Research Articles

Ferulic acid is present at relatively high concentrations in the cell walls of several plants. Agricultural lignocelluloses are now used as bioresources in industry. This study attempted to increase the free ferulic acid content present in lignocellulose by using thermostable esterase produced from thermophilic actinomycetes to hydrolyze ester bonds. Destarched wheat bran was used as a carbon source for the production of esterases from the newly isolated thermophilic actinomycetes species Thermobifida fusca. After 96 h of cultivation, the esterase activity that accumulated in the culture broth was 946.0 U/mL. Two percent of the destarched wheat bran was then hydrolyzed by crude esterase preparation for 16 h. The ferulic acid was accumulated in the culture broth at a concentration of 310.0 mM. The hydrolysate had better radical-scavenging ability for both 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical-scavenging ability, as well as reducing power than ferulic acid. These results showed that the ferulic acid-rich destarched wheat bran hydrolysate had good antioxidant properties. It is suggested that this process can be advantageous for the industrial production of antioxidants derived from agricultural bioresources.

The effect of pyrolysis temperature on the characteristics and metal sorption capacity of sugar cane straw derived–biochar (BC) was investigated. Biochar was produced at four temperatures (400, 500, 600, and 700 °C) before characterization for yield, ash and moisture content, pH, EC, pHPZC, elemental composition, nutrient content, CEC, TGA, and functional groups (FT-IR). Biochar alone and in mixtures containing 10%, w/w biochar with one of two different tropical soils (Entisol and Oxisol) was shaken for 24 h with a 2.0 mM solution (pH 4.5) of Zn or Cd in a batch sorption test. Increasing the pyrolysis temperature led to a reduction in the O/C and H/C molar ratios. The sorption capacity of biochar pyrolyzed at 700 °C was nearly four times greater than that produced at 400 °C. In the Entisol mixture, there was an increase up to seven-fold in the sorption of both Cd and Zn compared with the control (without BC). In the Oxisol mixture, there was a maximum 20% increase in sorption compared with the control. For the remediation of Cd- and Zn-contaminated substrates, the use of higher pyrolysis temperature biochars are recommended because of their higher metal sorption capacities.

The alkali-cellulase processing of biomass into glucose near where it is grown has already been demonstrated at laboratory scale. Glucose can be fermented locally or transported to distant facilities for the production of bioethanol as fuel. This renewable energy process uses materials and methods that are readily available and that can be implemented at local or regional sites near growing fields. This study evaluated the effects on glucose production of different durations and amounts of NaOH pretreatment as well as different lengths of time for adsorption of cellulase. The pretreatment of corn stover (CS) with NaOH at 0.1 g/g CS for 6 h at a temperature of 100 °C resulted in the most acceptable glucose release following enzymatic hydrolysis. The exposure of pretreated CS solids to cellulase for 1 h resulted in the most acceptable release of glucose following the volume expansion at 10-fold dilution. The residual solids remaining after 3 h of enzymatic hydrolysis can be recycled to increase yields. The resulting glucose solution can be concentrated to minimize transportation costs when delivered to conventional grain fermentation facilities. This study introduced new conditions that enhanced practicality of the alkali-cellulase processing of biomass by allowing the processing time to be reduced to 10 h.

Chinese fir (Cunninghamia lanceolata) has great potential as a future bio-energy resource in China. Thermogravimetry (TG) was used to investigate the thermal decomposition process of Chinese fir, including heartwood and sapwood. The Flynn-Wall-Ozawa and Coats-Redfern (modified) methods were used to determine the activation energy. A combination of TG and Fourier transform infrared spectrometry (TG-FTIR) was used to analyze the pyrolysis products. The TG curve indicated that the degradation processes of heartwood and sapwood were similar, but the degradation temperature of heartwood was lower than that of sapwood. The main decomposition occurred within the temperature range of 500 K to 660 K, and over 70% of the mass was degraded. The activation energy of Chinese fir with heartwood and sapwood changed slightly with an increase in conversion rate from 10 to 70. That of heartwood and sapwood was 155.38 to 158.37 KJ/mol and 155.93 to 180.04 KJ/mol, respectively, using the Flynn-Wall-Ozawa method. TG-FTIR analysis showed that the main pyrolysis products included absorbed water (H2O), methane gas (CH4), carbon dioxide (CO2), carbon monoxide (CO), acids and aldehydes, nitrogen dioxide (NO2), nitric oxide (NO), and ammonia gas (NH3). The results from this study are helpful for designing a better bio-energy manufacturing process for Chinese fir via gasification and pyrolysis methods.

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.

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.

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.

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.