As(V) --PhosO As(V) 2--PhosO EDA terms were also obtained for the As(V)-PhosO complexes to rationalize the differences between As(III) and As(V) adsorption. As(V) is mainly anionic in aqueous solution at pH=7; thus, electrostatics interactions will be directly proportional to the charge magnitude of anionic adsorbates and increasing as the As(V) negative charge increases. In fact, the EELEC magnitude considerably increases for adsorbed As(V) species compared to the As(III) adsorption, denoting the key role of permanent electrostatic driving forces in the As(V) complexation as stated by Sharma and Sohn . For instance, As(III), As(V) -, and As(V) 2-species are stabilized by electrostatic forces in 3.5, 6.5, and 10.3 eV, respectively.