Volume 14 Issue 4

The fire performance of green roofs has never been assessed numerically. In order to simulate its fire behavior, the thermal conductivity of a growing media must be determined as an important input parameter. This study characterized the thermal conductivity of a dry substrate and its prediction as a function of temperature, considering temperature effects on soil organic and inorganic constituents. Experimental measurements were made to provide basic information on thermophysical parameters of the substrate and its components. Thermogravimetric analysis was conducted to consider the decomposition of organic matter. An existing model of the thermal conductivity calculation was then applied. The results of calculated and measured solid thermal conductivity showed close values of 0.9 and 1.07 W/mK, which demonstrates that the model provided a good estimation and may be applied for green roof substrates calculations. The literature data of a temperature effect on soil solids was used to predict thermal conductivity over a range of temperatures. The results showed that thermal conductivity increased and depended on porosity and thermal properties of the soil mineral components. Preliminary validation of obtained temperature-dependent thermal conductivity was performed by experiments and numerical simulation.

Mixed office waste (MOW) pulp was biodeinked with crude enzyme extracted from Penicillium citrinum NCIM-1398. Crude enzyme dose was charged having activities of endo β-1,4-glucanase 6I U/g, xylanase 876.19 IU/g, and amylase 26.53 IU/g. The present study aimed to bleach the biodeinked MOW pulp with 3% H2O2 in the presence of a stabilizing agent viz. 0.1% ethylenediaminetetraacetic acid (EDTA) and 0.1% magnesium sulfate (MgSO4), which improved the pulp brightness up to 4.2% and the ERIC value was reduced by 24.1%. The residual H2O2 left in the pulp slurry after bleaching was subjected to peroxidase treatment using enzyme dose 0.017 U/g at 20 °C for 3 h at 200 rpm. Horseradish peroxidase reduced residual H2O2 in the pulp slurry from 0.30 to 0.05 g/L and improved the brightness of pulp to 88.1%, while the ERIC value was reduced by 20.9%. Potato peroxidase reduced residual H2O2 from 0.30 to 0.04 g/L, reduced the ERIC value by 30.9%, and improved the brightness to 89.2%. Peroxidase treatment was not only observed to consume the residual hydrogen peroxide left after the bleaching stage but also may come up as eco-friendly technology to recycle MOW paper as writing printing grade paper.

The breakdown of lignocellulosic biomass into fine chemicals is an essential subsequence process of bioconversion technology. However, the manner of decomposition can contribute significantly to inefficiency of the overall conversion. Certain low molecular weight byproducts of the lignin and hemicellulose within lignocellulosic hydrolysate are toxic, making it necessary to carry out a complicated detoxification process. In this study, detoxification of hydrolysate was performed by the adsorption and catalytic oxidation, as well as the integration of both techniques on the targeted compounds of acid-soluble lignin (ASL) and synthetic furfural. In spite of the high selectivity of its adsorption and catalytic oxidation, by relying on just these techniques, the hydrolysate was unable to completely remove ASL and furfural. However, by depositing Fe(0) nanoparticles on the surface active sites of the adsorbent, the integration of the adsorption-oxidation technique provided sufficient performance in the removal of ASL and furfural.

The biomass resources oil palm empty fruit bunch (EFB) and sugarcane bagasse, which are residues from the palm oil and sugar industries, continue to be investigated for more applications. With increasing concern for the environment, cleaner production has been a worldwide aim of researchers. In this study, thermomechanical pulp (TMP) from EFB and sugarcane bagasse was prepared with disc refining after steam pretreatment of the raw materials. Afterwards, refining and handsheet properties of TMP using various percentages of unbleached soda bagasse pulp (USBP) were studied. Fiber characterizations and handsheet properties showed that pulp of acceptable quality was obtained via thermomechanical pulping. Moreover, energy consumption during PFI refining of EFB TMP was higher than that of bagasse TMP. Physical properties were further enhanced through introduction of USBP. The results firmly support the feasibility of cleaner thermomechanical pulping of EFB and sugarcane bagasse.

The effect of moisture content on mechanical properties of corner furniture joints was evaluated for when different joining methods and materials were used. Results included statistical processing of the measured and calculated data and evaluation of the effect of selected factors on mechanical properties of joints caused by using mechanical fasteners and glue. The load-carrying capacity and stiffness of corner joints were investigated in two environments, humid and dry, with standard conditions for temperature and pressure, i.e., dry environment had a temperature of 23 °C ± 2 °C and relative humidity of 45% ± 5%, and the humid environment had a temperature of 23 °C ± 2 °C and relative humidity of 90% ± 5%. The two types of materials used were particleboard (PB) with a thickness of 12 mm and artificial stone (plastic) with a thickness of 12 mm. Both materials were tested individually as well as their combination. Epoxy and polyurethane (PUR) adhesives were used for the glued dowel joints. When the same materials were bonded, maximum load carrying capacity was achieved with PUR adhesive, material combination of plastic-plastic, and moisture content of 90%. The epoxy adhesive was most suitable for bonding materials with different properties.

