Research Articles

The vaporized heat of bound water in radiata pine wood sapwood, which was thermally treated at 200 °C, via N2 protection for 24 h, were studied using low-field nuclear magnetic resonance (LFNMR) and differential scanning calorimetry (DSC) analysis. The bound water was divided into two states using LFNMR, which were absorbed water bonded with cell wall polymers and condensed bound water in the micro-pores of cell wall, respectively. The mass of the two states of bound water vaporized during DSC test was calculated based on the total mass of bound water vaporized and the moisture content of different water states in the water-saturated sapwood obtained, respectively. The reduction of moisture during DSC test was monitored synchronously using thermogravimetric analysis. The results showed thermal treatment decreased the spin-spin time (T2) of absorbed bound water and increased T2 of condensed bound water. The moisture content of the two states of bound water was reduced by thermal treatment. The vaporized heat of the bonded bound water was increased and that of the condensed bound water was reduced, which agreed with the change of T2 in the LFNMR experiment. The results suggest that bound water in the thermal treated wood is easier to vaporize when the relative humidity condition is more than 60%.

Many agricultural activities generate large quantities of biomass wastes. Using these wastes to produce value-added products or energy has become very important in recent years. Heavy metals such as lead are among the most toxic chemical water pollutants from natural or anthropogenic sources. The goals of this work were to prepare three biochars from maize straw (BMS), sunflower straw (BSS), and wheat straw (BWS) under partial limited oxygen condition and to characterize their ability to adsorb Pb2+ from water. The sorption kinetics as well as the influence of solution pH and Pb2+ concentration was investigated. The three biochars had a good performance for Pb2+ adsorption. A greater adsorption efficiency was observed for BMS and BSS than for BWS. The physico-chemical properties of the biochars showed that the adsorption performance was correlated with preparation conditions, raw material types, higher total porosity, and micro-structure.

The activity and some properties of glucose oxidase (EC 1.1.3.4) of the wood-degrading fungus Lentinus (Panus) tigrinus VKM F-3616D were studied. The results showed that 12 days of dynamic liquid-phase cultivation increased the activity and the biosynthetic levels of the enzyme with maximal activity at day 6. After 6 days, a decrease in the glucose oxidase activity was observed. The enzyme isolated via ion exchange chromatography had an optimal pH of 4.0 and a temperature optimum of 50 °C. Spectrophotometry, fluorescence analysis, and IR Fourier spectroscopy showed that the enzyme was a flavoprotein and that its prosthetic group contains flavin adenine dinucleotide. The relative kinetic parameters of the enzyme were determined: the Michaelis constant (K_m) was 4.1 x 10^-3 M, and the maximal rate of the enzymatic reaction (V_max) was 0.36 IU. Results of electrophoresis in native and denaturing conditions were consistent with an enzyme structure having two equal subunits with a total molecular mass of approximately 160 kDa.

To investigate the properties of wood flour/high-density polyethylene composites (WF/HDPE) filled with different kinds of mineral components (CaCO3, talc powder, and wollastonite), WF/HDPE was prepared via a molding method. The thermal properties of WF/HDPE were analyzed with a comprehensive thermal analyzer, and the mechanical properties were measured. The moisture resistance was indicated by 24 h water absorption. The results indicated that both the mechanical and physical properties of WF/HDPE samples were improved remarkably by adding CaCO3, talc powder, or wollastonite. The tensile strength with talc powder was 83% higher than the composites without the additive. The maximum residual weight of the composites with added talc powder was 21.8% at 600 °C, which was 7.47% higher than that of the composites without additive. The composites with added talc powder exhibited better water resistance. Additionally, scanning electron microscopy (SEM) showed that the addition of talc powder enhanced the interaction between the components.

To evaluate the influence of different normal forces and contact temperatures on the frictional behavior of paperboard during the deep drawing process, a new measurement punch was developed to measure the normal force, which induced the friction within the gap between the forming cavity and punch. The resulting dynamic coefficient of friction was calculated and reproduced via a new developed substitute test for the friction measurement device, which was first introduced in Lenske et al. (2017). The normal force within the forming gap during the deep drawing process was influenced by the blankholder force profile, the contact temperature, and the fiber direction. The friction measurements with the substitute test showed a strong dependency between the applied normal force and the dynamic coefficient of friction. Furthermore the frictional behavior was influenced by the contact temperature and the wrinkle formation.

