영구자석 스크랩으로 합성한 산화철 나노입자의 물성에 미치는 열처리 온도의 영향

• Published in: Clean Technology, 28(2) Vol. 28; no. 2; pp. 110 - 116
• Main Authors: 홍성제(Sung-Jei Hong), 홍상혁(Sang Hyeok Hong), 조아진(Ajin Jo), 김용성(Young-Sung Kim), 김병준(ByeongJun Kim), 양수원(Suwon Yang), 이재용(Jae-Yong Lee)
• Format: Journal Article
• Language: Korean
• Published: 한국청정기술학회 2022
• Subjects: 화학공학; 물성; Permanent magnet scrap; 산화철 나노입자; Iron oxide nanoparticles; Iron by-product; 영구자석 스크랩; 철 부산물; 열처리 온도; Heat-treatment temperature; Physical properties
• ISSN: 1598-9712; 2288-0690

In this study, iron oxide (FeOx) nanoparticles were synthesized using iron (Fe) by-products recovered from NdFeB permanent magnet scraps, and the effect of heat-treatment temperature on the physical properties of the FeOx nanoparticles was investigated. In order to prepare the FeOx nanoparticles, 2.0 M ammonia (NH4OH) solution was added to an iron by-product solution diluted to c.a. 10 wt% in D.I. water, which led to the precipitation of the iron oxide precursor. Then, the FeOx nanoparticles were synthesized by heat-treatment at 300 ℃, 400 ℃, 500 ℃ and 600 ℃. After that, the physical properties of the FeOx nanoparticles were investigated in order to understand the effect of the heat-treatment temperature. The results of the X-ray diffraction (XRD) analysis showed that the diffraction peak in accordance with the direction increased as the heat-treatment increased, and a diffraction peak indicating the α-Fe2O3 crystal structure was detected at heat-treatment temperatures above 500 ℃. The BET specific surface area analysis revealed that the specific surface area decreased as the heat-treatment temperature increased to above 400 ℃. Observation with a high resolution transmission electron microscope (HRTEM) showed that rod-shaped nanoparticles were formed, and the size of the nanoparticles showed a tendency to increase as the heat-treatment temperature increased. 본 연구에서는 NdFeB 영구자석 스크랩으로부터 회수한 철(Fe) 부산물을 이용하여 산화철(FeOx) 나노입자를 합성하였고, 열처리 온도가 FeOx 나노입자의 물성에 미치는 영향을 관찰하였다. 이를 위해 D.I. water에 약 10 wt%로 희석한 철 부산물 용액에 2.0 M 암모니아(NH4OH) 용액을 투여하여 산화철 전구체를 석출하였고, 이를 300 ℃, 400 ℃, 500 ℃ 및 600 ℃로 각각 열처리하여 FeOx 나노 입자를 합성, 열처리 온도에 따른 FeOx 나노 입자의 물성을 관찰하였다. X-ray diffraction (XRD) 분석 결과 열처리 온도가 증가할수록 회절 피크가 성장하여 500 ℃ 이상에서 α-Fe2O3 결정구조와 일치하는 회절 피크가 검출되었다. BET (Brunauer-Emmett-Teller) 비표면적 분석 결과 400 ℃ 이상에서 열처리 온도가 증가할수록 비표면적이 감소하는 경향을 나타내었다. HRTEM (high resolution transmission electron microscope) 관찰 결과 rod 형 나노입자가 관찰되었고, 열처리 온도 증가에 따라 나노입자의 크기가 증가하는 경향을 나타내었다.