Performance of Fe nanoparticles for the Arsenic removal, a DFT study.

FUENTE SILVIA A; LESLIE L. ALFONSO TOBÓN; MARÍA M. BRANDA

Montevideo

Congreso; QUITEL 2016, 42nd International Congress of Theoretical Chemists of Latin Expression; 2016

Universidad de la República Uruguay

The significant pollution in groundwater with arsenic species has led, in vast regions of Argentine and Latin America, to explore possible ways toward their removal. This requires knowing the adsorption and reaction mechanisms of these species on different substrates. It is well known that iron has a high and selective affinity with arsenic, due to the formation of strong surface complexes [1]. In this study, the extended Fe (111) and (110) surfaces and two different nanoparticles (Fe32 and Fe59) were evaluated as catalytic substrates. Periodic Density Functional Theory (DFT) calculations were performed using the exchange correlation potential PBE with empirical dispersion correction by means of the VASP code [2]. The results showed the spontaneous reduction of the arsenic acid (H3AsO4, see Figure 1a) to arsenous acid (H3AsO3, see Figure 1b) when is adsorbed on the Fe(110) surface (see Figure 1c). From these results we decided to study the interaction of the oxyacid (H3AsO3) with different Fe substrates. H3AsO3 spontaneously decomposes on both nanoparticles and also on the (111) surface, remaining the different fragments linked to the substrates (see Figure 1d). First dehydrogenation reaction was also study and the energy minimal states and transition states were confirmed carried out frequency calculations. Climbing-image Nudged Elastic Band method (CI-NEB) was used to obtain the transition states (TS) for the studied reactions [3].