Nanoscaled zero valent iron/graphene composite as an efficient adsorbent for Co(II) removal from aqueous solution.
A magnetic graphene, i.e., nanoscaled zero valent iron/graphene (0FG) composite, was prepared, characterized and applied for the removal of Co(II) from aqueous solution. The magnetic graphene (0FG) was synthesized through reduction of graphene oxide (GO) and ferrous ions by potassium borohydride. The kinetics and isotherms of Co(II) adsorption onto 0FG were investigated. The mechanism for Co(II) removal was proposed based on the Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the X-ray absorption fine structure (XAFS) analysis. The results showed that pseudo second-order models and the Freundlich isotherm model fitted well with the data obtained. The adsorption capacity of 0FG was calculated from the Langmuir isotherm, which was 65.58, 101.60 and 134.27mg/g at 10, 20 and 30°C, respectively. Thermodynamic parameters suggested that the adsorption process was endothermic and spontaneous. Co(2+) was stabilized by γ-FeOOH/γ-Fe2O3/Fe3O4 on the surface of graphene sheets, forming CoFe2O4-like nanocrystals. The coordination numbers and interatomic distances indicated that Co(2+) mainly occupied the octahedral site, while pseudo-tetrahedral coordination may occur by dehydroxylation of Co(O,OH)6. Magnetic graphene is a potential adsorbent for Co(2+) removal.
Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing 100084, PR China.
Min
M
Xing
Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing 100084, PR China; Beijing Key Laboratory of Radioactive Waste Treatment, Tsinghua University, Beijing 100084, PR China. Electronic address: wangjl@tsinghua.edu.cn.
Jianlong
J
Wang
Adsorption; Co(II); Graphene; Magnetic graphene; Zero valent iron