Dra. Valdebenito-Escobar, Fabiola

This study evaluated the stability and reusability of amino-functionalized nanocellulose aerogels as CO2-adsorbent materials. The modified aerogels, synthesized via a controlled silylation using N-[3-(trimethoxysilyl) propyl] ethylenediamine (DAMO), demonstrated excellent thermal stability up to 250 °C (TGA) and efficient CO2 adsorption through chemisorption, which was the main adsorption mechanism. The performance of the aerogels was assessed using both adsorption isotherms and the decay pressure technique, revealing that CO2 adsorption capacity increased with higher amino group loading (4.62, 9.24, and 13.87 mmol of DAMO). At 298 K and 4 bar, CO2 adsorption capacity increased proportionally with the amino group concentration, reaching values of 3.17, 5.98, and 7.86 mmol of CO2 g−1 polymer, respectively. Furthermore, over 20 adsorption/desorption cycles, the aerogels maintained 95% CO2 desorption at ambient temperature, indicating their potential for industrial use. These findings highlight the aerogels suitability as stable, reusable materials for large scale CO2 capture and storage technologies.

Phosphorylated cellulose nanocrystals (P-CNCs) are a superior alternative to conventional sulfuric acid-derived CNCs because of their enhanced thermal and colloidal stability. However, further research is needed to understand the factors influencing their synthesis and properties for advanced material applications. In this study, P-CNCs were synthesized from bleached hardwood kraft pulp (BEKP) using a controlled hydrolysis method involving pretreatment with H3PO4 followed by reaction with metaphosphoric acid (HPO3) and urea. To optimize the process, a full factorial design was employed to evaluate the effects of reaction time (60–90 min) and HPO3 concentration (3–4 M). The P-CNCs were characterized using physicochemical, morphological, and thermal analyses. Surface charge densities ranged from 757 to 1993 mmol/kg, with exceptional colloidal stability, as evidenced by zeta potentials ranging from −30.17 to −67.40 mV. Statistical analysis showed that reaction time had a significant main effect on surface charge (p-value = 0.0022) and zeta potential (p-value = 0.0448), while a significant interaction between reaction time and HPO3 concentration was observed when analyzing the surface charge (p-value = 0.0097), suggesting a combined effect of these factors on the surface modification of CNC. Crystallinity indices ranged from 63.6% to 71.3%, and the thermal stability exceeded that of the raw material. These findings contribute to a better understanding of the surface modification and stability of P-CNCs and support efforts to sustainably produce functional CNCs for advanced composite applications.

Nowadays, leaves, bark, and branches are generated from the tree-pruning process in urban places, where their management is a problem because of the necessity of disposal. These wastes are lignocellulosic biomasses with poor properties for use in biofuel production, but with interesting projections for building block products such as phenol compounds. Therefore, extensive biomass characterization of urban pruning from Liquidambar styraciflua L. was developed to evaluate its composition as a tool for phenol production through thermal processing, in which solvent extraction is a complementary tool for selectivity improvement. The results showed high lignin content in bark and leaves at 45 and 28 %, respectively, compared with that in branches (14 %). Additionally, high extractives in leaves (14 %) could be an additional source of phenols. The lignin units were analyzed by Raman dispersion, revealing p–hydroxyphenyl (H) units in the bark, guaiacyl (G) units in the bark and leaves, and syringyl (S) units only in the branches. Furthermore, the micropyrolysis coupled with gas chromatography/mass spectrometry assay realized at 600 ◦C showed high presence of phenolic compounds in the three biomass investigated, where a high phenol concentration was identified in leaves, probably due to the S unit degradation during pyrolysis. With these results, an assay for bio-oil production was performed in a low-temperature pyrolysis reactor using leaves as feedstock, reaching a low bio-oil yield with high water content favored for the high inorganic content of leaves (13 %). The produced bio-oil was used for liquid–liquid extraction evaluation, where 1-octanol and methyl isobutyl ketone were identified as interesting solvents for catechol and phenol extraction, respectively. This article presents the challenge of characterizing each part of urban trees, which could be a tool to promote the use of urban pruning by studying the thermal degradation mechanism to implement processes for high-value products, such as phenols produced from L. styraciflua L.

The use of pellets as a replacement for firewood has been promoted in Chile to mitigate atmospheric pollution. However, their high demand has generated stock shortages, which has motivated the search for alternative sources of feedstock. Furthermore, invasive shrubs are a highly available biomass source for bioenergy production in central-southern Chile and may be a significant factor contributing to the spread and increasing virulence observed in wildfires across the region. This study aimed to determine the change in wildfire indicators related to the removal of invasive shrubs in selected zones in the Biobío region and to assess the physicochemical properties of the extracted biomass to develop a pellet formulation to produce a material conforming to ISO standards. The biomass management of Teline monspessulana, Ulex europaeus, and Rubus ulmifolius was evaluated using a fire simulation tool in three areas with contrasting physio-climatic conditions. Our simulation results demonstrated the effectiveness of shrub management on three critical wildfire indicators. Namely, significant decreases were observed in fireline intensity (kW/m) 58–75%, flame length (m) 0–40%, and heat per unit area (kW/m2) 86%. Furthermore, a biomass quality index (BQI) was developed based on the physicochemical parameters of the three shrubs assessed. Based on this BQI, T. monspessulana was selected as the most promising shrub biomass and was consequently used in a pilot shrub-pinewood blending to produce pellets. A blending of 20:80%m/m exhibited properties close to the ISO standard. Our results show that the management of invasive shrubs has the potential to minimize the virulence of wildfires, while the physicochemical characteristics and availability of one of the shrubs analyzed (T. monspessulana) make it a viable alternative biomass source for pellet production in the region.

The production of fatty acid methyl esters (FAME) from waste frying oil (WFO) was studied using fly ash as received as a heterogeneous catalyst. The fly ash used in this research had a high content of both CaO and SO3, two compounds that have been previously proposed as catalysts in FAME production. The study was carried out on the basis of a response surface methodology (RSM). The model generated by RSM predicted as optimal conditions to obtain a 100% FAME yield at a methanol-to-oil molar ratio of 3.1:1, 11.2 (wt.% based on oil weight) fly ash and a temperature of 59 C with agitation at 245 rpm and 6 h of reaction time. Additional experiments comparing anhydrous with aqueous medium showed that fly ash presented a high catalytic capacity to transform free fatty acids (FFA) into FAME through consecutive hydrolysis and esterification processes (hydroesterification) compared with that associated with the transesterification mechanism. According to the results, the fly ash used in this study would act as a multipurpose or “versatile” catalyst due to its chemical composition with constituents that act as acidic and basic catalysts, therefore, catalyzing the transesterification and hydroesterification reactions simultaneously and increasing the conversion yields of FAME.