Volume 9 Issue 3

Hydrolysis experiments of five cellulose samples (separated from two aquatic plants and three terrestrial plants, respectively) were conducted at various cellulase loadings (7 to 200 FPU/g cellulose). No obvious correlation was found between CrI and hydrolysis performance at low enzyme loadings (e.g. 7 and 28 FPU/g cellulose), as the hydrolysis was controlled by enzyme availability and the differences in cellulose structure were unimportant. At a sufficiently high enzyme loading (e.g. 200 FPU/g cellulose), the yield of reducing sugar was linearly proportional to the CrI value. Therefore, to establish such a correlation between cellulose structure and hydrolysis performance, hydrolysis experiments must be conducted under the conditions where enzyme availability is not a limiting factor. It was found that celluloses from sugarcane bagasse and water hyacinth have low CrI, achieve high sugar yields, exhibit fast reactions during enzymatic hydrolysis at low enzyme loadings, and can potentially be good feedstocks for bio-ethanol production.

In this study, cellulose possessing β-cyclodextrin (β-CD) is employed as a host molecule, and cellulose possessing ferrocene (Fc) is used as a guest polymer. The properties due to the host-guest interactions are presented. The results show that β-CD-cellulose and Fc-cellulose can form inclusion complexes wherein hydrophobic interaction caused by β-CD-cellulose and Fc-cellulose significantly affect the performance of the cellulose gel. A physical gel based on cellulose that can autonomously heal between cut surfaces after 24 h was formed under mild conditions. Moreover, ferrocene redox status affects the hydrophobic interaction, such that the hydrophobic interaction can strengthen the gel strength and affect the self-healing property.

The objective of this study was to evaluate phenolic compounds produced from the catalytic pyrolysis of pine sawdust by commercial catalysts. Eight types of commercial catalysts consisting of SiO2, montmorillonite, α-Fe2O3, HZSM-5 (Si:Al = 25:1), ZnO, γ-Fe2O3, HZSM-5 (Si:Al = 50:1), and nano-HZSM-5 (Si:Al = 50:1) were screened in a fixed bed reactor at a reaction temperature of 500 °C and a vapor residence time of 3 s. All the tested commercial catalysts exhibited different catalytic performances for the adjustment of the composition of the bio-oil. HZSM-5 (Si:Al = 25:1) significantly increased hydrocarbon production in the bio-oil, which is helpful for improving its heating value. The different types of phenols were reduced significantly from 17 to 7 with nano-HZSM-5 (Si:Al = 50:1); however, the phenols content also decreased from 32.6% to 23.28% compared with non-catalytic pyrolysis. Meanwhile, the addition of nano-HZSM-5 (Si:Al = 50:1) to the raw material provided the highest amount of furans (up to 38.8%) among the tested commercial catalysts. The inexpensive ZnO and γ-Fe2O3 also were surprisingly effective for the reduction of the variety of phenolic compounds detected by GC/MS, reducing that number from 17 to 10.

Solid urban wastes are a primary source of local and global contamination. One approach to slow their accumulation is by using them to obtain added-value products. One common example of these waste materials is the fiber from the husks of coconuts, i.e. coir. However, it is also known that microorganisms such as fungi can attack products containing natural fibers. In this respect, this study aimed to evaluate how the mechanical properties of an extruded composite made of 60% recycled HDPE and 40% discarded coir were affected due to accelerated weathering and Phanerochaete chrysosporium attack. The effect of P. chrysosporium on the materials’ mechanical properties before and after weathering, using an accelerated weathering (AW) test device, was evaluated by means of tensile and flexural analysis following ASTM standards. Samples were also characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). FTIR spectroscopy and SEM showed that both types of treatment degraded the surfaces of the tested samples. However, the mechanical performance was not seriously affected, which means that other fungal species would affect the composites to a lesser extent.

In this study, Eucalyptus globulus stumpwood samples collected from six different sites in Portugal were evaluated for their ease of pulping, using two delignification processes (kraft and alkaline sulfite-anthraquinone-methanol (ASAM)). Morphologically, the stumpwood included fibers with a mean length of 0.930 mm, diameter of 21.4 µm, lumen width of 9.1 µm, and cell-wall thickness of 6.1 µm. The Runkel ratio varied between 1.0 and 1.9, and the slenderness ratio ranged between 50.6 and 35.1. ASAM pulps presented higher yields and kappa numbers (49.3% and 36, respectively) when compared to kraft pulps (42.7% and 14, respectively). Extractive-free material increased pulp yield (51.7% and 47.5% for ASAM and kraft, respectively) and decreased kappa number (18 and 11). The kraft pulps showed a coarseness of 0.096 mg/m, curl of 5.2%, and 16.7% kinked fibers, while for the ASAM pulps, these values were 0.105 mg/m, 5.2%, and 16.3%, respectively.

