Research Articles

Process intensification is a process development methodology aimed at a considerable reduction in the energy consumption and process complexity. The approach has been applied to mechanical pulping process design. A process denoted as HC-LC-S consisting of single stage high consistency (HC) refining, followed by low consistency (LC) refining and screening was evaluated in mill trials at the Holmen Paper Braviken Mill in Sweden. After LC refining, the pulp was screened, and the reject fraction was fed back to LC refining. Two HC primary refiner types were evaluated, namely single disc (SD) and double disc (DD). Double disc chip refining was more suitable than SD refining for the HC-LC-S process because of the higher light scattering and lower shives content of the final pulp. The tensile index and shives content of the pulp produced with the DD-LC-S process was similar to that of the reference process, consisting of single stage DD refining and HC reject refining, but the fibre length and light scattering were somewhat lower. The specific refining energy was approximately 200 kWh/adt lower for the DD-LC-S process compared with the reference. Additionally, the auxiliary specific energy was 100 kWh/adt lower for the HC-LC-S processes, since a number of equipment units were omitted.

The capacities of white rot fungal treatments to degrade lignocellulose and further to improve the rumen degradability were examined in two kinds of corn stover (CAU3138 and ZN01). A total of seven fungi were evaluated according to their growth rates and selective values (SV) on both stovers under 28 °C for 28 days. Then, three selected fungi were evaluated by their in vitro gas production (IVGP) as a measure of rumen fermentation capacity. The results showed that Irpex lacteus, Pleurotus ostreatus, and Pleurotus cystidiosus had high speeds of colonization and high SV on both stovers. The IVGP of the ZN01 treated with any of the three fungi was lower than that of the raw stover, and the IVGP of the CAU3138 treated with P. ostreatus and P. cystidiosus had no significant change (P > 0.05). However, the IVGP of the CAU3138 treated with I. lacteus was significantly increased (P < 0.05) and further increased as the treatment time was prolonged. This study indicated that SV was not always a good predictor for the performance of the fungus. Here, I. lacteus performed best, regarding fungal growth and IVGP of the CAU3138.

The crown architecture and structural growth strongly affect the total volume and biomass of Norway spruce trees at a specific age. The main objective of this study was to explore the branching strategy of young spruce trees growing in a highly-dense naturally regenerated forest stand. The level of branching described by the Gravelius order of the growth units, as well as the unit’s branching direction and angles were analyzed. The significant factors that influence the occurrence frequency of growth units were the branching order and their life status. The results manifested the highest frequency of growth units in the first and second order in given conditions. A significant association between the branching direction of the mother unit and the first successive growth unit of higher order was revealed. Also, the mean branching angles were influenced by the branching order and relative position of the growth unit in relation to the mother unit. The branching angle distributions were left-skewed and the angles varied between 40° and 70°. The results improve our understanding of structural development of spruce crowns and can contribute to more realistic modeling of biomass production using tree growth simulators.

Paper pulp was produced by the kraft method using sorghum (Sorghum bicolor × S. bicolor sudanense) as the fibrous raw material. Two groups were cooked using active alkali at 10% and 14%. For each group, five sulfite ratios (0, 4, 8, 12, and 16%) were used, making a total of 10 different groups that were cooked. A literature study was conducted to determine the cooking temperature, the time needed to reach the maximum temperature, and the duration of cooking time at the maximum temperature. A total of 30 batches of paper were obtained from pulps without beating and from pulps beaten at values of 35 ± 2 °SR and 50 ± 2 °SR (Schopper Riegler) freeness. The aim was to determine the most suitable alkali and sulfite ratios by conducting standard tests for the yield, kappa number, and viscosity of the screened pulps and for the papers obtained from these pulps. The highest screened yield of cooked pulp was obtained under conditions of 14% active alkali and 12% sulfite. Since the mechanical properties of the paper obtained from this pulp were satisfactory when compared with those in the literature, it was concluded that these ratios could be recommended as a condition for cooking.

Laccase pretreatment is a promising approach to degrade lignin polymer for enhanced hemicellulose extraction from bagasse. A Box-Behnken design was employed to optimize microwave-assisted alkaline extraction of hemicellulose with the aim of maximizing the hemicellulose extraction yield. The effect of laccase pretreatment on the structural characteristics of the bagasse hemicellulose was studied with scanning electron microscopy and the Brunauer-Emmett-Teller method. The results showed that the lignin content of the bagasse decreased by 7.9% and the specific surface area increased by 95.9% after pretreatment with 160 U/g laccase for 6 h. The hemicellulose extraction yield was 88.7% under the optimum conditions of 8% NaOH, 50 min, and 900 W. The interaction between the NaOH concentration and extraction time, and between the extraction time and microwave power significantly affected hemicellulose extraction from the bagasse. Overall, the laccase pretreatment was beneficial to extraction of hemicellulose from bagasse using a microwave-assisted alkaline solution.

