Sang-Sook Park

Strength and microscopic characteristics of alkali-activated fly ash-cement

The effects of different activator concentration, liquid/fly ash ratio, and curing temperature and time on the compressive strength of specimens prepared from low-calcium fly ash activated with sodium hydroxide without the use of Portland cement were investigated. SEM, XRD and mercury intrusion porosimetry (MIP) were used to observed the structural feature, reaction products, and porosity and pore-size distribution of the specimens from alkaliactivated fly ash, respectively. It was found that the degree of reactivity, as shown by the compressive strength, the activator concentration and the ratio of liquid/fly ash, and the curing temperature always result to be significative factors. The 7, 14, and 28-day compressive strengths of specimens prepared from alkali-activated fly ash by 5M NaOH solution at 50 °C are 152, 219, and 263 kgf/cm2, while those from 6M solution are 184, 225, and 267 kgf/cm2, respectively. In SEM observation, the fly ash activated by the 5M NaOH solution shows a more continuous matrix with solid and non porous due to subsequent gel restructuring by amorphous alkaline aluminosilicate produced from alkali-activated fly ash.

Pyrolysis of Suncheon-Bay wild reed over zeolite catalysts

The catalytic fast pyrolysis of wild reed was carried out over HZSM-5 zeolite catalysts with two different SiO2/Al2O3 ratios, 23 and 280. The effects of the pyrolysis temperature and catalyst on the bio-oil yield were examined using a laboratory-scale batch-type quartz reactor for the pyrolysis experiments over the temperature range, 440–560 °C. The highest bio-oil yield was obtained between 520 °C and 560 °C depending on the catalytic conditions. The bio-oil yields obtained from catalytic pyrolysis were generally lower than those obtained from non-catalytic pyrolysis because of the cracking of large-molecular-mass products into gaseous species. Further experiments were carried out using the pyrolysis-gas chromatography/mass spectrometry at 550 °C for the in-situ analysis of the species distribution of the product bio-oil. Regardless of the use of catalyst, oxygenates were the most abundant products from the pyrolysis of wild reed, followed by phenolics. The fraction of total oxygenates was reduced consid...

Effect on Plant Growth and Antibiosis of Rice Straw Liquor Extracted from Rice Straw

Rice straw liquid was prepared from rice straw using simple pyrolysis furnace, and its effects on plant growth and antibiosis were investigated. Effects of straw liquid on plant growth of Oryza sativa L., Glycine max Merr. and Lactuca sativa L. and antibiosis of bacteria and mold of rice straw liquid were studied. Th rice straw liquid showed good results on plant growth and multiplication. Rice straw liquid showed a little antibiosis on bacteria but non antibiosis on mold. Rice straw liquid had minimal inhibitory concentration of 2.5-5% for bacteria.