Effect of catalyst types on economic feasibility and environmental impact of simultaneous levulinic acid and hydrochar production from cassava rhizome via acid catalytic hydrothermal process

Abstract

The economic feasibility and environmental impacts of simultaneous levulinic acid (LV) and hydrochar synthesis from cassava rhizome (CR) using H<inf>2</inf>SO<inf>4</inf> and HCl catalysts were investigated. In this study, CR was initially delignified with a KOH solution at 120 °C for 1 h, followed by conversion into LV and hydrochar using 0.1–0.7 M H<inf>2</inf>SO<inf>4</inf> at 175–225 °C for 1–3 h. The highest LV yield (15.34 wt.%) and selectivity (84.60%) were achieved at 225 °C for 2 h using a 0.4 M H<inf>2</inf>SO<inf>4</inf>. Characterization of the resulting hydrochar revealed fuel properties comparable to coal, indicating its potential as a coal substitute. Notably, the HCl-catalyzed process demonstrated superior economic feasibility, with an internal rate of return (IRR) of 57.60% and a minimum selling price of $21.70/kg LV, attributed to its higher LV yield. Furthermore, LV produced via the HCl system exhibited a lower environmental impact (96.75 kg CO<inf>2</inf> eq./kg LV), highlighting the critical influence of catalyst selection on productivity, economic viability, and environmental sustainability.