Browsing by Author "Reyes-Contreras, Pablo"

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Maximizing Bioethanol Production from Eucalyptus globulus Using Steam Explosion Pretreatment: A Multifactorial Design and Fermenter Development for High Solid Loads
    (2023) Troncoso-Ortega, Eduardo; Valenzuela, Roberto; Reyes-Contreras, Pablo; Castano-Rivera, Patricia; Schiappacasse, L-Nicolas; Parra, Carolina
    Steam explosion pretreatment is suitable for bioethanol production from Eucalyptus globulus wood. Multifactorial experiment designs were used to find the optimal temperature and residence time required to obtain the best glucose yield from the enzymatic hydrolysis of pretreated materials. The chemical composition, crystallinity index, morphology and polymerization degree of the pretreated materials were correlated with enzymatic accessibility. Simultaneous saccharification and fermentation (SSF) using a fed-batch strategy was applied to three different laboratory-scale fermenters. The optimization of the pretreatment was obtained at 208 degrees C and 11 min. However, the enzymatic hydrolysis performance did not show significant differences from the material obtained at 196 degrees C and 9.5 min, which was determined to be the real optimum, owing to its lower energy requirement. The vertical fermenter with type "G" blades and the horizontal fermenter with helical blades were both highly efficient for reaching ethanol yields close to 90% based on dry wood, and ethanol concentrations close to 9.0% v/v.
  • Thumbnail Image
    Item
    Maximizing bolaina wood utilization: extraction of cellulose nanofibers from sawdust waste
    (2024) Diaz, Shirley; Mora, Hector Gonzales; Gacitua, William; Bustos, Cecilia; Reyes-Contreras, Pablo; Aguayo, Maria Graciela
    This study focuses on the utilization of bolaina sawdust waste from the Peruvian Amazon for the production of cellulose nanofibers (CNFs). Bolaina is known for its rapid growth and extensive wood usage, which generate significant amounts of sawdust waste. The objective of this research was to physicochemically study this biomass source and the conversion of this waste into valuable nanocellulosic materials. The results showed that CNF yields from holocellulose (CNF-BH) and alpha-cellulose (CNF-B alpha) gave high nanofibrillation yields of 80.6% and 74.7%, respectively. The CNFs were disintegrated into nanoscale fibers using microfluidizer treatment, resulting in CNF-BH displaying a thicker, gel-like aspect, while CNF-B alpha showed a more liquid aspect. The FTIR spectra showed peaks associated with -CH2 groups, C = O stretching vibrations of carboxyl and acetyl groups in hemicelluloses, and cellulose I and II vibrations. TGA analysis demonstrated that both CNFs had two stages of degradation, with a maximum peak degradation temperature of 240 degrees C in the first stage and 310 to 350 degrees C in the second stage. The XRD patterns of CNF-BH and CNF-B alpha showed differences in the crystallinity index, with values of 68.1% and 75.4%, respectively. The differences in crystallinity between the two CNFs can be explained by the alkaline purification method to which the alpha-cellulose sample was subjected. Overall, the CNFs exhibited a high crystallinity index and thermal stability, making them promising candidates for various applications in materials science and aiding in the development of sustainable materials.
  • No Thumbnail Available
    Item
    Pretreated Eucalyptus globulus and Pinus radiata Barks: Potential Substrates to Improve Seed Germination for a Sustainable Horticulture
    (2023) Escobar-Avello, Danilo; Ferrer, Victor; Bravo-Arrepol, Gaston; Reyes-Contreras, Pablo; Elissetche, Juan P.; Santos, Jorge; Fuentealba, Cecilia; Cabrera-Barjas, Gustavo
    Commercial forest plantations in Chile are dominated by pine (Pinus radiata) and eucalyptus (Eucalyptus globulus). Tree bark is the main by-product of the forestry industry and has low value, but great potential for use as an agricultural substrate. However, the direct use of bark fibers may cause plant phytotoxicity due to the presence of polyphenolic and other compounds. This study aims to evaluate the physicochemical properties of E. globulus and P. radiata bark after water extraction treatments. The phytotoxicity of the resulting extracted bark alone and that mixed with commercial substrates (coconut fiber, moss, peat, and composted pine) at different ratios (25 to 75 wt%) were assessed using the Munoo-Liisa vitality index (MLVI) test. For all treatments, the seed germination and growth of radish (Raphanus sativus) and Chinese cabbage (Brassica rapa) species were evaluated and compared to a commercial growing medium (peat) as a control. The optimal mixture for seed growth was determined to be 75% extracted E. globulus bark fiber and 25% commercial substrates such as peat (P), coconut fiber (C), moss (M), and composted pine (CP), as indicated by the MLVI and germination results. Two phytostimulant products, chitosan and alginate-encapsulated fulvic acid, were added to the best substrate mixture, with the purpose of improving their performance. Encapsulated fulvic acid at 0.1% w/v was effective in promoting plant growth, while chitosan at all of the concentrations studied was effective only for mixture 75E-25CP. The mixture of E. globulus fiber and commercial substrates, containing a high proportion of water-extracted fiber (75%), shows the potential to be used in the growth of horticultural crops and in the plant nursery industry.
  • No Thumbnail Available
    Item
    The Role of Eucalyptus Species on the Structural and Thermal Performance of Cellulose Nanocrystals (CNCs) Isolated by Acid Hydrolysis
    (2022) Gil-Castell, Oscar; Reyes-Contreras, Pablo; Barra, Pabla Andrea; Teixeira Mendonca, Regis; Carrillo-Varela, Isabel; Badia, Jose David; Serra, Angels; Ribes-Greus, Amparo
    Cellulose nanocrystals (CNCs) are attractive materials due to their renewable nature, high surface-to-volume ratio, crystallinity, biodegradability, anisotropic performance, or available hydroxyl groups. However, their source and obtaining pathway determine their subsequent performance. This work evaluates cellulose nanocrystals (CNCs) obtained from four different eucalyptus species by acid hydrolysis, i.e., E. benthamii, E. globulus, E. smithii, and the hybrid En x Eg. During preparation, CNCs incorporated sulphate groups to their structures, which highlighted dissimilar reactivities, as given by the calculated sulphate index (0.21, 0.97, 0.73 and 0.85, respectively). Although the impact of the incorporation of sulphate groups on the crystalline structure was committed, changes in the hydrophilicity and water retention ability or thermal stability were observed. These effects were also corroborated by the apparent activation energy during thermal decomposition obtained through kinetic analysis. Low-sulphated CNCs (E. benthamii) involved hints of a more crystalline structure along with less water retention ability, higher thermal stability, and greater average apparent activation energy (233 kJ center dot mol(-1)) during decomposition. Conversely, the high-sulphated species (E. globulus) involved higher reactivity during preparation that endorsed a little greater water retention ability and lower thermal stability, with subsequently less average apparent activation energy (185 kJ center dot mol(-1)). The E. smithii (212 kJ center dot mol(-1)) and En x Eg (196 kJ center dot mol(-1)) showed an intermediate behavior according to their sulphate index.