Volume 8 Issue 4

Surfactants made from modified lignin are attracting growing attention; therefore, a lignin-phenol nonionic surfactant named ML-AL has been prepared by modifying liquefied industrial alkali lignin (L-AL). Its basic physical and chemical properties have been shown to be favorable. In this work, anionic surfactants of sodium fatty acid soap (carbon numbers 12, 16, and 18) and sulfur-containing anionic surfactants (sodium dodecyl sulfate and sodium dodecyl benzene sulfonate) were chosen to mix with ML-AL in water-soluble media. The surface properties of each binary mixed solution system with anionic surfactant were investigated. At the same time, the mixed micelles formed by ML-AL and each anionic surfactant were studied. Non-ideal mixed micelles were obtained via ML-AL and the tested anionic surfactant. The interaction parameter (βM) and excess free energy (ΔGexcess) were both negative. Meanwhile, the critical micelle concentration (CMC) values of mixed systems (formed by ML-AL and each anionic surfactant in aqueous solution) were lower than those of a single-component system (ML-AL or single anionic surfactant). There was an optimum dosage ratio of about 0.4 in terms of synergistic effects. This research could provide a foundation for practical applications of combinations with anionic surfactants in aqueous solution.

Dendrocalamus sinicus, which is the largest bamboo species in the world, has broad prospects for use in biomass-energy and biorefinery applications. In this study, five soluble hemicelluloses fractions were sequentially isolated with 80% ethanol (containing 0.025 M HCl or 0.5% NaOH), and alkaline aqueous solutions (containing 2.0, 5.0, or 8.0% NaOH) at 75 °C for 4 h from dewaxed D. sinicus, and their structural properties were examined. Gel permeation chromatography analysis revealed that the hemicelluloses isolated from D. sinicus had a wide distribution of molecular weights. The hemicelluloses isolated by ethanol had lower weight-average molecular weights (ranging from 17380 to 19620 g/mol), while the hemicelluloses isolated using alkaline aqueous solutions had higher weight-average molecular weights (ranging from 22510 to 42150 g/mol). Neutral sugar analysis indicated that the soluble hemicelluloses were mainly composed of arabinoglucuronoxylans, followed by minor amount of starch. Spectroscopic analyses suggested that the isolated arabinoglucuronoxylans from bamboo (D. sinicus) could be defined as a linear (1→4)-β-linked-xylopyranosyl backbone to which α-L-arabinofuranose and/or 4-O-methyl-glucuronic acid units were attached as single-unit side chains via α-(1→3) and/or α-(1→2) linkages.

Turkey oak is a wood species widely distributed in Southeastern Europe and in Italy, where it is mainly present in the Apennine Mountains. Compared to other oaks, Turkey oak is less valued because of its tendency to crack, its lower technological quality, and its lower durability. The aim of the present work was to improve wood quality by treating Turkey oak through combined steaming and thermal treatment under vacuum conditions. Wood was steamed at a temperature between 100 to 110 °C and thermally treated in vacuum at 160 °C using two different technologies, i.e., the press vacuum plant and the Termovuoto® plant. The treated material was characterized in terms of mass loss, color change, hygroscopicity, and compression strength for both heartwood and sapwood. Results slightly differed according to the treatment or combination of treatments adopted. In general, a significant increase in dimensional stability and an improved color homogenization were obtained together with the maintenance of a good wood quality. Concerning mechanical properties, thermo-vacuum treatment increased the compression strength, while steaming had the opposite effect.

Lignin was extracted from the solid coproduct of a lignocellulosic ethanol production by a solid-liquid extraction method using N,N-dimethyl formamide. This coproduct was the residue of a steam explosion pretreatment followed by enzymatic hydrolysis process. The coproduct was used as received and also after washing. Lignin content of the solid coproduct was reduced from 63% to 43% after lignin extraction. Fourier transform infrared spectroscopy (FTIR), molecular weight measurement (GPC), and elemental analysis provided information about the chemical structure and molecular weight of the fractions. The extracted lignin had lower molecular weight (~ 5000 Da.) and higher carbon content (63%) compared to the residue of extraction (Mw ≈ 8000 Da. and carbon % = 48%). Thermal stability measurements of the samples by thermogravimetry (TGA) showed that the extracted lignin had the highest carbon residue. Effects of different heating cycles on the glass transition temperature (Tg) were measured. The Tg of the soluble fraction was lower than that of the coproduct. Results of the X-ray diffraction (XRD) showed the crystalline structure of cellulose in both the coproduct and the solid residue after extraction. This extraction and material characterization is helpful for liquid processes such as solution spinning or electrospinning. The thermal properties can be used for optimization of heat treatment processes such as carbonization.

Different kinetic models have been proposed to characterize torrefaction of biomass, demonstrating dependencies on the raw material, experimental system, reaction time, and temperature. Conventionally, stationary processes have been used for kinetics studies of the torrefaction process. In this research, the torrefaction of red oak (Quercus rubra) in a bench-scale fluidized reactor was studied with emphasis on determining the kinetic parameters and improving the final material energy density. Mass loss and ultimate, proximate, and gross calorific analyses were performed on the resulting torrefied material. The primary reaction variables were the temperature (230 °C, 270 °C, 300 °C, and 330 °C) and the residence time (10 min, 20 min, and 30 min). The effect of temperature on the mass loss and energy density was much more significant than that produced by the increase in residence time. For the conditions studied, a one-step kinetic model with a first-order reaction proved adequate to describe the torrefaction of red oak in the fluidized reactor. The reaction rate constant (k) for the torrefaction reaction was found to be 0.212 min-1 at 300 °C. The activation energy and frequency factor were 11.9 kJ/mol and 2.57 min-1, respectively.