Producing nanocellulose from lignocellulosic plants is difficult but can be achieved with microwave-assisted treatment. However, the changes in dimensions during the process have not been investigated thoroughly. In this study, kenaf bast was used to produce cellulose nanofibers using microwave, chemical, and ultrasonic treatments. Fiber sizes were monitored throughout the experiment using an optical microscope and scanning electron microscopy (SEM). The kenaf single fiber cells were also isolated and measured. The results showed that the duration of microwave treatment notably influenced the destruction of kenaf fibers, and the concentration of NaOH in the chemical treatment had only a limited effect on the reduction of kenaf particle size. Both the microwave and chemical treatments were able to destruct the kenaf fibers longitudinally, and the ultrasonic treatment was able to reduce cellulose particles from micro-size to nano-size.

A new method of testing mechanical properties of mortise-and-tenon joints is put forward. The contact force relaxation behavior of joints for 3 h with tenons in different grain orientations and tenon fits were studied. The results showed that the initial and final contact force of joints with tenons in radial grain orientation were all larger than those in tangential grain orientation in the same tenon fit. The regression equations generated in this paper were able to predict the contact force relaxation behavior of joints with tenons in different grain orientations, tenon fits, and time, and the errors were all within 20%. In addition, the ratio of loss for contact force of joints with tenons in radial grain orientations was greater than that with tenons in tangent in the same tenon fit. The ratios of loss decreased from 51% to 31% in two grain orientations of tenon with tenon fits increasing from 0.2 mm to 0.5 mm with an increment of 0.1 mm. The method proposed in this paper was able to predict the contact force relaxation of mortise-and-tenon joints. The relaxation of contact force in a joint should be considered when designing mortise-and-tenon joint furniture.

Cellulosic butanol is a very promising renewable fuel to consider for the future transportation market. However, the seasonal availability of the raw materials, high maintenance cost, and high logistical cost of the biomass energy supply chain are the main factors impeding the commercialization and large-scale-production of this energy source. Furthermore, research focusing on an environmental or green supply chain network design of cellulosic butanol has been insufficient. This study focused on designing a green supply chain network for cellulosic butanol. A life cycle analysis was integrated into a multi-objective linear programming model to optimize the cellulosic butanol supply chain network. With the objectives of maximizing the economic profits and minimizing the greenhouse gas emissions, the proposed model can optimize the location and size of a bio-butanol production plant. The mathematical model was applied to a case study in the state of Missouri, and solved the tradeoff between the feedstock and market availabilities of sorghum stem bio-butanol.

The dimensional stability and resistance to degradation of wood can be improved using high temperature heat treatment under anaerobic conditions; however, mildew growth can have a deleterious impact on its appearance and commercial value. In this study, wood samples were impregnated in copper-containing solutions at high pressure before being recovered and cured at high temperatures to create treated wood samples with nano copper particles. This copper impregnated wood (up to 6.35% copper content) suppressed the growth of Botryodiplodia theobromae Pat. and Aspergillus niger van Tieghem with 100% efficiency, and Penicillium citrinum Thom with 75% efficiency. However, the growth of Trichoderma viride Pers. was not suppressed. These results demonstrate that copper curing can be used to extend the scope, performance, and lifetime of heat-treated wood, enabling it to be used for a new range of applications.

Biochar is a carbon-rich product generated from the incomplete combustion of biomass through pyrolysis. Biochar plays an important role in removing pollutants from the environment. In this study, biochars were obtained from peanut shell agricultural waste by the limited-oxygen method at 300, 500, and 700 °C. The adsorption capacity of imidacloprid onto the biochar was increased with the increasing pyrolysis temperature. The solution temperature and biochar dosage had positive effects on the adsorption of imidacloprid. The adsorption capacity of the biochar on imidacloprid was increased with the increasing of pH in acid and neutral solution but slightly decreased in weak base solution (pH 9). An analysis of adsorption kinetics showed that the adsorption of imidacloprid on the biochar perfectly followed pseudo-first-order and pseudo-second-order models with R2 coefficients above 0.97. Furthermore, the Langmuir and Freundlich models highly correlated with the sorption isotherm data. In summary, this study confirmed that peanut shell biochar is an efficient adsorbent for the removal of the pesticide imidacloprid.