Volume 14 Issue 3

Experimental and numerical investigations were performed for pure pulverized biomass combustion in a 300 kW laboratory swirl burner with a pre-combustion chamber. This work investigated a bluff body at the burner tip and how that affected the combustion characteristics in comparison with a conventional annular orifice burner. The combustion performances were assessed by measuring the temperature distribution in a pre-combustion chamber and furnace, oxygen concentration, and emissions (CO and NOx). Simulations were carried out and validated, providing insight on flow aerodynamics, particle trajectories, species concentrations, and temperature in a pre-combustion chamber and furnace. It was concluded that the bluff body provided a superior performance in terms of flame attachment and combustion efficiency. However, the emissions were high due to the contribution of thermal NOx.

Effects of wollastonite substitution were investigated relative to the mechanical, physical, and microstructural properties of a wood fiber-cement composite. Wollastonite content of 0%, 3%, 6%, and 9% and lignocellulosic material (kraft fibers) content of 10%, 20%, and 30% were used based on the dry weight of cement. Then the lignocellulosic material and the resulting board samples were compared to a control (without wollastonite). Modulus of rupture (MOR), modulus of elasticity (MOE), water absorption, and fire resistance tests were conducted to examine the characteristics of the board composite. The results showed that the mechanical properties of wood fiber-cement composite were improved by the 9% wollastonite substitution. The fire-resistance of the composite board was improved when the wollastonite content was increased. Furthermore, cement boards with 9% wollastonite exhibited lower water absorption in comparison to the other specimens. Scanning electron microscopy (SEM) results showed that the calcium hydroxide formed hydrated calcium silicate gel (C-S-H gel) after the addition of wollastonite. The SEM images showed that the micro-structure of the boards were improved by increasing the nano-wollastonite content.

A rapid and green preparation of lignin nanoparticles was demonstrated starting from bio-refinery lignin containing grafted carbohydrates. The particles were prepared by recovering a fraction of the lignin, which contained 24% carbohydrate (by weight) as the insoluble fraction in 0.5 M NaOH. The carbohydrate content of this fraction was verified with a wet chemistry analytical technique, nuclear magnetic resonance, and X-ray diffraction. This fraction was then dissolved in a NaOH/urea/water system and added dropwise to water under a high shear, which rapidly formed precipitated particles in a size range of approximately 100 nm. This carbohydrate-containing fraction of the lignin was soluble in a green solvent system that was not suited for lignin alone. The generated particles were stable in different organic solvents and water. Overall, the dissolution of the bio-refinery lignin in the NaOH/urea/water system, followed by precipitation in water can be regarded as a green and rapid method to produce stable nanoparticles. The generated nanoparticles, containing both carbohydrates and lignin, are expected to have unique applications because of their bi-component nature. Furthermore, this is the first publication to show how materials with high levels of lignin can be solubilized in solvents that are conventionally used for cellulose.

This study determines an optimum method to predict Turkish Medium Density Fiberboard (MDF) production values using ARIMA (Box-Jenkins), regression, and Artificial Neural Network (ANN). The prediction performance of these methods is also compared. A total of 14 independent variables, likely to influence MDF production, were determined, and the production values of the next 9 years (2017-2025) were predicted on the basis of these variables. The test results indicate that the best Mean Squared Error (MSE), Mean Absolute Percentage Error (MAPE), and Mean Absolute Deviation (MAD) prediction performance belongs to the prediction performed with ANN.

Poplar chips before and after a magnesium (Mg) pretreatment were pyrolyzed under different temperatures to obtain pristine and Mg-modified biochar samples (i.e., 300/BC, 450/BC, 600/BC, 300Mg/BC, 450Mg/BC, and 600Mg/BC). The biochars were used to evaluate how pyrolysis temperature and Mg modification influenced their capacity to adsorb ammonium and phosphate from eutrophic waters. An increased temperature caused an increase in carbonization degree, a more developed porous structure, and a decrease in the functional groups on biochar. The Mg modification was helpful for the development of a porous structure and the preservation of functional groups. The optimal ammonium adsorption was obtained by 300Mg/BC. This was attributed to the enriched functional groups. The maximum adsorption capacity was 58.6 mg/g. The 600Mg/BC sample exhibited optimal adsorption for phosphate with a maximum adsorption capacity of 89.0 mg/g, which was ascribed to the large surface area, the positively charged surface, and the metal oxides effect. A pseudo-second-order kinetic model and Langmuir–Freundlich isothermal model well described the adsorption of ammonium and phosphate on the modified biochar.

