Volume 11 Issue 3

Crude oil as a non-renewable resource is creating new challenges in many industrial sectors. Unsteady costs of crude oil at present and expected increases in the future are due to its limited availability as a finite resource, and these costs negatively impact the industry for wood-based panels, which use petrochemical resins in binding agents. Furthermore, wood panels that are conventionally bonded using urea formaldehyde diffuse formaldehyde into the surrounding air. To achieve independence from petrochemical products and harmful formaldehyde emissions, alternatives for their substitution are in demand. An alternative approach is the enzymatic activation of lignin located on the surface of thermomechanical pulp (TMP) fibers. The present study shows the results of internal bond strength (DIN EN 319 1993), modulus of rupture (DIN EN 310 1993), and thickness swelling (EN 317 2003) of medium-density fiberboards (MDF) bonded with laccase-mediator-system (LMS). Caffeic acid (CA), 4-hydoxy benzoic acid (HBA), and vanillic alcohol (VAl) were used as mediators. The physical and technological properties of MDF, such as internal bond strength, modulus of rupture, and thickness swelling, mostly fulfilled the European standards.

Production of bioenergy from cellulosic sources is likely to increase due to mandates, tax incentives, and subsidies. However, unchecked growth in the bioenergy industry has the potential to adversely influence land use, biodiversity, greenhouse gas (GHG) emissions, and water resources. It may have unintended environmental and socioeconomic consequences. Against this backdrop, it is important to develop standards and protocols that ensure sustainable bioenergy production, promote the benefits of biofuels, and avoid or minimize potential adverse outcomes. This paper highlights agronomic information on switchgrass, a high-potential bioenergy feedstock, and the role of specialized certification programs. The existing sustainability standards and protocols were reviewed in order to identify key gaps that justify a certification program specifically for switchgrass-based bioenergy. The criteria and indicators that should be considered for such a certification program are outlined.

Softwood fibers pretreated with a monocomponent endoglucanase were used to prepare a series of cellulose nanofiber qualities using a microfluidizer and 2 to 34 MWh ton-1 of energy input. The specific surface area was determined for the series using critical point drying and gas adsorption. Although the specific surface area reached a maximum of 430 m2 g-1 at 11 MWh ton-1, the nanofiber yield and transmittance continued to increase beyond this point, indicating that more energy is required to overcome possible friction caused by an interwoven nanofiber network unrelated to the specific surface area. A new method for estimating the surface area was investigated using xyloglucan adsorption in pure water. With this method it was possible to follow the disintegration past the point of maximum specific surface area. The technical significance of these findings is discussed.

The migration behavior of the alkali metals and chlorine were studied during rice straw and corn straw gasification in a fixed bed reactor at various temperatures using thermodynamic equilibrium calculations, X-ray diffraction (XRD), and scanning electron microscopy/energy dispersive spectrometry (SEM-EDS). The results showed that K and Na were released mostly in chloride form. The release of potassium, sodium, and chlorine increased upon the increase in temperature from 600 to 1000 °C. The maximum amounts of potassium, sodium, and chlorine that were released from rice straw were 38.9%, 18.7%, and 34.9%, respectively. The maximum amounts of potassium and chlorine that were released from corn straw were 24% and 43.6%, respectively, which occurred at 1000 °C. The maximum amount of sodium released from corn straw was 77.6%, at 700 °C, and the amount of sodium released was greater than that of potassium. Most of the potassium and sodium was converted into insoluble carbonate, sulfate, silicate, and aluminosilicate compounds in the gasification ash.

To enhance the removal of mercury (Hg(II)) and cadmium (Cd(II)) from aqueous solutions, rice bran (RB) was reacted with epichlorohydrin and then modified with ethylenediamine and sodium chloroacetate to bear iminodiacetate functional groups. The modified rice bran (MRB) was characterized by Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), energy dispersive spectroscopy (EDS), back titration, and X-ray photoelectron spectroscopy (XPS). The adsorption properties of MRB for Hg(II)/Cd(II) ions were also evaluated in batch experiments. The sorption kinetic experimental data were best described by the pseudo-second-order model. The maximum adsorption capacity (163.9 mg/g for Hg(II) at pH 5.0 and 106.4 mg/g for Cd(II) at pH 6.0) was observed at 298 K, and the isotherm adsorption equilibrium of MRB was followed by Langmuir isotherm equation. The major adsorption mechanisms should be predominantly controlled by the formation of complexes between the functional groups of MRB and Hg(II)/Cd(II) ions as well as ion-exchange. The regeneration experiments showed that the MRB could be successfully reused for six cycles when 0.1 M HCl eluent was used.

