Syntheis and characterization of an aqueous nanometric iron hydroxide suspension suitable for the removal of As(III) and As(V)

Synthesis and characterization of an aqueous nanometric iron hydroxide suspension has been reported which may be used for the simultaneous removal of As (III) and As (V) from contaminated water. Acetic acid (1:1) is used as the peptization agent for making the suspension and optimum peptization pH is between 2.7–2.8. The suspension was characterized using different analytical techniques such as XRD, SEM, TEM, AFM and DLS. In the pH range of 2.7–2.8 particle diameter was less than 100 nm and particle size distribution was nearly normal. XRD, SEM, TEM and AFM confirmed the presence of nanometric crystals of Fe₂O₃ and FeOOH in the room temperature-air dried suspension. Efficient As(III) and As(V) removal, as separate entity as well as in conjunction, was demonstrated with the suspension. The removal process was governed by the sol-gel principle. The suspension showed loading capacities greater than 80mg/g for both As(III) and As(V). As(III) removal was interfered by phosphate ions while halide ions aided As(V) removal. Studied iron hydroxide suspension enjoys a number of advantages over the conventional arsenic adsorbents and may be viewed as a viable technological solution for the remediation of As(III) and As(V).