Volume 4 Issue 2

The term “hydrothermal” comes originally from the field of geology. Hydrothermal reactions generally can be defined as reactions in the presence of aqueous solvents under high temperature and pressure. Such reactions played a very important role during formation of fossil fuels. On the basis of the natural phenomena, we have conducted a series of studies concerning hydrothermal conversion of biomass into value-added products. This article gives an overview of some recent advances in our research on hydrothermal conversion of biomasses, mainly including the production of low molecular weight carboxylic acids, such as acetic acid, lactic acid, and formic acid, from carbohydrate and lignocellulosic biomasses, as well as glycerin, which is a by-product of the bio-diesel fuel manufacturing process.

Waterproofing of corrugated packaging with wax or polyethylene hinders recyclability and so is incompatible with current socioeconomic goals of sustainability. Therefore, alternative coating technologies are sought. This study describes our feasibility study of electrohydrodynamic spraying (EHS) towards waterproofing corrugated boxes. Water resistance properties of electro-sprayed polymer-solvent solutions and latex systems air dried onto linerboard surface are reported. Optimization of spraying parameters led to observations of applied coating roughening on a nano-to-micron scale that correlated with increased water contact angle of the treated linerboard. An EHS latex formulation, compared to polymer solvent system, has shown better adhesion to linerboard. EHS application of latex produced a surface coating texture of droplets, which minimizes liquid water absorption, forming a nanopore matrix (of 3 – 50 nm diameter pores) that enabled the transmission of water vapor. Linerboard treated by EHS latex was advantageously found to be comparatively transpiring to water vapor at room temperature and refrigeration conditions, which is encouraging for commercial application of the technique.

In this work, the effect of the alkali-treatment and its variables viz., time and concentration of alkali, on the creep properties of jute fibre were studied. It was demonstrated that this kind of treatment leads to several changes in fine structure, such as voids creation and fibre fibrillation. The creep behaviour was measured for the alkali treated as well as the dewaxed fibres. Creep value was much higher in the 17.5% NaOH treated fibres compared to the dewaxed fibres. In the 8 hrs treated fibres, the creep was slightly more than the 20 mins treated fibres. XRD study revealed that experimental alkali treatment conditions resulted in closer packing of cellulose chains or rather increased crystallinity. Hence closer arrangement of the molecular chains (higher crystallinity) will reduce the creep extension, as expected.

Activated lignin having a surface area of 1023 m2 g-1 has been prepared from sulfate lignin that was treated by 30% H2O2 and carbonized at 300 °C in order to test the chromium (VI) adsorption from aqueous solution. The influence of contact time, pH, initial concentrations of adsorbent and adsorbate, and temperature on the adsorption capacity were investigated. The maximum removal of Cr(VI) was found to be 92.36 % at pH=2 and a contact time of 80 min. Optimal concentration of lignin and Cr(VI) were found to be 3.8 g L-1 and 180 mg L-1, respectively. The adsorption kinetics data fitted well with a pseudo-second-order equation, and the rate of removal of chromium was found to speed up with increasing temperature. Activation energy for the adsorption process was found to be 18.19 kJ mol-1. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherm and isotherm constants for the adsorption of Cr (VI) on lignin. These constants and correlation coefficients of the isotherm models were calculated and compared. Results indicated that Cr (VI) uptake could be described by the Langmuir adsorption model. The maximum adsorption capacity (qm) of Cr (VI) on lignin was 75.75 mg g-1 at 40°C. The dimensionless equilibrium parameter (RL) signified a favorable adsorption of Cr (VI) on lignin and was found to be between 0.0601 and 0.818 (0<RL<1). The thermodynamic parameters such as ΔG°, ΔS°, and ΔH° were calculated, and it was found that the reaction was spontaneous and endothermic in nature. This study indicates that lignin has the potential to become an effective and economical adsorbent for removal Cr (VI) from waste water.

Desmodur VTKA and Urea formaldehyde) on wooden materials (Scotch pine and oriental beech) cut tangentially and radially impregnated with Tanalith-C, creosote, and sodium silicate in layer (3, 4, 5) of laminated veneer lumber (LVLs) on thermal conductivity. The lowest thermal conductivity of 0.103 Kcal/mh°C was obtained in Scotch pine, cut tangentially, impregnated with creosote, bonded with urea formaldehyde, and 3 layer LVL. The highest thermal conductivity of 0.185 Kcal/mh°C was obtained in oriental beech, cut radially, impregnated with Tanalith-C, bonded with PVAc, and 5 layers LVL. Consequently, oriental beech wood cut radially and impregnated with Tanalith-C, bonded with PVAc adhesive and 5 layers in LVL can be used as a material in construction where the thermal conductivity is required. Scotch pine wood cut tangentially and impregnated with creosote, bonded with urea formaldehyde adhesive and 3 layers in LVL can be used as a material in construction where the insulation is required.