Tests were conducted to determine the bending moment capacity of 215 red oak and 140 white oak T-shaped rectangular mortise and tenon joints. Rails measured 22.2 mm by 63.5 mm in cross section; tenons measured 32 mm in length by 38 mm in height by 9.5 mm in thickness. Specimens were assembled with a 40% solid content polyvinyl acetate adhesive. The average bending moment capacity of the red oak specimens was 353 Nm with a standard deviation of 48 Nm; in the white oak specimens, it was 358 Nm with a standard deviation of 62 Nm. The lower tolerance limits of the red oak specimens at the 75|75, 90|75, 75|90, 90|90, and 95|95 confidence|proportion levels were 318, 316, 289, 286, and 266 Nm, respectively, whereas in white oak specimens, the values were 314, 308, 273, 268, and 240 Nm, respectively.  Overall, the results indicated that the use of statistical lower tolerance limits procedures provide a systematic means of relating standard deviations to mean values in determining reasonable design values for the moment capacity of the joints. Conclusions were not reached concerning which confidence|proportion level might be best suited for determining reasonable design values for furniture joints, but the results did illustrate the consequences of a given choice.

Ionic liquids (ILs) were used in the dissolution of oil palm biomass, primarily empty fruit bunches (EFB), oil palm fronds (OPF), and oil palm trunks (OPT). These ILs acted as alternative solvents that could dissolve biopolymer molecules up to 5 wt.%. The IL, [emim][OAc] was the best solvent, dissolving EFB, OPF, and OPT of 99%, 100%, and 97%, respectively, at 100 ⁰C and 16 h. The lignin content of the regenerated oil palm solids for all biomass was quantified and showed significant reduction up to 35%; fiber length was also reduced as the heating time increased after IL dissolution. Also, the effect of ILs on the different parts of oil palm biomass fibers was thoroughly studied. The lignin content was quantified.

This study evaluates the effect of 1% to 5% NaOH treatments of cotton stalk particles on the chemical composition and physical and mechanical properties of particleboards produced with this material. Gas chromatography and Fourier transform infrared (FTIR) spectroscopy indicated that the extractive, hemicellulose, and lignin content of the particles decreased during the alkali treatments, whereas the cellulose content increased. Thermogravimetric analysis (TGA) indicated that the untreated particles exhibited higher thermal stability than the particles treated with NaOH. The decrease in thermal stability of alkali-treated particles seems to be due to degradation of chemical components. Alkali treatments raised water absorption (WA) and thickness swelling (TS) of the produced particleboards. Except for 1% NaOH, the treatments reduced the modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond (IB) strength in relation to the board made with untreated particles. The 1% NaOH treatment of cotton stalks was more effective and beneficial, leading to particleboards with satisfying MOE, MOR, and IB values that met the requirements for general-purpose particleboards used in dry conditions, as indicated by the TS-EN 312 (2012) standard.

In this study, Xylosma racemosum was selected as the raw material and its compressive strength was predicted through nondestructive methods. The test data consisted of 160 near-infrared (NIR) absorption spectra of the wood samples obtained using an NIR spectrometer, with the wavelength range of 900 to 1900 nm. The original absorption spectra were pre-processed with multiplicative scatter correction (MSC) and Savitzky-Golay (SG) smoothing and divided into several intervals using the backward interval partial least squares (BiPLS) method. The optimal combination of intervals with the smallest root mean square error of cross validation (RMSECV) value was selected, and a genetic algorithm (GA) was used to select featured wavelengths. Finally, a partial least squares (PLS) regression model was established with the featured wavelengths. The BiPLS-GA-PLS model outperformed the other models, resulting in a high prediction correlation coefficient of 0.927 and a root mean square error rate of 4.06. Based on the results, it is feasible to accurately measure the compressive strength of wood processed by different methods using near-infrared spectroscopy.

Water hyacinth (Eichhornia crassipes) is an aquatic flowering plant that belongs to the Pontederiaceae family. The plant is a freshwater hydrophyte that grows in subtropical and tropical regions of the world. The objective of this study was to determine the physicochemical characterization of roots, stems, and leaves of E. crassipes. The pH, ash, 1% alkali solubility, extractives, lignin, holocellulose, tannins, and calorific value were determined. Our results showed that the mineral content is relatively high, whereas that for lignin and tannins is low. The pH is moderately acid, and the soluble substances easily dissolved in alkali or organic solvents. Potassium, calcium, and silicon are the major constituents present in the ash of this plant. The determined calorific value was approximately 14.4 MJ/kg.