Ammonium carbonate as a catalyst for lignocellulose pretreatment and a nitrogen source for fermentation

Abstract

In this work, ammonium carbonate (AC), a product released during the regeneration of ammonia-based carbon capture process, was evaluated as an alkaline catalyst for the pretreatment of lignocellulose; and as a nitrogen source in the subsequent fermentation process for bioethanol production. Response surface methodology was employed to attain an optimum pretreatment condition in terms of AC concentration (15–25%), reaction time (5–15h) and temperature (60–100°C). The highest enzymatic digestibility of 59.9% was achieved with AC concentration of 20.0% at 79.5°C of treatment temperature for 9.46h of reaction time. A fermentation medium containing ammonium ion derived from the liquid hydrolysate after the AC-based pretreatment was found to enhance the final concentration of ethanol produced by Saccharomyces cerevisiae from 9.13g/L to 13.30g/L. These results indicate that AC can indeed serve as a catalyst option for pretreating lignocellulosic biomass and has an added advantage of being used as a nitrogen source for the fermentation process.