Revalorization of Pleurotus djamor Fungus Culture: Fungus-Derived Carbons for Supercapacitor Application

Abstract

Currently, there is increasing interest and effort directed to developing sustainable processes, including in waste management and energy production and storage, among others. In this research, corn cobs were used as a substrate for the cultivation of Pleurotus djamor, a suitable feedstock for the management of these agricultural residues. Revalorization of this fungus, as an environmentally friendly carbon precursor, was executed by taking advantage of the intrinsic characteristics of the fungus, such as its porosity. Obtaining fungus-derived porous carbons was achieved by hydrothermal activation with KOH and subsequent pyrolysis at 600, 800, and 1000 °C in an argon atmosphere. The morphologies of the fungal biomass and fungus-derived carbons both exhibited, on their surfaces, certain amorphous similarities in their pores, indicating that the porous base matrix of the fungus was maintained despite carbonization. From all fungus-derived carbons, PD1000 exhibited the largest superficial area, with 612 m2g−1 and a pore size between 3 and 4 nm recorded. Electrochemical performance was evaluated in a three-electrode cell, and capacitance was calculated by cyclic voltammetry; a capacitance of 60 F g−1 for PD1000 was recorded. Other results suggested that PD1000 had a fast ion-diffusion transfer rate and high electronic conductivity. Ultimately, Pleurotus djamor biomass is a suitable feedstock for obtaining carbon in a sustainable way, and it features a defined intrinsic structure for potential energy storage applications, such as electrodes in supercapacitors.

Hydrochars Derived from Spent Coffee Grounds as Zn Bio-Chelates for Agronomic Biofortification

“…Generally, this process leads to an increase in fixed carbon, ashes, and carbon content, with a decrease in volatile matter and oxygen content also occurring [11][12][13]. The vast majority of studies conducted on hydrochar generation found in existing literature are focused on aspects of bioenergy and chemistry [14,15], with very little information existing on the use of hydrochar in the agronomic field [16,17]. The use of spent coffee grounds (SCG) as an organic soil amendment has recently been studied due to their interesting macronutrient composition, of mainly lignin, cellulose, and hemicellulose, as well as their diverse array of mineral and bioactive compounds [18].…”