Sustainable lactic acid production from agrifood residues via subcritical water hydrolysis and nanofiltration

Abstract

The valorization of agri-food biomass offers a promising pathway for sustainable bioproduct generation, aligning with circular economy principles. This study investigates the production of lactic acid (LA) through the subcritical water hydrolysis (SWH) of selected agrifood residues, followed by its separation using micro- (MF) and nanofiltration (NF). Agri-food residues rich in hemicelluloses, such as corn stover, were subjected to SWH in the presence of heterogeneous catalysts such as Yb 3+ salts [1] and Ca(OH)2) to maximize LA yield, achieving concentrations of up to 14.4 g/L under optimized reaction conditions. The subsequent NF process employed membranes with varying molecular weight cut-offs to assess LA recovery efficiency, flux, and rejection rates. Membrane fouling and the influence of operating parameters such as pressure and feed concentration were also evaluated using synthetic solutions. The optimal NF configuration achieved good LA concentration with minimal co-product contamination, demonstrating the potential for effective LA purification. This integrated approach not only addresses the disposal challenges associated with agrifood residues but also provides a sustainable route for high-value LA production. The findings underscore the feasibility of coupling SWH and membrane technology for lactic acid production and recovery, contributing to resource-efficient agricultural practices and waste valorization.