Research Articles

Pulps were sampled from three major points of a deinking pulping line and classified as fibers fraction, fines fraction, and aqueous phase, respectively, then extracted with tetrahydrofuran (THF) or methyl tert-butyl ether (MTBE). Sticky contaminants in the extractives were examined by GC-MS analysis. The results showed that the contaminants can be grouped as adhesive substances, wood extractives, lignin-derivatives, and other organic acids, of which the adhesive substances were accounted as the major component. Contents of sticky components in each group and their removal were further evaluated according to the related unit operation. Adhesives remaining in fibers and fines fractions were removed by the post-flotation. Wood extractives and degraded residual lignins were also released to some extent from pulp fibers during heat-dispersing, and then removed during the post-flotation.

Brazil is one of the major producers of sugarcane (Saccharum officinarum) in the world and consequently produces large quantities of waste such as sugarcane bagasse, which can be used as inert support for the production of aroma compounds by SSF. The aim of this study was to evaluate the centesimal composition and particle size distribution of sugar cane bagasse, as well as its applicability as support for the production of 6-pentyl-α-pyrone by SSF. Analyses were performed in triplicate to evaluate the levels of carbohydrates, proteins, lipids, and moisture in the waste. Also evaluated were the particle size distribution and morphology structure of the sugarcane bagasse. The aroma compound produced shows that the studied waste can be used for 6PP production by Trichoderma harzianum IOC 4042 by SSF process. By kinetic production of aroma it is concluded that the seventh day of fermentation yielded the largest production of the aroma compound, as published for other studies.

The influence of a chelating surfactant, different foaming agents, cationic polyelectrolytes, pH value, and temperature on the purification efficiency of process waters from a mechanical pulp mill has been studied by flotation in a 1 L customized unit. Turbidity measurements and gas chromatography (GC) were carried out to determine the removal and characteristics of dissolved and colloidal substances (DisCo). The manganese ion content in the process waters before flotation and the metal chelate removal capacity by flotation were determined by Inductively Coupled Plasma (ICP) and Atomic Absorption Spectrometry (AAS) measurements. It was found that a 99% removal of complex bound manganese ions and a 94% decrease in turbidity of the TMP water produced at the laboratory can be achieved in a single-stage flotation with a chelating surfactant and a foaming agent. Furthermore, a 91% decrease in turbidity, the removal of up to 96% of resin and fatty acids, and 93% of triglycerides from TMP water can be obtained after application of a foaming agent.

This study evaluates the individual and interaction effects of wood extractives, acid copper chromate (ACC), and boric acid (B) on the resistance to fungus of treated wood species. Walnut (Juglans regia L.) heartwood extractives were extracted with hot water, methanol, and ethanol solvents. Test specimens were prepared from beech sapwood (Fagus orientalis) to meet BS 838 (1961) requirements, then exposed to white-rot fungus, Trametes versicolor, for 14 weeks under laboratory conditions. Extractives of walnut heartwood contributed to increased resistance against fungus attack in the presence of B preservative only. The lowest weight loss (0.12%) occurred in the samples treated with 3.5% hot water extract and 1% boric acid, and the highest weight loss occurred in the control samples (23.7%). Results indicated that there was significant difference between the weight loss and actual retention for all treatments, but there was not any significant difference between the weight loss of treatments containing B preservative. The weight loss of samples treated with hot water extract (18.32%) was less than samples treated with methanol and ethanol extracts (21.5% and 23.1%, respectively). There was significant difference between the individual and interaction effects of wood extractives on the resistance to fungus of treated wood species. An emulsified mixture of B and walnut heartwood extractives controlled decay fungus on beech wood better than the mixture of ACC and walnut heartwood extractives, but ACC alone controlled decay fungus on beech wood better than the emulsified mixture of ACC and walnut heartwood extractives.

In this study Mikania micrantha particle (MP) and fiber (MF) were added to recycled high density polyethylene (rHDPE) for producing natural fiber (or particle) reinforced plastic composites (NFRPC) by the flat-platen pressing process. The results showed that the flexural strength and stiffness of NFRPC were significantly improved through incorporating M. micrantha particle and fiber. Higher aspect ratio of reinforcement displayed stronger mechanical properties. The vertical density profile in composites significantly influenced the mechanical properties of NFRPC. A conventional V-shaped profile and a uniform vertical density profile (homo-profile) were observed in MP and MF based NFRPC, respectively. Additionally, with increasing lignocellulose content, a more uniform vertical density profile and higher wood screw holding strength were observed. These results indicate M. micrantha particle and fiber are excellent reinforcements for NFRPC applications.

