Research Articles

Alkaline darkening has a negative effect on chemimechanical pulps produced from various eucalypt chips. For instance, the pulp’s brightness has been found to drop rapidly when alkali addition exceeds its optimum amount. Therefore, to compare the effects of different media on brightness gain, eucalypt mechanical pulps were bleached using a typical peroxide bleaching sequence in a water medium and in an ethanol-water (E/W) medium. Various pulp brightness levels and changes of residue chemicals in the spent bleaching liquors were investigated. Compared to water medium, the net brightness gain notably increased when using the E/W medium at the same chemical dosages. The rate of pulp brightness loss caused by increasing alkali dosage dropped in the E/W medium. Analyses based on ultraviolet-visible diffuse reflectance spectra of bleached pulps, as well as gel permeation chromatography and pyrolysis-gas chromatography-mass spectrometry spectra of the residues in the spent bleaching liquors, indicated that the contributions to brightness improvement from ethanol-water media could be explained by the selective dissolution and removal of phenolic- or guaiacyl-structured lignin fragments that result in the formation of chromophoric groups under alkaline conditions.

Biomass pyrolysis technology has important developmental prospects for biofuels and chemicals. Biochar as one of main pyrolysis products has excellent performance in soil improvement and adsorption of harmful elements. The environmentally persistent free radicals (EPFRs) in corn stalk powder and biochar obtained by pyrolysis at different temperatures were tested by electronic paramagnetic resonance spectrometry. After pyrolysis treatment, the biochar had a large number of stable free radicals. With increased pyrolysis temperature, the peak width of the free radicals signal in biochar decreased remarkably, and the widest peak of free radicals signal in biochar was presented at 450 °C, which was 0.69×10-4 T. The g-factor of free radicals in biochar decreased continuously as the temperature increased, while the peak height of free radicals first increased and then decreased. The peak height at 600 °C was only 23.8% of the peak height at 500 °C. The concentration of EPFRs in biochar increased with the increase of temperature from 450 °C to 500 °C, while it decreased at higher temperature (>500 °C). This phenomenon was similar to the trend of bio-oil collection efficiency. The experimental results showed a correlation between EPFRs of biochar and bio-oil yield at different pyrolysis temperatures.

The ink-absorption capacity is an important factor for evaluating the printing quality of paper. In this study, the effects of different parameters of papermaking on the ink-absorption capacity of paper were investigated. The results showed that hardwood pulp exhibited better performance in increasing the absorptivity of paper compared with softwood pulp. When the content of hardwood pulp in paper was increased from 0% to 100%, the ink mark length decreased from 5.1 cm to 4.3 cm. Furthermore, a basis weight change from 100 g/m2 to 60 g/m2 increased the ink-absorption capacity, as revealed by a decrease of the ink mark length from 4.8 cm to 4.4 cm. Both sizing agent and beating degree affected the ink-absorption performance of the paper. For example, a shorter ink mark length of 5.1 cm was obtained at a low beating degree of 5000 r compared with that of 5.1 cm at 15000 r.

Time-domain nuclear magnetic resonance (TD NMR) technology has been used for pore detection in porous materials for a long time, but there are few pore detection methods for microporous-mesoporous materials. The surface of different materials is obtained by pore detection of known pore materials. Relaxation rate, which obtains aperture information, has an important practical significance for the application of time-domain NMR technology in the characterization of porous materials. In this study, the T2 peaks of pores of known pore size materials, namely zeolite molecular sieves (0.3 nm and 1 nm) and anodized aluminum porous membranes (30 nm and 90 nm), were used to calculate the pore surface relaxation of zeolite molecular sieve with 0.3 nm pore size and 1 nm pore size. The ratio of the rate of the surface is 3.379; the ratio of the pore surface relaxation ratio of the 30 nm and 90 nm apertures of the anodized aluminum porous film is 3.031. This result is very close to the pore size ratio, indicating that the surface relaxation rate of the same material is directly related to the pore size, while the T2 peak can qualitatively measure the pore size.

The forest products industry is one of the most powerful industry branches of Turkey, and as in other developing countries, Turkey has a persistent trade deficit. The present paper aims to evaluate the forest industry products of Turkey regarding their economic contribution by Entropy-TOPSIS, which is a hybrid multicriteria decision making method. The evaluation was done to specify the products which will be able to create currency inflow most for reducing the trade deficit and help economic development. According to computations, the most contributing products are medium-density fiberboard (MDF), high-density fiberboard (HDF), industrial roundwood, and particle board. In addition, household and sanitary papers, as well as other paper and paper board products were found to have great economic potential.

