Funcionalización química y enzimática de celulosa para el desarrollo de un biomaterial con propiedad hidrofóbica.
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Date
2025
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Universidad de Concepción
Abstract
La hidrofilicidad de la celulosa limita sus aplicaciones industriales que requieran propiedades hidrofóbicas. En este trabajo, se evaluó comparativamente la hidrofobización de polimorfos I y II de celulosa de pulpa de eucalipto mediante acetilación química y enzimática. Los polimorfos son estructuras cristalinas distintas, siendo celulosa I con ordenamiento de cadenas paralelo respecto al terminal reductor y la celulosa II con ordenamiento antiparalelo de las cadenas. Los polimorfos se prepararon tratando la pulpa con NaOH (7% m/v para celulosa I, 20% m/v para celulosa II) y se caracterizaron mediante SEM, XRD y FTIR. Para la acetilación química, se empleó anhídrido acético/ácido sulfúrico, mientras que la enzimática utilizó lipasa (con una actividad enzimática de 5,2 U/mg) en DMSO/buffer fosfato. La hidrofobicidad de las fibras obtenidas fue determinada por el grado de acetilación (GA) y capacidad de absorción de aceites (OAC). Los resultados mostraron que la celulosa II presentó un mayor grado de sustitución (GA máximo: 1,1 en 8 h de reacción vs. 0,9 en 24 h de reacción para celulosa I), así como mayor capacidad de absorción de aceite (OAC 85,2% vs. 70,1%), además de menor índice de cristalinidad (38,5% vs. 58,6%) y morfología observada por SEM (estructura porosa con fibras rizadas y desorganizadas vs. fibras planas y compactas en celulosa I). La acetilación enzimática demostró mayor grado de acetilación en menor tiempo de reacción que la acetilación química (GA ≥1,0 en 2-8 h vs. 8-24 h en química). Se concluye que la selección del polimorfo y el método de acetilación son determinantes para las propiedades finales del biomaterial, destacando el potencial de la celulosa II modificada enzimáticamente para aplicaciones como adsorbente de lípidos y posiblemente de hidrocarburos.
The hydrophilicity of cellulose limits its industrial applications that require hydrophobic properties. This study comparatively evaluated the hydrophobization of cellulose polymorphs I and II from eucalyptus pulp through chemical and enzymatic acetylation. Polymorphs are distinct crystalline structures: cellulose I has a parallel chain arrangement with respect to the reducing end, whereas cellulose II has an antiparallel chain arrangement. The polymorphs were prepared by treating the pulp with NaOH (7% w/v for cellulose I, 20% w/v for cellulose II) and characterized by SEM, XRD, and FTIR. For chemical acetylation, acetic anhydride/sulfuric acid was used, while enzymatic acetylation employed lipase (with an enzymatic activity of 5.2 U/mg) in DMSO/phosphate buffer. The hydrophobicity of the obtained fibers was determined by the degree of acetylation (DA) and oil absorption capacity (OAC). The results showed that cellulose II exhibited a higher degree of substitution (maximum DA: 1.1 after 8 h of reaction vs. 0.9 after 24 h for cellulose I), as well as greater oil absorption capacity (OAC 85.2% vs. 70.1%), along with a lower crystallinity index (38.5% vs. 58.6%) and a morphology observed by SEM (porous structure with curly and disorganized fibers vs. flat and compact fibers in cellulose I). Enzymatic acetylation demonstrated a higher degree of acetylation in less reaction time than chemical acetylation (DA ≥1.0 in 2-8 h vs. 8-24 h for chemical). It is concluded that the selection of polymorph and the acetylation method are decisive for the final properties of the biomaterial, highlighting the potential of enzymatically modified cellulose II for applications as a lipid adsorbent and possibly for hydrocarbons.
The hydrophilicity of cellulose limits its industrial applications that require hydrophobic properties. This study comparatively evaluated the hydrophobization of cellulose polymorphs I and II from eucalyptus pulp through chemical and enzymatic acetylation. Polymorphs are distinct crystalline structures: cellulose I has a parallel chain arrangement with respect to the reducing end, whereas cellulose II has an antiparallel chain arrangement. The polymorphs were prepared by treating the pulp with NaOH (7% w/v for cellulose I, 20% w/v for cellulose II) and characterized by SEM, XRD, and FTIR. For chemical acetylation, acetic anhydride/sulfuric acid was used, while enzymatic acetylation employed lipase (with an enzymatic activity of 5.2 U/mg) in DMSO/phosphate buffer. The hydrophobicity of the obtained fibers was determined by the degree of acetylation (DA) and oil absorption capacity (OAC). The results showed that cellulose II exhibited a higher degree of substitution (maximum DA: 1.1 after 8 h of reaction vs. 0.9 after 24 h for cellulose I), as well as greater oil absorption capacity (OAC 85.2% vs. 70.1%), along with a lower crystallinity index (38.5% vs. 58.6%) and a morphology observed by SEM (porous structure with curly and disorganized fibers vs. flat and compact fibers in cellulose I). Enzymatic acetylation demonstrated a higher degree of acetylation in less reaction time than chemical acetylation (DA ≥1.0 in 2-8 h vs. 8-24 h for chemical). It is concluded that the selection of polymorph and the acetylation method are decisive for the final properties of the biomaterial, highlighting the potential of enzymatically modified cellulose II for applications as a lipid adsorbent and possibly for hydrocarbons.
Description
Tesis presentada para optar al título de Ingeniero/a en Biotecnología Vegetal.
Keywords
Celulosa, Eucaliptos, Acetilación