Research Articles

The yield and kappa number of kraft pulps from tall wheatgrass, tall fescue, tall oatgrass, and Miscanthus were determined after pulping with 0.9% active alkali per 1% lignin content in raw materials. Fibre properties and test papers were also studied to evaluate the usefulness of these plants for papermaking. These results were compared with pulps prepared from birch and pine wood. Kraft pulps from the straws of grasses had yields similar to that of pulp from pine wood and lower kappa numbers than pulps from birch and pine wood. The tested pulps exhibited a favourable number of fibres in 1 g of pulp, and they resulted in papers with clearly differentiated properties from very resistant to rupture dense papers with very low air permeability, to less resistant to breaking more bulky papers.

Corn stalk rind (CSR) was treated with Trametes hirsuta lg-9 and then refined into pulp. The biotreatment resulted in loss of paper strength and brightness, but energy consumption during refining (ECR) was reduced. Meanwhile, multiple linear regression was carried out, for which ECR served as the dependent variable, and the yield and infrared relative absorbance intensities at 3414 cm-1 and 1653 cm-1 of the biotreated CSR served as independent variables. Results showed that the determining parameters of the biotreated CSR may be used to predict the ECR. In this work, delignified corn stalk pith (CSP) was added to aspen alkaline hydrogen peroxide mechanical pulp (APMP). The CSP enhanced the strength properties of the aspen APMP and inhibited yellowing. The biomechanical pulping of CSR has the potential to produce a low-cost green pulp, and the delignified CSP can serve as a pulp additive.

Porous cellulose aerogel materials are attracting increasing interest due to their promising potential in multiple fields. In this paper, highly porous and mechanically strong cellulose aerogels were successfully prepared from microcrystalline cellulose and dissolving pulp in ionic liquid BmimCl via a sol–gel polymerization method. The surface morphology and physical properties were characterized by scanning electron microscopy, X-ray diffraction, and compression tests, etc. The differences in microstructure, crystalline structure, and mechanical performance of these two kinds of cellulose aerogels were studied and compared. Moreover, the two cellulose aerogels were used as adsorbents to remove dye, oil, and organic solvents. The kinetics and equilibrium capacity were investigated. Results indicate that the cellulose aerogels with high degrees of polymerization have much better mechanical strength and adsorption properties than the cellulose aerogels with low degrees of polymerization.

In the present work, enzymatic/mild acidolysis lignin (EMAL) was isolated from the raw material Cunninghamia lanceolata, and hydrothermal depolymerization was carried out in subcritical water (from 250 to 350 °C) using a cylindrical autoclave. The results revealed that the lowest yield of solid residue and highest liquid product yield were achieved at 325 °C. The liquid products were primarily composed of phenolic monomers and oligomers. As the reaction temperature increased, repolymerization of the liquid products and dehydrogenation and deoxidation of the solid residues occurred. The high heating value (HHV) of the residues was larger than that of the EMAL, and it reached a maximal level at 275 °C. Hydrothermal depolymerization and condensation reactions took place simultaneously even under mild conditions (250 °C). Carbonization of the EMAL was remarkable when the reaction temperature reached 325 °C.

The load-bearing capacity of joints using thin steel elements for wood buildings was considered. Six variants of a specific type of joint consisting of two wood elements in a ceiling structure joined by steel angles were experimentally tested. These variants differed in utilization of nails as well as screws (of various lengths) for wood. Another observed factor was the percentage of holes filled in the angles. In this work the percentage of holes filled means how many of the holes in the steel angles were filled by nails/screws. The evaluation characteristic was the maximum loading force at the breaking point. Based on the results, a set of recommendations for designing a specific type of joint with steel angles was formulated. The results showed that during loading of the joints, tensile stresses occur in the direction perpendicular to the fibers, which causes a failure of the wood parts of the joints.

Woody biomass is an abundant, renewable energy source. Forest residue is the fraction remaining after harvest and the outtake of wood timber, including tree tops and bark. Compared with the wood portion, bark has a wide variation of ash content. Wood usually has a relatively low ash content, while bark has considerably higher ash content, which may generate clinker in the furnace and thereby tends to create more demand for maintenance. High ash content also generates more particulate emissions. Different types of bark were studied in the present work in terms of their effect on energy content, moisture, and ash content. The ash content of three different samples (Norway spruce, birch, and European beech) were measured at 550 and 815 °C. The results showed the impact of bark content on all parameters, in particular the calorific value and ash content. The ash content increased with increasing bark content. The addition of 1% bark content resulted in increases of ash content in the range 0.033 to 0.044%.

