Research Articles

In the conversion process of lignocellulose into fuel ethanol, the enzymatic hydrolyzed or fermented lignocellulosic residues are produced as byproducts. In order to further recycle these byproducts, this study used the enzymatic hydrolyzed residues of sugarcane bagasse (EHR-SCB) as the media for culturing Lentinula edodes. The sugarcane bagasse (SCB), pretreated by liquid hot water (LHW), was hydrolyzed for 120 h with cellulase to obtain the EHR-SCB. The EHR-SCB was mixed with wheat bran and gypsum powder in a certain proportion to make six kinds of media. The media containing 50% and 60% EHR-SCB could cultivate Lentinula edodes, due to their rational ratio of carbon to nitrogen and mineral contents. Compared with Lentinula edodes sold in the market, the one cultured in the medium containing 50% EHR-SCB had a little higher content of amino acids except cysteine and proline, and mineral elements except zinc, while that cultured in the medium containing 60% EHR-SCB had a lower content of amino acids except serine, glutamic acid, glycine, methionine, tyrosine, and arginine, and mineral elements except selenium, copper, chromium, and manganese. After harvesting Lentinula edodes, the mushroom residues might be further used as media for obtaining value-added products or composting for manure.

Trace elements, at tolerable concentrations, are either part of the active site or act as an activity modulator of ligninolytic enzymes of white-rot mushrooms. They are usually in plant raw materials in a non-toxic amount or non-available and extractable forms. This study evaluated the effects of Fe, Zn, and Se on the activity of laccase and Mn-oxidizing peroxidases of P. ostreatus and P. pulmonarius during solid-state fermentation of grapevine sawdust. The studied species showed different levels of tolerance to the trace elements. A stimulatory effect of the microelements on laccase activity was demonstrated in P. ostreatus, while Fe and Zn were strong inhibitors of the activity of P. pulmonarius, which was contrary to Se, independent of the cultivation period. With the exception of SeO2, activity of Mn-oxidizing peroxidases in P. ostreatus was suppressed in various levels by the elements. However, in P. pulmonarius, activity against phenol red oxidation in the presence of external Mn2+ was stimulated by the elements on day 7, while on day 10, activity inhibition by Fe and Zn and stimulation by Se was noted. The effect on activity against phenol red oxidation in the absence of external Mn2+ was the opposite.

Wheat straw pulp can be considered to be one of most important raw materials for specialty and functional paper products. Bleaching sequences involving laccase and xylanase were applied to bleach wheat straw pulp. The bleached pulp properties after a sequence of xylanase (X), laccase (L), and extraction (E), i.e. XLE, were compared with those of LE and LEX sequences. It was found that the XLE bleaching sequence was the most suitable sequence for laccase and xylanase synergetic biobleaching. The bleaching results of OXLEQP and OQP beaching sequences (where O stands of an oxygen stage, Q indicates a chelation stage, and P means peroxide) were compared. For a specific target brightness level of over 80% ISO, XL pretreatment was found to save 28.6% of the H2O2 requirement and increase the viscosity by 6.7% compared with the OQP bleaching sequence. It was also found that synergetic biobleaching could decrease the consumption of refining energy. There were no detectable adsorbable organic halides found in the biobleaching effluents.

The aim of the present study was to determine the surface roughness of heat-treated Scots pine (Pinus sylvestris L.), Eastern beech (Fagus orientalis L.), Uludağ fir (Abies bornmülleriana Mattf.), and sessile oak (Quercus petraea L.) wood material samples following planing by the cutters of a horizontal milling machine. The samples that were heat-treated at 140 ºC or 160 ºC for 3, 5, or 7 hours were then processed by star blades or razor blades, which are the most frequently used blade types in a milling machine. The surface roughness of the samples was determined by a touch (spined) scan device (TIME TR200), as indicated by the ISO 4287 principle. The results of the study indicate that heat treatment decreases the surface roughness value of the wood material and a significant difference in surface roughness cannot be detected between planing using the razor blade or the star blade.