Polyhydric alcohols are known as excellent solvents for converting the main components of lignocellulose into liquefied products. However, the substances that precipitate in water include not only lignin, but also humins, especially when the lignocellulosic raw material has a high content of carbohydrates. Therefore, the main objective of this study was to investigate the composition of water-insoluble solids from the liquefaction of oil palm trunk using the solvent polyethylene glycol (PEG)/glycerol (4:1, w/w) and by using sulfuric acid as the catalyst. The results showed that the water-insoluble components had a relatively higher average molecular weight and polydispersity than those of the water-soluble components and liquefied products. The production of sugar monomers during liquefaction led to the condensation of furan products (hydroxymethylfurfural and furfural) to form humins. In this case, the humins were incorporated with the lignin and liquefying reagent.

Bamboo hardness test standards are not available. This study developed a new test method for bamboo indentation hardness with the U-shaped cylindrical and V-shaped compression heads in bamboo rings with different lengths. The mechanical behaviors of bamboo rings under two kinds of compression heads were analyzed. The results showed that U-shaped indentation hardness and V-shaped indentation hardness were closely correlated with compression strength and that the difference between U-shaped indentation hardness and V-shaped indentation hardness was significant. However, the bamboo rings with different lengths showed no significant difference in indentation hardness.

Arbuscular mycorrhizae (AM) fungi can increase the biomass of host plants that are used as biofuel feedstock. However, little is known about the effects of AM fungi during aqueous ammonia pretreatment of biomass to remove lignin or on the enzymatic hydrolysis of cellulose. The analysis of mycorrhizal colonization (Rhizophagus irregularis or Glomus versiforme) on stems of black locust (Robinia pseudoacacia) plants in their first and second year of growth revealed that the presence of AM fungi and the growth time significantly influenced the lignin and cellulose content of untreated black locust but had no effect on the content of stems pretreated with aqueous ammonia. The presence of AM fungi and/or the growth time also affected the black locust stem structure and the chemical structure of lignin. Hydrolysis of mycorrhizal and non-mycorrhizal biomass produced similar glucose yields (except for the second-year R. irregularis biomass, which produced significantly less glucose than the other treatments). The results suggest that mycorrhizal black locust biomass is a suitable substrate for biofuel production.

This study focused on the physical and chemical characterization of Chinese maize stalk leaf ash (MSLA) calcined at 500, 700, and 850 °C and MSLA residual leaching in aqueous solutions. The grain size distribution, chemical composition, and microstructure of MSLA were investigated using a laser Mastersizer, X-ray fluorescence, and scanning electron microscopy. The ash samples obtained before and after dissolving were analyzed using X-ray powder diffraction and X-ray photoelectron spectroscopy to identify the present minerals and observe the 2p atomic orbit of surface silicon and aluminum (Si 2p and Al 2p) transformation behaviors. The zeta potential and pH values of hybrid solutions were tested for various dissolving times. Silica was the predominant component observed in the MSLA. As dissolving time increased, the pH value gradually decreased, and the zeta potentials first slightly decreased and then remarkably increased. Quartz was identified in the MSLA. Another polymorphous crystalline form of silica, cristobalite, only appeared in the 850 °C sample. The binding energies of Si 2p and Al 2p shifted, which transformed the XPS peaks after the thermal and aqueous solution treatment of MSLA. These findings can be utilized to study the application potential of MSLA in cementing systems.

This work, for the first time, identified the phytochemical constituents of leaves, fruits, stem barks, and wood branches extracted from the tree pruning wastes of Leucaena leucocephala (Lam.) de Wit. grown in Egypt, showing 49, 29, 34, and 27 phytocomponents, respectively, as assayed by gas chromatograph-mass spectroscopy (GC-MS) analysis. The major components of leaves were 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester (17.7%), betulin (15.7%), lupeol (14.7%), androstan-17-one,3-ethyl-3-hydroxy-, (5à)- (12.3%), 9,12,15-octadecatrienoic acid, methyl ester, (Z,Z,Z)- (11.6%), betamethasone (9.7%), and β-sitosterol (9.1%). The major phytocomponents of fruits were β-sitosterol (55.7%), 3beta-hydroxy-5-cholen-24-oic acid (48.7%), 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester (42.9%), lupeol (29.3%), betulin (15.8%), stigmasterol (12.8%), and campesterol (7.6%). The major phytocomponents of stem barks were 1,2-benzenedicarboxylic acid, diisooctyl ester (65.7%), β-sitosterol (27.2%), betulin (22.1%), lupeol (21.1%), and 9,12-octadecadienoic acid (Z,Z)-, methyl ester (8.8%). Wood branches contained β-sitosterol (60.1%), 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester (47.2%), lupeol (22.5%), campesterol (15.6%), and stigmasterol (14.1%). Most of the identified compounds have been reported to possess important biological activities, such as antimicrobial, anti-inflammatory, anticancer, anti-arthritic, antioxidant, and antidiabetic activities. The four constituents of L. leucocephala were statistically independent in these phytocomponents. The phytocomponents in five solvents were mixed in describing the four constituents. These constituents of L. leucocephala are potential bioresources for phytopharmaceutics.