Single-Crystal Structures of Li+-exchanged Zeolite X (FAU, Si/Al = 1.09) from Aqueous Solution Depends on Ion-exchange Temperatures at 293 and 333 K

김후식,고성운,임우택 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.10

Two single crystals of fully dehydrated partially Li+-exchanged zeolite X were prepared by the exchange of Na-X, Na92Si100Al92O384 (Si/Al = 1.09), with Li+ using aqueous 0.1 M LiNO3 at 293 (crystal 1) and 333 K (crystal 2), followed by vacuum dehydration at 623 K and 1 × 10−6 Torr for 2 days. Their structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd3 at 100(1) K. Their structures were refined using all intensities to the final error indices (using the 1281 and 883 reflections for which (Fo > 4σ(Fo)) R1/R2 = 0.075/0.244 and 0.074/0.223 for crystals 1 and 2, respectively. Their compositions are seen to be |Li86Na6|[Si100Al92O384]-FAU and |Li87Na5|[Si100Al92O384]-FAU, respectively. In crystal 1, 17 Li+ ions per unit cell are at site I’, 15 another site I’, 30 at site II, and the remaining 16 at site III; 2 Na+ ions are at site II and the remaining 4 at site III’. In crystal 2, 32 and 30 Li+ ions per unit cell fill sites I’ and II, respectively, and the remaining 25 at site III’; 2 and 3 Na+ ions are found at sites II and III’, respectively. The extent of Li+ exchange increases slightly with increasing ion exchange temperature from 93% to 95%.

완전히 탈수되고 부분적으로 칼슘 이온으로 교환된 제올라이트 A의 셀레늄 수착 화합물의 구조 연구

김후식,박종삼,임우택 한국암석학회·(사)한국광물학회 2020 광물과 암석 (J.Miner.Soc.Korea) Vol.33 No.3

Single crystal of fully dehydrated and partially Ca2+-exchanged zeolites A (|Ca4Na4|[Si12Al12O48]-LTA) was brought into contact with Se in fine pyrex capillary at 523 K for 5 days. Crystal structure of Se-sorbed |Ca4Na4|[Si12Al12O48]-LTA has been determined by single-crystal X-ray diffraction techniques at 294 K in the cubic space group Pm m (a = 12.2787(13) Å). The crystal structure of yellow |Ca4Na4Se4|[Si12Al12O48]-LTA has been refined to the final error indices of R1/wR2 = 0.0960/0.3483 with 327 reflections for which Fo > 4(Fo). In this structure, 4 Na+ and 4 Ca2+ ions fill every 6-ring site: These ions are all found at three crystallographic positions, on 3-fold axes equipoints of opposite 6-rings. Selenium atoms are found at three crystallographically distinct positions: 2 Se atoms per unit cell at Se(1) are located opposite 6-rings in the sodalite cavity (Se(1)-Na(1) = 2.53(5) Å) and 1 at Se(2) opposite 4-rings (Se(2)-O(1) = 2.76(10) Å) and 1 at Se(3) opposite 6-rings in the large cavity (Se(3)-Na(1) = 2.48(5) Å). Two molecular of Se2 (Se(1)-Se(1) = 2.37(7) or 2.90(8) Å and Se(2)-Se(3) = 2.91(5) ) Å) are found in all sodalite cavity and large cavity. Other clusters such as Se4 and Se8 could be existed in large cavity. The interselenium distances turned out to be longer that of gases Se2 molecule. Ca2+ 이온으로 부분적으로 치환된 제올라이트 A (|Ca4Na4|[Si12Al12O48]-LTA) 단결정과 Se을 가는 모세관에 넣은 후 523 K 에서 5일동안 반응을 시켜 Se이 흡착된 제올라이트 A 단결정을 합성 하였다. 이 결정의 구조는 294 K 에서 단결정 X-선 회절 기술을 이용하여 Pm3m (a = 12.2787(13) Å) 입방 공간군에 속함을 확인 하였고, Fo> 4s(Fo)를 사용하여 최종 오차 인자를 R1/wR2= 0.0960/0.3483로 정밀화 하였다. 이 구조에서는 4개의 Na+ 와 4개의 Ca2+ 이온이 모든 6-ring 자리에 채워져 있었으며, 이들 이온들은 모두 6-ring 맞은편의 3-fold 축 상의 결정학적 위치에서 발견되었다. Se 원자들은 뚜렷하게 서로 다른 3개의 결정학적 위치에서 발견되었다. 단위 세포당 2개의 Se(1) 원자는 sodalite cavity 내 6-ring 맞은편 (Se(1)-Na(1) = 2.53(5) Å), 1개의 Se(2) 원자는 4-ring 맞은편 (Se(2)-O(1) = 2.76(10) Å), 그리고 1개의 Se(3) 원자는 large cavity 내6-ring 맞은편 (Se(3)-Na(1) = 2.48(5) Å)에 각각 위치하고 있었다. 2가지 형태의 Se2 분자 (Se(1)-Se(1) = 2.37(7) or 2.90(8) Å and Se(2)-Se(3) = 2.91(5)) Å)가 sodalite cavity와 large cavity 내에서 발견되었으며, Se4 와 Se8 과 같은 형태의 클러스터가 large cavity 내에 존재할 수 있었다. 이들 클러스터내 Se 원자들 사이의 거리는기체상태의 Se2 분자내 Se 원자 사이의 거리보다 더 길게 나타났다.