Phenolic-rich bio-oil can be selectively produced from catalytic fast pyrolysis of biomass impregnated with K3PO4, K2HPO4, or KH2PO4. In this study, the catalytic effects of the three catalysts on the pyrolytic product distribution were investigated and compared via analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments. The results indicated that the three catalysts were all able to inhibit the pyrolytic decomposition of holocellulose to form volatile organic products, while promoting the formation of phenolic compounds from lignin. Hence, phenolic-rich bio-oil could be selectively produced. Among the three catalysts, K3PO4 and K2HPO4 possessed similar capability to increase the yield of the phenolics, which was better than KH2PO4. The phenolic contents among the total pyrolytic products steadily increased as the K3PO4 or K2HPO4 dosage increased. The maximal peak area of the phenolics reached as high as 68.8% (at 50 wt.% K3PO4) or 50.6% (at 50 wt.% K2HPO4) of the total peak area. Therefore, based on these results, K3PO4 was the best catalyst for the selective production of phenolic-rich bio-oil.

In order to study the thermal stability of accelerated-curing PF resin, the curing behavior of fresh PF resin was investigated in the presence of single accelerator of methylolurea derivatives (MMU), magnesium hydrate (Mg(OH)2), 25% aqueous solution of sodium carbonate (Na2CO3), and propylene carbonate (PC). Also their optimum combination was added in fresh PF resin. The thermal stability of cured phenol-formaldehyde (PF) resins was studied using thermogravimetric analysis TG/DTA in air with heating rates of 5, 10, 15, and 20 °C min-1. Thermal degradation kinetics were investigated using the Kissinger and Flynn-Wall-Ozawa methods. The results show that these accelerators can promote fresh PF resin fast curing, and the degradation of accelerated-curing cured PF resin can be divided into three stages. Single accelerator MMU, Mg(OH)2, and Na2CO3 can promote fresh PF curing at low temperatures in the first stage, while the structure of PF resin which was added with MMU and PC was more rigid, according to thermal degradation kinetics. A novel fast curing agent which is compound with MMU+Na2CO3 for PF resin is proposed; not only can it maintain the advantage of fast curing of the single accelerator Na2CO3, but it also improves the thermal stability of PF resin.

One of the major steps in setting up a bioenergy utilization system is to determine the potential availability of forest biomass. This study illustrates the methodology of estimating the spatial availability of primary forest residues in naturally occurring brutian pine forests, which are considerable components of forest biomass. A spatial database system was created to respectively calculate the theoretical, technical, and spatially economical biomass potentials that were subject to limitation by stand ages, forest functions, site indexes, slopes, and distance zones. To quantify primary forest residues (PFR), the conversion rates were processed, ranging from 24.1% to 26% of allowable cut volume for early thinning, 15 to 20% for thinning, and 11.1% for final felling. The results showed that the total accumulation of theoretical primary forest residues was 86,554.7 green tons in 10 years’ time, 71% of which could be ecologically available. Furthermore, the spatially available biomass potential was 6,095.4 tons per year within a radial distance of 30 km. In the future, the proposed hierarchical process can be applied to brutian pine stands in the Mediterranean region using a larger dataset that will provide a truer representation of the regional variation.

The environmentally-friendly procedure of oxygen treatment (O) and peroxide treatment with oxygen and anthraquinone as a catalyst (Po-AQ) was studied for isolation of cellulose from bagasse pith (BP) mainly consisting of parenchyma cells. The optimal conditions were: 20% alkali dosages with 12% BP consistency at 120 °C for 3 h under 0.6 MPa initial oxygen pressure for the O step; then 8% H2O2, 20% NaOH, and 0.3% AQ charges with 8% BP consistency at 120 °C for 6 h under the same oxygen pressure for the Po-AQ step. And the optimum process was: BP pretreated by cool-water extraction was firstly O-treated, and after finishing O treatment, intermediate pulp which was manually separated from effluent, was continuously processed by Po-AQ treatment. Based on the conditions above, this process can yield 37.1% of cellulose sample, containing 7.01% hemicelluloses and 0.57% lignin. The representative samples were characterized by gas chromatography (GC), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM).

Woody debris (WD), including coarse woody debris (CWD) and fine woody debris (FWD), is an essential structural and functional component of forest ecosystems. This study was carried out in Caspian hardwood forest sites. In this study, the volume and composition of WD were inventoried by line intersect sampling and fixed area plot sampling in unmanaged and managed forests on 6 compartments (3 managed and 3 unmanaged). Estimates of the total volume of WD in managed and unmanaged forests ranged from 11.9 m3.ha-1 to 25.82 m3.ha-1, respectively. The results of independent t tests indicated that the amount of CWD in the unmanaged forests was significantly higher than CWD in the managed ones (t22, 0.05 = 2.64, P = 0.015). Also, the results of independent t tests indicated that the amount of FWD in the managed forests was significantly higher than FWD in unmanaged forests (t4, 0.05 = 5.07, P = 0.007). In the unmanaged forests, WD in decay classes 3, 4, and 5 accounted for 77% of the total WD volume, but in the managed forests, WD in decay classes 1 and 2 accounted for 87% of the total WD volume. The results suggest preserving the current unmanaged forests (protected forests) and maintaining the structural and functional integrity of woody debris.