It has been reported that a conductivity of 100 S/cm of carbonized cellulose is obtained when the carbonization temperature is higher than 2000 °C. However, such high temperatures require expensive equipment and are energy consuming. In this study, carbonized multi-walled carbon nanotubes (MWCNTs)/cellulose composites fibers with a conductivity of 105 S/cm were prepared. They were prepared based on cellulose (in the carbonization temperature 1000 °C), a naturally abundant and low-cost material. The mechanism of improving electrical conductivity was studied. The MWCNTs played the role of a conductive bridge between the nano-carbonization cellulose blocks. As the template of cellulose graphitization, MWCNTs not only can improve the degree of cellulose graphitization but can also change the microstructure of carbonization cellulose from nano-spheres to sheets. This preparation method can be applied to other carbon materials to make highly conductive fibers or various conductive structure materials, such as a conductive film or an aerogel. This study broadens the application of cellulose in the field of electricity. The obtained conductive fibers have great potential in a range of applications, such as wearable electronics and low-cost energy storage.

Initial water leaching affects were studied relative to the rot resistance of 21 tropical wood species to the brown-rot fungus Coniophora puteana and the white-rot fungus Trametes versicolor. The rot resistance of tropical woods, determined by their weight loss (∆m) at 6-weeks fungal attack, was differently influenced by the initial water leaching, as follows: in the 1st group of eight durable species (dark red meranti, macassar ebony, cerejeira, merbau, santos rosewood, zebrano, wengé, and karri) there occurred a very significant decrease of their high rot resistance (with statistical confidence in the range 99 to 99.9% for different species); in the 2nd group of 10 durable species (ipé, yellow balau, doussié, bubinga, ovengol, padouk, iroko, blue gum, maçaranduba, and makoré) there did not occur a decrease of their high rot resistance; and in the 3rd group of three less durable species (okoumé, tineo, sapelli) a weaker rot resistance did not change due to leaching. The durable tropical woods (18 species from the 1st and 2nd groups) were more resistant to the brown-rot fungus (∆mC.p.-average = 0.72%) than the white-rot fungus (∆mT.v.-average = 1.07%). However, this phenomenon was no longer apparent after water leaching (∆mC.p.-Leached-average = 2.61%; ∆mT.v.-Leached-average = 2.32%).

A high-speed milling test was performed with a self-developed wood-plastic composite using uncoated and coated carbide cutting tools. The nose width was used to represent the tool wear. An advanced tool measurement system was adopted to measure the wear of each tool. The influence of some cutting parameters, including spindle speed, feed rate, axial cutting depth, and radial cutting depth, on the tool wear was analyzed using a single factor test method. Scanning electron microscopy was used to observe the wear morphology on the rake and clearance face of the tool before and after the tool was worn. The results showed that the tool nose width increased with increased axial cutting depths or spindle speeds, while the radial depth under the condition of the same cutting length decreased with an increase in the feed rate. Moreover, the main form of tool wear was abrasive wear and coating peel-off when the wood-plastic composites were machined with high-speed milling.

An ultraviolet (UV) aging test chamber was used to analyze the aging behaviors of wood flour-poly (lactic acid) (PLA) 3D printing filaments under different temperatures. The materials were granulated using a twin-screw extruder, and the filaments were prepared using a single-screw extruder. The aging resistance was determined by comparing the color, tensile strength, scanning electron micrographs, and water absorption rate of the filaments before and after being processed. The aging behaviors tended to be stable when tested at 40 °C for 80 h, or 50 °C for 60 h, or 60 °C for 40 h. At this status, the tensile strength of the filaments was reduced by 44% compared to the originals; the internal structure of the filaments was severely damaged from the SEM images, and obvious porosities can be identified. The water absorption rate was greatly improved. The chromatic degradation (△E*) increased to 10.8 when tested at 40 °C, while this value increased to 10.9 at 50 °C and 10.8 at 60 °C. Therefore, the increase of aging temperature accelerated the UV aging process. It is recommended to add some ultraviolet absorbent into the filaments in order to improve the UV resistance of the materials.

The ability of woody plant species to remediate heavy metals contaminated soils was investigated with the addition of sewage sludge. Jatropha curcas, Hibiscus cannabinus, Acacia mangium, and Syzygium cumini growth was monitored on an Oxisol- and an Ultisol-treated soil with sewage sludge at a level of 0% w/w, 5% w/w, or 10% w/w. The sewage sludge was found to enhance soil fertility, as shown by an increase in soil pH, cation exchange capacity, exchangeable bases (potassium, calcium, and magnesium), available phosphorous, total carbon, and total nitrogen. However, zinc and copper accumulated in soils at toxic levels; thus, they had to be removed before being used for crop production. The concentration of the two heavy metals in Jatropha curcas and Hibiscus cannabinus at harvest were higher than those of Acacia mangium and Syzygium cumini. The high uptake of zinc and copper by the first two plant species was the result of their high translocation factor, although the bio-concentration factor was low. Thus, Jatropha curcas and Hibiscus cannabinus were considered tolerant to zinc and copper toxicity and able to remove the metals efficiently from the contaminated soils.