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

김후식,박종삼,임우택,김정진,서정민 한국토양비료학회 2013 한국토양비료학회지 Vol.46 No.4

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 Fd and Fd m at 100(1) K for crystals 1and 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.

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

김후식,이석희,박규혜,박용현,박준우,황지현,박종삼,최식영,임우택 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.3

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.

국민학생의 과학 탐구능력 조사

김후식 한국교원대학교 과학교육연구소 1993 청람과학교육연구논총 Vol.3 No.1

Na+ 경쟁이온이 존재하는 수용액에서 Zeolite A 내 Sr2+ 이온의 선택성 및 분포에 관한 결정학적 연구

김후식,박종삼,임우택 한국광물학회 2022 광물과 암석 (J.Miner.Soc.Korea) Vol.35 No.1

방사성 핵종 제거를 위한 천연 제올라이트 특성 연구

김후식 ( Hu Sik Kim ),박원광 ( Won Kwang Park ),이하영 ( Ha Young Lee ),박종삼 ( Jong Sam Park ),임우택 ( Woo Taik Lim ) 한국광물학회 2014 광물과 암석 (J.Miner.Soc.Korea) Vol.27 No.1

국내 경상북도 포항 및 경주지역에서 채취한 4종의 천연 제올라이트를 X-선 회절, X-선 형광분석, 열시차 분석, 열중량 분석 및 양이온교환능 분석을 통해 특성분석을 수행하였다. 이들 제올라이트의 주성분은 구룡포(Ku)는 휼란다이트, 포항(Po)은 클라이놉틸로라이트와 석영이 혼합된 모데나이트이며 양북A (Ya-A)는 휼란다이트, 클라이놉틸로라이트 및 석영이 함유된 일라이트이며, 양북B (Ya-B)는 휼란 다이트와 클라이놉틸로라이트가 혼합된 일라이트이다. 4종의 제올라이트는 Si, Al, Na, K, Mg, Ca, Fe을 함유하고 있었다. 구룡포 (Ku) 제올라이트의 양이온 교환능이 다른 지역의 제올라이트 보다 높게 나타났다. Cs 및 Sr의 흡착실험은 25 ℃에서 수행하였으며, 흡착자료를 기초로 Langmuir와 Freundlich 흡착 등온식에 대한 적합성을 평가하였다. 흡착공정은 Langmuir 흡착 등온식이 잘 맞았으며, 양북 A 제올라 이트가 다른 제올라이트 보다 Cs+ 및 Sr2+ 이온의 제거에 가장 효과적임을 보여주었다. The four natural zeolites collected in Pohang and Gyeongju area, Kyungsangbuk-do, Korea, were characterized by XRD, XRF, DTA, TGA, and CEC analysis. The primary species of these zeolite are heulandite, modenite, illite, and illite in Kuryongpo (Ku), Pohang (Po), Yangbuk-A (Ya-A), and Yangbuk-B (Ya-B) samples. The XRF analysis showed that the four zeolites contain Si, Al, Na, K, Mg, Ca, and Fe. Cation exchange capacity of Kuryongpo (Ku) zeolite was the highest compared to other zeolites. The adsorption capacities of Cs and Sr in the four natural zeolites were compared at 25 ¡E. On the basis of adsorption data Langmuir and Freundlich adsorption isotherm model were confirmed. The equilibrium process was descried well by Langmuir isotherm model. This study shows that Ya-A zeolite is the most efficient for the Cs+ and Sr2+ ion adsorption compared to the other natural zeolites.

