Effective liquid-liquid fractionation methods of the heavy bio-oil have been pursued to improve the key biomass functionalities. Here, fast-pyrolysis bio-oil derived from eucalypt wood was fractionated in cold water to separate insoluble- and water-soluble fractions. We focus on the water-soluble fraction, a promising renewable source of chemicals with potential antimicrobial approaches. Fast-pyrolysis bio-oil was fractionated in three oil-to-water ratios, 1:100, 1:50, and 1:35, separating the pyrolytic lignin and producing water-soluble fractions as byproducts. The water-soluble fractions were analytically investigated through physicochemical properties, chemical composition by chromatography, phenolic content, antioxidant activity, antimicrobial activity, and their storage stability. Higher water content in the pyrolytic lignin separation resulted in higher yield and solids concentration in the water-soluble fractions, with the presence of high value-added chemicals, such as catechol, vanillin, and levoglucosan. Levoglucosan was the dominant chemical identified in the water-soluble fractions, notably for the 1:50 oil-to-water ratio. These remarkable chemicals and a high phenolic content contribute to both high antioxidant and antimicrobial activities. Despite the low concentration, all water-soluble fractions exhibited intense inhibition of Trametes versicolor and Gloeophyllum trabeum fungi. The fraction 1:50 completely inhibited the fungal activity. Both 1:100 and 1:50 fractions showed antibacterial activity for Escherichia coli and Staphylococcus aureus. Regardless of the oil-to-water ratio, water-soluble fractions exhibited a relative storage chemical stability under accelerated aging conditions for 43 days. Therefore, water-soluble fractions of fast-pyrolysis bio-oil derived from a simple method to separate pyrolytic lignin are functional materials with remarkable properties and, hence, upgrading bio-oil based on their functionalities.
Este trabalho teve como objetivo analisar a molhabilidade superficial da madeira da espécie Manilkara huberi (Maçaranduba) aplicando-se dois tipos de substâncias. Para isso, utilizou-se o goniômetro na obtenção dos ângulos de contato, no qual empregou-se três amostras com dimensões de 2,5 x 2,5 x 1,8 cm, em que estas foram lixadas com lixa 220. Os líquidos foram água destilada e formamida, com o volume da gota de 5 μL. Verificou-se que a madeira de Maçaranduba apresentou diferenciação na molhabilidade de sua superfície, tanto nos tipos de líquidos quanto nos tempos observados, em que, a água expôs os ângulos mais elevados. A substância formamida demostrou baixo ângulo de contato e se diferenciou nos dois tempos avaliados.
A simple method to extract pyrolytic lignin from bio-oil is under agitation in water or organic solvent. This process produces a water-insoluble fraction (pyrolytic lignin) and a water-soluble fraction (WS). In this study, we used a physical fractionation technique with water as a liquid agent to separate the two fractions of the fast pyrolysis bio-oil and obtain the WS — the object of study — to test its efficiency as a protective agent for lignocellulosic materials. The study aimed to investigate the efficiency of the aqueous phase (WS) as a water-repellent agent when impregnated into Pinus elliotti wood. To obtain WS, we used two bio-oil:water ratios (1:50 and 1:100) and two agitation speeds (17,000 and 8,500 RPM); they were respectively named WS50 and WS100, both with an average yield of 61% WS. Gas chromatography coupled with mass spectrometry (GC-MS), thermogravimetry (TGA), contact angle, and scanning electron microscopy (SEM) were used to characterize the WS and the veneers impregnated with it. There were no morphological changes on their surface, especially regarding the non-coating of the wood pits; meanwhile, the TGA showed visible changes in the degree of thermal degradation of the impregnated material related to the chemical composition of the WS identified in the GC-MS. There was a significant increase, on average 62%, in the apparent contact angle of the impregnated wood, approximately 126°. The WS has shown to be efficient as a protective agent by converting the hydrophilic surface of Pinus elliotti into a hydrophobic one, and this effect partially remained after 45 days of exposure.
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