Comprehensive utilization of dairy manure to produce glucose and hierarchical porous carbon for supercapacitors

Abstract

Dairy manure, one of the most abundant agricultural wastes generated in livestock farming, was pretreated with KOH aqueous solution to relieve the constraint of lignin, thus facilitating cellulose hydrolysis. The generated black liquor waste was used to prepare porous carbon. Glucose yield of 261 g/kg was obtained from dairy manure pretreated in 0.73 wt% HCl aqueous solution, much higher than that obtained from crude dairy manure (116 g/kg). The generated black liquor, mainly containing lignin and KOH, was employed to prepare porous carbon via a self-templating method. The obtained material had a three-dimensional (3D) hierarchical structure and was applied for supercapacitors. Good capacitance of 202 F/g was obtained in a two-electrode system with 6 M KOH electrolyte. The porous carbon-based electrode showed excellent cycling stability with retention of 100% after 3000 galvanostatic charge–discharge (GCD) cycles. This work provides a scalable strategy for comprehensive utilization of lignocellulosic biomass resources.