Development of iron oxide nanoparticle adsorbents for arsenic and fluoride removal

The study was designed to synthesize iron oxide nanoparticles and to investigate their application as a sorbent to remove fluoride and arsenic from contaminated water. The nanoparticles, synthesized by co-precipitation, were extensively characterized by X-ray diffraction analysis, Brunauer-EmmettTeller analysis and zeta potential analysis. The size and morphology of the particles were determined by scanning electron microscopy, which revealed an average particle size of ~130 nm. The synthesized nanoparticles were stable for at least 4 h in static conditions as evidenced by particle size measurements. Batch sorption studies were carried out, and sorption isotherms and reaction kinetics were analyzed. The iron oxide nanoparticles were not effective in fluoride removal at the pH and concentrations studied. They followed the Freundlich isotherm model and fitted well with pseudo-first-order reaction for As(III) and As(V) with R2 value of 0.93 and 0.98 at pH 7, respectively. The maximum sorption capacity of the nanoparticles for As(III) and As(V) at pH 7 were 909 and 3,333 µg/g, respectively. The results of the study showed that the synthesized nanoparticles can be promising adsorbents for As removal in small-scale water systems.