Volume 16 Issue 1

Flame-retardant silicate-intercalated calcium aluminum hydrotalcites (CaAl-SiO3-LDHs) were synthesized to treat bamboo for retardancy, to overcome the bamboo’s flammability and reduce the production of toxic smoke during combustion. The microstructure, elemental composition, flame retardancy, and smoke suppression characteristics of the bamboo before and after the fire-retardant treatment with different pressure impregnation were studied using a scanning electron microscope (SEM), elemental analysis (EDX), and cone calorimetry. It was found that CaAl-SiO3-LDHs flame retardants can effectively fill and cover the cell wall surface and the cell cavity of bamboo without damaging the microstructure. As compared to the non-flame-retardant bamboo, the heat release rate (HRR) of the CaAl-SiO3-LDHs flame-retardant bamboo was significantly reduced, the total heat release (THR) decreased by 31.3%, the residue mass increased by 51.4%, the time to ignition (TTI) delay rate reached 77.8%, the mass loss rate (MLR) decreased, and the carbon formation improved. Additionally, as compared to the non-flame-retardant bamboo, the total smoke release (TSR) of the CaAl-SiO3-LDHs flame-retardant bamboo decreased by 38.9%, and the carbon monoxide yield (YCO) approached zero. Thus, the CaAl-SiO3-LDHs flame-retardant bamboo has excellent flame-retardancy and smoke suppression characteristics.

The antifungal activities of 19 plant essential oils against six wood mold and stain fungi (Aspergillus niger, Penicillium citrinum, Trichoderma viride, Botryodiplodia theobromae, Fusarium moniliforme, and Alternaria alternata) were investigated with the in vitro medium method. The chemical compositions and volatilization rates of the essential oils were analyzed by gas chromatography–mass spectrometry and oven heating, respectively. Antifungal effects of the essential oils on fresh Pinus massoniana wood were evaluated by dipping treatment. The average antifungal efficacies of the essential oils varied from 0.1 to 1.0, and oils of Cinnamomum cassia, Syzygium aromaticum, and Thymus mongolicus showed the greatest antifungal activities and completely inhibited the growth of all six fungi. The essential oils presented great differences in their main chemical components, and a significant negative linear correlation (Pearson correlation coefficient = -0.627, p < 0.01) was found between antifungal efficacy and volatilization rate, indicating that both chemical composition and volatilization rate are important factors influencing the antifungal activities of essential oils. Eight essential oils effectively inhibited the growth of fungi in Pinus massoniana wood with an absorption of 65.51 g/m2 ± 13.78 g/m2, and they have the potential to be environmentally friendly anti-mildew agents.

This study combined chemical ultrasonic modifications and microwave oven heating to prepare a novel adsorbent, bagasse iron oxide biochar, (BIBC) to remove phosphate from aqueous solutions. The characterization of BIBC was made by energy dispersive spectrometry (EDS), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses, and the mechanism of phosphorus adsorption on BIBC was researched by adsorption batch experiments with emphasis on pH, dosages of BIBC, initial phosphorus concentration, and adsorption time. The BIBC’s BET specific surface area and pore volumes were 81.94 m2 g−1 and 26.74 cm3 g−1, respectively. The pH for the optimal phosphorus adsorption by BIBC ranged from 5.0 to 7.0. The maximum adsorption capacities of phosphorus (according to the Langmuir model) were 3.62, 4.06, and 4.32 mg g-1 at temperatures of 25, 35, and 45 °C, respectively. Electrostatic interaction, surface adsorption of phosphorus on BIBC, and ion exchange were the main mechanisms of phosphorus adsorption. According to XPS results, Fe2p was involved in the adsorption reaction. The adsorption of phosphorus by BIBC is considered to be mainly chemical adsorption. The BIBC was stable under a pH range from 4.0 to 10.0 and secondary pollution did not result.

Lignocellulosic ethanol production at high temperature offers advantages such as the decrease of contamination risk and cooling cost. Recombinant xylose-fermenting Saccharomyces cerevisiae has been considered a promising strain for ethanol production from lignocellulose for its high inhibitor tolerance and superior capability to ferment glucose and xylose into ethanol. To improve the ethanolic fermentation by xylose at high temperature, the strain YY5A was subjected to the ethyl methanesulfonate (EMS) mutagenesis. A mutant strain T5 was selected from the EMS-treated cultures to produce ethanol. However, the xylose uptake by T5 was severely inhibited by the high ethanol concentration during the co-fermentation in defined YPDX medium at 40 °C. In this study, the simultaneous saccharification and co-fermentation (SSCF) and the separate hydrolysis and co-fermentation (SHCF) processes of sugarcane bagasse were assessed to solve this problem. The xylose utilization by T5 was remarkably improved using the SSCF process compared to the SHCF process. For the SHCF and SSCF processes, 48% and 99% of the xylose in the hydrolysate was consumed at 40 °C, respectively. The ethanol yield was enhanced by the SSCF process. The ethanol production can reach to 36.0 g/L using this process under high-temperature conditions.

