Research Articles

An experimental study was conducted to investigate the effect of size on the strength properties of Chinese larch (Larix gmelinii) dimension lumber. 7546 pieces of dimension lumber were sampled in three sizes, 40 by 65 mm, 40 by 90 mm, and 40 by 140 mm. After visually-grading and grouping, mechanical properties of bending strength, tensile strength, and compression strength parallel to grain were measured in a full-size test. Using nonparametric estimates, the combined length and width size effect parameters of H and L were 0.21 and 0.23 for the bending strength. The width effect parameters were 0.29 in H and 0.33 in L for the ultimate tensile strength parallel to grain. The width effect parameters of H and L were 0.12 and 0.20 for the ultimate compression strength parallel to grain. These size effect factors between H and L could be used when using the lumber for practical purposes.

In this study, a mathematical model of tangential tensioning stress in the edge of a circular saw blade tensioned by multi-spot pressure was established by theoretical analysis for the quality control of circular saw blades. The multi-spot pressure tensioning process was assumed to include three mechanical processes: the one-spot pressure process; the process of elastic deformation of a disk with a through-hole subjected to uniform, radial compressive stress; and the stress superposition process. The tangential tensioning stress on the edge of the circular saw blade could be accurately predicted by the established mathematical model. The model for the tangential tensioning stress on the edge of the circular saw blade tensioned by multi-spot pressure was shown to be correct by measured values.

As a lignocellulosic material, wastepaper is a potential material for ethanol production. However, little research on the enzymatic hydrolysis of wastepaper pulp has been conducted. In this study, the enzymatic hydrolysis of different waste pulp fractions (R80 represents greater than 80-mesh wastepaper pulp, R80-180 represents the range of 80- to 180-mesh wastepaper pulp, and R180 represents smaller than 180-mesh waste paper pulp) were carried out at 50 °C, pH 4.8, for 96 h, with a substrate concentration of 5% (w/v) and cellulase loading of 18 FPU/g cellulose. In terms of the specific surface area, fiber structure, and surface morphology, R80-180 had the highest affinity to cellulase and therefore the highest glucose yield of 80.33%. R180 had the lowest glucose yield (55.36%) because of its high ash content (21.36%), which reduced the adsorption of cellulase to cellulose. The enzymatic hydrolysis of R80 mixed with R80 or R80-180 was also studied. Results indicated that adding R80-180 increased the glucose yield of R80. The highest glucose yield (82.57%) was obtained when 15% R80-180 was mixed with R80. However, the glucose content decreased when R180 was mixed with R80 because of its high ash content.

The effects of process parameters (adhesive spread, press time, and applied pressure) on the response parameter (shear strength) of pine wood bonded with PVAc were studied. Response surface methodology was applied for design of experiments and for analysis of results. A mathematical model was developed to establish the relationship between the process parameters and response parameters. The results showed that the major factors were adhesive spread and applied pressure. The shear strength increased as the adhesive spread and applied pressure increased within certain ranges.

Pyrolysis of corn stalk with a solid heat carrier was studied under temperatures ranging from 430 to 620 °C. The solid heat carrier used was high-temperature ash from a CFB boiler. The yields of three products and their characteristics were investigated. Moreover, the distributions of sulfur and nitrogen in the products were determined. The results indicate that with increasing temperature, the char yield decreased, gas yield increased, and calorific value of the gas increased from 10.13 to 16.65 MJ/m3. The yield of bio-oil reached a maximum, 14.24 wt.%, at 510 °C. Light-oil in the bio-oil accounted for more than 69.12 wt.%. The elemental composition of the char and char ash were analyzed. The distribution of sulfur and nitrogen in the char decreased to 60.44 and 46.52 wt.%, respectively, depending on the raw materials used. These results provide basic data for the possible industrial application of corn stalk.

