High efficient removal of 4-aminophenylarsonic acid from aqueous solution via enhanced FeOOH using Mn(VII).

Abstract

Efficient removal of 4-aminophenylarsonic acid from contaminated water sources is essential to mitigate arsenic pollution. We proposed a competent technique to achieve 4-aminophenylarsonic acid removal via adsorption on enhanced α-FeOOH using various concentrations of Mn(VII). The elimination rate of 4-aminophenylarsonic acid applying FeOOH with Mn(VII) was dependent on acidic conditions. More than 99.9% of 4-aminophenylarsonic acid was eliminated in a 6-min reaction time under acidic conditions. The reaction of 4-aminophenylarsonic acid was fast at 4.0 and 5.0 pH, with its complete oxidation into arsenate and the liberation of manganese Mn(II) in the initial stage of the reaction. Similarly, the reaction rate constant (kobs) decreased from 0.7048 ± 0.02 to 0.00155 ± 0.00007 as the pH increased from 4.0 to 9.0. Oxidation capacity was considerably enhanced via the removal of electrons from 4-aminophenylarsonic acid to Mn(VII) after the creation of its radical intermediate and further change in Mn(III) to Mn(II) in the solution. The results showed that Mn(VII) played a crucial role in 4-aminophenylarsonic acid degradation at a low pH (e.g., 4.0), and the oxidation process proceeded in different manners, namely, electron transfer, hydroxylation, and ring-opening. These results illustrated that Mn(VII) is an effective, economic purification process to mitigate 4-aminophenylarsonic acid generated from poultry waste.