Volume 13 Issue 1

The aim of this study was to investigate the potential of Typha latifolia L. stem and leaf powder (T-SLP) to remove methylene blue (MB), a cationic dye, from aqueous solutions. The T-SLP was used without any modification. The batch adsorption experiments were carried out at 25 °C under varying operating parameters, namely pH, initial concentration, contact time, and adsorbent dose. Equilibrium isotherms and kinetics were used for data analysis. The surface morphology of the adsorbent and the possible interactions between the T-SLP and MB were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The experimental data fitted well to the Langmuir model, with a maximum adsorption capacity of 126.6 mg g-1. The efficiency of dye removal in the substrate was high, reaching a maximum value of 98.69%. Intra-particle diffusion was involved in the adsorption process, and the pseudo-second-order kinetics was the best fit for the adsorption of MB onto T-SLP, with a high correlation (R2 ≥ 0.9993) for all initial MB concentrations studied. The results of this work revealed that T-SLP can be used as a potential alternative for the rapid removal of MB from aqueous solutions.

To improve nitrogen fertilizer efficiency and minimize the negative impact of nitrogen fertilizer on the environment, a novel three-dimensional network polymer material with slow release character was prepared based on hydroxymethylated lignin (HML) and urea/hydroxymethylurea/urea-formaldehyde polymers (U/HU/UF) through solution polymerization. The novel material (Lignin-U/HU/UF) was characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance spectra (1H NMR), and distortionless enhancement by polarization transfer analysis (DEPT 135). The N release characteristics of the material were determined by soil leaching experiments under laboratory conditions. On this basis, the release profiles of total nitrogen and other nitrogenous compounds (NH4+ and NO3-) were investigated. The experimental data showed that lignin can be used as a majority component in material, which trapped polymers such as urea, hydroxymethylurea, and urea-formaldehyde to improve slow-release properties of fertilizer. The results indicated that the eco-friendly material (Lignin-U/HU/UF) with good controlled-release capacities potentially could be applied in agriculture and horticulture.

Silver nanoparticles (AgNPs) have been applied as an antifungal agent, which results in AgNPs contamination of agricultural waste that interferes with the lignocellulosic enzymes produced by fungi. Therefore, this study examined the production of carboxymethylcellulase (CMCase) and manganese-dependent lignin peroxidase (MnPase), using barley straw treated with AgNPs. Trichoderma asperellum growth was not inhibited at 25 ppm AgNPs, while negligible growth inhibition was observed at 50 ppm AgNPs, which was not observed with Aspergillus terreus and Curvularia lunata. T. asperellum was the highest producer of CMCase and MnPase using barley straw with or without 25 ppm AgNPs versus A. terreus or C. lunata. AgNPs addition to barley straw before T. asperellum inoculation played a role in repressing enzyme activities (CMCase 156.33 U/mL and MnPase 1.28 U/mL); however, addition of AgNPs (50 ppm) after 10 days of incubation showed the highest activity (CMCase 160.67 and 1.35 U/mL MnPase). Optimum temperature for enzyme production by T. asperellum using untreated and treated barley straw was 35 °C and 30 °C, respectively. Enzyme activities increased with increasing polyoxyethylenesorbitan monooleate surfactant concentrations up to 0.25 mL/g substrate without AgNPs, whereas the activity decreased with AgNPs (25 ppm). The exception to this observed trend was at low concentrations of the surfactant (0.10 mL/g substrate).

It is necessary to know the type and quantity of wastes to select the proper applications and waste management strategies. This study investigates the type, quantity, and utilisation methods of wastes generated by micro-sized enterprises that produce timber and furniture, which are two major sub-sectors of the forest products industry in Trabzon. A total of 885 enterprises of manufacturing timber and furniture in Trabzon were identified by reviewing the records from the professional chambers of commerce. The stratified sampling method was used to compare the sub-sectors, and the sample size was determined as 120. Among these, 70 furniture- and 50 timber-producing enterprises were interviewed. The chi-square test was used to determine whether the applications of timber and furniture enterprises are dependent on each other. In general, there are no differences in waste utilisation applications and education level between the sub-sectors. The percentage of the owners/managers that received any vocational training is 77.5% in two sub-sectors. In general, engineered wood wastes are used as fuel. The majority of the owners/managers in the timber industry believe that their waste has an economic value compared to those in the furniture sector. The total amount of wood waste generated by sectors was 528 tons in a month.

Machinability issues during drilling of wood-based materials were evaluated. Three types of standard wood-based materials of substantially different internal structures, i.e., fibreboards, particle boards, and veneer boards, were selected as test samples. The experiment consisted of drilling holes through samples made of 14 different materials. The purpose of the experiment was to determine the quality of the edges of the holes and to evaluate values of the cutting force and torque. The obtained results were used to determine the relative machinability indexes based on the machining quality and cutting forces. These indexes were defined by referencing the obtained data of each tested material to one selected reference material: medium density fibreboard. The experimental data showed that the machinability index based on the quality criterion was not correlated with the index based on the cutting force criterion. The quality index was not correlated with the basic, routine parameters of wood-based boards. However, the cutting forces index sometimes showed a significant correlation of this type. The quality index showed the influence of the internal structure and homogeneity of the different types of materials.