Medicinal plants, such as Polyalthia longifolia (Indian mast tree), are important therapeutic sources for curing human diseases. In this work P. longifolia leaf extract was characterized by chromatographic and spectral fingerprinting techniques, phytochemical and heavy metal analyses, and microscopy. Light microscopy of a transverse section of the leaf of P. longifolia revealed the presence of various plant cells. Phytochemical screening results revealed the presence of alkaloids, triterpenoids, tannins, saponin, anthraquinones, and glycosides in the extract. The concentrations of heavy metals determined in the extract were well below the permissible limit. Nine peaks observed in the HPLC spectra showed the presence of various compounds in the extract. The GCMS method used for quantification of (3β,4α,5α,9β)-4,14-dimethyl-9,19-cycloergost-24(28)-en-3-yl acetate (i.e., cycloeucalenol acetate) in the extract was rapid, accurate, precise, linear (R2 = 0.8752), and robust. The HPTLC analysis showed ten specific peaks for the methanolic extract of P. longifolia leaf. Twelve major peaks in the range of 4,000 to 500 cm-1 were observed in the FTIR spectra, which represented various specific functional groups in the extract.

Enzymatic/Mild Acidolysis Lignin (EMAL) was isolated from Cunninghamia lanceolata and eucalyptus woods. The chemical structure and thermochemical properties were characterized by means of elemental analysis, Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TG), and pyrolysis-gas chromatography combined with mass spectrometry (Py-GC/MS). The EMAL isolated from Cunninghamia lanceolata (C-EMAL) had larger HHV (higher heat value) in comparison to the EMAL isolated from eucalyptus (E-EMAL) due to the greater carbon content of the C-EMAL. The E-EMAL had more syringyl units, whereas the C-EMAL contained more guaiacyl units. It was observed that thermal decomposition occurred over a wide temperature range, and that at a given starting temperature, within the same sample, a higher heating rate produced a higher temperature at which maximum weight loss peaked. The pyrolysis products were mainly composed of carboxylic acids, alcohols, ketones, aldehydes, olefins, alkanes, esters, ethers, and phenols. At all pyrolysis temperatures, the largest components of the pyrolysis products obtained from C-EMAL were the phenols.

The properties of non-treated and hydrochloric acid (HCl)-treated oil palm ash (OPA)-filled natural rubber (NR) composites were investigated in terms of swelling behavior, rubber-filler interaction, ageing resistance, dynamic mechanical analysis, and thermal stability. The incorporation of OPA resulted in a lower degree of swelling in the NR composites, which was even lower after HCl treatment. Concerning the rubber-filler interaction, the HCl-treated OPA had better interfacial interaction with the NR matrix than that of non-treated OPA, resulting in higher crosslink density and improved ageing resistance. The dynamic mechanical properties of NR composites were better with the incorporation of HCl-treated OPA compared to non-treated OPA, in that they showed a higher storage modulus and lower mechanical loss factor. Thermogravimetry analysis revealed that the HCl treatment process did not affect the thermal stability of OPA-filled NR composites.

The effects of ground calcium carbonate (GCC) modification through the polyelectrolyte multilayering technique on deposition kinetics were investigated. The surface charge of GCC particles was changed from negative to positive through Layer-by-Layer (LbL) multilayering with polyelectrolytes on GCC particles. The LbL multilayered GCC particles could deposit onto negatively charged cellulose fibers due to electrostatic attraction. Deposition kinetics followed modified Langmuir kinetics, which describe the dynamic equilibrium of deposition and detachment of the particles. The multilayer that had more affinity to the fibers had the higher deposition rate constant. The multilayer with a branched polyelectrolyte showed a low detachment rate constant compared to the linear polyelectrolyte, which led to a high equilibrium deposition amount for the particle. Application of high shear had adverse effects on deposition. However, LbL multilayered GCC particles showed reversible deposition characteristics after lowering the stirring speed.

Brazil is the world’s largest producer of charcoal, mainly for the steel industry. Fresh wood has high moisture content, which reduces its use for energy. Thereby, drying is a fundamental step for charcoal production. This work aimed to determine longitudinal variation in stem diameter, wood basic density, moisture content, and calorific value of Eucalyptus urophylla and Corymbia citriodora logs. These logs were taken from different longitudinal positions on the trees and dried for 90 d; the net calorific value was determined based on the gross calorific value and moisture content. Curves and models were generated based on this data for moisture content and net calorific value during the 90-d period. The logs from the base and middle of C. citriodora trees had lower initial moisture content, and, after 90 d of drying, all logs from the top reached the equilibrium moisture. Drying the logs increased the wood calorific value, with an increase of 49.36%, 63.86%, and 85.98% for those of the base, middle, and top, respectively. The models generated had a high coefficient of determination and a low standard error.