Many herbaceous lignocelluloses suitable for ethanol production have high extractives contents, such as some straws and corn stover. The high extractives content might affect pretreatment or enzymatic hydrolysis. In this study, extractives were removed from corn stover, and then extractives-free corn stover and ordinary corn stover were respectively pretreated using a liquid hot water (LHW) method and hydrolyzed to evaluate the effect of extractives on cellulose digestibility. Extractives-free corn stover presented higher cellulose digestibility than ordinary corn stover after the same pretreatment conditions. A total of 87.3% of cellulose was digested in extractives-free corn stover, compared to 71.0% in ordinary corn stover, after pretreatment at 200 °C for 20 min. It is speculated that some water-soluble extractives could buffer H+ ions from water and acetic acid during LHW pretreatment process, reducing xylan removal. Another reason for these results might be that some extractives could condense on corn stover after LHW pretreatment, which hinders cellulose hydrolysis.

This paper describes a simple rapid staining microcolorimetric method for analytical fibre material identification using colour vectors of stained fibre material photography. The number of morphological characteristics (nM), number of stains (nS), colour information dimensionality (nDC), and picture elementary points number (npx) can play a key role in distinguishing fibre materials, correct identification, discriminatory power dP (%), and efficacy. Experiments were performed to achieve the most accurate results with a minimum volume of data; the dimensionality reduction was made experimentally by setting nM = 0, nS = 1, nDC <1, 3>, and the effect of number of pixels on the dP (%) was measured. The correct identification was achieved by less than 100 pixels when using 2 colour vectors, and by less than 50 pixels when using 3 colour vectors: R, G, and B. The real area of the pixels used for correct identification was less than 0.1 mm2 in the used model system of the cellulose fibre materials.

Pre-hydrolysis is an important step in the poplar residual slab dissolving pulp production process, as it aids in removing as much hemicellulose as possible from the cellulose fibers. In the pre-hydrolysis process, a portion of lignin also dissolves, along with the hemicelluloses. The presence of lignin in prehydrolysis liquor (PHL) is detrimental to the separation of xylo-oligosaccharide from the prehydrolysis liquor. This study researched lignin removal from PHL with three coagulating agents, namely aluminum sulfate (alum), polyaluminum chloride (PAC), and polydiallyldimethyl ammonium chloride (pDADMAC). It was found that the removal of lignin increased as the dosage of the alum, PAC, and pDADMAC increased. Additionally, the highest retention of xylo-oligosaccharide in the PHL occurred at dosages of 120 mg/L for alum and 160 mg/L for PAC and pDADMAC. The contents of the other oligosaccharides in PHL fluctuated irregularly with increasing dosages of the alum, PAC, and pDADMAC.

Trunks and stumps of various deciduous species act as natural habitats for Ganoderma lucidum. The chemical composition of their cell wall affects the development of fungal ligninolytic enzyme system as well as its ability to degrade lignin from the plant cell wall. Additionally, numerous compounds structurally similar to lignin can be degraded by the G. lucidum enzyme system which could take important roles in various biotechnological processes. The laccases, which are the dominant enzymes synthesized by G. lucidum, have been studied more extensively than the Mn-oxidizing peroxidases. Therefore, this study aimed to create the dynamics profile of Mn-oxidizing peroxidases activities in four G. lucidum strains, classifying and determining their properties depending on the cultivation type and plant residue as a carbon source in the medium, as well as to establish whether intraspecific variety exists. The findings suggest that submerged cultivation appeared to be a more appropriate cultivation type for enzyme activities compared with solid-state cultivation, and oak sawdust was a better carbon source than wheat straw. Under the optimum conditions, on day 14, G. lucidum BEOFB 431 was characterized by the highest levels of both Mn-dependent and Mn-independent peroxidase activities (4795.5 and 5170.5 U/L, respectively). Strain, cultivation type, and carbon source were factors that affected the profiles of Mn-oxidizing peroxidases isoenzymes.