Volume 17 Issue 3

Biochar is recognized as an effective sorbent for environmental management and many other applications. Herein the authors report biochar derived from moss Racomitrium japonicum L., prepared via pyrolysis at 400 °C to 1000 °C. The biochar was characterized by thermal gravimetric analysis (TGA), elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy diffraction (XPS), as well as the ability to remove Sr2+ from aqueous solutions. The results indicated that a biochar with high thermal stability, specific surface area, and dense and mesoporous pores was obtained, with surface functional groups enhancing the adsorption process. Equilibrium adsorption data were consistent with the Langmuir isotherm model, indicating surface homogeneity, with maximum Sr2+ adsorption capacity of 225 mg/g at 25 °C. These results demonstrate that the R. japonicum moss biochar can be used to develop an efficient adsorbent for the removal of Sr (II) from aqueous solution and suggests its utility for further application in removing heavy metals from water.

Biosorption is considered a promising technique for removing heavy metals from water. However, a biosorbent is usually prepared in the form of biomass powder that has drawbacks in stability and uniformity. Herein, a spherical lignocellulose-based anion exchanger (LCB-AE) was prepared from sugarcane bagasse through the method of dissolution-regeneration of biomass followed by quaternary ammonium modification. Dissolution-regeneration conditions of raw biomass were optimized, and the prepared materials were characterized by element composition analysis, pore-structure analysis (mercury intrusion porosimetry), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and carbon-13 nuclear magnetic resonance (13C-NMR) analyses. The LCB-AE has a macro-porous structure and a rough surface occupied mainly by quaternary ammonium and hydroxyl groups. Adsorption selectivity of LCB-AE follows the order of CrO42- > PO43- > SO42- > NO3-, and adsorption isotherms agree well with the Langmuir model, which suggests the experimental exchange abilities are approximately 0.8 to 0.9 mEq/g. These results show that LCB-AE as a new spherical biosorbent has the potential to be used for anions removal from water.

The constants of the drying kinetics models of short-grain rough rice were determined under isothermal conditions between a temperature of 40 °C and 100 °C. The initial moisture content of the rough rice was 28.2% dry basis. The results revealed that increasing the drying temperature and drying duration decreased the moisture content of the rough rice. The lowest rough rice moisture content (15.58% dry basis) was achieved at a drying temperature of 100 °C and a drying duration of 6 h. Four well-known models, i.e., Page, Newton, Logarithmic, and Henderson and Pabis, were evaluated. The models were evaluated based on the highest coefficient of determination value; the lowest root means square error, and the Chi-square value. The Page and Logarithmic models fit four and three cases of the seven drying curves, respectively, among the four evaluated models. Accordingly, combining the Page and Logarithmic models in an integrated model resulted in a model that fits all the seven studied curves. Furthermore, increasing the air temperature from 40 °C to 100 °C increased the moisture diffusivity from 1.5517 × 10-9 m2/s to 4.2698 × 10-9 m2/s. As a result, the activation energy value reached 16.43 kJ/mol for short-grain rough rice under the studied drying conditions.

Using the molecular dynamics software Materials Studio, a micro-level carbon dioxide – cellulose model was established to study the supercritical carbon dioxide drying of eucalyptus wood. The change of the primary components of the eucalyptus wood cellulose were also studied, by simulating various pressures, i.e., 10, 15, 20, 25, and 30 Pa, and simulating a temperature of 323 K. Results showed that the diffusion coefficient of carbon dioxide decreases as the pressure increases, and it reaches the maximum at 20 Pa, which was confirmed by the number of hydrogen bonds in the carbon dioxide cellulose model. Combined with the comprehensive analysis of the mechanical parameters, the Poisson’s ratio γ and the ratio of bulk modulus to shear modulus (K/G) values of cellulose first increased and then decreased as the pressure increased, and the Young’s modulus increased as the pressure increased. From a microscopic point of view, the study shows that eucalyptus cellulose has good mechanical properties when dried by supercritical carbon dioxide under a pressure of 20 Pa. The simulation results of the dynamic model agreed well with the measured results, and the simulation results support the previous experimental data and the practical application results in production.

The Covid 19 pandemic has led to considerable destruction of social and economic areas at a global level. This study aims to determine the economic impact of the Covid 19 pandemic on the Turkish forestry sector. In this context, 5 years (from 2017 to 2021) of wood-based product sales of an administrative unit, which carries out regional forestry activities in Turkey, were studied. The data concerning the product groups were subjected to a Laspeyres price index analysis based on the base period weight through the price and estimated price increase rate variables. In addition, correlation analysis was utilized to determine the relationships between the determined variables. The findings showed that the Covid 19 pandemic led to decreases in the Laspeyres price index values for the price and estimated price increase rates when compared with the pre-pandemic period, which was different on a product group’s basis. As a result, it can be said that the Covid 19 pandemic process created a considerable potential for a loss of income in wood-based products, which is one of the primary outputs of the forestry sector, and as of 2021, a recovery process has started.

