Arsenic is of serious health concern due to its toxicity and carcinogenicity. Adsorption is considered to be one of the most promising technologies for arsenic removal. In recent years, synthesized metal oxide nanoadsorbents have been extensively studied for arsenic adsorption, which demonstrated superior performance because of their large surface areas from their nano-size and preferred surface properties. However, the separation of nanoadsorbents from treated water bodies still remains as a challenge to their potential application in real water treatment practice. The inefficient separation could cause their dispersion into the aqueous environment, resulting in the operation cost increase and potential damages to both natural organisms and the environment.In this work, a superparamagnetic ultrafine magnesium ferrite (Mg0.27Fe2.50O4) nanoadsorbent was created by doping Mg2+ into ultrafine a-Fe2O3 nanocrystallite during the solvent-thermal process. The specific surface area of Mg0.27Fe2.50O4 largely increased due to the Mg-doping, subsequently enhancing its arsenic adsorption performance on both As(III) and As(V) species compared with the ultrafine a-Fe2O3 nanoadsorbent we developed before. Furthermore, a proper amount of ~ 10% Mg-doping into iron oxide crystal lattice caused a crystal structure change from the rch a-Fe2O3 phase to a single magnesium ferrite phase with cubic spinel structure, which endowed the ultrafine Mg0.27Fe2.50O4 nanoadsorbent a superparamagnetic behavior with a high saturation magnetization. Thus, no magnetic attraction existed when there was no external magnetic field applied during the water treatment, which is beneficial to its better dispersion and the subsequent better contact efficiency with arsenic species in water. After the water treatment, however, the external magnetic field applied could induce its easy magnetic separation from treated water bodies. Then, the ultrafine Mg0.27Fe2.50O4 nanoadsorbent could be easily recovered by NaOH washing and reused for arsenic removal.

Synthesis of superparamagnetic magnesium ferrite nanoadsorbent and its effective arsenic (III, V) removal performance and easy magnetic separation

247th National Meeting (2014)

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