Volume 13 Issue 2

This paper presents the effects of a low velocity impact test on the hybrid composites of kenaf and Kevlar. In recent years, there has been a trend to replace the synthetic fibers, used as reinforcement in epoxy composites formation, with natural fibers due to their low cost, high flexibility, biodegradability, and recyclability. In order to surpass the low mechanical strength of natural fibres in comparison to the conventional composites, hybrid composites combining both types of fibres was introduced. This combination will lead to improvement in the mechanical strength and biodegradability of epoxy composites, which is important for waste reduction and protection of the environment. The materials were fabricated in a seven-layer laminate configuration utilizing a ratio of 3:1:3 (Kevlar:kenaf:Kevlar) for a hybrid composite. This combination earlier had been found to give the best tensile test performance. An original composite with seven layers of kenaf (full kenaf) and one with seven layers of Kevlar (full Kevlar) were also prepared for comparison. The selected specimens underwent a low velocity impact test with variations in energy. The failure mode was observed. The results showed that a seven layer laminate only withstood an impact energy below 30 Joules, and it failed when the impact energy approached 40 Joules. The hybrid composites approached the quality performance of full Kevlar and exhibited better mechanical properties than full kenaf composites. Therefore, the novel hybrid composites can be used for product development in environmentally friendly technologies.

To remove methylene blue (MB) from water, rhamnolipid-modified biochar (BC-RL) was synthesized via a facile method. The surface structures and properties of the biochar (BC) and BC-RL were characterized by scanning electron microscopy, Fourier transform infrared spectra, X-ray diffraction spectra, X-ray photoelectron spectra, N2 adsorption-desorption isotherms, and Raman spectra. The results showed that modification with rhamnolipid remarkably increased the functional groups on the BC-RL, but reduced the surface area. The MB removal efficiency of the BC-RL increased with an increase in the adsorbent loading and temperature. Moreover, the adsorption performance of the BC-RL was obviously higher than that of the BC, which was mainly attributed to the increased number of functional groups. The adsorption kinetic data was fitted well to the pseudo-second-order model with a coefficient of determination greater than 0.999. The coefficients of determination of the adsorption isotherm fitted by different models decreased in the following order: BET > Freundlich > Langmuir. This indicated that the adsorption of MB onto the BC-RL involves a multilayer formation process. These results suggested that the BC-RL could be an environmentally benign and cost-effective adsorbent for the removal of MB from aqueous solutions.

The main goal of this paper was to clarify to what extent extractives and wood structure determine the surface properties of hardwoods, mainly tropical. The role of wood extractives relative to properties, such as wettability and free surface energy, has been confirmed. The most significant seemed to be cyclohexane extractives. It was further found that in the case of tested tropical wood species, the extractives contents were high. Moreover the important role of axial parenchyma in wood wettability was established. It was established that multiple regression analysis could be useful in understanding wood properties as the result of the complex structure of wood. The obtained data is crucial from a practical point of view for its disclosure of those wood species that require surface modification prior to varnish coating.

Wood as a flammable material can be characterized by fire and technical parameters, such as initial temperatures of its degradation, caloric heat, caloric value, and explosion limits. These parameters reflect the suitability of using a particular type of wood for construction purposes or as biofuel. This article presents selected characteristics of beech wood (Fagus sylvatica L.) particles (dust fractions) on the basis of continual thermal loading. The thermal properties of beech particles were characterized by thermogravimetric analysis (TG), which indicated different thermal degradation patterns for different dust fractions. The beech wood dust consisted mainly of fractions of 80 µm, 32 µm, and < 32 µm, which was 70.50% of the sample. These fractions form explosive mixtures with air, and their thermal degradation involves only one step.

Poplar wood (Populus euramericana cv. “I-214”) was impregnated by pulse dipping at 0.7 MPa to 0.8 MPa for 30 min with a catalyst Ln∼SO₄²⁻/TiO₂–SiO₂, itaconic acid, and silica sol. Then, the modifier was cured within the wood micropores during in situ polymerization via kiln drying. The treated wood exhibited increased mechanical strength and decreased hygroscopicity. The modified samples were also characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results from the FTIR analysis indicated that the itaconic acid and SiO₂ polymerized with the active groups of the wood cell wall. The TGA revealed that the crosslinking reaction between the modifier and wood enhanced the thermal stability of the composite. Lastly, the SEM results indicated the presence of the good interfacial adhesion in the wood modifier between the wood fibers and polymer.