Morphological changes were examined in the wood cells of the Taxodium hybrid ‘zhongshanshan’ during the drying process, using wood sectioning and image processing methods. The results showed that the radial and tangential shrinkage rates were 2.7% and 5.8%, respectively. The tracheids displayed greater tangential than radial shrinkages, and latewood tracheids presented greater radial and tangential shrinkages than earlywood tracheids. The wood rays had little effect on cell lumen and tangential shrinkages of tracheids, unless they were adjacent to them. Shrinkage anisotropy was caused by the combined effect of difference between earlywood and latewood, and the inhibitory effect of wood rays. The fiber saturation point of Taxodium hybrid ‘zhongshanshan’ was between 33.3% and 38.3%. This study provided a scientific basis for the drying of the Taxodium hybrid ‘zhongshanshan’.

The effectiveness was evaluated for an established wood preservative, zinc borate, prepared in an agitating bead mill to extensively reduce its particle size. The generated micro- or nano-particles of zinc borate were characterized by X-ray powder diffraction, and the particle size distribution was determined to evaluate the effect of milling. Then the fungicidal effectiveness of the zinc borate of both milled and unmilled samples were assayed against brown- and white-rot fungi, on culture medium and on conifer and hardwood as substrates. Treated wood samples were subjected to leaching tests. Scanning electron microscopic images of wood samples were examined to analyze the distribution of zinc borate within the wood. The micronized zinc product kept its crystal structure intact, and it increased the proportion of particles with diameters below 100 nm by 25% when compared to the unmilled product. Malt extract-agar medium supplemented with 2.5% of w/w milled and unmilled zinc borate inhibited fungal growth tested. Both milled and unmilled zinc borate protected the wood when not subjected to leaching. The milled sample of zinc borate improved resistance to leaching, which would allow its application in environments of high moisture content; however, it did not improve the fungicidal action against decay fungi.

A cellulose derivative with multiple coordination sites for metals composed of cellulose powder and 1,2-pheneylnediamine was synthesized and evaluated as an adsorbent for metal ions from wastewater. The cellulose powder was generated from the solid waste of the olive industry. The adsorption efficiency of the cellulose amine polymer toward Fe(III) and Pb(II) was investigated as a function of adsorbent dose, temperature, pH, and time. The adsorption parameters that lead to excellent adsorption efficiency were determined. In addition, the polymer showed an excellent extraction efficiency toward approximately 20 metal ions present in a sewage sample. The cellulose amine derivative had several coordination sites that included amine, hydroxyl, and aromatic groups. The diversity and frequency of the coordination sites explained the high efficiency of the polymer for metal ions. The thermodynamic analysis results supported the spontaneous adsorption efficiency of the polymer at room temperature. The adsorption process fit well with the Langmuir adsorption isotherm model.

Natural and artificial weathering treatments were studied to determine the change of wood properties as a function of exposure time. This paper aimed to provide general information about the mechanical performance of wood under natural and artificial weathering treatments and define a relationship between them. The eight strength classes of ABNT NBR 7190 (1997) were considered, in addition to a paired sampling approach. The modulus of elasticity and conventional strength value in static bending, strength in compression parallel to the grain, hardness perpendicular to the grain, and the elastic limit in the static bending test were investigated. Linear regression models for mechanical performances under artificial and natural aging treatments of the exposure time were made and tested using an analysis of variance. According to the results, 360 days of natural weathering provoked a change in mechanical performance of 15.72% that included a decrease in strength and modulus of elasticity and an increase in elastic limit. Twelve hours of the artificial weathering treatment provided the effect of 6.22 days of natural weathering exposure.

The primary objective of this research was to assess and to model the hygrothermal properties of CLT panels made from three distinct combinations of spruce lumber and laminated strand lumber (LSL). The hygrothermal performance of these materials both individually and in conjunction in CLT has not been investigated before and is an important indicator of CLT building wall performance. CLT panels consisting of spruce as a face layer absorbed moisture more rapidly when that face layer was exposed to higher moisture concentration compared to CLT panels consisting of LSL as a face layer. The accumulation of moisture between layers increased with placement of the LSL as a core layer. Based on the smaller diffusion coefficient, moisture transport through the CLT panels made of LSL was slower. Modelling with a finite element-based program showed that the temperature in the panels when exposed to a severe gradient equilibrated within two days, as shown by both experimental and simulated results. For moisture transfer, the diffusion coefficient variation with moisture content and temperature based on the Arrhenius equation produced simulation results in agreement with experimental results but the moisture transfer was much slower than the heat transfer.