경량전철 복합 적층판의 환경변화에 대한 저속충격특성

김후식(Kim Hu-Shik),김재훈(Kim Jae-Hoon),이영신(Lee Young-Shin),박병준(Park Byung-Jun),조정미(Cho Jeong-Mi) 한국철도학회 2002 한국철도학회 학술발표대회논문집 Vol.- No.-

Glass/phenolic composite laminates have been used in the field of non-flammable light rail transit and their applications have expanded more widely. Low velocity impact tests have been used to evalute the effect of temperature and acceleration aging on low velocity impact response of phenolic matrix composites reinforced with woven E-glass fabric. The damage of matrix cracking and delamination are suddenly reduced the compressive strength after impact. The damage area increases with increasing temperature and impact energy. UT C-scan is used to determine damage areas by impact loading. Therefore, all this observations indicate reduced impact damage resistance and damage tolerance of the laminates at elevated temperature.

경쟁 이온 존재하에 Zeolite A 내 Sr<SUP>2+</SUP> 이온의 결정학적 연구

김후식(Hu Sik Kim),김정진(Jeong Jin Kim),김영훈(Young Hun Kim),임우택(Woo Taik Lim) 한국암석학회 2022 한국암석학회 학술발표회 논문집 Vol.2022 No.6

제올라이트 광산개발을 위한 천연 제올라이트의 특성 분석 및중금속 이온 흡착 특성 연구

김후식 ( Hu Sik Kim ),김영훈 ( Young Hun Kim ),백기태 ( Ki Tae Baek ),임우택 ( Woo Taik Lim ) 한국광물학회 2015 광물과 암석 (J.Miner.Soc.Korea) Vol.28 No.4

국내 경상북도 포항 지역에서 채취한 6종의 천연 제올라이트를 X-선 회절, X-선 형광분석, 열시차 분석, 열중량 분석 및 양이온교환능 분석을 통해 특성분석을 수행하였다. 이들 제올라이트의 주성분은 구룡포A (Ku-A), 구룡포B (Ku-B), 구룡포C (Ku-C), 동해A (Dh-A), 동해B (Dh-B), 동해C (Dh-C) 모두 모데나이트, 알바이트 및 석영이 함유되어 있었다. 6종의 제올라이트는 Si, Al, Na, K, Mg, Ca, Fe을 함유하고 있었으며 구룡포C (Ku-C) 제올라이트의 양이온 교환능이 다른 지역의 제올라이트 보다 높게 나타났다. 6종의 천연 제올라이트를 이용하여 Pb(2+), Cd(2+) 및 Cu(2+) 등의 중금속 이온을제거하는데 소요되는 반응 시간의 효과를 비교하였다. 6종의 천연 제올라이트 모두 Pb(2+), Cd(2+) 및Cu(2+) 제거율이 매우 낮게 나타났다. 이는 6종의 천연 제올라이트에 함유된 제올라이트의 함량이 매우낮기 때문으로 판단된다. 본 연구 결과는 제올라이트 광석의 중금속 흡착능력은 제올라이트의 함량, 즉 광석의 품위에 크게 의존되는 경향을 보여주고 있다. The six natural zeolites collected in Pohang area, Kyungsangbuk-do, Korea, were characterized by XRD, XRF, DTA, TGA, and CEC analysis. The primary species of these zeolite are modenite, albite, and quarts in Kuryongpo-A (Ku-A), Kuryongpo-B (Ku-B), Kuryongpo-C (Ku-C), Donghae-A (Dh-A), Donghae-B (Dh-B), and Donghae-C (Dh-C) samples. The XRF analysis showed that the six zeolites contain Si, Al, Na, K, Mg, Ca, and Fe. Cation exchange capacity of Kuryongpo-C (Ku-C) zeolite was the highest compared to other zeolites. The capabilities of removing heavy metal ions such as Pb(2+), Cd(2+) and Cu(2+) were compared. The effect of reaction time in removing heavy metal ions was studied. The experimental results showed that the efficiency of removal was low for Pb(2+), Cd(2+) and Cu(2+) ions. These may be caused by the low content of zeolite in the six natural zeolites.This indicates that the adsorption capacity roughly tends to depend on the zeoite contents, ie., the grade of zeolite ore.