To reveal the effects of vascular bundle and sheath-node tissues on mechanical strength, moso bamboo (Phyllostachys pubescens) was investigated via compression, bending, and tension tests. Quantitative analysis was applied on vascular bundle and sheath-node tissues using a mosaicking technique and Image-Pro Plus 6.0 software. Based on the analysis of internode and node specimens, it was found that 1) there was a significant difference between the tissues proportion and mechanical strength. A high tissues proportion resulted in a high compression strength, tension strength, and modulus of rupture, but a low modulus of elasticity. 2) There was no significant correlation between the tissues proportion and failure modes. 3) The presence of a bamboo node decreased the modulus of rupture, modulus of elasticity, and tension strength, but it did not affect the compression strength. 4) A bamboo node increased the likelihood of brash tension failure in the bending test and splintering tension failure in the tension test, but decreased the probability of splitting failure in the compression test. 5) The effects of bamboo node on strength were due to the irregular sheath-node and undifferentiated vascular bundles.

The charring properties and temperature profiles were studied for laminated bamboo exposed on one-side to ISO 834 fire. A linear model was adopted to represent the charring depth-time relationship. The average charring rate of laminated bamboo was around 1 mm/min, and the charring rate decreased as the total time increased. The temperature of the char front was approximately 270 °C, which was determined via analysis of the time-temperature curve. An additional mathematic model was developed to predict the temperature distribution in the uncharred zone under such conditions, and an abrupt change in temperature was witnessed near the char front. When compared to several different timber species found in previous literature and fire resistance standards, the charring rate of laminated bamboo was relatively high; therefore, future research should focus on way to strengthen the fire retardancy of laminated bamboo.

Pot experiments were conducted to investigate the impact of biochar loading level on soybean growth and physico-chemical properties of alkaline soil. Biochar derived from corn straw was mixed with alkaline soil at 0%, 2.5%, 5%, and 10% loading levels and exposed to the natural elements. Soybean was used as the test crop. The results indicated that a single application of biochar positively and significantly improved soybean productivity and quality attributes of the tested alkaline soil. Soybean yield peaked at 5% loading level, but it declined at 10% loading. Applications of biochar at 5% and 10% loading significantly increased total soil porosity by 4.14% and 5.09%, and decreased the soil pH value by 0.07 and 0.24 units, respectively. Biochar addition significantly increased water holding capacity, total organic carbon content, total nitrogen, Olsen-P, available potassium, and cation exchange capacity. The results indicated that applications of corn straw biochar to alkaline soil improved soybean growth and promoted the physico-chemical properties of alkaline soil. However, the negative effects of increased C:N ratios and soil exchange sodium percentages at higher biochar loading levels should be taken into account when applying biochar as amendments to alkaline soils.

The utility properties of paper are dependent on the modification of the structure of the cellulose fibers, which is achieved via refining. The most important outcomes of the refining process are changes in the internal fibrillation and the shortening of the cellulose fibers. There are numerous opinions published in literature describing the relationship of these parameters and their impact on the final paper properties. These publications have been primarily based on the results of measurements conducted using insufficiently precise methods and simple speculations. The authors of this work decided to determine the effect of the refining intensity on the progress of internal fibrillation and shortening of cellulose fibers and the interrelation between these effects. Refining was performed with a laboratory Hollander beater, which was able to apply different refining loads. Utilizing additional control equipment, the specific edge load was also calculated. Finally, the impact of the refining effects (fibrillation and shortening) on the final properties of the paper were investigated.

The influence of different heat treatment levels on the contents of alkylresorcinol and homologues (ARs) was evaluated using wheat bran from two different wheat cultivars. The ARs in the wheat bran were destroyed by all heat treatments investigated in this study (oven treatment, microwave treatment, autoclave treatment, and extrusion treatment). The results showed that the loss rate of ARs by different heat treatment was oven treatment > autoclave treatment > extrusion treatment > microwave treatment, indicating that microwave treatment was more suitable for stabilizing wheat bran than the other three heat treatments. Both temperature and time of heat treatment had effects on the ARs of wheat bran. Higher temperatures and longer times of the treatment resulted in higher loss rates of ARs of wheat bran. The thermal stability of ARs homologues was different between wheat varieties, which may result from the variance of their structure and other components in wheat bran.