Removal of Tl(I) Ions From Aqueous Solution Using Fe@Fe₂O₃ Core‐Shell Nanowires

Abstract

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(I) 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, ¼ 10 3 $ 10 4 mL/g). The Tl(I) 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(I) 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 DH 0 and DG 0 values revealed Tl(I) 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, energydispersive 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(I) from aqueous solution.

Adsorptive performance of nanosized zero‐valent iron for V(V) removal from aqueous solutions

“…Among the physical and chemical synthesis techniques available for nZVI, liquid‐phase reduction was utilized using sodium borohydride as the reducing agent. For this purpose, 7.25 g FeCl 3 · 6H 2 O was dissolved in 25 mL of a 4:1 (v/v) ethanol/water mixture and gently stirred on a magnetic stirrer.…”

“…Nanosized zero–valent iron (nZVI) has become an effective material for the removal of various toxic aqueous ions in recent years due to small particle size, ease of preparation, low standard potential, large surface area and being environmentally friendly since elemental iron itself has no known toxic effect and is one of the most abundant elements in the earth's crust . In this study, removal of V(V) was investigated for the first time using nZVI.…”

In Situ Measurement of Thallium in Natural Waters by a Technique Based on Diffusive Gradients in Thin Films Containing a δ-MnO2 Gel Layer

“…Tl stock solutions were prepared by dissolving TlNO 3 or Tl­(NO 3 ) 3 ·3H 2 O (Acros, Belgium) in 0.1 mol·L –1 HNO 3 (Sigma–Aldrich) and then diluting with Milli-Q water (18.2 MΩ·cm, Millipore). Gel-making reagents include 40% acrylamide solution in water (from BDH), a patented agarose-derived cross-linker (2%; DGT Research Ltd., Lancaster, U.K.), ammonium persulfate (APS; from BDH) initiator for making a 10% water solution, N , N , N ′, N ′-tetramethylethylemediamine (TEMED) catalyst (99%; Electron, BDH), and Chelex-100 resin (200–400 mesh, Bio-Rad).…”

“…n EXPERIMENTAL SECTION Reagents, Materials, and Solutions. Tl stock solutions were prepared by dissolving TlNO3 or Tl(NO3)3•3H2O (Acros, Belgium) in 0.1 mol L -1 HNO3 (Sigma-Aldrich, USA) and then diluting with Milli-Q water 39 Speciation modeling. Tl species were assessed using the PhreeQC software with a series of equilibrium constants from the literature [41][42][43] (Supporting information (SI), Table S1) for the interpretation of the results.…”

Thallium(I) Oxidation by Permanganate and Chlorine: Kinetics and Manganese Dioxide Catalysis

“…Given the low efficiency of thallium removal by conventional treatments, some available technologies − have been developed to advance its removal to meet the strict environmental standard. Xu et al and Liu et al reviewed the latest approaches for Tl removal, including chemical precipitation/coagulation, adsorption, solvent extraction, ion exchange processes, and biotechnology, and summarized their advantages and disadvantages.…”