Photoluminous Response of Biocomposites Produced with Charcoal.

Due to the possible effects of global warming, new materials that do not have a negative impact on the environment are being studied. To serve a variety of industries and outdoor applications, it is necessary to consider the impact of photoluminosity on the performance of biocomposites in order to accurately assess their durability characteristics and prevent substantial damage. Exposure to photoluminosity can result in adverse effects such as discoloration, uneven surface, loss of mass, and manipulation of the intrinsic mechanical properties of biocomposites. This study aims to evaluate general charcoal from three pyrolysis temperatures to understand which charcoal is most suitable for photoluminosity and whether higher pyrolysis temperatures have any significant effect on photoluminosity. Porosity, morphology, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy of charcoal were analyzed. Charcoal obtained at a temperature of 800 °C demonstrates remarkable potential as a bioreinforcement in polymeric matrices, attributable to its significantly higher porosity (81.08%) and hydrophobic properties. The biocomposites were characterized for flexural strength, tensile strength, scanning electron microscopy (SEM), FTIR, and x-ray diffraction (XRD). The results showed an improvement in tensile strength after exposure to photoluminosity, with an increase of 69.24%, 68.98%, and 54.38% at temperatures of 400, 600, and 800 °C, respectively, in relation to the treatment control. It is notorious that the tensile strength and modulus of elasticity after photoluminosity initially had a negative impact on mechanical strength, the incorporation of charcoal from higher pyrolysis temperatures showed a substantial increase in mechanical strength after exposure to photoluminosity, especially at 800 °C with breaking strength of 53.40 MPa, and modulus of elasticity of 4364.30 MPA. Scanning electron microscopy revealed an improvement in morphology, with a decrease in roughness at 800 °C, which led to greater adhesion to the polyester matrix. These findings indicate promising prospects for a new type of biocomposite, particularly in comparison with other polymeric compounds, especially in engineering applications that are subject to direct interactions with the weather.

Antimicrobial activity and chemical profile of wood vinegar from eucalyptus (Eucalyptus urophylla x Eucalyptus grandis - clone I144) and bamboo (Bambusa vulgaris).

Microbial resistance to drugs is a public health problem; therefore, there is a search for alternatives to replace conventional products with natural agents. One of the potential antimicrobial agents is wood vinegar derived from the carbonization of lignocellulosic raw materials. The objectives of the present work were to evaluate the antibacterial and antifungal action of two kinds of wood vinegar (WV), one of Eucalyptus urograndis wood and another of Bambusa vulgaris biomass, and determine their chemical profile. The antimicrobial effect was assessed against Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enteritidis, Escherichia coli, Streptococcus agalactiae, and Candida albicans. The minimum inhibitory concentration and the minimum bactericidal and fungicidal concentrations were determined. Micrographs of the microorganisms before and after exposure to both kinds of wood vinegar were obtained by scanning electron microscopy. The chemical profile of the eucalyptus and bamboo vinegar was carried out by gas chromatography and mass spectrometry (GC/MS). Both types of WV presented significant antimicrobial activity, with the bamboo one having a higher efficiency. Both studied pyroligneous extracts seem promising for developing natural antimicrobials due to their efficiency against pathogens. GC/MS analyses demonstrated that the chemical profiles of both kinds of WV were similar but with some significant differences. The major component of the eucalyptus vinegar was furfural (17.2%), while the bamboo WV was phenol (15.3%). Several compounds in both WVs have proven antimicrobial activity, such as acetic acid, furfural, phenol, cresols, guaiacol, and xylenols. Together, they are the major in the chemical composition of the organic fraction of both WVs. Bamboo vinegar had a more expressive content of organic acids. Micrographs of microorganisms taken after exposure to both kinds of wood vinegar displayed several cell modifications. The potential of both types of wood vinegar as a basis for natural antimicrobial products seems feasible due to their proven effect on inhibiting the microorganisms' growth assessed in this experiment.

Clues about wood density and trace-element variability of Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby for bioenergy use.

The interest of biofuel producers in Neotropical species that have high growth rates, slight wood density variability, and elemental composition that does not compromise the environment has increased in recent decades. We investigated the density and chemical characteristics of wood of Schizolobium parahyba var. amazonicum (Huber × Ducke) Barneby as a source for the generation of bioenergy. Apparent radial wood density profiles (X-ray densitometry (XRD)) and the elemental distribution (X-ray fluorescence (XRF)) of Cl, S, K, and Ca in the wood of nine S. parahyba var. amazonicum trees, divided into three diameter classes (I = 15.5, II = 19.5, and III = 23.5 cm) were analyzed. The high heating value (HHV) of the wood samples was determined, and the energy density was estimated by the product of the HHV and the apparent density. Trees that grew better (classes II and III) produced wood with higher density. These trees showed higher concentrations of K and S, and lower concentrations of Ca and Cl. The highest Cl concentrations were observed in classes with smaller diameters. The chlorine levels met the standards for use of this wood as fuel, but the sulfur levels were higher than the threshold recommended by the ISO 17225-3:2021 guidelines, which can limit the use of the species for certain energy uses. The wood of S. parahyba var. amazonicum had interesting characteristics for the production of bioenergy due to its low density, so it can be used in the production of solid biofuels such as pellets and briquettes. Monitoring chlorine and sulfur is important, since during the combustion of biomass they are released into the atmosphere and can negatively contribute to the effects of climate change.

