Volume 15 Issue 2

Static and dynamic effects of palm leaf stem stalk (PLSS) powder were investigated relative to the bi-directional palm stalk fiber reinforced epoxy composites. The PLSS bio-filler was incorporated into the epoxy resin by varying its content from 0 to 15 wt%. The hybrid palm-epoxy composites were manufactured using the hand-lay-up technique followed by light compression molding. The results for the mechanical properties of the PLSS particle (15 wt%)/palm/epoxy composites indicated an improvement in the tensile modulus, flexural modulus, and impact strength by approximately 33, 32, and 21%, respectively, when compared to the palm/epoxy composite. The dynamic mechanical analysis (DMA) of the composites showed an enhancement in the storage modulus, loss modulus and damping capacity (tan ) by approximately 75, 95, and 47%, respectively, when compared to the palm/epoxy composite. The fiber-matrix interaction was studied using a Cole-Cole plot analysis. The swelling and degradation resistance of the composites was increased with filler addition.

Wood has been used in many areas including the marine environment due to its important properties. However, marine borers cause damage that shortens the service life of wooden materials. Marine borers have a wide distribution and employ different attack mechanisms depending on the geographical region. In this study, wood samples prepared from the Pinus sylvestris L. species were subjected to marine exposure for seven months in the Eastern, Central, and Western Black Sea Regions. Results showed that Teredo navalis marine borer was observed in all three regions. The N, Mg, S, Cl, Ca, Fe, Zn, and Pb content of the samples noticeable increased after the marine trial. According to Fourier transform infrared analysis, carbohydrate content of the samples decreased noticeable, while lignin content increased.

An innovative experimental protocol is presented, linking a nondestructive (on computed tomography scanner) and destructive approach (bending test on electrostatic press). This study aimed to evaluate the annual growth ring’s impact on the mechanical behavior of wood. The tests were carried out on temperate specimens (Pseudotsuga menziesii and Abies alba Mill) from the Massif Central Region of France and tropical specimens (Aucoumea klaineana Pierre, Milicia excelsa, and Pterocarpus soyauxii) from Gabon. The connection between the mechanical parameters, taken from these tests and their structural characteristics, are also highlighted. Based on these results, a database was formed of the annual growth ring’s impact on the mechanical characteristics of these species. A link was found between the annual growth ring and the mechanical and physical characteristics of the species. The number and width of the earlywood ring and its mechanical properties were also investigated for each type of species. This comparison and the link highlighted was possible due to the study of the impact of dry density’s specimens, considered in this work as an adjustment parameter on the study of the mechanical behavior of these species.

The co-gasification of wheat straw and wet sewage sludge for hydrogen-rich gas production was investigated in a fixed bed reactor with corn stalk char (CSC)-supported catalysts. The Ni/CSC, Ni-Fe/CSC, and Ni-Fe-La/CSC catalysts were characterized via ultimate analysis, X-ray fluorescence, thermogravimetric, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, and Fourier transform infrared spectroscopy analyses. A series of experiments were performed to explore the effects of reactor temperature, catalyst type, moisture content of wet sludge, and catalyst recycling performance on the composition and yield of gasification gases. The experiments demonstrated that the nickel-iron alloy (Fe0.64Ni0.36) was detected in the Ni-Fe-La/CSC catalyst, and the Ni-Fe-La/CSC catalyst showed much higher hydrogen production compared with the Ni/CSC and Ni-Fe/CSC catalysts. Furthermore, La2O3 effectively maintained the catalytic performance of the catalyst by relieving carbon deposition. Compared with non-catalyst biomass gasification, H2 yield increased from 3.80 mol/kg to 11.96 mol/kg using Ni-Fe-La/CSC catalyst at 600 °C. The newly developed tri-metallic Ni-Fe-La/CSC catalyst exhibited high catalytic activity for biomass gasification at low temperature.

Climate change with more frequent extreme weather events and prolonged winter periods with un-frozen, wet soil is causing frequent wind damage events in forests. Trees with higher mass point and heavier weight are more prone to wind damage; however, limited information exists on distribution of biomass under naturally moist conditions. Such information is essential to improve models of wind damage prediction. Therefore, the aim of the present study was to assess the biomass distribution and the parameters important for wind-load of Norway spruce (Picea abies (L.) Karst.). Samples were collected in the year 2019 from 87 trees growing on two different sites, corresponding to freely drained mineral and peaty mineral soils at the age of 55 and 88 years, respectively. Tree diameters at breast height, height, and height of first living branch were measured. Tree stems were pruned and cut into 2-m-long fragments and weighed (fresh weight) afterwards. A biomass distribution model was developed to estimate fresh weight of the stem of Norway spruce using easy measurable tree variables. Relative height of the mass point and height of living branches were higher in peaty mineral soil than on freely drained mineral soil, which was an indicator for higher windthrow risks.

