Efficient arsenic(III) removal from aqueous solution by a novel nanostructured iron-copper-manganese trimetal oxide

Abstract

The removal of arsenite [As(III)] has attracted increasing attentions because it is higher toxic and more difficult to be removed from water than arsenate [As(V)]. For efficient As(III) uptake, a nanostructured iron-copper-manganese trimetal oxide (ICM) was therefore synthesized using a simultaneous oxidation and co-precipitation approach at room temperature. The as-prepared ICM exhibits multifunctional properties, which can not only oxidize effectively As(III) but also sorb the produced As(V). The maximal sorption capacity of As(III) reaches up to 131 mg/g under neutral conditions, which outperforms the majority of adsorbents reported in the literature. The As(III) sorption drops gradually as solution pH increases. However, it is not significantly influenced by ionic strength and present anions except for PO 4 3− , implying a relatively high selectivity. The active sorption sites of spent ICM can be easily restored through NaOH solution treatment. The removal of As(III) is a complicated process involving in both oxidation and adsorption, in which inner-sphere surface complexes are formed. The oxidation of As(III) to As(V) is mainly ascribed to the Mn oxide content in composite, whereas the adsorption of formed As(V) is predominately attributed to the Fe oxide and Cu oxide. The ICM might act as a promising alternative to remove arsenic from groundwater and wastewater, due to its good performance, low cost, facile synthesis and high reusability. • A novel nanostructured Fe-Cu-Mn trimetal oxide sorbent was fabricated. • The sorbent has a high sorption capacity for As(V) and As(III). • The sorbent is highly effective for As(III) removal at trace concentration. • As(III) uptake is mainly achieved by adsorption coupled with oxidation. • The spent sorbent can be easily regenerated and repeatedly used.