Hydrothermal synthesis of hdyroxyapatite-zeolite from blast furnace slag고로 슬래그를 이용한 수산화인회석-제올라이트의 열수 합성

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Blast furnace slag, an industrial by-product from ironwork, is emerging as a potential raw material to synthesize both hydroxyapatite and zeolite. These two materials has the outstanding performance to adsorb pollutants in water. However, the technology to synthesis hydroxyapatite-zeolite composite from blast furnace slag has received low attention. In this study, the effects of hydrothermal synthesis of hydroxyapatite-zeolite composite from blast furnace slag on the change of various synthesis conditions, such as temperature, alkalinity and chemical composition of blast furnace slag used, were investigated. The characteristics of the synthesized hydroxyapatite-zeolite composites are investigated via XRD, FT-IR, BET/BJH, and SEM/EDX tests. In the results, the temperature and the alkalinity affected the crystallinity, crystal phases, microstructures, and adsorption capacities of synthesized samples. The crystallinity tended to increase as temperature increased. Under $90^\circ C$, hydroxyapatite was synthesized only but above $90^\circ C$, zeolite was additionally synthesized. Moreover, hydroxysodalite was synthesized over $150^\circ C$. The sample synthesized at $90^\circ C$ had the highest specific surface area due to the formation of zeolite. On the other hand, as the alkalinity increased, the crystallinity of products increased, but above certain alkalinity, the alkalinity only affected the crystal phase of products. Hydroxyapatite and zeolites were synthesized with 3M of NaOH solution but hydroxysodalite was additionally synthesized at high alkalinity. Due to its low adsorption performance, $Cs^+$ adsorption capacity decreased when hydroxysodalite was synthesized. On the other hand, the specific surface area of hydroxyapatite crystals decreased as alkalinity increased due to crystal aggregation. The chemical composition of blast furnace slag affected the crystal phase and adsorption capacity as much $Al_2O_3$ contents accelerated zeolite formation, microstructure since $SiO_2/Al_2O_3$ molar ratio decreased and zeolite type was changed. On the other hand, less Ca and $PO_4$ contents to synthesize hydroxyapatite compared with alkalinity and temperature resulted in the substitution of the other ions into hydroxyapatite. This phenomenon led to change in specific surface area and adsorption capacities of hydroxyapatite.
Advisors
Lee, Hae-Kiresearcher이행기researcher
Description
한국과학기술원 :건설및환경공학과,
Publisher
한국과학기술원
Issue Date
2020
Identifier
325007
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 건설및환경공학과, 2020.8,[v,107 p. :]

Keywords

제올라이트▼a수산화인회석▼a흡착제▼a열수 합성법▼a합성 조건▼a수질 정화; Zeolite▼ahydroxyapatite▼aadsorbents▼ahydrothermal synthesis▼asynthesis condition▼awater purification

URI
http://hdl.handle.net/10203/284495
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=926279&flag=dissertation
Appears in Collection
CE-Theses_Ph.D.(박사논문)
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