Washington Luiz Esteves Magalhães

Cellulose nanocrystals/cellulose core-in-shell nanocomposite assemblies.

We report herein for the first time how a co-electrospinning technique can be used to overcome the issue of orienting cellulose nanocrystals within a neat cellulose matrix. A home-built co-electrospinning apparatus was fabricated that was comprised of a high-voltage power supply, two concentric capillary needles, and one screw-type pump syringe. Eucalyptus-derived cellulose was dissolved in N-methylmorpholine oxide (NMMO) at 120 degrees C and diluted with dimethyl sulfoxide (DMSO) which was used in the external concentric capillary needle as the shell solution. A cellulose nanocrystal suspension obtained by the sulfuric acid hydrolysis of bleached sisal and cotton fibers was used as the core liquid in the internal concentric capillary needle. Three flow rate ratios between the shell and core, four flow rates for the shell dope solution, and four high voltages were tested. The resultant co-electrospun composite fibers were collected onto a grounded metal screen immersed in cold water. Micrometer and submicrometer cellulose fiber assemblies were obtained which were reinforced with cellulose nanocrystals and characterized by FESEM, FTIR, TGA, and XRD. Surprisingly, it was determined that the physical properties for the cellulose controls are superior to the composites; in addition, the crystallinity of the controls was slightly greater.

Near infrared spectroscopy (NIRS) as a potential tool for monitoring trade of similar woods: Discrimination of true mahogany, cedar, andiroba, and curupixá

Abstract Mahogany is one of the most valuable woods and was widely used until it was included in Appendix II of the Convention on International Trade in Endangered Species as endangered species. Mahogany wood sometimes is traded under different names. Also, some similar woods belonging to the Meliaceae family are traded as “mahogany” or as being of a “mahogany pattern”. To investigate the feasibility of the use of near infrared spectroscopy for wood discrimination, the mahogany (Swietenia macrophylla King.), andiroba or crabwood (Carapa guianensis Aubl.), cedar (Cedrela odorata L.), and curupixá (Micropholis melinoniana Pierre) woods were examined. Four discrimination models based on partial least squares-discriminant analysis were developed based on a calibration set composed of 88 samples and a test set with 44 samples. Each model corresponds to the discrimination of a wood species from the others. Optimization of the model was performed by means of the OPUS® software followed by statistical analysis software (Matlab®). The observed root mean square errors of predictions were 0.14, 0.09, 0.12, and 0.06 for discriminations of mahogany, cedar, andiroba, and curupixá, respectively. The separations of the species obtained based on the difference in the predicted values was at least 0.38. This makes it possible to perform safe discriminations with a very low probability of misclassifying a sample. This method can be considered accurate and fast.

Near infrared spectroscopy and chemometrics for predicting specific gravity and flexural modulus of elasticity of Pinus spp. veneers

In the plywood industry, the assessment of the flexural static modulus of elasticity (MOE) and specific gravity (SG) of veneers is important for quality control. The rapid assessment of these properties by near infrared (NIR) spectroscopy was examined using 312 Pinus spp solid wood veneers collected from a Brazilian plywood plant. Partial least squares (PLS) regression calibrations (based on 75% of the samples) for MOE and SG were obtained using all available wavelengths (PLS) and only statistically significant wavelengths [jack-knifing PLS (j-kPLS)]. Correlation coefficients (r) for the calibrations ranged from 0.80 to 0.83, while the ratios of performance to deviation ranged from 1.67 to 1.78. When applied to a separate test set (25% of the samples), statistics similar to those reported for the calibrations were obtained. For both MOE and SG, the j-kPLS calibrations performed marginally better than calibrations based on the full spectrum. The models constructed with only statistically significant wavelengths may be more robust as wavelength selection avoids any unnecessary information for the prediction of MOE and SG. This study demonstrates that NIR spectroscopy could potentially be used for in-line assessment of the MOE and SG of pine veneers.

