Volume 8 Issue 3

The objective of this study was to assess the chemical properties of wood from six clones of Eucalyptus spp. relative to charcoal yield and its properties, determine the correlations between the evaluated parameters and identify a clone of Eucalyptus having the greatest potential for charcoal to steelmaking use. The study of chemical properties included analysis of elemental composition, contents of cellulose, hemicelluloses, lignin, and ash, the syringyl/guaiacyl ratio (S/G), and the index of crystalline cellulose in the wood. The pyrolysis of wood was done in an electric laboratory oven. The gravimetric yield in charcoal, the content of volatile matter, fixed carbon and ash, higher heating value, and elementary composition were determined. Data were subjected to an analysis of variance, and after the difference between them was established, the Tukey test was applied. The Pearson correlation was employed as well. The results indicated that the contents of carbon, oxygen, and hydrogen in the wood significantly affected the charcoal yields and its higher heating value. Higher rates of crystalline cellulose favored the gravimetric yield in charcoal. The S/G ratio contributed more to the charcoal yield when compared to total lignin content.

Larch tannin resin (LTNA) was prepared by a microwave modified cross-linking reaction. The adsorption of chromium(VI) from an aqueous solution by LTNA was studied using batch adsorption experiments. LTNA has a large number of pores, the size of which are about 250 nm. After adsorption, the internal structure of the LTNA resin assumed an obvious three-dimensional network. The adsorption of Cr(VI) on LTNA was investigated as a function of pH, dose of adsorbent, and adsorption time. The results indicated that the removal of Cr(VI) was pH-dependent. The optimum adsorption was observed at pH 1.0, and the maximum adsorption capacity was 9.134 mg/g. The Cr(VI) adsorption by the LTNA gel obeyed the Langmuir adsorption isotherm. The kinetic processes of Cr(VI) adsorption onto LTNA could be acceptably explained by the pseudo-second order kinetic rate model. Thermodynamic parameters revealed the spontaneity and exothermic nature of adsorption. Desorption of adsorbed Cr(VI) was successfully realized with a 0.1 M NaOH solution.

Sodium hydroxide (NaOH) has been used as an alkali source in conventional hydrogen peroxide bleaching. In the present work, partial and total replacement of NaOH with magnesium hydroxide (Mg(OH)2) as the alkali source for hydrogen peroxide bleaching of deinked pulp was studied. The bleached pulp was studied with respect to brightness, post color (P.C.) number, and mechanical properties (i.e., the tensile, tear, and burst indices). The bleaching effluent was measured for residual peroxide, pH value, and chemical oxygen demand (COD). The main results from this work were that the brightness and mechanical properties of bleached pulp increased while the P.C. number declined when NaOH was partially replaced with Mg(OH)2. However, the total substitution of NaOH with Mg(OH)2 resulted in a slight decrease in the brightness and mechanical properties in comparison with NaOH as the sole alkali source. Additionally, the residual peroxide of the bleaching filtrate increased from 3% to 61% and the COD load of the bleaching effluent decreased from 20% to 25% when NaOH was replaced with Mg(OH)2 at various replacement ratios.

High-density polyethylene (HDPE) and natural fiber composites were prepared by melt compounding and injection molding. The influence of fiber type (i.e., pine, bagasse, rice straw, and rice husk) and the addition of coupling agents on the composite properties were investigated. The use of 30 wt% fiber enhanced the tensile and flexural properties of neat HDPE, but decreased the impact strength. The comprehensive mechanical properties of HDPE/natural fiber composites were significantly improved by the addition of 2 wt% maleated polyethylene (MAPE). The toughness was further enhanced with the use of 5 wt% maleated triblock copolymer styrene-ethylene/butylene-styrene (MASEBS). The composites had higher crystallization peak temperatures and lower crystallinity levels than neat HDPE, and their thermal stability was lower than that of HDPE. The reduced storage modulus and increased loss tangent showed that MASEBS performed as a flexibilizer in composites.

To develop a composite fiberboard with high electromagnetic shielding effectiveness (SE) and an easily industrialized process, electroless nickel-plated carbon fiber technology was used to improve the conductivity and electromagnetic properties of carbon fiber and carbon fiber sheets. The SE of composite fiberboards laminated with nickel-plated carbon fiber with different arrangements was also studied. The results showed that the best plating scheme in this study was a NiSO4 concentration of 35 g/L, plating temperature of 70 °C, pH of 9, and plating time of 15 min. When nickel-plated carbon fiber in a grid arrangement was added to the core between two fiberboards, the minimum and maximum SE of 19 x 19 grid arrangement was 41.54 dB and 63.73 dB in the 200 to 1000 MHz frequency range, respectively, and reached medium grade. SE of composite fiberboard laminated with double layers of plated carbon fiber sheet ranged from 45.29 dB to 52.01 dB and reached medium grade. It is thus feasible to use two-layer nickel-plated carbon fiber with a 19 × 19 grid arrangement to make composite fiberboard with high SE, mechanical properties greater than the national standard, and an easily industrializable process.

