Volume 12 Issue 1

The results from Voith Sulzer refining, porosity, and morphology studies of bleached Pinus radiata fibers showed the main effects described for hornification in dried pulps compared with never-dried pulps. Dried pulps showed higher deformations, measured as an increase in kinks. However, these deformations were shown to be reversible, based on zero-span development after Voith Sulzer refining. It is hypothesized that the observed changes in refining energy, drainability, tensile, zero span, bulk, and optical properties upon drying can be explained based on a combination of mechanisms including delamination and microfibril disarrangement and aggregation in the cell wall. Results suggested that drying-induced deformations and changes in orientation of fiber wall segments were similar to those observed in processing. Solute exclusion and nuclear magnetic resonance results also confirmed expected decreases in pore volume and average pore size for dried pulps (pores under 220 nm in size) and increase in cellulose inner crystallinity upon drying.

The solubility of four lignin samples and their acetylated forms was determined in a series of organic solvents to investigate the relationship between solubility and the solubility parameter. The solubility parameter of lignin samples and acetylated lignin was calculated based on the number of atoms or groups on lignin units. Lignin samples were obtained by isolating lignin from lignocellulosic bioethanol residues (Lignin 1 [L1]), isolating lignin from kraft hardwood black liquor (Lignin 2 [L2]), commercial kraft softwood lignin (Lignin 3 [L3]), and commercial soda non-wood lignin (Lignin 4 [4]). The solubility of lignin in organic solvents was not predictable due to poor correlation between the solubility of lignin and its solubility parameter. However, the solubility of lignin in an organic solvent depended on the molecular weight and the aliphatic hydroxyl number of the lignin. L2, with a lower molecular weight than other lignin samples, had the highest solubility in organic solvents, and L3, with highest aliphatic hydroxyl number, had the lowest solubility in organic solvents. All acetylated lignins were soluble in most of the organic solvents. Furthermore, the molecular weights of the soluble parts of all four lignins in ethyl acetate were found to be lower than the original lignins.

This bio-chemical study focuses on obtaining high-quality hemp fiber. The effects of the structures and properties of hemp fibers in different treatment periods were studied. Moreover, the changes of the surface morphology, chemical composition, and breaking tenacity of hemp fibers were researched by scanning-electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), fluorescence microscopy, and fiber tensile testing. The results showed that by virtue of the enzyme scouring process, alkali refining process, and bleaching process, the pectin, lignin, and hemicellulose and other impurities were removed. Through the single factor experiment, the optimal process conditions for the bio-chemical combination of the degumming process were obtained. These conditions included 10 g of dried hemp fibers, 15% (v/v) pectinase solution, a temperature of 50 °C, a duration of 120 min, pH 8.0 (phosphate buffer), a liquor ratio (w/v) of 1:10, and 0.0625 mol/L NaOH. In these conditions, the residual gum content and breaking tenacity were 4.8% and 49.8 cN/tex, respectively, indicating that the treated hemp fibers met the requirements of the spinning process.

Biomass utilization is vital for developing sustainability in the bioenergy sector. In this work the effects of high ash content on the heating properties of wood chips were evaluated. In an analysis of 450 wood chips samples, the ash content, moisture content, and gross calorific value were determined, and a generalized linear model was created to identify the relationship between the gross calorific value and the ash content of the wood chips. The mean ash content of the analyzed wood chips samples was 2.64%, the mean moisture content was 38.8%, and the mean gross calorific value was 19.43 MJ kg-1. Statistical analyses showed that 49% of the gross calorific value variability was due to the ash content variability. A one percent increase in ash content resulted in a 0.11 MJ kg-1 decrease of gross calorific value. The estimated costs of ash disposal at various ash contents were calculated. Burning wood chips with 5% ash content would lead to depositing an extra 5.6 megatons in the US or 21.2 megatons in the EU, compared to burning wood chips with 2.5% ash content.

Three typical biomass fuels—rice husk, rice straw, and corn cobs—were combusted to understand the effects of ashing temperature on ash fouling and slagging characteristics. The ashes generated from combustion at 600 °C and 815 °C were characterized thoroughly with regard to their chemical composition. The systematic slagging/fouling indices of biomass were used to study the effects of ashing temperature on ash fouling and slagging propensities. The results showed that ashing temperature had a remarkable influence on ash composition, particle size distribution, ash morphology, ash fusibility, and thermal properties. Increased ashing temperature resulted in the expansion of ash particles together with the volatilization of alkali metals in the form of inorganic salts. Morphology analysis indicated that high ashing temperatures promoted biomass ash slagging. Ash fusion points increased at elevated ashing temperatures, while the ash content decreased. As a result of the volatilization and decomposition of biomass ash, a four-step mechanism of weight loss was clearly identified by thermal analysis. All prepared biomass ashes resulted in slagging and fouling problems at different levels during the thermo-chemical conversion of biomass.

Kluyveromyces marxianus S1.17, obtained by electroporation-mediated genome shuffling between K. marxianus G2-16-1, a cellobiase-producing yeast, and Pichia stipitis JCM 10742T, gave a maximum ethanol production level (of 0.86 g/L) from the hydrolysate of dilute sulfuric acid treated sugarcane leaves when treated under aerobic conditions for 72 h, compared to the ethanol production level of 4.73 g/L from the acid-treated sugarcane leaves fermented by the simultaneous saccharification and fermentation process under oxygen-limited conditions. The total ethanol produced from sugarcane leaves by K. marxianus S1.17 was 5.59 g/L (0.10 g/g, dry weight).

Biochar is widely used as an adsorbent to remove heavy metals from aqueous solutions. To investigate the contribution of soluble minerals (mainly anions) to Pb2+ removal in solution, wheat straw biochar was washed with deionized water to remove soluble minerals. Batch adsorption was conducted using washed biochar (WBC) and unwashed biochar (BC) to absorb Pb2+. After washing, the pH and ash content of biochar were reduced, while the specific surface area and total pore volume were increased. Adsorption kinetics of Pb2+ onto BC and WBC were well fitted to the pseudo-second-order model (R2 > 0.99). Pb sorption on BC and WBC were better fit with the Langmuir model (R2 = 0.96 to 0.97) than the Freundlich model (R2 = 0.71 to 0.87). The Langmuir maximum adsorption capacity of Pb on BC was 99.7 mg g-1, which was 4.5-fold higher than that on WBC when the initial solution pH was 5.0. The concentration of SO42-, CO32-, SiO32-, and PO43- in the equilibrium solution was reduced by 69, 89, 97, and 41%, respectively, with the increase of initial Pb2+ concentration. The difference of Pb2+ adsorption capacity between BC and WBC proved that the soluble anions in biochar play an important role in Pb2+ sorption onto biochar.