Biochar has the potential for use as a carrier of plant growth promoting rhizobacteria. The biochar in this experiment was produced by the pyrolysis of cotton stalks at high temperatures. Fourier transform infrared spectroscopy (FTIR) and an elemental analyzer characterized the structure and composition of the biochar, while scanning electron microscopy (SEM) observed the relationship between the bacteria and biochar. This study investigated the effects of biochar on the growth of Bacillus subtilis SL-13, a plant growth promoting rhizobacteria, as well as the adsorption of B. subtilis SL-13 to biochar under different conditions. The addition of biochar in a liquid nutrient broth medium was thought to promote the growth of B. subtilis SL-13 bacteria. The SEM images showed that the bacteria entered into the tubular structure of biochar. The adsorption of bacteria onto biochar increased with decreasing biochar particle size. The B. subtilis SL-13 population in biochar was maintained at 106 colony forming units g−1 (CFU) of biochar for up to 120 d. Therefore, the biochar could provide a beneficial microenvironment for the slow release and prolonged survival of bacteria as a carrier in future practical applications.

A tensile test was conducted to investigate the mechanical properties of hybrid bio-composites that have potential for application in helmet shells. Helmets can protect users from serious injuries, reducing traumas and deaths. Military helmets are made with 19 layers of Kevlar, and bicycle helmets are made of glass fibre reinforced plastic materials that are costly. Replacing or reducing these synthetic fibres with plant fibres would reduce costs and may allow for such materials to be recyclable, biodegradable, and more abundant, as the material has been ground or crunched. Flax woven fibre was used to fabricate one panel of composite (Flax only) and three panels of hybrid composite (FLXC, FLXG, and FLXK). In this project, the epoxy resin was modified by weight with 0 wt.%, 0.5 wt.%, 1 wt.%, 1.5%, and 2 wt.% multi-walled carbon nanotubes (MWCNTs). This study examined the effect of multi-walled carbon nanotube (MWCNT) concentration on the tensile properties of hybrid biocomposites. The experimental results suggested that the MWCNTs played an important role in improving the mechanical performance of hybrid biocomposites. It was found that optimum carbon nanotube (CNT) concentration improved the tensile performance of the materials by 2% to 5%. However, an excess CNT concentration led to the deformation of materials and reduced their mechanical performance.

Effects of adding pulping black liquor in the preparation of briquettes were evaluated relative to the properties of the resulting pulp black liquor briquettes. The addition of 2% binder (pregelatinized starch) and a molding pressure of 5 MPa were sufficient to obtain briquettes that complied with DB13/1055 (2009). When 30% of pulping black liquor was added in the preparation of briquettes, the compressive strength, shatter index, moisture content, and the content of volatile matter and ash of the resulting briquettes increased. Moreover, the combustion performance of the briquettes after the addition of black liquor was higher, where the briquettes exhibited an enhanced ignition point, a more stable combustion process, and a 50% higher sulfur-fixation ratio after combustion, compared to the ordinary briquette. However, the thermal stability and calorific value decreased and the ash after combustion of the black liquor briquette contained a higher content of high melting point salts. Therefore, the addition of pulping black liquor in the composition of briquettes should be moderate. The preparation of black liquor briquettes provides an efficient way for utilization of black liquor.

Some mechanical and physical properties and the formaldehyde content of uncoated oriented strand boards (OSBs) that were made from Scots pine (Pinus sylvestris L.), manufactured with different thicknesses, and bonded with polymeric methylene di(phenyl isocyanate) (pMDI) resin were evaluated. All of the mechanical and physical properties were affected significantly by the OSB type (3 and 4) and thickness of the panels, except for the thickness swelling after 24 h and measured formaldehyde content. The measured mechanical and physical properties of the OSB panels satisfied the standard requirements. The densities of the panels ranged from 554.2 kg/m³ to 580.2 kg/m³ and from 573.8 kg/m³ to 610.7 kg/m³ for OSB/3 and OSB/4, respectively, which met the standard requirements. The measured mechanical and physical properties of the OSB/4 panels were higher than those of the OSB/3 panels, but there were no differences in the thickness swelling after 24 h and measured formaldehyde content. Low formaldehyde contents were found for OSB/3 (0.00 mg/100 g and 0.29 mg/100 g) and OSB/4 (0.18 mg/100 g and 0.47 mg/100 g).

Cryogenic treatment via liquid nitrogen (LN) was evaluated as a means to improve the capability of impregnation and penetration in fir and spruce wood. There are a few vital problems that occur during the impregnation process of wood protection. One problem is that refractory woods have different anatomical features that make the impregnation process difficult. For the specimens that were conditioned with the air and oven, the retention changes were determined with an image analysis, scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). In addition, the density and equilibrium moisture content (EMC) values were measured. The LN treatment resulted in degradation in the bordered pits. Then, the margo and torus bonds were torn, the bordered pits were opened, and the liquid transportation of wood was facilitated. It was determined that the LN treatment and impregnation increased the depth and dispersion capability of the penetration. The LN treatment helped facilitate the flows from pores to pores by hindering the aspirations of the bordered pits, and thus the flow of chemicals was facilitated. Obtaining deeper penetration in refractory wood species will result in an improved impregnation process.