Influence of groundwater occurring ions on the kinetics of As(III) adsorption reaction with synthetic nanostructured Fe(III)-Cr(III) mixed oxide

Nanoparticle (20-30 nm) agglomerates of synthetic hydrous Fe(III)-Cr(III) mixed oxide (NHICO) were used for As(III) adsorption from aqueous solutions. The parameters investigated were the effects of (i) incinerating temperature on NHICO and (ii) solution pH. Kinetics of As(III) adsorption reaction with NHICO (incinerated at 350 °C) was mainly investigated taking groundwater co-occurring ions at the background at optimum pH 7.0 (± 0.2). Results indicated that the NHICO incinerated at 350 °C showed highest capacity of As(III) removal at pH 7.0 (± 0.2) from aqueous phases. The kinetic data of As(III) adsorption by NHICO described the pseudo-second order model very well. The capacities of As(III) removal (qe) obtained at equilibrium from experiments were found too close with the modeled values. Again, the qe values obtained in the presence of ions at background was found ranged in ± 5% of that in the absence of ion, excepting HCO3−. The qe value of As(III) in the presence of HCO3− was notably greater than that in the absence of any ion indicating increase of As(III) removal capacity by NHICO. Values of the rate constants increased with lowering As(III) concentrations. Therefore, NHICO incinerated at 350 °C should be an efficient medium for filtrations of high As(III) contaminated groundwater.