This study investigated the feasibility of using an electron beam (EB) process to cure chemically impregnated wood products. Maple wood planks were impregnated with the low-viscosity resins 1,6 hexanediol dimethacrylate (HDDA) and trimethylolpropane trimethacrylate (TMPTA). The addition of nanoparticles into the formulation was also studied. The impregnated wood was then cured by EB irradiation. The EB curing method utilizes highly energetic electrons at a controlled energy level to polymerize and cross-link the polymeric materials. The thermal analysis results of differential scanning calorimetry (DSC) confirmed that the curing of chemically impregnated wood by electron beam radiation was validated. Polymerization exotherms were observed for the neat acrylate resin and formulations of acrylate/nanoparticles impregnated maple samples. No polymerization exothermal peaks were observed for both EB-cured impregnated maple and control maple samples, confirming that EB irradiation can serve as an efficient curing method to polymerize acrylate-impregnated wood products. The surface hardness of the EB-cured impregnated maple wood was improved up to 200%.

High-specific surface area activated carbon with distinct pore texture was prepared using bio-oil phenol-formaldehyde (BPF) resin as the raw material and KOH as the activator for chemical activation. The carbonization process was characterized with thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR).The pore texture was characterized with measurements obtained by N2 adsorption analysis and scanning electron microscopy (SEM). It was found that adding bio-oil to phenol-formaldehyde resin can partly enhance the thermal stability and improve the textural properties of activated carbon. The functional groups of BPF resin gradually disappeared in the carbonization reaction with increasing temperature. The activated carbon prepared by BPF resin with 30%wt bio-oil exhibited the optimal perfomance.

Escalating demand, along with EPAct 2005, has led the United States government to assume a twofold leadership approach of energy security and environmental practices. This has initiated several important issues pertaining to cellulosic biofuel production. However, little is known about what is needed for the U.S. to lead long-term renewable energy security, how the US will develop and implement leading environmental energy practices, what supply capabilities and refining technologies are available to produce renewable fuels, and how funding can be used to adopt available technologies. This article examines geographical aspects, operational status, and barriers tending to prevent the successful commercialization of non-food cellulosic ethanol projects in the U.S. from secondary sources. Outcomes of this research can be used to further understand inhibitors that impact the production and commercialization of ethanol from non-food cellulosic sources.

Change of pH has been identified as the most significant parameter in modulating the transition between the conversions of acids into solvents in acetone-butanol-ethanol (ABE) fermentation by Clostridia. Thus, ABE fermentation at various phosphate buffer concentrations and initial pH values was conducted using pure glucose and sugars derived from pretreated oil palm empty fruit bunch (OPEFB). A higher solvent concentration (2.93 g/L) was obtained in the fermentation using 20 g/L of glucose with buffer compared with one without buffer that produced 1.34 g/L of solvents. Approximately 8.77 and 9.15 g/L of solvents were produced from fermentation using 40 g/L of glucose with and without buffer, respectively. In the latter conditions, at an initial pH of 5.5, 8.77 g/L of solvents was obtained, which was the highest concentration compared to other initial pH values. Increasing the buffer concentration to 0.2 M at an initial pH of 6.0 resulted in acid accumulation of 16.83 g/L but reduced the solvent production to 1.36 g/L. In addition, ABE fermentation using 20 g/L of sugars from pretreated OPEFB produced 2.25 g/L of solvents with a yield of 0.13 g/g, which was comparable with fermentation using 20 g/L of glucose conducted in a buffering system.

Black liquor produced from pulping with a high value of chemical oxygen demand (COD) and biological oxygen demand (BOD) is highly harmful if discharged into the environment directly. One possible way to decrease the damage to the soil and water is to reuse the organic substances contained in it to cultivate yeasts for producing single-cell proteins (SCP) while reducing the COD. With this in mind, this study is devoted to treatment technology and the comprehensive utilization of black liquor. Various parameters were evaluated, and the COD of black liquor, initial pH, and nitrogen sources had significant influences on biomass and crude protein production. The research resulted in the maximum values of COD removal rate and crude protein production with 78.78 ±3.21% and 1.18 ±0.02 g/L achieved, respectively, under the optimized condition of black liquor concentration (60%), the recruitment of urea (0.5 g/L), initial pH (6.0), temperature (34 °C), shaking speed (180 rpm), and incubation time (36 h). Furthermore, this study provided a potential viable treatment of black liquor and revealed a feasible way to make full use of black liquor for the economical production of SCP.