title: Removal of Hg(II) by poly(1-vinylimidazole)-grafted Fe3O4@SiO2 magnetic nanoparticles.
abstract: Fe3O4@SiO2 magnetic nanoparticles modified by grafting poly(1-vinylimidazole) oligomer (FSPV) was fabricated as a novel adsorbent to remove Hg(II) from water. Fourier transform infra-red spectroscopy confirmed the successful grafting of oligomer, and thermogravimetric analysis showed FSPV had a high grafting yield with organic content of 22.8%. Transmission electron microscopy image displayed that FSPV particles were polymer-coated spheres with size of 10-20 nm. With saturation magnetization of 44.7 emu/g, FSPV particles could be easily separated from water with a simple magnetic process in 5 min. The Hg(II) adsorption capacity of FSPV was found to be 346 mg/g at pH 7 and 25 °C in 10 mM NaCl. Moreover, the removal of Hg(II) by FSPV was not obviously affected by solution pH (from 4 to 10) or humic acid (up to 8 mg/L as TOC). The presence of seven common ions including Na(+), K(+), Ca(2+), Mg(2+), Cl(-), NO3(-), and SO4(2-) (up to 100 mM ionic strength) slightly increased the adsorption of Hg(II) by FSPV. X-ray photoelectron spectroscopy analysis revealed that the N atom of the imidazole ring was responsible for the bonding with Hg(II), whereas the bonding of Hg with N did not result in cleavage of Hg-Cl bond in HgCl2 and HgClOH. The regeneration of Hg(II)-loaded FSPV could be achieved with 0.5 M HCl rapidly in 10 min, and the removal of Hg(II) maintained above 94% in five consecutive adsorption-desorption cycles. Therefore, FSPV could serve as a promising adsorbent for Hg(II) removal from water.
authors.affiliation: The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Chao
authors.initials: C
authors.lastname: Shan
authors.affiliation: The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Zhiyao
authors.initials: Z
authors.lastname: Ma
authors.affiliation: The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China. Electronic address: tongmeiping@pku.edu.cn.
authors.forename: Meiping
authors.initials: M
authors.lastname: Tong
authors.affiliation: The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Jinren
authors.initials: J
authors.lastname: Ni
mesh_terms: D000327:Adsorption; D005290:Ferric Compounds / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry*; D007477:Ions; D007700:Kinetics; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008628:Mercury / Q000302:isolation & purification*; D011145:Polyvinyls / Q000737:chemistry*; D059027:Recycling; D012822:Silicon Dioxide / Q000737:chemistry*; D012996:Solutions; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000302:isolation & purification
chemical_list: D005290:Ferric Compounds; D006812:Humic Substances; D007093:Imidazoles; D007477:Ions; D058185:Magnetite Nanoparticles; D011145:Polyvinyls; D012996:Solutions; D014874:Water Pollutants, Chemical; C524090:poly(1-vinylimidazole); C000499:ferric oxide; D012822:Silicon Dioxide; D008628:Mercury
keywords: Adsorption; Imidazole; Magnetic nanoparticle; Magnetite; Mercury; Silica