Magnetic core-shell iron(II,III) oxide@layered double oxide microspheres for removal of 2,5-dihydroxybenzoic acid from aqueous solutions

Sheng Tang; Guo Hui Chia; Hian Kee Lee

doi:10.1016/j.jcis.2014.09.038

Magnetic core-shell iron(II,III) oxide@layered double oxide microspheres for removal of 2,5-dihydroxybenzoic acid from aqueous solutions

J Colloid Interface Sci. 2015 Jan 1:437:316-323. doi: 10.1016/j.jcis.2014.09.038. Epub 2014 Sep 23.

Authors

Sheng Tang¹, Guo Hui Chia¹, Hian Kee Lee²

Affiliations

¹ Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
² Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore; National University of Singapore Environmental Research Institute, T-Lab Building #02-01, 5A Engineering Drive 1, Singapore 117411, Singapore. Electronic address: chmleehk@nus.edu.sg.

PMID: 25441367
DOI: 10.1016/j.jcis.2014.09.038

Abstract

Magnetic core-shell Fe3O4@layered double oxide (Fe3O4@LDO) microspheres were synthesized and utilized as adsorbent in the removal of 2,5-dihydroxybenzoic acid (2,5-DHBA) from aqueous samples. Due to the "memory effect", the microspheres showed higher adsorption capacity compared with Fe3O4@layered double hydroxide. The Fe3O4@LDO microspheres were easily recovered after the experiment via the application of a magnetic force. The effect of mass of Fe3O4@LDO, temperature and time on adsorption efficiency were investigated using batch experiments. Adsorption was in conformance with the Langmuir model, with a maximum adsorption capacity of 188.7 mg/g. Recyclability experiments indicated that adsorption efficiency did not decrease noticeably after 3 cycles of adsorption-calcination. The Fe3O4@LDO microspheres were evaluated by considering matrix-matched aqueous samples spiked with 2,5-DHBA. Under optimized conditions, 98.4% of the 2,5-DHBA analyte in the sample can be effectively removed from an aqueous solution within 4 h. The results indicate that Fe3O4@LDO microspheres have the potential to be employed as highly efficient, convenient, and low-cost magnetic adsorbents in the removal of 2,5-DHBA from water.

Keywords: 2,5-Dihydroxybenzoic acid; Fe(3)O(4)@layered double oxide; Magnetic microspheres; Memory effect; Removal.