Prehydrolysis kraft pulping is an effective approach to produce dissolving pulp, which can be used for viscose application. The prehydrolysis process using hot liquid water could remove hemicellulose and loosen the compact cell wall, thus facilitating subsequent pulping and bleaching processes. In this study, the composite severity factor (CSF) was used to reveal the intensity of prehydrolysis treatment and its effect on the pulping and bleaching process by combining the temperature, time, and pH variables. Results showed that the optimum CSF was 6.61, which produced a pulp with α-cellulose of 92.3%, degree of polymerization (DP) of 1081, brightness of 85.1% ISO, and Kappa number of 0.61. In addition, the fiber quality, crystalline structure, and microstructure of pulps were characterized by FQA (fiber quality analysis), XRD (X-ray diffraction), and SEM (scanning electron microscopy).

The aim of this study was to investigate the developmental physiology of sweet chestnut trees (Castanea sativa Mill.) of different age groups (≥ 25, ≥ 50, ≥ 100, ≥ 200, and ≥ 400) in the Catalzeytin district of Kastamonu, Turkey. For this purpose, photosynthetic pigments, proline, total soluble protein, glucose, sucrose, total soluble carbohydrate and starch values, malondialdehyde (MDA) and hydrogen peroxide (H2O2) concentration, and also ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD) activities were measured in leaf samples. Hence, significant differences were found in the amounts and concentrations of all types of chlorophyll, carotenoid, proline, total soluble protein, glucose, sucrose, total soluble carbohydrate, starches, MDA, H2O2, APX, CAT, and SOD among the trees of different age groups. While the chlorophyll a value was low in young trees, the chlorophyll b value was low in older trees. It was determined that the MDA content was high in old trees, whereas it was low in young trees. While the amounts of glucose, sucrose, total soluble carbohydrate, and starch were highest in ≥ 400-year-old trees, they were lowest in the young trees. Both APX and CAT activities were high in young trees, whereas SOD activity was lowest in ≥ 400-year-old trees.

The aim of this study was to investigate degraded birch trees (Betula pendula Roth) that suffered from a harmful fungus called Piptoporus betulinus. The main chemical analysis of B. pendula degraded by the fungus, included the holocellulose, alpha-cellulose, and lignin contents and was determined in cold and hot water and alcohol-benzene solubility in 1% NaOH mixtures. This fungus caused B. pendula to lose mass and chemical properties. The declining amount of holocellulose mass loss was 6.7% according to the holocellulose test. This decrement caused the quality of the birch holocellulose to decline. The total loss difference was 9.8% according to the alkaline solubility analysis of the 1% NaOH test and 14.3% according to the density analysis of the test. The loss difference was 4.2% according to the alcohol-benzene analysis of the test.

Achieving mild and efficient extraction of high purity lignin from corncob acid hydrolysis residue is essential for efficient lignin application. In this study, enzymatic/mild acidolysis lignin (EMAL) and deep eutectic solvent (DES)-lignin were extracted from corncob acid hydrolysis residue. The structural features of the two lignin fractions were investigated by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), and 31P-nuclear magnetic resonance (31P-NMR). The highest DES-lignin yield of 58.8 wt% was achieved at 120 °C with a choline chloride-to-lactic acid (ChCl-to-Lac) molar ratio of 1:10 and a reaction time of 12 h. The FTIR analysis indicated a higher amount of guaiacyl units in EMAL than DES-lignin. Furthermore, condensation and fragmentation occurred simultaneously under DES pretreatment, but the fragmentation reaction was dominant. The structural characteristics investigated will allow for more effective lignin usage.

Volatile compounds are released when bamboo culms are used as eating utensils. Volatile compounds of Dendrocalamus latiflorus, Phyllostachys pubescens, and P. makinoi culms were extracted using solid-phase microextraction (SPME). The bamboo culms were steamed or baked at different temperatures (100 °C and 230 °C) and durations (5 min, 30 min, and 60 min). Gas chromatography-mass spectrometry (GC-MS) analyses showed that, regardless of heating method and duration, P. makinoi culms comprised the most species of volatile compounds, with sesquiterpenes being the major compounds. Steaming and baking D. latiflorus culms at 100 °C for 30 min yielded more volatile compounds than baking at 230 °C. Benzenoids were the chief compounds in heated D. latiflorus and P. pubescens culms, with phenylacetaldehyde being the dominant constituent. Phenylacetaldehyde has fragrances of herb, flower, and oil. Moreover, the major volatile compound cyclosativene, which gives a terpene-like aroma, was obtained when P. makinoi culms were heated for different durations. After baking at 230 °C for 30 min, the major volatile compound released from P. makinoi culm was α-muurolene (41.19%), which produces a woody aroma. After continuous baking for 60 min, DT 1, a kind of diterpene compound, increased remarkably in relative content, while the content of α-muurolene decreased notably.