Impact of hydrolysis on surface area and energy storage applications of activated carbons produced from corn fiber and soy hulls

Abstract

Complete utilization of lignocellulosic biomass through the creation of value-added coproducts is one of the key strategies of the Bioenergy Technologies Office (BETO) for the cost-effective production of biofuels and biochemicals. A green approach to producing lightweight and high specific surface area (SSA) activated carbons (ACs) from sustainable biomass sources is of great interest to producers and users of energy devices such as batteries and supercapacitors. While direct conversion from biomass has been studied extensively, AC with relatively high surface areas can be produced more cost-effectively when leveraged as a co-product from a biorefinery. In this paper, we discuss the production of high specific surface area activated carbons from residual fiber (fiber remaining after extraction of C5-sugars) generated as part of a C5 biorefinery. The surface, morphological characteristics using SEM and TEM, and energy storage behavior of ACs produced using the C5 extracted residual fiber were evaluated in the present study. The ACs produced from the residual fiber delivered an order of magnitude higher surface area than the one directly from corn pericarp fiber and soy hulls. The surface area of the ACs produced from pre-hydrolysis DDG was only 10 m2/g compared to 689 m2/g for soy hulls whereas after hydrolysis these values increased significantly (DDG: 1700 m2/g and soy hulls: 1300 m2/g). TEM images indicated high exfoliation, explaining the change in surface area values. Under the same current density (500 mA/g) the cycling performance of the ACs increased as the surface area increased significantly.

Keywords

• Agricultural residues
• Hydrolysis
• Activated carbon
• Surface area characterization
• Surface morphology