Conversion of Non-biodegradable Super Absorbing Polymer (SAP) Waste into MnO-rich Functional Supercapacitor Carbon by a Sustainable, Low-Temperature Activation Process

A non-biodegradable super absorbing polymer (SAP) is primarily used in biomedical devices and female menstrual sanitary waste pads. Its safe disposal is a massive problem that needs global strategic cognizance. The sanitary waste is mainly comprised of high molecular weight acrylate-based polymers having higher water-absorbent properties with a significant carbon atom-based cross-linked backbone. Here we have derived a workable energy storage material from menstrual sanitary waste with minimal energy input, making it environmentally viable. In this study, a rich carbon matrix was produced from pyrolysis of sanitary waste pads with KMnO4 based activation at 300 °C. The obtained carbon showed the presence of MnO moieties having desirable properties as a supercapacitor electrode. The stored energy density in the synthesized carbons was found to be 11.23 Wh kg–1 at a 0.275 kW kg–1 power density. The derived carbon shows excellent capacity retention of 84% and electrochemical stability until 10,000 cycles. These porous functional carbons produced from non-biodegradable SAPs thus make a sustainable potential resource for energy storage applications.