Hydrothermal carbonization valorization as an alternative application for corn bio-ethanol by-products

Abstract

Corn Wet Distillers' Fibre (Corn Fibre) and Corn Condensed Distillers' Solubles (CDS) are by-products of the corn-ethanol production process with limited investigation of their valorization potential available in the literature. In this work, we perform hydrothermal carbonization (HTC) on Corn Fibre and CDS at reaction temperatures ranging from 180 °C to 300 °C. The solid products were characterized by ultimate and proximate analysis, HHV, TGA, FT-IR, Py-GC-MS, and SEM. The liquid process water composition was characterized by GC-MS analysis, and the total organic carbon (TOC) was determined. The produced hydrochar had a higher heating value of up to 33.91 MJ/kg, and nitrogen content as high as 3.91% Nitrogen at 77.35% Carbon. The hydrochar had a much higher ratio of hydrogen to oxygen content than most hydrochars from biomass investigated in the literature. The process water for CDS had a high quantity of hydrocarbons and high liquid carbon yield, whereas the process water from Corn Fibre contains large quantities of hydroxymethylfurfural (HMF). These findings indicate that HTC of Corn Fibre and CDS may be a promising alternative pathway for producing valuable chemicals or high-quality hydrochar for fuel or higher value applications which can utilize nitrogen content, such as activated carbons.