Volume 12 Issue 3

The effects of 12 common metal ionic compounds on the laccase catalytic activity in reactions using guaiacol as the substrate was determined using spectrophotometry. Furthermore, the influence of several metal ionic compounds on the generation of reactive oxygen species (ROS) by oxidation of lignin in jute fiber under laccase catalysis was studied by electron paramagnetic resonance (EPR) spectroscopy using N-tert-butyl-alpha-phenylnitrone (PBN) as the spin-trapping agent. Common metal cations, such as K+, Na+, Mg2+, Ca2+, and Cu2+ and the anion SO42- had almost no effect on laccase activity during the initial stage of the catalytic reactions. High concentrations of the Mn2+ ion exhibited weak inhibition of laccase; Ag+ and NO3- showed a moderate inhibitory effect on laccase activity during the initial stage of the catalytic reactions. Fe2+ had no direct effect on the binding of laccase to its substrate, but strongly retarded the progress of the catalytic reaction by reducing the intermediate free radicals. The ions Cl-, Fe3+, and Ag+ exhibited either strong inhibitory effects on the catalysis of the substrate or a destructive effect on the structure of laccase itself. Furthermore, the results showed that an appropriate concentration of Cu2+ helped to promote the thermal stability of laccase during the enzymatic reaction. This study could help researchers to avoid the use of inhibitory exogenous metal ions and anions in the application of laccase and to maximize the value of laccase.

Wood plastic composites are an interesting development in composite materials. They have gained wide market interest recently because of their sustainable material sources and beneficial material properties. Because thermosets or thermoplastics are involved in the composites, the material is temperature-dependent and susceptible to considerable dimensional changes with the variation of temperature. To minimize waste generation and enable reheated material post-processing, the distortion and displacement of the composite material has to be controlled precisely in different temperature ranges. This article studies ways to control this displacement and proposes a solution with an odometer and polynomial curve fit.

A novel medium-density fibreboard produced by an ultrasonic-assisted wheat straw pulp (UWP) was obtained without adhesives. It was then coated with a superhydrophobic sol solution integrated with an in vitro addition of two fire retardants (polyhedral methyl-silsesquioxane and ammonium polyphosphate) during the process of sol-gel reaction involving the two silane precursors tetraethyl orthosilicate (TEOS) and tridecafluorooctyltriethoxysilane (FAS). The coated UWP medium-density fibreboard (UPB) had good strength properties and possessed excellent hydrophobicity (water contact angle (WCA) above 150°), and flame-resistant properties (limiting oxygen index (LOI) improved by 5% compared with the original sample with a LOI of 18%). Meanwhile, the fibreboard also exhibited outstanding anti-permeability towards water (kept constant WCA for more than 1 h).

The impact of technical and technological parameters on the quality of machining during milling of thermally modified pine wood (Pinus sylvestris L.) was studied. Experiments were conducted to evaluate the effects of tools (α = 30°, β = 45°, γ = 15°, 20°, and 30°), material (natural material, thermally treated at 160 °C, 180 °C, 210 °C, and 240 °C), and technological factors, such as cutting speed (20 m.min-1, 40 m.min-1, and 60 m.min-1) and feed rate (6 m.min-1, 10 m.min-1, and 15 m·min-1) on the quality of the machined surface (standard deviation of surface Ra). The roughness measurements were realized by a non-contact method using a laser. This paper aimed to highlight which one of the technological or tool factors had the greatest impact on the quality of the surface of heat-treated wood in face milling. The importance of the parameters impact on surface quality was in the following order: rake angle, feed rate, thermal treatment, and cutting speed.

Current approaches in logistics are focused on sustainable development of enterprises and society. Small and medium enterprises (SMEs), in this case wood-processing enterprises, can achieve this goal by implementing green logistics strategies in business practice. The main objective of this paper is to propose an algorithm for the implementation of green logistics activities in wood-processing SMEs, through a survey aimed at analyzing the accelerators and barriers to implementation in business practice. The research has been evaluated via methods of testing the statistical hypothesis (binomial test, Chi-squared, Friedman test, Wilcoxon test), methods of descriptive statistics, and data visualization. The survey found that one of the most significant determinants for implementing green logistics activities in a wood-processing enterprise is a decrease in cost. Based on the performed analysis, a model for the implementation of green logistics activities for wood-processing SMEs was proposed that includes appropriate activities that ensure the sustainable development of wood-processing SMEs in Slovakia.

The improvement of the hydrogen-poor composition of bio-oil is important for its cracking to produce aromatic hydrocarbons. In this work, a mild hydrogenation pre-treatment and methanol cocracking were combined to implement proper hydrogen supplementation for cracking. Acetic acid (HAc), hydroxypropanone (HPO), and cyclopentanone (CPO) were selected as model compounds and mixed to prepare a simulated distilled fraction (SDF) of bio-oil. The hydrogen supply and transfer behaviours in hydrogenation-cracking were investigated. For the conversion of individual components: HAc was difficult to be hydrogenated, and therefore in the cracking stage, the conversion and oil phase yield were low; ketones were successfully hydrogenated to alcohols, and thus high aromatic hydrocarbon yields were achieved. Hydrogenation-cracking of SDF showed that the inferior performance of HAc was improved by an internal hydrogen transfer, namely the alcohols produced from ketones supplied hydrogen for HAc conversion. However, because of the high HAc content in SDF, this hydrogen supplement was not sufficient. Therefore, methanol (MeOH) was used as the coreactant for secondary hydrogen supply. The integral efficient conversion of SDF and MeOH to aromatic hydrocarbons was achieved when the MeOH blending ratio was 30%. Finally, a reaction mechanism of hydrogenation-cocracking was proposed.

It is well established that current flame retardant (FR) products at disposal generate various ecological hazards. Irrespective of their environmental impacts, the FR market is growing and is estimated to reach 2.8 million tons globally in 2018. In the textile domain, FRs are incorporated into baby clothing, pushchairs, car seats, etc. When disposed, these FR textile products end up in a landfill or are incinerated. These disposal processes are unsustainable. With landfilling, there is a huge chance of the FR product leaching into the environment. Similarly, FRs decrease energetic yields in the incineration process due to incomplete combustion. To cope with such issues, degradation and elimination of the FR product from the textile products before disposal could be a sustainable alternative. This study dealt with the preliminary degradation of flame retardant from the cotton textiles and its thermal characterization. Energy valorization by gasification is considered beneficial opposed to incineration with overall low energy recovery. The initial optimum gasification conditions including FR-treated cotton as a feeding material and potential outcomes of FR-treated cotton after degradation were characterized.

The effects of ultraviolet (UV) irradiation on the changes in color and chemical structure of the surfaces of unbleached, PNaOH-, and PMg(OH)2- bleached deinked pulp (DIP) were studied by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The analysis of color changes in pulp surfaces during the photo yellowing was performed by measuring the brightness loss, post color (PC) number, and CIELAB parameters (L*, a*, b*, and ΔE*). The results showed that the pulp brightness loss, PC number, and chromatic aberration had a linear relationship with b*. During the UV irradiation, the pulp brightness loss, PC number, and chromatic aberration (ΔE*) increased quickly, and then the changes slowed down. After being irradiated with UV for 360 min, the band intensity of the pulps at 1729 cm-1 increased distinctively and a new band at 1674 cm-1 appeared. This indicated that p-quinone groups were produced during the irradiation process, thus resulting in paper yellowing. The band intensity at 1674 cm-1 of PMg(OH)2-bleached pulp was lower than that of PNaOH-bleached pulp, which indicated that the brightness stability of PMg(OH)2 pulp was better than that of PNaOH pulp.