Song-Yung Wang

Effects of manufacturing conditions on the adsorption capacity of heavy metal ions by Makino bamboo charcoal

The objective of this study was to investigate the effects of manufacturing conditions on the adsorption capacity of heavy metal ions by Makino bamboo charcoal. Results show that the specific surface area and iodine number of bamboo charcoal activated at 900 degrees C were larger than those of bamboo charcoal activated at 800 degrees C. The specific surface area of bamboo charcoal activated at 800 degrees C by carbon dioxide was larger than that of charcoal activated by steam. However, a contrary result was observed when the activation temperature was 900 degrees C. The total volume and proportion of micropores in bamboo charcoal activated by carbon dioxide were greater than those in the other sample groups. However, the total volume and bulk volume of meso- and macropores, and average pore diameter for bamboo charcoal activated by steam were greater than those in the other sample groups. Using 5g bamboo charcoal (10-30 mesh) with a soaking time of 24h, a better adsorption effect on Pb2+ (100%), Cu2+ (100%), and Cr3+ (88-98%) was found. However, medium frequencies were observed for the adsorption of Cd2+ (40-80%) and Ni2+ (20-60%). Very limited adsorption of As5+ was detected in this study. For the same charcoal grain sizes, the adsorption capacity of 0.5g of charcoal was better than that of 0.1g. The improved adsorption effect of the sample group activated by steam was compared with the sample group activated by carbon dioxide.

Preparation of activated carbons from corn cob catalyzed by potassium salts and subsequent gasification with CO2

In the present study, granular activated carbons were prepared from agricultural waste corn cob by chemical activation with potassium salts and/or physical activation with CO2. Under the experimental conditions investigated, potassium hydroxide (KOH) and potassium carbonate (K2CO3) were effective activating agents for chemical activation during a ramping period of 10 degrees C/min and subsequent gasification (i.e., physical activation) at a soaking period of 800 degrees C. Large BET surface areas (>1,600 m2/g) of activated carbons were thus obtained by the combined activation. In addition, this study clearly showed that the porosity created in the acid-unwashed carbon products is substantially lower than that of acid-washed carbon products due to potassium salts left in the pore structure.

Evaluation of standing tree quality of Japanese cedar grown with different spacing using stress-wave and ultrasonic-wave methods

The quality of wood in 47-year-old standing trees of Japanese cedar grown in five plantation sites with different spacing (A, 1×1m; B, 2×2m; C, 3×3m; D, 4×4m; E, 5×5m) was evaluated using stress-wave and ultrasonicwave propagation methods. The magnitude of the velocities of these waves and the calculated dynamic modulus of elasticity (MOE) were used as indexes for assessing wood quality in standing trees. Results indicated that plantation spacings had moderate influence on the stress-wave and ultrasonic-wave velocities, and the degree of influence varied with the wave-propagating direction. Regardless of the testing method used, the velocities of waves propagated parallel to the grain in the standing trees with medium and poor growth conditions were significantly greater than those with superior growth conditions. The dynamic MOE of the trunk of standing trees of Japanese cedar was calculated by adjusting the effective mobility of free water and effective density in the trunk at various moisture contents. Results indicated that the dynamic MOE of wood in the standing trees of Japanese cedar was affected somewhat by the testing methods used. Furthermore, the dynamic MOE of the wood in the standing trees varied with the growth conditions imposed.

Dynamic modulus of elasticity and bending properties of large beams of Taiwan-grown Japanese cedar from different plantation spacing sites

The effect of plantation spacings (types A-E) on the bending strength and dynamic modulus of elasticity of 41-year-old Taiwan-grown cedar (Cryptomeria japonica D. Don) was investigated. The results indicate that the highest values for the static bending modulus of elasticity (MOE), modulus of rupture (MOR), and dynamic modulus of elasticity (EDℓ, EDt) occurred in trees obtained from those most densely planted (type A); there was a significant difference between type A and the other four spacing types (B, C, D, and E), but there were no significant differences among those four types. Interrelations among MOE, MOR, EDℓ, and EDt could be represented by positive linear regression formulas, which revealed highly significant differences. The relations among the square value of stress-wave transmission velocity (Vt2 and Vt2) and MOE, MOR, EDl, and EDt, respectively, could be represented by positive linear regression formulas. The differences were highly significant.

Application of the drilling resistance method for annual ring characteristics: evaluation of Taiwania (Taiwania cryptomerioides) trees grown with different thinning and pruning treatments

Abstract The effects of various thinning and pruning methods on the density profile and annual ring characteristics of Taiwania (Taiwania cryptomerioides Hay.) using the drilling resistance technique were investigated. The results showed that thinning caused wider annual rings than medium thinning or no thinning, and pruning caused narrower annual rings than no pruning. Moreover, the thinning treatment affected annual rings more effectively than the pruning treatment. The average ring density after the thinning treatments showed a trend as follows: no thinning > medium > heavy. This indicates that thinning reduces the average ring density. The average ring density after the pruning treatments showed a trend as follows: medium > no pruning > heavy. However, the differences between thinning and no thinning were not statistically significant. The percentage of latewood in Taiwania after these three thinning and pruning treatments are shown. The results with silvicultural treatments have the order: medium > not treated > heavy, but there are no statistically significant differences among thinning, pruning, and thinning where pruning interactions were observed. Moreover, there were highly significant negative relations between the average ring width and the various ring densities for Taiwania, but the determination coefficients were small. In addition, there was a highly positively significant relation between the latewood percentage and latewood width.

