Banca de DEFESA: JOSE DALADIE BARRETO DA COSTA FILHO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSE DALADIE BARRETO DA COSTA FILHO
DATE: 02/12/2025
TIME: 15:00
LOCAL: Virtual
TITLE:

Fractionation of corncob via oxidative–organosolv pretreatment: evaluation of liquor recycling and valorization of the residual lignin

KEY WORDS:

Spent liquor recycling, Reuse, Depolymerization, Hydroxycinnamic Acids, Waste valorization, Zero waste, Biorefining

PAGES: 156
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Tecnologia Química
SPECIALTY: Produtos Naturais
SUMMARY:

This work explored the corn cob—an abundant lignocellulosic residue from grain processing—as a versatile platform for an integrated biorefinery route. Initially, an oxidative–organosolv pretreatment was applied with the dual objective of producing ethanol and recovering high-purity lignin both from the pretreatment liquor and from the residual solid obtained after enzymatic hydrolysis (EHL). The partial recycling of the pretreatment liquor demonstrated strong potential for cost reduction, as pretreatments carried out with 50% recycled reagent solution or full replacement of its components performed equivalently to those using entirely fresh reagents up to the fourth cycle. A decline in efficiency was only observed from the fifth cycle onward. Despite slight changes in thermal stability and UV absorption, liquor recycling enhanced lignin recovery while maintaining its suitability for higher-value applications. EHL was subsequently employed as the feedstock for the production of p-coumaric acid (p-CA), a high-value phenolic compound of industrial relevance. The integrated strategy combining alkaline depolymerization with persulfate oxidation proved effective. Experimental design analyses enabled the evaluation of the effects of critical variables: higher EHL concentrations and increased reaction time and temperature improved p-CA yield, whereas excess persulfate or overly high NaOH:EHL ratios reduced product formation. Under optimized conditions, approximately 5 g of p-CA were obtained per 100 g of EHL—one of the highest yields reported for this route when working with residues derived from lignocellulosic biomass processing. The non-depolymerizable fraction of EHL (nD-EHL), generated as the final residue after multiple valorization steps, was assessed as an adsorbent for methylene blue dye. Although its performance was lower than that of conventional lignocellulosic adsorbents, the material still exhibited useful adsorption capacity. Overall, the results demonstrate a robust, sustainable, and integrated biorefinery pathway capable of converting a single agricultural residue—the corn cob—into multiple value-added products: 2G ethanol, high-purity lignin, p-coumaric acid, and a residual adsorbent material. The combination of oxidative–organosolv pretreatment, liquor recycling, lignin recovery, and alkaline–oxidative depolymerization highlights a promising approach for the complete utilization of lignocellulosic biomass, fully aligned with the principles of the circular bioeconomy.

COMMITTEE MEMBERS:
Presidente - 1584174 - DOMINGOS FABIANO DE SANTANA SOUZA
Interno - ***.656.434-** - CARLOS EDUARDO DE ARAÚJO PADILHA - UFRN
Interno - 1547970 - JACKSON ARAUJO DE OLIVEIRA
Externa à Instituição - LUZIA SERGINA DE FRANCA NETA
Externo à Instituição - EMMANUEL DAMILANO DUTRA - UFPE