The high demand of wood as a raw material can be expected to soon lead to a severe shortage, resulting in drastic competition between various mills. This competition will be worsened by a restriction of forest cuttings in Quebec. One of the solutions to this problem would be to develop a mixed panel in which the strands of core layer are substituted by outer bark particles, and in this particular case, by particles of white birch. This type of panel could be used as siding panels and for the fabrication of boxes, bins, and commercial shelving. The objective of the present research work concerns the design, the manufacture, and the evaluation of mechanical and physical properties of this type of panel. Two manufacturing factors were taken into account: the strands orientation in the face layers and the alkali treatment made on the bark particles used in the core layer. All produced mixed panels met and exceeded almost all CAN3-0437 R-1 and O-1 property requirements. The alkali treatment of bark particles did not improve the mechanical properties of manufactured panels. The statistical analysis method that was used made it possible to choose the panel with non-oriented wood strands in the surface layers and alkali treated bark particles in the core layer as the best by taking into account only the bending strengths in both major and side axes of a panel.

Bio-oil produced from fast pyrolysis of biomass has been investigated as a renewable fuel and as a source of industrial chemicals. The lignin fraction of bio-oil produced from wood in our fast pyrolysis reactor was separated by using only water and methanol with a 25% yield based on bio-oil weight. This separation procedure appears to be of lower cost than the reported extraction procedure using ethyl acetate as solvent. The isolated pyrolytic lignin was smoothly incorporated into phenol-formaldehyde resins at 30%, 40%, and 50% phenol replacement levels, and the resultant resins were evaluated as oriented strand board core-layer binders. The evaluation results indicated that the pyrolytic lignin is effective for up to about 40% replacement of phenol in synthesizing wood adhesive type PF resins.

The blending of polypropylene with lignin derived from chemical wood pulp manufacture makes it possible to prepare optically transparent films (thickness 50-60μm) with acceptable mechanical properties in the absence of a commercial stabilizer. The lignin preparation in the concentration 1-2 wt% possessed the ability to act as a processing stabilizer and as an antioxidant during thermal aging of polypropylene films. A DNA-protective effect of lignin in mice testicular cells and mice peripheral blood lymphocytes against oxidation stress was examined using in vitro experiments. Hydrogen peroxide and visible light-excited methylene blue (MB) were used as DNA damaging agents. The isolated cells were preincubated with lignin before treatment with the oxidative agents. The level of breaks in the DNA was measured by a comet assay. The results showed that preincubation with lignin significantly decreased the level of strand breaks induced by both oxidants in mice lymphocytes and testicular cells.

The use of ionic liquids (ILs) has provided a new platform for efficient utilization of wood. In this paper, applications of ILs in wood-related industries are reviewed. First, the dissolution of wood in ILs and its application are described. Then the ILs used for wood preservation and improvement of wood anti-electrostatic and fire-proof properties are illustrated. Finally, “green” wood processing with ILs is discussed. Although some basic studies of ILs, such as their economical syntheses and toxicology are eagerly needed and some engineering problems still exist, research for application of ILs in wood-related industries has made great progress in recent years.

Three white-rot fungi: Daedalea elegans, Polyporus giganteus, and Lenzites betulina were screened for their lignin degrading abilities on rice straw, maizecob, sawdust of Terminalia superba, and sugarcane bagasse at different time intervals (30, 60, and 90 days). All the fungi demonstrated varying levels of ligninolytic capability with different degrees of lignin degradation in all the fermented substrates. A significant difference (p<0.05) was observed in the mycelia extension of Daedalea elegans grown on the different agro-industrial wastes. D. elegans gave maximum extension of 4.5 cm on sugarcane bagasse. The highest lignin reduction of 92.9% (p<0.05) was recorded in maize cob fermented with Daedalea elegans after 90 days. On the basis of lignocellulosic material degraded, it is concluded that the white-rot fungi offer a better alternative to conventional ways of disposing these waste substances. This paper considers the ability of indigenous white-rot fungi to degrade lignin as a way of using them in effective waste management.