The dimensional variations of green wood samples induced by organic solvents have been studied. The solvents used (ethanol, isopropanol, acetone, and acetonitrile) covered a wide range of polarity and were studied pure and in aqueous solutions over a wide range of concentrations. Samples of normal and tension wood of poplar were used in order to minimize the effect of hydrophobic extractives on the wood-solvent interactions. The evolution of wood volume and of tangential strain with the concentration of the organic solvents shows a behavior similar to gels, with a significant swelling for solutions of intermediate polarity. The similarity of volume obtained in water and less polar pure organic solvents strikingly contrasted the different effects of water and organic solvents on dry wood. Low-polarity solvents were extremely effective in the stress release of tension wood, as indicated by the pattern of longitudinal shrinkage. Solvent exchange does not affect the mesoporous structure of the cell walls of tension wood and is a promising way to reduce internal stress in wood products.

Tea (Camellia sinensis L.) fruit peel, the main byproduct during the manufacture of tea seed oil, was used as raw material for the recovery of phenolic antioxidants. The effect of ethanol concentration, extraction time, and extraction temperature on total phenolic content (TPC) and ferric-reducing antioxidant power (FRAP) of the extracts from tea fruit peel was investigated. The maximum predicted TPC (47.5 mg GAE/g dry peel) was obtained under the optimum recovery conditions (43% ethanol, 60°C, and 33 min) given by using response surface methodology (RSM). A high correlation (R2 = 0.929, p < 0.01) between TPC and FRAP value was identified by linear regression analysis. Furthermore, gallocatechin (GC) and epigallocatechin (EGC) were found to be the major individual catechins in the extracts from tea fruit peel. Ethanol/aqueous extraction has been presented as an effective method for the recovery of phenolic antioxidants from tea fruit peel.

Changbai larch (Larix olgensis Henry) is one of the main plantation species in the northern part of China, but so far its utilization has been limited to solid wood, pulping, and paper products. As part of a national initiative, the objective of this work was to develop a good understanding concerning how stand management practices affect larch wood and veneer properties. To cope with the variation of initial and final stand density, the term “relative thinning intensity (RTI)” was introduced to describe the effect of stand thinning on the resulting wood and veneer properties. Nine representative sample trees each from four stands were harvested, then trimmed and bucked. Six 1.25 m long bolts along the entire tree stem were systematically cut to peel 2.6 mm thick veneers. Clear wood specimens were also sawn from matched bolts for mechanical testing for the purpose of comparison and validation. The correlation between the main tree variables and properties of clear wood and veneer was analyzed, and the influence of RTI on key wood and veneer properties was examined and compared. A good correlation was found in density and modulus of elasticity (MOE) between larch clear wood and veneer, giving an R2 of 0.75 and 0.71, respectively. This indicates that veneering can be potentially used to characterize this larch species. The stand with the lowest RTI had the shortest rotation but yielded the best properties of both clear wood and veneer, which highlights the importance of stand management in terms of thinning.

Under certain conditions involving uneven exposure to weather, stains related to the extractives can reduce the aesthetic appeal of western red cedar in exterior applications such as fence boards, siding, and sidewall shingles. Selected chemical treatments were evaluated for their ability to inhibit the formation of extractives stain. DDACarbonate, alkyl amine oxide, and combinations thereof delayed extractives stain formation in an accelerated field test, with higher loadings having greater effect.

A woody (eucalyptus (Eu)) and two herbaceous materials (sweet sorghum bagasse (SSB) and sugarcane bagasse (SCB)) were used to evaluate the effect of liquid hot water (LHW) pretreatment on enzymatic hydrolysis of various lignocelluloses. The results showed that enzymatic hydrolysis efficiency of pretreated materials was SCB>SSB>Eu at 5% solids loading, while SSB>SCB>Eu was at 10% and 20% solids loadings. This indicated the enzymatic hydrolysis efficiency of SCB could be influenced by solids concentration. The differences in surface morphology, crystalline structure, and functional groups of pretreated samples were also examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. SEM photographs and crystallinity indexes (CrI) showed that the structural compactness was Eu>SSB>SCB for both of untreated and treated materials. FTIR spectra showed that the conspicuousness of physicochemical changes was SCB>SSB>Eu. The differences in enzymatic hydrolysis efficiency of pretreated materials can be ascribed mainly to the structural differences.