Biodegradation of lignocellulosic waste from chestnut residues is an important biological process of added value for this sector according to the Chestnut National Plan for agriculture. Dynamic parameters during biodegradation under natural conditions of chestnut burr, leaf, and plant biomass litter are reported in this study. Microbiological and physical-chemical characterisation of chestnut wastes was carried out to monitor this specific biodegradation, to understand the progress and limits of the process and to analyse the compost-like organic substance obtained. Physical-chemical parameters, such as temperature, pH, and water activity, were influenced by the composition of the raw materials and by seasonal climatic conditions. Moreover, microbiological monitoring was assessed by culture-dependent and independent methods. Cellulolytic, hemicellulolytic, and ligninolytic populations were counted to determine different microbial activity during biodegradation process. The functional microbial groups analysed showed different trends, but all were found at high concentrations (7 to 9 log CFU/g). In addition, PCR-DGGE was performed for bacterial and fungal populations to evaluate the microbial diversity. The similarity level during the process was generally very high, both for bacterial and fungal populations. These data are the first on suitable natural degradation for chestnut forests.

A previous study of synthesizing low mole ratio urea–formaldehyde (UF) and urea–melamine–formaldehyde (UMF) resins, which included an acidic reaction step at the beginning of the typical resin synthesis procedure to obtain higher uron-type methylene–ether group contents, was repeated with the acidic reaction step extended to a higher viscosity. Compared to previous resins, the synthesized resins showed additional increases in the uron-type and linear-type methylene–ether groups, resulting in longer storage times, longer pot lives, longer gel times, and comparable internal bond strengths and water absorption values of particleboards; however, the formaldehyde contents (FC) of boards increased. It was concluded that the extended acidic reaction resulted in increased formaldehyde emission potential of boards because of additional methylene–ether groups formed. The results led to the hypothesis that the FC values of current UF resin-bonded boards are mainly due to the methylene–ether-type groups present in significant levels in UF and UMF resins.

Ni/Cu/Al/Fe hydrotalcite precursor was synthesized by a co-precipitation method. The activity of the reduced precursor for one-step conversion of maltose into sorbitol in the presence of H2 and extremely low phosphoric acid was investigated. XRD and XPS tests provided the essential properties of the precursor and prepared magnetic catalyst. Effects of various processing parameters towards the reaction performance were studied in detail. A desired sorbitol yield of 93.1% was attained at 458 K for 3 h with a catalyst dosage of 20%. A catalyst recycling experiment demonstrated that Ni4.63Cu1Al1.82Fe0.79 was a better catalyst and could be reused three or four times. The specific reasons for catalyst deactivation were considered in depth.

Thermally-modified wood is not sufficiently durable for exposure to environments in which severe biological deterioration is likely. So in this study, samples of southern yellow pine sapwood were first subjected to thermal modification and then impregnated with the alkaline copper quat-type D (ACQ-D) wood preservative. Three heating temperatures (180, 200, and 220 °C) and two concentrations of ACQ-D solution (0.90% and 1.35%) were used in the experiments. The copper retention, percentage of copper leaching, and concentrations of copper ions in the leachates collected during the leaching tests were evaluated using inductively coupled atomic emission spectrometry (ICP-AES). Fourier transform infrared spectroscopy (FTIR) analysis was also used to interpret the differences in leaching performance between thermally-treated and unheated wood samples. The pseudo-second-order model of copper leaching was developed with the experimental leaching data, which could determine the amounts of copper ion leaching and predict the final percentage of copper leaching during the leaching process. As a result, compared to the control group, the copper retention of the thermally- modified wood samples was lower, while the percentage of copper leaching was higher. This observation could be explained by the lower number of copper ion fixation sites in the thermally-treated wood.

A long-term onsite assessment of the hygrothermal performance of a wood frame wall system is presented in this work. The system was applied in a wood demonstration house within the Lake Tai climate zone of Suzhou, China. The hygrothermal performance of the cavity insulation wall was determined from the temperature, relative humidity, and from the temperature of the wood material surface throughout the year. The results clearly indicated the effect of the cavity insulation, cladding cavity ventilation, and air-vapor barrier. Thermal performance was very good due to the wall cavity insulation. Cladding cavity ventilation was effective at low relative humidity of the insulated wall cavities. Condensation and mold growth were not found inside the wall during the test period. The wood frame wall system had good hygrothermal performance and may be widely used in hot summer and cold winter climate zones in China.