Hu Sik Kim

Synthesis and Characterization of Selenium-sorbed Ca 2+ -exchanged Zeolite A for High-performance Feed

This study was carried out to develop high-performance feed using selenium-sorbed Ca 2+ -exchanged zeolite A. The contents of Se increased with increasing reaction temperature and the content of Ca 2+ ions in Ca 2+ -exchanged zeolite A. A synthesized high-performance feed (0.306 ppm) was applied to poultry farming for 4 and 7 weeks, respectively. Se contents in chicken meats and eggs were 18.8, 27.2, and 94.1 ppb and 73.7, 14.9, and 64.5 ppb for control (retail chicken meats), 4, and 7 weeks, respectively; Ca contents were 3.8, 9.9, and 11.9 ppm and 48.6, 48.3, and 53.6 ppm, respectively. In conclusion, Se and Ca contents in chicken meats increased as feeding periods increased, but significant differences were not observed in the eggs.

Li+-exchanged Zeolites X and Y (FAU) from Undried Formamide Solution

Two single-crystals of fully dehydrated, partially Li+-exchanged zeolites X (Si/Al = 1.09, crystal 1) and Y (Si/Al = 1.56, crystal 2), were prepared by flow method using 0.1 M LiNO₃ at 393 K for 48 h, respectively, followed by vacuum dehydration at 673 K and 1 × 10 -6 Torr. Their structures were determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3and Fd3m at 100(1) K for crystals 1 and 2, respectively. They were refined to the final error indices R₁/wR₂ = 0.065/0.211 and 0.043/0.169 for crystals 1 and 2, respectively. In crystal 1, about 53 Li+ ions per unit cell are found at three distinct positions; 9 at site I’, 19 at another site I’, and the remaining 25 at site II. The residual 25 Na+ ions occupy three equipoints; 2 are at site I, 7 at site II, and 16 at site III’. In crystal 2, about 31 Li+ ions per unit cell occupy sites I’ and II with occupancies at 22 and 9, respectively; 3, 4, 23, and 3 Na+ ions are found at sites I, I’, II, and III’, respectively. The extent of Li+ ion exchange into zeolite X (crystal 1) is higher than that of zeolite Y (crystal 2), ca. 73% and 56% in crystals 1 and 2, respectively.

Chromaticity (b*) and Transmittance of ITO Thin Films Deposited on PET Substrate by Using Roll-to-Roll Sputter System

Indium Tin Oxide (ITO) thin films on Polyethylene Terephtalate (PET) substrate were prepared by Roll-to-Roll sputter system with targets of 5 wt% and 10 wt% SnO2 at room temperature. The influence of the chromaticity (b*) and transmittance properties of the ITO Films were investigated. The ITO thin films were deposited as a function of the DC power, rolling speed, and Ar/O2 gas flow ratio, and then characterized by spectrophotometer. Their crystallinity and surface resistance were also analyzed by X-ray diffractometer and 4-point probe. As a result, the chromaticity (b*) and transmittance of the ITO films were broadly dependent on the thickness, which was controlled by the rolling speed. When the ITO films were prepared with the DC power of 300 W and the Ar/O2 gas flow ratio of 30/1 sccm using 10 wt% SnO2 target as a function of the rolling speeds 0.01 through 0.10 m/min, its chromaticity (b*) and transmittance were about -4.01 to 11.28 and 75.76 to 86.60%, respectively. In addition, when the ITO films were deposited with the DC power of 400W and the Ar/O2 gas flow ratio of 30/2 sccm used in 5 wt% SnO2 target, its chromaticity (b*) and transmittance were about -2.98 to 14.22 and 74.29 to 88.52%, respectively.

Characterization of Li + -ion Exchanged Zeolite Y using Organic Solvents

To investigate the tendency of Li + exchange from polar organic solvents, Li + -ion exchange into zeolite Y (Si/Al = 1.56) was attempted by undried methanol (crystal 1) and formamide (crystal 2) solvent. Two single crystals of Na-Y were treated with 0.1 M LiNO3 in each of the two solvents at 323 K, followed by vacuum dehydration at 723 K. Their structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd3m, at 100(1) K. In both structures, Li + for Na + ions filled preferentially sites I’ and II. The remaining Na+ ions occupied sites I’, II, and III’ in both structures, in additional to above sites, and Na + ions occupied site I in crystal 2. While the 68 % exchange of Li + for Na + was achieved from undried methanol, only 40 % exchange was observed from undried formamide, indicating that the undried methanol was more effective than undried formamide as solvent for Li + exchange under the conditions employed.