Controlled release for crop and wood protection: Recent progress toward sustainable and safe nanostructured biocidal systems

We review biocide delivery systems (BDS), which are designed to deter or control harmful organisms that damage agricultural crops, forests and forest products. This is a timely topic, given the growing socio-economical concerns that have motivated major developments in sustainable BDS. Associated designs aim at improving or replacing traditional systems, which often consist of biocides with extreme behavior as far as their solubility in water. This includes those that compromise or pollute soil and water (highly soluble or volatile biocides) or those that present low bioavailability (poorly soluble biocides). Major breakthroughs are sought to mitigate or eliminate consequential environmental and health impacts in agriculture and silviculture. Here, we consider the most important BDS vehicles or carriers, their synthesis, the environmental impact of their constituents and interactions with the active components together with the factors that affect their rates of release such as environmental factors and interaction of BDS with the crops or forest products. We put in perspective the state-of-the-art nanostructured carriers for controlled release, which need to address many of the challenges that exist in the application of BDS.

Durabilidade de madeira de eucalipto citriodora (Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson) tratada com CCA em ambiente amazônico

The intense economic exploration has caused a decrease of the original stock of Amazon woody species, including those of high natural durability used in soil contact. The lack of those species results in increased price that makes economically unfeasible of the use, an alternative is the replacement by planted species of fast-growing treated with preservatives. Another advantage of to use species planted to replace the traditional species is environmental, because this will reduce the exploratory pressure on these species. The objective of this study is to evaluate the degree of biological degradation of eucalyptus citriodora wood (Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson) treated with chromated copper arsenate (CCA) under vacuum and pressure process and exposed in field experiment in Rio Branco-AC. The experiment was implemented in May 2005 with cuttings treated with CCA and not treated. The variables evaluated were: 1) degradation by fungi, 2) degradation by termites, and 3) region or part of the piece affected. After the 3rd evaluation (47 months of test), 100% of the specimens without treated were classified with the maximum degree of degradation and, in contrast, 100% of the specimens treated with CCA, after 60 months of test, were classified with the minimum degree of degradation. The parties of the pieces without treatment with the higher and the lesser degrees of degradation were, respectively, the inferior head and the aerial part above 10 cm of soil. The degradation caused by fungi was slightly lower than that of termites. The field experiment has shown that is technically feasible the use of eucalyptus wood to replace the traditional species of the Amazon.

Assessment of Nano Cellulose from Peach Palm Residue as Potential Food Additive: Part II: Preliminary Studies

High consumption of dietary fibers in the diet is related to the reduction of the risk of non-transmitting of chronic diseases, prevention of the constipation etc. Rich diets in dietary fibers promote beneficial effects for the metabolism. Considering the above and recognizing the multifaceted advantages of nano materials, there have been many attempts in recent times to use the nano materials in the food sector including as food additive. However, whenever new product for human and animal consumption is developed, it has to be tested for their effectiveness regarding improvement in the health of consumers, safety aspects and side effects. However, before it is tried with human beings, normally such materials would be assessed through biological tests on a living organism to understand its effect on health condition of the consumer. Accordingly, based on the authors’ finding reported in a previous paper, this paper presents body weight, biochemical (glucose, cholesterol and lipid profile in blood, analysis of feces) and histological tests carried out with biomass based cellulose nano fibrils prepared by the authors for its possible use as food additive. Preliminary results of the study with mice have clearly brought out potential of these fibers for the said purpose.

Caracterização Física e Térmica de Compósito de Poliuretano Derivado de Óleo de Mamona Associado com Partículas de Bambu

Composites of Polyurethane (PU) resin derived from castor oil and bamboo particles (Dendrocalamus giganteus) were prepared by pressing with 10, 15 and 20% weight of PU. The aim of this study was to develop a new application of wastes from bamboo manufacture, minimizing the negative impact to the environment, adding a resin free of volatile organic compounds (COV). The composite characterization was performed with physical and thermogravimetric analysis. The association of PU and bamboo particles produced the expected effects, including a decrease in moisture content, swelling and water absorption as PU percentage increased. The Shore D hardness increased with the percentage of resin PU in the composite.

