Our motivation is to clarify the role of partially oxidized phosphorene to control water-soluble methylarsenicals, which to our knowledge, has not yet been explored. In particular, the present work addresses a DFT study for (i) the adsorption ability of phosphorene for uptake of methylated As III and As V species in water environments, (ii) adsorption conformations, (iii) the interaction mechanisms and nature of the physical or chemical adsorption, and (v) recovery of the adsorbent material as a new technology for water treatment.