Otherwise, the arsenic uptake onto phosphorene oxide is examined according to the oxidation degree. For comparative purposes, the arsenic uptake onto a very low oxidized surface [PhosO(1:)] slightly increases the Eads values (up to 15%) with respect to intrinsic phosphorene. Consequently, intrinsic phosphorene and reduced phosphorene oxides with a very low-oxidized character perform similarly in arsenic removal. Conversely, medium- As(V) -, and As(V) 2-reach adsorption energies of 1.1, 1.7, and 1.8 eV onto PhosO(1:4), respectively. Interestingly, the As(III) adsorption strength increases up to 38% compared to oxidized graphene (Eads0.8 eV) , which require chemical functionalization with minerals for an efficient arsenic adsorption in composite materials . Remarkably, related mineral oxides have shown adsorption energies of 1.1 eV for As(III) removal (e.g., gibbsite, iron oxides, and titanium dioxides), which have been widely described as efficient arsenic adsorbents . Hence, medium-oxidized PhosO structures are excellent arsenic nanoadsorbents compared to mineral surfaces, allowing to reach adsorption energies above 1.1 eV without requiring additional chemical functionalization and reducing the costly and time-consuming methods for the synthesis of composites.