Arsenic removal using hydrous nanostructure iron(III)–titanium(IV) binary mixed oxide from aqueous solution

The synthetic bimetal iron(III)–titanium(IV) oxide (NHITO) used was characterized as hydrous and nanostructured mixed oxide, respectively, by the Föurier transform infra red (FTIR), X-ray diffraction (XRD) pattern and the transmission electron microscopic (TEM) image analyses. Removal of As(III) and As(V) using the NHITO was studied at pH 7.0 (±0.1) with variation of contact time, solute concentration and temperature. The kinetic sorption data, in general, for As(III) described the pseudo-first order while that for As(V) described the pseudo-second order equation. The Langmuir isotherm described the equilibrium data (303 (±1.6) K) of fit was well with the Langmuir model. The Langmuir capacity ( q m, mg g −1) value of the material is 85.0 (±4.0) and 14.0 (±0.5), respectively, for the reduced and oxidized species. The sorption reactions on NHITO were found to be endothermic and spontaneous, and took place with increasing entropy. The energy (kJ mol −1) of sorption for As(III) and As(V) estimated, respectively, is 9.09 (±0.01) and 13.51 (±0.04). The sorption percentage reduction of As(V) was significant while that of As(III) was insignificant in presence of phosphate and sulfate. The fixed bed NHITO column (5.1 cm × 1.0 cm) sorption tests gave 3.0, 0.7 and 4.5 L treated water (As content ≤ 0.01 mg L −1) from separate As(III) and As(V) spiked (0.35 ± 0.02 mg L −1) natural water samples and from high arsenic (0.11 ± 0.01 mg L −1) ground water, respectively when inflow rate was (0.06 L h −1).