As wood is an orthotropic and natural material, there are several properties required for its use in civil construction. The apparent density has been used to estimate physical and mechanical properties of wood, as it is easy to determine experimentally, unlike other determinations, which involve the use of equipment available only in large research centers. Using the Brazilian standard ABNT NBR 7190 and linear and non-linear regression models, this research aimed to evaluate their accuracy in estimating the compressive strength parallel to the fibers (fc0) as well as their characteristic value (fc0,k). This study considered 72 tropical wood species from native forests that were divided into the 4 strength classes of this standard. For the set formed by all species, the linear polynomial model was the best fit, resulting in a determination coefficient of just over 70%.

Physical chemical methods were used to treat papermaking white water used to produce plant fiber mulch sheet that contained fine fibers and inorganic fillers as suspended solids. The ordinary chemical oxygen demand (CODCr) was obviously reduced after the papermaking white water was treated by the flocculant. By comparing three different coagulants (aluminum sulfate (Al2(SO4)3), poly-aluminum chloride (PAC), and poly(diallyldimethylammonium chloride) (PDADMAC)) and flocculant (poly-acrylamide copolymer (PAM)) to process papermaking white water, it was found that Al2(SO4)3 had the best coagulation effect and the lowest cost. The best flocculation conditions were 2,733 mg/L of Al2(SO4)3 and 4.52 mg/L of PAM to treat the papermaking white water. Under the best flocculation conditions, the CODCr was less than 300 mg/L. The goal of closed recycling and zero discharge of white water in the production process of plant fiber mulch sheet was realized.

As a key component of mechanized maize harvesting, the performance of the ear picking device directly affects the operational level of a maize harvester. Because the short harvest period of maize and the multiple experimental factors that lead to the field and bench tests cannot meet the actual research and developmental needs of manufacturing a maize harvester, this paper uses virtual prototype technology to study the influence of design and the motion parameters of a longitudinal horizontal roller in terms of picking performance. Based on the establishment of the finite element model of the corn and the ear picking device, this paper establishes evaluation indicators respectively, analyzes and evaluates the influence of the picking roller and the ground inclination angle, the picking roller speed, and the forward speed of the harvester on the performance of ear picking. Finally, a virtual orthogonal test analysis was carried out for the two factors of the picking roller speed and the forward speed of the harvester, and the significant influence of the picking roller speed and the forward speed of the harvester on the performance of the picking was compared. The research results of this paper can provide reference for optimizing the design of ear picking mechanism.

The basic physical properties of hemp seeds were measured to determine the correlations between these properties to facilitate the planning of seed sorting operations. The basic dimensions (length, width, and thickness), terminal velocity, angle of external friction, and mass were determined in the selected seeds. The seeds were subjected to a uniaxial compressive strength test to determine the force required to damage a seed, the corresponding displacement, and the energy consumed during the trial. The seed sorting was based on the basic dimensions of the seeds in order to divide the seeds into groups with similar average mass. The hemp seeds were most effectively sorted with the use of a screen with slotted apertures. The optimal set of screens should separate approximately 11% to 24% of the seeds into a fraction with the lowest seed thickness, and approximately 16% to 21% of the seeds into a fraction with the highest seed thickness. The basic seed dimensions significantly influenced the specific mass of the individual hemp seeds, and the corresponding correlations are most effectively described by power functions.

This article presents an attempt to estimate the nonlinear, multivariable dependence between the main (tangential) cutting force (FC) and the processing parameters and moduli of elasticity of oak wood (Quercus robur) during peripheral milling with a straight edge. The analysis indicated that the tangential force (FC) was affected by cutting depth (cD), feed rate per tooth (fZ), rake angle (γF), elastic modulus by stretching along the grain (ESA), elastic modulus by stretching perpendicular to the grain (ESP), elastic modulus by compression along the grain (ECA), and the elastic modulus by compression perpendicular to the grain (ECP). It was found that the elastic moduli (ESA, ESP, ECA, ECP) very well described the mechanical properties of processed wood. Several interactions between the examined parameters (namely, ESA·γF, ESP·γF, ECP·γF, fZ·γF, and fZ·cD) were confirmed in the developed relationship FC = f(ESA, ESP, ECA, ECP, fZ, cD, γF).

Magnesium sulfate (MgSO4) is the most widely used protector for alleviating the effects that metal ions have on cellulose degradation. However, the efficiency of MgSO4 is limited by the oxygen delignification conditions. This work discusses the factors influencing MgSO4 efficiency in terms of cellulose protection and delignification. The type and concentration of metal ions, delignification rate, additions order, and mixing degree of MgSO4 should affect the cellulose degradation during oxygen delignification in the presence of MgSO4. The most adverse effects on cellulose are observed with Mn2+ and Fe2+ ions followed by Cu2+ and Fe3+. MgSO4 addition can diminish such negative effects; however the protection becomes reduced in the presence of higher concentrations of metal ions. In addition, the optimum MgSO4 application level is closely dependent on the delignification rate and metal ions concentration. Adding MgSO4 is optional for pulps with trace metal ions at relatively low delignification levels, but it is essential for pulps with concentrated metal ions or when the oxygen delignification rate is relatively high. More simply, when the added MgSO4 is thoroughly mixed with the pulp before the addition of NaOH, it exhibits a prominent effect on cellulose protection.