pores of the activated carbon. ► Ultrafine eskolaite was obtained by calcining the chromium-loaded activated carbon.