Study of As(III) and As(V) Oxoanion Adsorption onto Single and Mixed Ferrite and Hausmannite Nanomaterials.

The removal of arsenic(III) and arsenic(V) from an aqueous solution through adsorption on to FeO, MnFeO, 50% Mn substituted FeO, 75% Mn substituted FeO, and MnO nanomaterials was investigated. Characterization of the nanomaterials using XRD showed only pure phases for MnO, MnFeO, and FeO. The 50% and 75% substituted nanomaterials were found to be mixtures of MnO and FeO. From batch studies the optimum binding pH of arsenic(III) and arsenic(V) to the nanomaterials was determined to be pH 3. The binding capacity for As(III) and As(VI) to the various nanomaterials was determined using Isotherm studies. The binding capacity of FeO was determined to be 17.1 mg/g for arsenic(III) and 7.0 mg/g for arsenic(V). The substitution of 25% Mn into the FeO lattice showed a slight increase in the binding capacity for As(III) and As(VI) to 23.8 mg/g and 7.9 mg/g, respectively. The 50% substituted showed the maximum binding capacity of 41.5 mg/g and 13.9 mg/g for arsenic(III) and arsenic(V). The 75% Mn substituted FeO capacities were 16.7 mg/g for arsenic(III) and 8.2 mg/g for arsenic(V). The binding capacity of the MnO was determined to be 13.5 mg/g for arsenic(III) and 7.5 mg/g for arsenic(V). In addition, interference studies on the effects of SO, PO, Cl, and NO investigated. All the interferences had very minimal effects on the As(III) and As(V) binding never fell below 20% even in the presence of 1000 ppm interfering ions.