Water-jet assisted nanosecond laser process was used to avoid the process defects of traditional nanosecond laser on wood. Korean pine was used as the experimental material. A factorial design of experiment was performed. The influence of cutting speed and laser power on the kerf width was compared with and without the water-jet assisted system. The surface morphology of processed wood kerf was observed via scanning electron microscopy (SEM). The results showed that kerf width increased with increased laser power and decreased with increased cutting speed. When the cutting speed was 50 mm/s and the laser power was 6 W, the minimum value of the kerf width was 0.26 mm with the water-jet assisted system involved, and the surface quality was excellent. The experimental results were processed by analysis of variance and multi-linear regression analysis. Moreover, prediction model of process parameters and kerf width was established, and the prediction model had better prediction accuracy, providing certain theoretical basis for predicting kerf width of wood processed by water-jet assisted nanosecond laser.

This study presents the chemical compositional analysis of cow manure in terms of holocellulose (35.97%), lignin (19.02%), and ash (17.47%). Activated carbons (of specific surface area 114 to 893 m²/g, iodine value 219 to 718 mg/g, methylene blue adsorption value 40.5 to 501 mg/g, and ash 16.17% to 22.3%) were prepared from cow manure by using various activator compounds such as potassium carbonate. The results showed that the activation effect of potassium carbonate and zinc chloride was better under the given conditions. The main ash found in the activated carbons was silica, which was reduced to about 3% by washing with sodium hydroxide solution. The prepared activated carbons were used to treat the wastewater from the cow farm and for the pollutant removal that effectively met the discharge standard requirements. These results indicated that the production of activated carbons from cow manure is a promising method for the cleaner production in intensive dairy farms.

The burning of cattle manure for domestic use, and plant biomass left out in fields, is a common practice in South Asia, specifically Pakistan. According to the 2014 government of Pakistan (GOP) survey, Pakistan had 171 million head of cattle that would produce 345 billion kg of manure, which could easily be converted into 150 billion m³ of biogas. The focus of the present study was to evaluate the benefits from co-digestion of cattle manure (CM) with Dalbergia sissoo leaves (DSL) and Malus domestica leaves (MDL), with a focus on changes in the biodegradability, C/N ratio effect, and synergistic effect. The idea was to adjust the C/N ratio to increase biodegradability at mesophilic range to help the process to produce more methane than 100% manure-based digestion. First, the ideal pH and temperature conditions for mesophilic anaerobic digestion (AD) were optimized to carry out further co-digestion under the same conditions. The results of co-digestion revealed a 40% (251 NmL CH₄/g VS) increase in methane yield by replacing 20% of volatile solid in CM-based AD reactors with MDL. This combination also presented a biodegradability of 59% and a synergistic effect (θ) value of 1.40, which corresponded to highly positive synergism reflecting the optimum growth conditions. The DSL/CM co-digestion also followed the same pattern, and the maximum methane yield of 229 NmL CH₄/g VS was obtained using a 20/80 DSL/CM combination.

Policy makers and investors often need to consider trade-offs between alternative biomass-based energy supply options. Supply cost potentials for three bioenergy feedstocks prevalent in Canada including agricultural residues, dedicated woody crops, and forest harvest residues are summarized. Each feedstock has its own particular cost characteristics depending on the quantities involved. Importantly, this synthesis revealed significant differences in the uncertainty associated with the cost estimates, with agricultural residues having the greatest variation, followed by woody crops and postharvest forest residues, respectively. One implication of this uncertainty is that the attractiveness of each feedstock option likely depends on local market demand conditions and producer circumstances, making definitive aggregate supply estimates challenging.

Microcrystalline cellulose was pyrolyzed and catalytically graphitized under temperatures ranging from 1000 °C to 1600 °C in the presence of nickel (Ni). Optimal conditions for graphitization were determined, along with the structure and conductivity of the resulting samples. The optimal conditions were identified as heating at 1400 °C for 3 h with 3 mmol Ni loading per gram of carbon. The samples obtained had excellent graphitic crystallinity comparable to that of commercial graphite. However, in the absence of Ni loading, no obvious graphitic structure appeared after heating under the same conditions, indicating that Ni was an efficient catalyst for the graphitization of cellulose-based carbon. High-resolution transparent electron microscopy (HRTEM) images showed well-defined graphitic structures of more than 30 layers with slice gaps of 0.340 nm. The conductivities of the samples treated under different temperatures varied from 27 S·cm^-1 to 54 S·cm^-1 under 20 MPa of pressure, and higher temperatures led to higher conductivity due to better graphitic crystallinity. This study fills an important area of research on the catalytic graphitization of cellulose and provides a reference for the preparation of other cellulose-based graphitic materials.