Monitoring the process is crucial for ensuring high quality in wood-based panel production. Interest in the distribution of resin in fibers and particles has increased during the last couple of decades. This study considered the potential to determine urea formaldehyde (UF) resin content in fiber mat using near-infrared (NIR) spectroscopy. Fiber mats with various resin contents were investigated with NIR combined with the partial least squares (PLS) regression and root mean square error of calibration and validation (RMSECV). The external factors, such as the distance between the fiber optic probe and the sample surface and light sources, were also evaluated. The results showed that this technique can sufficiently determine the resin content in the resinous fiber mat with accuracy of up to 95%. The light sources and the distances from the probe to the surface did not significantly influence the discrimination and prediction of resin content.

Camellia seed shell (CSS) was torrefied at 200, 230, 260, and 290 °C for 30 minutes in a tubular reactor under a nitrogen atmosphere. The effect of temperature on the fuel quality and combustion characteristics of the torrefaction samples was investigated. The pyrolysis characteristics and kinetics of the raw materials at different heating rates were studied. Compared to the raw material, the roasted samples had an increase in the higher heating value (HHV) range of 0.33 to 4.18 MJ/kg, which reached 24.21 MJ/kg at 290 °C. The mass and energy yield ranged from 93.8% to 65.2%. The decrease in energy yield was much higher than the increase in HHV. The enhancement factor and energy yield correlated well (R2> 0.99). The combustion behavior and kinetics of the torrefaction samples were studied in detail using the First Order Pseudo Bi-component Separate-stage Model (PBSM-O1). From an economic point of view, the best torrefaction temperature for CSS was 260 °C.

A large-format manufacturing process of electric heating floors for indoor heating was evaluated in this work using large-format high-density fiberboard as the substrate, carbon fiber paper as the electric heating element, and semi-cured melamine resin film as the bonding material to elevate its production efficiency. The semi-cured melamine resin film permeated the carbon fiber paper to form a glued structure via hot-pressing process, which improved the water resistance and insulation of the electric heating layer. The internal bonding strength of the floor reached 1.63 MPa with the enhanced waterproof properties. The temperature rise of both the electric heating floor and the assembled floors can reach 20.5 °C within 60 min under the voltage of 220 V. There was a small difference of approximately 2 °C in the ambient temperature between the heights of 0.6 m and 1.8 m above the running assembled electric heating floors. The power of the assembled 16 pieces of floors stabilized at 830 W after the continuous electrification for 12 h in this test condition, which demonstrated the comfortable and high-efficiency heating performance of the assembled electric heating floors.

ThermoWood is a wood modification method that is used to improve the wood application and dimensional stability of wood. In this study, poplar wood (Populus nigra) was used in two age groups of 18- and 38-year-old trees to investigate the effect of tree age, thickness, and depth of heat-treated timbers on mechanical properties and density. In each age group, the timbers were prepared according to thickness of 40, 50, and 60 mm. The experimental samples were prepared from the surface (S) and middle (M) depth of heat-treated timbers based on age and thickness. Some properties of heat-treated and control wood such as density (oven-dry density, air-dry density, and basic density) and mechanical properties (modulus of rupture (MOR), modulus of elasticity (MOE), and impact strength) were measured. In general, density and mechanical properties of heat-treated wood were decreased compared with the control samples. Density and mechanical properties of heat-treated and control wood samples were increased from 18- to 38-year-old trees. There were no differences in density and mechanical properties after changing thickness. Surface and middle depth specimens of heat-treated timbers showed a positive effect on the impact strength but had no considerable effect on densities and other strengths of heat-treated wood timbers.

The addition of polyvinylamine (PVAm) in the wet-end of the papermaking process was investigated. The changes in pulp drainage, vacuum dewatering, tensile strength, and air permeance were measured with and without PVAm. Both chemi-thermomechanical pulp (CTMP) and bleached kraft pulp were used. The dewatering and drainage abilities of the different pulps was examined by measuring the dewatering resistance (°SR), the water retention value (g/g), and the vacuum dewatering. The tensile strength and air permeance values were tested on paper sheets. The results showed that the initial dewatering was faster for pulps with PVAm, and this effect was greater for the CTMP and at higher basis weights. The strength increased when PVAm was added but only if the pulp was washed before sheet forming. The unwashed pulp with PVAm had worse formation, which resulted in lower tensile strength values. The air permeance of the sheets was higher with the addition of PVAm, primarily as a result of higher flocculation. Adding PVAm to the stock suspension in the wet-end of the paper machine has great potential for end-products that require high air permeance and tensile strength properties. PVAm could also act as a dewatering enhancing agent, but caution must be taken regarding the potential of formation problems.