Nondestructive evaluation techniques for assessing dynamic modulus of elasticity of moso bamboo (Phyllosachys edulis) lamina

Bamboo, an extensively used material in Asia, is becoming an increasingly available structural (e.g., flooring and furniture) material in Taiwan. The bending strength and dynamic modulus of elasticity of moso bamboo (Phyllosachys edulis) laminae were investigated using ultrasonic-wave and drilling resistance techniques. The strength quality of bamboo was reduced after steaming treatment and was significantly affected by node characteristics. The transverse variations of the mean drilling resistance value (R) gradually increased outward from the bamboo cavity layer. There were very significant positive relationships among density (ju), the drilling resistance value (R), the dynamic modulus of elasticity (Eb), the modulus of elasticity (MOE), and the modulus of rupture (MOR), although the coefficients of determination were small. Combining ultrasonic-wave and drilling resistance techniques is efficient in estimating and establishing the dynamic modulus of elasticity (REb). Values of REb for moso bamboo increased with increasing ju, R, Eb, MOE, and MOR, and the relationships could each be represented by positive linear regression formulas.

Electromagnetic shielding efficiency of the electric field of charcoal from six wood species

Six wood species were carbonized under various carbonization temperatures and nonoxygen conditions to obtained charcoal. The effects of wood species, rate of temperature rise, and carbonization temperature on the electromagnetic shielding efficiency (ESE) of the electric field were investigated. The wood species used in this study were Japanese cedar, China fir, western hemlock, red oak, fortune paulownia, and Taiwan acacia. Tested materials were carbonized in a high-temperature oven under the following conditions: rate of temperature rise 1°–5°C/min; carbonization temperature 500°–1100°C, with temperature intervals of 100°C; maximum temperature maintained for 1 h; and flow rate of nitrogen 300 ml/min. The electromagnetic insulation strength system was used to detect the ESE of the electric field of charcoal. It was found that western hemlock and fortune paulownia charcoal showed maximum ESE values of of 36 and 61 dB generated at a carbonization temperature of 1000°C. The charcoals derived from four other wood species showed maximum ESE values of 28 dB for Japanese cedar, 23 dB for China fir, 32 dB for red oak, and 38 dB for Taiwan acacia, respectively, at a carbonization temperature of 1100°C. The ESE value for fortune paulownia charcoal was similar to those of metal nets. The relations between ESE and logarithmic values of resistivity (log ρ) could be represented by a negatively exponential formula.

Effects of moisture content and specific gravity on static bending properties and hardness of six wood species

This study was designed to investigate the effects of moisture content (MC) and specific gravity (SG) on the bending strength and hardness of six wood species including Japanese cedar (Cryptomeria japonica D. Don), China fir (Cunninghamia lanceolata), western hemlock (Tsuga heterophylla), red meranti (Shorea spp.), Selangan batu (Shorea spp.), and red oak (Quercus spp.). The experimental results are summarized as follows: Effects of MC and SG on the strength (MOR), stiffness (MOE), and hardness (HB) could be represented by a multiregression formulas. A negative correlation existed between these properties and MC, whereas a postive correlation showed between them and the SG. The changing rate of these properties induced by 1% MC changes varied with the wood species: 2.6% change in MOR was observed in Japanese cedar, China fir, western hemlock, red meranti, and Selangan batu; and 3.9% was found in red oak. For MOE, a 0.58% change was observed in Japanese cedar, China fir, and red meranti; western hemlock and Selangan batu exhibited 1.2% and red oak 2.5%. For hardness, a 1.1% change was observed in Japanese cedar, western hemlock, and red oak; red meranti and China fir exhibited 3.3%; and Selangan batu 1.8%.

Effects of thinning and pruning on knots and lumber recovery of Taiwania (Taiwania cryptomerioides) planted in the Lu-Kuei area

This study investigated the effects of various thinning and pruning methods on the knots (number and size) and lumber recovery from Taiwania (Taiwania cryptomerioides Hay.) plantation trees. The results showed that heavy thinning caused more knots and larger-diameter knots than medium or no thinning; moreover, pruning caused fewer numbers of knots and smaller-diameter knots than no pruning. Better-quality Taiwania trees occurred with the no-thinning/no-pruning treatments, as shown by analyzing the knots, although the results also showed that the healing process seemed to have produced not completely clear wood during the 9 years after the pruning treatment. The thinning intensity slightly enhanced the lumber recovery of logs. Pruning did not affect lumber recovery from taiwania trees and logs. Thinning increased the lumber recovery per tree due to an increase in the diameter at breast height.

Dynamic modulus of elasticity and bending properties of young Taiwania trees grown with different thinning and pruning treatments

The effects of different thinning and pruning methods on the bending strength and dynamic modulus of elasticity (DMOE) of young Taiwania (Taiwania cryptomerioides Hay) were investigated. The average DMOE, modulus of elasticity (MOE), and modulus of rupture (MOR) in the thinning treatments showed the following trend: no thinning > medium thinning > heavy thinning. This indicates that thinning reduces average bending properties. The average DMOE, MOE, and MOR in the pruning treatments showed the following trend: medium pruning > no pruning > heavy pruning. According to this tendency, better average qualities of lumber and specimens were from wood subjected to no-thinning and medium-pruning treatments according to an ultrasonic wave technique and static bending tests. However, most results showed no statistically significant differences among thinning, pruning, and thinning and pruning treatments. The average values of DMOE, MOE, and MOR of visually graded construction-grade lumber were significantly greater than those of below-grade lumber. Moreover, there were very significant positive relationships between density, ultrasonic velocity, DMOE, MOE, and MOR, although the determination coefficients were small.