Valorizing corn stover waste into valuable bioproducts using subcritical water hydrolysis

Author(s)

da Rosa, Rafael Gabriel ; Castro, Luiz Eduardo Nochi ; Barroso, Tiago Linhares Cruz Tabosa ; Ferreira, Vanessa Cosme ; Bittencourt, Paulo Rodrigo Stival ; Rostagno, Mauricio Ariel ; Forster-Carneiro, Tania

• Document type: Journal article
• Source: BIOFUEL RESEARCH JOURNAL-BRJ; v. 12, n. 1, p. 27-pg., 2025-03-01.

Abstract

This study examined the behavior of the semi-continuous hydrolysis process of corn stover (CS) in subcritical water, focusing on the effects of varying pH levels (1, 2, 4.5, 7, and 8) and temperatures (113, 130, 170, 210, and 226 degrees C). The results showed that the process at 170 degrees C and pH 1 was able to recover the highest amount of phenolic compounds (76.82 mg Gallic Acid Equivalents g-1), consequently demonstrating the highest antioxidant activities by the Ferric Reducing Antioxidant Power (FRAP) (423.85 mu Mol TEAC g-1) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (293.12 mu Mol TEAC g-1) methods. Additionally, it was possible to obtain the highest concentration of sugars (cellobiose, glucose, and xylose) (460.92 mg g-1). High temperatures (226 degrees C and pH 4.5) produced the highest amount of organic acids (1,157.19 mg g-1). The formation of inhibitors was observed only at temperatures of 170 and 210 degrees C at a pH of 1.0. The highest yields of sugars, organic acids, and inhibitors were 0.565, 1.123, and 0.665 mg g-1 of carbohydrates, respectively. The statistical analysis identified the optimal conditions for the recovery of various compounds: phenolic compounds at 190.7 degrees C and pH 1, soluble proteins at 187.4 degrees C and pH 1, sugars at 134.9 degrees C and pH 1, organic acids at 223.59 degrees C and pH 4.1, and for minimizing inhibitors at 114.95 degrees C and pH 7.3. EcoScale analysis identified subcritical water as the most sustainable and efficient method for CS hydrolysis. Subcritical water treatment effectively recovers valuable compounds from CS, promoting a circular economy by valorizing waste and reducing resource dependence. (c) 2025 Alpha Creation Enterprise CC BY 4.0 (AU)

• FAPESP's process: 21/04096-9 - Integration of the extraction/hydrolysis processes in subcritical water and purification for the valuation of grape bagasse in a biorrefinery concept
• Grantee: Luiz Eduardo Nochi de Castro
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 18/14582-5 - Development of a two-dimensional extraction, separation and analysis system for evaluating the bioactivity of phytochemicals
• Grantee: Maurício Ariel Rostagno
• Support Opportunities: Research Grants - Young Investigators Grants - Phase 2
• FAPESP's process: 23/02064-8 - Sustainable bioprocesses for the valorization of cashew apple bagasse (Anacardium occidentale): integration of hydrothermal pretreatment and fermentation processes to produce value-added compounds in a biorefinery concept
• Grantee: Tiago Linhares Cruz Tabosa Barroso
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 22/02305-2 - Evaluation of subcritical water hydrolysis in an automated reactor with in-line analysis of compounds with higher added value from pitaya peels (Hylocereus undatus)
• Grantee: Vanessa Cosme Ferreira
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 18/14938-4 - Waste2energy: integration of supercritical technologies and anaerobic digestion through an automated system for the production of biofuel precursors
• Grantee: Tânia Forster Carneiro
• Support Opportunities: Research Grants - Young Investigators Grants - Phase 2