Banca de QUALIFICAÇÃO: JOSE DALADIE BARRETO DA COSTA FILHO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSE DALADIE BARRETO DA COSTA FILHO
DATE: 06/11/2025
TIME: 15:00
LOCAL: Remoto
TITLE:

Recovery and valorization of lignin: production of p-coumaric acid from residual lignin derived from corn cob ethanol production

KEY WORDS:

Valorization, Corn Cob, Lignin, p-Coumaric Acid.

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

Pretreatment represents one of the main costs of the bioethanol production process, accounting for approximately 18 to 20% of total costs. However, it is a crucial step in disrupting the lignocellulosic matrix, increasing enzymatic accessibility to cellulose and hemicellulose, and ensuring the preservation of other biomass components for later valorization. This study focused on corn cob, a lignocellulosic residue from grain processing, with the aim of extracting and characterizing lignin, establishing a promising route for the production of viable fermentable sugars for bioethanol production. Oxidative-organosolv pretreatment was applied, and recycling its liquid fraction was evaluated as a strategy to reduce operating costs. Pretreatments with 50% recycled reagent solution and complete component replacement were as effective as those performed with entirely new reagents up to the fourth cycle, with a gradual decline in efficiency starting in the fifth cycle. Liquor recycling slightly affected the characteristics of the recovered lignin, particularly regarding thermal stability and UV absorption capacity. However, this approach allowed for higher lignin recovery and demonstrated that partial liquor recycling is a viable route for cost reduction without significant performance losses. The lignin isolated from the pretreatment and the residual solid from enzymatic hydrolysis (EHL) were highly pure, suitable for use as value-added materials. In this study, EHL was also used as a raw material for the production of p-coumaric acid (p-CA), a phenolic compound with high industrial value. The conversion of EHL to p-CA was achieved by integrating alkaline depolymerization with oxidation using sodium persulfate. Experimental design analyses identified NaOH concentration as a key variable in the cleavage of ester and ether bonds, while persulfate acted as an oxidant, increasing the p-CA yield. Under optimized conditions, approximately 5 g of p-CA were obtained per 100 g of EHL. Thermal analysis before and after depolymerization suggests that preferential cleavage occurs at the β–O–4 bonds. The non-depolymerizable EHL fraction (nD-EHL) was subsequently evaluated for its adsorption capacity for methylene blue dye. Although its adsorption performance was inferior to that of conventional lignin-based adsorbents, nD-EHL still demonstrated adsorption capacity. Considering that this material represents the final residue after multiple valorization steps—from the bioethanol production route to phenolic acid recovery—it has potential for use in systems with low dye concentrations or as a component of composite adsorbents. Overall, the proposed integrated approach demonstrates a sustainable biorefinery strategy in which multiple high-value products are derived from a single agricultural residue—corn cob. The combination of oxidative-organosolv pretreatment, liquor recycling, lignin recovery, and subsequent alkaline-oxidative depolymerization in p-CA highlights a promising pathway toward full utilization of lignocellulosic biomass and advancement of circular bioeconomy concepts.

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