Synthesis and characterization of maghemite submicron particles: novel adsorbent for arsenic removal.

We have studied the structural and magnetic properties of maghemite submicron particles and their arsenic adsorption properties. The chemical method for the synthesis of these novel submicron particles consisted of the thermally activated partial oxidation and solid phase transformations of magnetite particles. The crystallographic structure of the synthesized particles prepared at different time intervals of thermal treatment (10 min, 30 min, 60 min, and 90 min) was characterized using powder X-ray diffraction and Rietveld refinement. Moreover, the magnetic properties were examined using a conventional 57Fe Mössbauer spectrometer and an alternating gradient magnetometer applying a field of ± 12 kOe at room temperature. The concentration of arsenic was determined, before and after removal experiments, by inductively coupled plasma-atomic emission spectroscopy. The results showed that the submicron particles synthesized by this method exhibit a cubic inverse spinel structure with a particle size distribution in the range of 80–170 nm. According to Mössbauer spectrometry, the particles are composed of a magnetically ordered core and a disordered surface region. Room temperature magnetization curves confirmed an interacting weakly ferrimagnetic behavior with saturation magnetization of 60 emu g− 1 and coercive field of 60 Oe. Additionally, the submicron particles are capable of efficiently decreasing the arsenic(V) content in water from 100 µg/L to below 10 µg/L (the current recommended limit of arsenic in drinking water according to the World Health Organization guideline) and it can be recycled by the application of an external magnetic field. [ABSTRACT FROM AUTHOR]