Briquette production as a sustainable alternative for waste management in the tannin extraction industry.

Tannins are polyphenols that can be extracted from different parts of the plant and have different known commercial applications. The extraction of tannins generates a significant amount of low-density wastes. An alternative that can be applied to ensure energy reuse of this low-density waste is a densification process, such as briquetting. Thus, this research work aimed to assess the energy potential of the residue from the extraction of tannins of different forest species, aiming at its energy reuse in the form of briquettes. Stem barks of 6 forest species (Acacia mangium, AM; Anacardium occidentale, AO; Anadenanthera colubrina, AC; Azadirachta indica, AI; Mimosa caesalpiniaefolia, MC; Mimosa tenuiflora, MT) were used after tannin extraction. Bulk density, energy (higher, lower, and net heating value) and thermal (TG/DTG) properties, and chemical constitution (extractives, lignin, and holocellulose) of the materials were determined. In addition, briquette compaction ratio, apparent density, volumetric expansion, and water adsorption over the days were evaluated. The highest bulk densities were found in the barks of Anadenanthera colubrina (0.529 g.cm-3) and Mimosa tenuiflora (0.407 g.cm-3), whereas the species that showed the best result of higher heating value was Acacia mangium (20.44 MJ.kg-1), followed by Azadirachta indica (19.39 MJ.kg-1) and Mimosa caesalpiniifolia (18.85 MJ.kg-1). Briquetting increased the density of the evaluated material by 2.3 to 4.9 times. All briquettes produced with wastes from tannin extraction evaluated in this work showed potential for energy production. With more information on the quantification of waste generated and data on the economic viability of production, these tannin-producing industries can benefit both environmentally and economically, by reusing these wastes for energy production.

Yield loss during bleaching of pulp of Pinus radiata previously delignified with oxygen.

The pulp bleaching process removes or transforms the chromophore groups in the pulp, so that the final product reaches a desired brightness. However, this chemical treatment inevitably results in yield loss. Therefore, the objective of this work was to quantify the yield loss caused during the bleaching of kraft pulp of Pinus radiata delignified with oxygen. The material was submitted to three distinct ECF sequences (D0(EPO)D1D2, D0(EPO)D1P, and Z/EDP). At the end of each bleaching stage, the pulp brightness and the loss of gravimetric yield of the process were determined, and the generated filtrates were collected. From these filtrates, the pollutant load of the effluent was determined by measuring the content of total dissolved solids, the chemical oxygen demand, the concentration of total organic carbon carbon, and the adsorbable organic halogens. Among the whole sequences, the Z/EDP sequence had the lowest gravimetric yield, the highest pollutant load in the collected filtrate, and lowest potential for adsorbable organic halogens generation. There was good correlation between the loss of yield from the bleaching process and the organic load of the generated effluent; and among the techniques studied, the quantification of total organic carbon was the most appropriate method for the indirect quantification of the yield loss during the bleaching process of the studied material.

Physical-mechanical properties of wood panel composites produced with Qualea sp. sawdust and recycled polypropylene.

Adhesive-free wood-plastic composite panels made with lignocellulosic wastes, and recycled plastics can be a sustainable option for generating useful "green" products. The present work assessed the physical-mechanical properties of adhesive-free panels produced with Qualea sp. sawdust and recycled polypropylene (PP). Discarded PP packaging was used. The packages were washed and ground with a laboratory knife mill until particle size of 10 to 14 mesh. Qualea sp. sawdust was sieved to select particle size of 14 to 30 mesh. Four experimental treatments were assessed by varying the percentages of PP and sawdust, as follows, 60 and 40%, 70 and 30%, 80 and 20%, and 90 and 10%, in an entirely randomized design with 3 panels per treatment, totaling 12 panels. The mats were hot-pressed at 180 °C during 20 min, the first 10 min under pressure of 1.0 MPa and the remaining 10 min at 42 MPa. Physical-mechanical properties of the panels were obtained as follows: density, moisture content, water absorption, thickness swelling, moduli of elasticity and rupture, and Rockwell hardness. In general, an increase of the percentage of PP provided higher dimensional stability to the panels, but there was no significant influence on mechanical strength.