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Journal of Nanomaterials
Volume 2016, Article ID 8032615, 10 pages
Research Article

Nanocomposites of Magnetite and Layered Double Hydroxide for Recyclable Chromate Removal

1Department of Chemistry and Medical Chemistry, College of Science and Technology, Yonsei University, Wonju, Gangwon-do 26493, Republic of Korea
2Future Industries Institute, Division of Information Technology, Engineering and Environment, University of South Australia, Mawson Lakes, SA 5095, Australia

Received 7 April 2016; Revised 19 September 2016; Accepted 11 October 2016

Academic Editor: Yu-Lun Chueh

Copyright © 2016 Gyeong-Hyeon Gwak et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Nanocomposites containing magnetic iron oxide (magnetite) nanoparticles and layered double hydroxide (LDH) nanosheets were prepared by two different methods, exfoliation-reassembly and coprecipitation, for aqueous chromate adsorbent. According to X-ray diffraction, scanning electron microscopy, and atomic force microscopy, both nanocomposites were determined to develop different nanostructures; LDH nanosheets well covered magnetite nanoparticles with house-of-cards-like structure in exfoliation-reassembly method, while coprecipitation resulted in LDH particle formation along with magnetite nanoparticles. Zeta-potential measurement also revealed that the magnetite surface was effectively covered by LDH moiety in exfoliation-reassembly compared with coprecipitation. Time, pH, concentration dependent chromate adsorption tests, and magnetic separation experiments exhibited that both nanocomposites effectively adsorb and easily collect chromate. However, exfoliation-reassembly nanocomposite was determined to be slightly effective in chromate removal by ~10%. Chromate adsorbed nanocomposites could be regenerated by treating with bicarbonate and the regenerated nanocomposites preserved ~80% of chromate adsorption efficacy after three times of recycling.