Carbon Sequestration Through Hydrothermal Carbonization of Expired Fresh Milk and its Application in Supercapacitor

This study investigated the production of natural nitrogen doped carbon from expired fresh milk for use in a supercapacitor electrode. The material was prepared by hydrothermal carbonization followed by sequential KOH-H3PO4 activation. Carbon modified with KOH at a ratio of 1:1 had the largest BET surface area of 465 m2/g. The presence of surface functional groups also played an important role in determining the specific capacitance. The highest specific capacitance of 186.3 F/g was obtained from carbon modified with C:KOH at 1:1 and 50 wt% H3PO4. An electrochemical impedance study suggested that charge storage resembled a modified Randles circuit. Carbon derived from expired milk and exposed to sequential KOH and H3PO4 modification was shown to be a promising candidate material for use as electrodes in EDLC supercapacitors, while simultaneously reducing food waste.