Superparamagnetic nanomaterial Fe₃O₄–TiO₂ for the removal of As(V) and As(III) from aqueous solutions

ABSTRACT

A magnetically separable nanomaterial Fe₃O₄–TiO₂ was synthesized and characterized which was subsequently used for the removal of arsenic (V) from aqueous solutions. The surface morphology, magnetic properties, crystalline structure, thermal stability and Brunauer–Emmet–Teller surface area of the synthesized Fe₃O₄–TiO₂ nanoparticles (NPs) are characterized by scanning electron microscope and high-resolution transmission electron microscope, vibrating sample magnetometry, X-ray diffractometer, thermogravimetric analysis and multi point function surface area analyzer. The saturation magnetization of Fe₃O₄–TiO₂ NPs was determined to be 50.97 emu/g, which makes them superparamagnetic. The surface area of Fe₃O₄–TiO₂ NPs was as much as 94.9 m²/g. The main factors affecting adsorption efficiency, such as solution pH, reaction time, initial As(V) concentration and adsorbent concentration are investigated. When the adsorption isotherms were analyzed by the Langmuir, Freundlich and Dubinin-Radushkevich models, equilibrium data were found to be well represented by Freundlich isotherm, and adsorption on Fe₃O₄–TiO₂ NPs fitted well with pseudo-second-order kinetic model. The maximum adsorption capacity of As(V) on Fe₃O₄–TiO₂ NPs, calculated by the Freundlich model was determined at 11.434 µg/g. 1.0 g/L of Fe₃O₄–TiO₂ NPs was efficient for complete removal of 100 µg/L As(V) in 1 h. Fe₃O₄–TiO₂ NPs was also effective for 93% removal of 100 µg/L As(III). Matrix effect was determined using As(V)-contaminated well water. Successfull results were obtained for purification of real well water containing 137.12 µg/L As(V). Results show that Fe₃O₄–TiO₂ NPs are promising adsorbents with an advantage of magnetic separation.

KEYWORDS:

• Fe₃O₄–TiO₂
• nanoparticles
• arsenic
• adsorption
• magnetic separation

Acknowledgement

The author thanks KOSKI for their help in taking well water sample and performing chemical composition analyses.

Disclosure statement

No potential conflict of interest was reported by the authors.