Removal of Tl(I) Ions From Aqueous Solution Using Fe@Fe 2 O 3 Core‐Shell Nanowires

• Published in: Clean : soil, air, water Vol. 44; no. 9; pp. 1214 - 1224
• Main Authors: Deng, Hongmei, Zhang, Zijun, Xu, Nan, Chen, Yongheng, Wu, Honghai, Liu, Tao, Ye, Hengpeng
• Format: Journal Article
• Language: English
• Published: 01.09.2016
• ISSN: 1863-0650; 1863-0669
• DOI: 10.1002/clen.201500403

A unique nanoscale zero‐valent iron, Fe@Fe 2 O 3 core–shell nanowire (FCSN) was synthesized and evaluated as adsorbent for effective removal of thallium(Ι) ions. Adsorption of Tl(I) onto FCSNs was pH‐independent and strongly dependent on ionic strength. However, even under high ionic strength condition, the FCSNs still showed fairly good adsorption capacity (distribution coefficient, K d,  = 10 3  ∼ 10 4  mL/g). The Tl(Ι) adsorption reached equilibrium within 180 min, and followed the pseudo‐second‐order rate equation. The adsorption capacity is 17.8 mg/g with an initial Tl(Ι) concentration of 10 mg/L at 303 K. The adsorption equilibrium data were fitted better by the Langmuir and Freundlich isotherm than the D–R isotherm. The thermodynamic parameters were estimated and the Δ H 0 and Δ G 0 values revealed Tl(Ι) adsorption on FCSNs was an endothermic and spontaneous process. The desorption and regeneration studies demonstrated that FCSNs still retained high Tl(I) removal efficiency after five consecutive adsorption–desorption processes. The as‐prepared and Tl‐loaded FCSNs were characterized by X‐ray powder diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy to identify elements and structure of the FCSNs, and verify the removal mechanisms. The characterization results suggested that the possible removal mechanism involved the dominant Tl(I) sorption, followed by the partial transformation of Tl(I) into Tl 2 O, precipitating on the surface of FCSNs without any redox reaction taking place. These results suggest that FCSNs may be the potential sorbents for the detoxication of Tl(Ι) from aqueous solution.