Banca de QUALIFICAÇÃO: OTAVIO LIMA DA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : OTAVIO LIMA DA SILVA
DATE: 17/07/2026
TIME: 09:00
LOCAL: Via Google Meet
TITLE:

Synthesis of Cellulose Acetate Polymeric Membranes from Green Coconut Husk Fiber for Carbon Dioxide (CO2) and Methane (CH4) Separation

KEY WORDS:

Cellulose acetate; green coconut shell; CO₂ capture; membranes

PAGES: 81
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SPECIALTY: Processos Bioquímicos
SUMMARY:

Due to intense urbanization and industrialization, greenhouse gas (GHG) emission levels have risen unchecked—particularly those of carbon dioxide (CO2), a primary driver of the intensified greenhouse effect. Against this backdrop, reducing carbon emissions and developing technologies for their separation and capture have become global priorities. Natural gas processing involves the presence of gases such as CO2. Dense membranes can be employed in gas permeation processes, such as the separation of contaminant gases. In this context, cellulose acetate films are preferred due to their hydrophilic nature and their chemical and mechanical stability. Their high chemical affinity for CO2 enables their use in separation processes for the purification of natural gas (methane). One alternative method for producing cellulose acetate involves using agro-industrial waste, given its high cellulose content. In this study, coconut fiber served as the cellulose source for the production of cellulose triacetate (TAC). Initially, to obtain cellulose, two pretreatments were evaluated: oxidative alkaline (M1) and a combination of dilute acid (H2SO4) and oxidative alkaline (M2) pretreatments, aiming to reduce the lignin and hemicellulose content of the biomass. Pretreatment M1 reduced the lignin content of the raw biomass by 50%, whereas M2 primarily reduced hemicellulose content. X-ray diffraction (XRD) analyses of the coconut fiber (CF) samples revealed a significant increase in the crystallinity index to 52.61% (CF-M1) and 56.6% (CF-M2), compared to 28.77% for the raw material. Both pretreatments preserved cellulose content, and M1 also preserved hemicellulose content. Cellulose acetates (CA) were obtained via a homogeneous acetylation reaction and designated as CA-M1 and CA-M2. The degree of substitution (DS) and viscosity-average molar mass (Mv) of these polymers were determined, yielding triacetates (TAC) with DS values of 2.89 and 2.75, respectively, and Mv values of 19.3 and 15.8 kDa. Dense membranes were synthesized from CA-M1 and CA-M2 using the evaporation-induced phase separation (EIPS) technique; dichloromethane (DCM) proved to be the most suitable solvent for membrane synthesis. The CA-M2 membrane exhibited a structure that was more flexible, stronger, and less opaque than the CA-M1 membrane. Notably, in the next stage of the study, the resulting membranes will be evaluated for CO2 sorption, as well as CO2 and CH4 gas permeability and selectivity.

COMMITTEE MEMBERS:
Presidente - 1346198 - EVERALDO SILVINO DOS SANTOS
Interna - 3214434 - NATHALIA SARAIVA RIOS
Externa ao Programa - 1218001 - LIANA FRANCO PADILHA - UFRNExterna à Instituição - BRUNA MARIA EMERENCIANO DAS CHAGAS - UFRN