Modifying Fe3O4 microspheres with rhodamine hydrazide for selective detection and removal of Hg2+ ion in water

Rhodamine hydrazide modifying Fe 3 O 4 microspheres (Fe 3 O 4 -R6G) was developed for selective detection and removal of mercury ion from water. With a saturation magnetization of 74.2   emu/g, the Fe 3 O 4 -R6G could be simply recollected from water with magnetic separation within a few minutes. The selectivity and adsorption ability of Fe 3 O 4 -R6G for metal cations were studied by fluorophotometry and atomic absorption spectrometry, respectively. The results showed that Fe 3 O 4 -R6G exhibited excellent selectivity for sensing mercury ion over other metal ions in aqueous solution, and also adsorbed 91% of mercury ion. The maximum adsorption capacity of the Fe 3 O 4 -R6G for Hg 2+ ion was 37.4   μmol   g −1 . The Fe 3 O 4 -R6G was successfully applied to the determination of Hg 2+ in environmental samples, and could be used repeatedly by treatment with tetrabutylammonium hydroxide.