Effect of different pre-treatments on the redispersion capacity of spray-dried microfibrillated cellulose: Elaboration and characterization of biofilms.

This study aimed to evaluate the influence of the addition of the cationic surfactant cetyltrimethylammonium bromide (CTAB) in microfibrillated cellulose (MFC/CNFs) suspensions submitted to different pretreatments to produce redispersible spray-dried (SD) MFC/CNFs. Suspensions pretreated with 5 % and 10 % sodium silicate and oxidized with 2,2,6,6,-tetramethylpiperidinyl-1-oxyl (TEMPO) were modified with CTAB surfactant and subsequently dried by SD. The SD-MFC/CNFs aggregates were redispersed by ultrasound to produce cellulosic films by the casting method. In summary, the results demonstrated that the addition of CTAB surfactant to the TEMPO-oxidized suspension was critical to achieving the most effective redispersion. The experimental results obtained using micrographs, optical (UV-Vis), mechanical, water vapor barrier properties, and the quality index confirmed that the addition of CTAB to the TEMPO-oxidized suspension favored the redispersion of spray-dried aggregates, development of cellulosic films with attractive properties, offering possibilities for the elaboration of new products, for example, in the production of bionanocomposites with higher mechanical performance. This research brings interesting insights into the redispersion and application of SD-MFC/CNFs aggregates, strengthening the commercialization of MFC/CNFs for industrial use.

Pectin-based color indicator films incorporated with spray-dried Hibiscus extract microparticles.

Colorimetric films incorporated with anthocyanins as an indicator for freshness monitoring have aroused growing interest recently. The pH-sensing colorimetric film were developed based on pectin (HM), containing aqueous hibiscus extract microparticles (HAE). HAE microparticles were obtained by spray drying with different wall materials (Inulin -IN, maltodextrin- MD and their combination). The films were obtained on large scale by continuous casting. These films were characterized for physicochemical analysis, morphological structure, thermal and barrier properties, antioxidant activity, and color change at different pH. The addition of HAE microparticles caused relevant changes to HM-based films, such as in mechanical behavior and improved barrier property (11-22% WVTR reduction) depending on the type of wall material used and the concentration added. It was verified with the thermal stability of films, with a slight increase being observed. The color variation of smart films was entirely pH-dependent. Overall, the proposed color indicator films showed unique features and functionalities and could be used as an alternative natural pH indicator in smart packaging systems.

Evaluation of Queen Palm residues and kraft lignin in the production of biofuels using densification and slow pyrolysis technology.

This study aims to enhance the energy use of two products of industry - Queen Palm residue and kraft lignin (KF) - through the combination of two technologies - briquetting and slow pyrolysis. The addition of 20% KF provided briquettes with higher physical, energy, and mechanical properties. The yields of the pyrolysis products were affected by both the pyrolysis temperature and the addition of KF. In the bio-oil, the presence of phenols, methyl phenols, and methoxy phenols was highlighted; these compounds were present in greater quantities in the treatments with KF. It is concluded that combining the briquetting and pyrolysis processes produces both energy and economic benefits because it is possible to transport lighter loads with the same amount of energy per volume. Under the briquetting conditions adopted in this study, the addition of KF as a binder is necessary because this results in briquettes with better physical, energy and mechanical properties.

Briquettes of acai seeds: characterization of the biomass and influence of the parameters of production temperature and pressure in the physical-mechanical and energy quality.

Agro-industries, leveraged by the high demand of acai products, promote environmental impact through the generation of wastes in several locals in Amazon. The use with bioenergetic purposes has capacity to mitigate these scenario. Thus, the aim of the study was to characterize the biomass of acai seeds and establish the technical parameters of temperature and pressure of work to the production of briquettes of physical, mechanical and thermal quality. Temperatures of 120, 140 and 160 °C; and pressures of 15, 20 and 25 MPa were studied. We analyzed the briquettes mechanical compressive strength, rate of water absorption, rate of volumetric expansion and energy and apparent density. To the characterization of in natura seeds, the proximate analysis, chemical composition (extractives, holocellulose and lignin contents), higher, lower and useful heating value were determined. The proximate analysis indicated biomass thermal resistance, potential to direct burning and conversion by thermochemical processes. The lignin content may increase briquettes compressive strength produced in high temperatures. It was observed that the temperature had more influence in the evaluated briquettes characteristics than the pressure. The compressive strength was greater in 160 °C and 15 MPa briquettes, indicating that the lignin works as binder in this temperature, however, with pressure improvement the resistance is not favored due to the limit of resistance to compaction. The rate of water absorption decreased with the pressure increase and the temperature statistically affected in 140 °C briquettes. We observed volumetric expansion values in consonance to other found in dense biofuels of the literature. Further, the apparent density and energy density were favored by pressure improvement and the temperature helped in the increase of the apparent density. Moreover, the produced briquettes presented gain in the apparent density regarding the in natura biomass and had energy density comparable to coal and adequate to co-firing in boilers.

Influence of particle size on the physico-mechanical and energy properties of briquettes produced with coffee husks.

Briquetting is a technology with the potential to convert agricultural wastes into solid biofuels with improved handling, transport, storage, and energy efficiency characteristics. It is important to study the variables related to the briquetting process and the raw material because these parameters can affect the quality of the final product. Thus, the objective of this study was to investigate the influence of particle size on the physico-mechanical and energy properties of briquettes produced with coffee husks. Three particle size fractions were obtained: particles larger than 1.8 mm, in the range of 1.8-1.2 mm, and smaller than 1.2 mm. The coffee husk briquettes were prepared in a densification system at 120 °C and 15 MPa for 15 min. The physical, mechanical, and energy characteristics such as apparent density, volumetric expansion, compressive strength, abrasion resistance, and energy density were determined. A combustibility test was also carried out. The results showed that particle size influenced the apparent density, compressive strength, and energy density of the briquettes. However, there was no significant difference in the volumetric expansion or abrasion resistance of the densified products among the treatments. In general, the briquettes made with particles smaller than 1.2 mm had better physico-mechanical and energy characteristics.