Changes of wettability of medium density fiberboard (MDF) treated with He-DBD plasma

Abstract The effects of two power levels (50 and 150 W) and five time levels (10, 20, 40, 60 and 120 s) of glow discharge in helium dielectric barrier discharge (He-DBD) has been investigated in the context of surface modification of medium density fiberboard (MDF) panels. He-DBD elevated the surface wettability of MDF panels as assessed by dynamic contact angle (CA) measurements including the determination of surface free energy, droplet volume and spreading contact area of droplets. The chemical changes of the MDF surfaces were also characterized by X-ray photoelectron spectroscopy (XPS). Expectedly, the apparent CA and droplet volume decreased with increasing power and time of glow discharge, mainly at the 150 W power level. The oxygen content of the surfaces, the surface free energy and the spreading contact area increased upon treatment. At higher energy levels the treatment time could be reduced, which is essential for future applications in industrial processes.

Pre-treatment of eucalypts biomass towards enzymatic saccharification

Background There are a few possible ways to produce ethanol from lignocellulosic biomass, for instance, thermochemical and acid hydrolysis. However, enzymatic hydrolysis of carbohydrates is considered the greenest process for saccharification, followed by sugar fermentation into ethanol. The main challenge of the enzymatic saccharification process is that cellulose is not exposed to the enzyme action in the lignin matrix. The cellulose molecules are arranged in semi-crystalline nanofibrils immersed in lignin matrix with hemicelluloses (polyoses) and extractives between them acting as coupling agents. These nanofibrils are placed together to form helical microfibrils inside the cell wall. Thus, a pre-treatment is necessary to make room for the enzymes to reach the cellulose fibril surfaces in order for the whole process to become economically feasible. There are many pre-treatments proposed in specialized literature, but their efficiencies are dependent on the biomass composition [1-4]. Moreover, these treatments have to address some constraints such as the recyclability of the chemicals used, low consumption of energy, and sustainability concerns. We devised a future possibility of a cellulose pulp mill to be transformed into a biorefinary, where besides cellulose pulp, ethanol could also be produced. In the Brazilian pulp mill industry, the process most commonly used is the Kraft process, so the digestion with green and white liquors can be adapted for pre-treatment towards enzymatic saccharification. Also, the industry had already tackled recycling of the black liquor – obtained after wood chips digestion –, recuperating thermal energy by burning lignin and recovering the green liquor. This work is part of our research to evaluate some modifications on the green liquor digestion towards enzymatic saccharification. We evaluated efficiencies of some pre-treatments with green liquor through enzymatic hydrolysis for holocellulose saccharification.

Controlled biocide release from hierarchically-structured biogenic silica: surface chemistry to tune release rate and responsiveness

Biocides are essential for crop protection, packaging and several other biosystem applications. Therein, properties such as tailored and controlled release are paramount in the development of sustainable biocide delivery systems. We explore the self-similar nano-organized architecture of biogenic silica particles to achieve high biocide payload. The high surface area accessibility of the carrier allowed us to develop an efficient, low energy loading strategy, reaching significant dynamic loadings of up to 100 mg·g−1. The release rate and responsiveness were tuned by manipulating the interfaces, using either the native hydroxyl surfaces of the carrier or systems modified with amines or carboxylic acids in high density. We thoroughly evaluated the impact of the carrier-biocide interactions on the release rate as a function of pH, ionic strength and temperature. The amine and carboxyl functionalization strategy led to three-fold decrease in the release rate, while higher responsiveness against important agro-industrial variables. Key to our discoveries, nanostructuring thymol in the biogenic silica endowed systems with controlled, responsive release promoting remarkable, high and localized biocidal activity. The interfacial factors affecting related delivery were elucidated for an increased and localized biocidal activity, bringing a new light for the development of controlled release systems from porous materials.