title: Efficient removal of free and nitrilotriacetic acid complexed Cd(II) from water by poly(1-vinylimidazole)-grafted Fe3O4@SiO2 magnetic nanoparticles.
abstract: Poly(1-vinylimidazole)-grafted Fe3O4@SiO2 magnetic nanoparticles (FSPV) were developed to remove both free Cd(II) and nitrilotriacetic acid (NTA) complexed Cd(II) from water. The adsorption capacity of NTA-complexed Cd(II) (42.1 mg/g) was larger than that of free Cd(II) (24.8 mg/g). Free Cd(II) and NTA-complexed Cd(II) could be reduced from 50 μg/L to below 5 μg/L within 10 and 20 min, respectively. FSPV could effectively remove trace free and NTA-complexed Cd(II) over broad pH ranges of 5-10 and 5-11, respectively. Moreover, the presence of seven coexisting ions (up to 100 mM) including four cations (Na(+), K(+), Ca(2+), and Mg(2+)) and three anions (Cl(-), NO3(-), and SO4(2-)) all slightly promoted the removal of both free and NTA-complexed Cd(II) onto FSPV. The removal of free Cd(II) or NTA-complexed Cd(II) was not obviously affected by the presence of Ni(II) and Co(II) (50 μg/L), humic acid (up to 3 mg/L as TOC) or alginate (up to 8 mg/L as TOC). In addition, FSPV could be regenerated with 10 mM HCl in 10 min, and the removal of both types of Cd(II) maintained above 95% in five consecutive adsorption/regeneration cycles. Therefore, FSPV could be utilized as promising adsorbent for both free and NTA-complexed Cd(II).
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
keywords: Adsorption; Cadmium; Imidazole; Magnetic nanoparticle; Nitrilotriacetic acid