Water molecules demonstrate lower adsorption energies for adsorption on either intrinsic or oxidized phosphorene (Eads 0.14 and 0.28 eV for Phos-H2O and PhosO-H2O, respectively), adopting an intermolecular distance from oxygen to nanoadsorbent of 2.5-2.6 Å (Fig. ). The adsorption energy of water onto intrinsic phosphorene or phosphorene oxide is always lower (at least 40%) than methylarsenicals adsorption, showing the selectivity of methylarsenicals to be absorbed in aqueous environments. In this sense, water molecules are non-competitive factors for arsenic remotion with phosphorene-based nanoadsorbent.