Xylan, the major component of hemicellulose in hardwoods and various grasses, has great potential for bio-refinery applications such as the production of energy and high value-added chemicals. A convenient and environment-friendly catalytic process for the conversion of xylan into furfural in ultrapure water using chromium-loaded perovskite-type oxides as the solid catalyst has been investigated. The crystalline and morphologies of the catalysts were studied by X-ray diffraction analysis (XRD) and scanning electron microscope analysis (SEM), and the reactions were optimized by varying different parameters. It was found that LaCo0.8Cu0.2O3 modified with 1.5wt% chromium had the highest catalytic activity in the transformation of xylan to furfural at a temperature of 433 K in a 1:600 weight ratio of xylan to hyperpure water for 10 h; the corresponding yield was 21.2% for furfural. Furthermore, a possible mechanism for the dehydration of xylan to furfural using Cr-LaCo0.8Cu0.2O3 as a catalyst is proposed.

Specific Edge Load (SEL) and Specific Energy Consumption (SEC) are nowadays the most popular parameters for defining the intensity of pulp refining. As a result, these factors are widely used in industrial practice. The purpose of this research was to determine limitations connected with use of these parameters during bleached kraft pulp refining. Performed tests showed that, despite keeping the SEL and SEC at constant level, changes of pulp refiner consistency always modified the character of the refining process. Obtained results showed that neither SEL nor SEC are fully reliable parameters to describe and to control the refining process.

This work explores the use of mechanical (MP), thermomechanical (TMP), and chemi-thermomechanical (CTMP) pulps from orange tree pruning fibers (OPF) as reinforcing elements of polypropylene (PP) composites. Due to the nature of the natural fibers, the use of a coupling agent is needed to attain a good interface and to prevent fiber slippage from the matrix. The main objective of the present work was to investigate the orientation factor, the interfacial shear strength, and the intrinsic strength of the OPF. Coupled and non-coupled composites were formulated and tested, optimizing the coupling agent content with the objective of maximizing the tensile strength of the composites. Hirsch and Kelly-Tyson models and the Bowyer-Bader methodology were used to compute the micromechanic properties. The contribution of subcritical, supercritical fibers, and matrix were also calculated.

A simple one-step method was developed for rapid separation and quantification of the linear xylo-oligosaccharides (XOS) and cello-oligosaccharides (COS) mixtures by using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). By exploiting small ion-exchange behavioral differences of various oligosaccharide components on the CarboPac PA200 column, a two-stage binary gradient elution program of NaOAc-NaOH solution was established. Subsequently, nine linear oligomers were separated simultaneously and readily within 30 min, in the order of: xylobiose, cellobiose, xylotriose, xylotetraose, cellotriose, xylopentaose, cellotetraose, xylohexaose, and cellopentaose. The method was applied successfully in the analysis and determination of different lignocellulosics processing products. The system provides a convenient and powerful analytical tool for technical research and development on polysaccharide components bioconversion in lignocellulosic biomass processing.

The effect of filler modification using methacrylic acid (MAA) on polypropylene (PP)/cocoa pod husk (CPH) composites was studied. The performances of unmodified and modified PP/CPH composites were analyzed for torque development, tensile properties, and thermal properties. The presence of MAA increased the stabilization torque of the PP/CPH composites. The tensile strength and modulus of the modified PP/CPH composites were improved compared to unmodified PP/CPH composites, but the elongation at break was reduced. The crystallinity and thermal stability of the PP/CPH composites increased after modification with MAA. All the composite property changes were due to the improvement in filler-matrix adhesion and this was confirmed by scanning electron microscopy (SEM).

Bio-fibers have been used for some time to reinforce thermoplastic composites; such structures are being used in a variety of commercial applications. In this study, wood fiber and flax fiber were used to reinforce high-density polyethylene (HDPE) formed by extrusion. The flexural, tensile, and impact resistance properties of the resulting flax fiber/wood fiber/HDPE (F/W/HDPE) composites were measured and modeled as a function of the volume fraction of flax fiber. Finally, the correctness of the modified model was verified. Based on the measurement data, the volume fraction of flax fiber was shown to play an important role in determining the mechanical properties of these composites. With increasing flax fiber volume fraction, the flexural strength, tensile strength, tensile modulus of elasticity, and impact resistance of the composites generally increased. However, the flexural modulus decreased. Based on the rule of mixtures (ROM) model, two coefficients were introduced and a new curve-fitting model was established based on measurements of macrostructure. Compared with the traditional ROM model, the new model developed in the present study could describe the flexural strength, tensile modulus, and impact strength of F/W/HDPE composites more accurately.