Adsorption of Pb ( II ) , Ni ( II ) and Sr ( II ) Ions

of past research 1) The individual and competitive adsorption of metal ions on graphene oxides (GOs) studies by experimental and DFT calculation The heavy metal ions can be accumulated in living tissues, so they must be removed from polluted water. Graphene oxides (GOs) are considered as the ideal adsorbent material because the large quantities of oxygen-containing functional groups strengthen their hydrophilicity and adsorption capacity towards the heavy metal ions and positively charged organic molecules besides the high specific surface area like graphene. However, different metal ions often coexist in the wastewaters and aquatic environment rather than single metal ions. Although, much work focuses on the single metal ion adsorption on GOs, there are few reports on the competitive adsorption of coexisting metal ions on GOs. In addition, the theoretical calculation for investigating the interaction between metal ions and GOs is scarce. In the context of wastewaters, the information of competitive adsorption of coexisting metal ions on GOs is important and useful for improving the absorption capacity of GOs towards specific metal ions. In my study, the individual and competitive adsorption of Pb(II), Ni(II) and Sr(II) on GOs were investigated by experimental and DFT studies. We have successfully explained the experimental observations by DFT calculation. In this work, we have revealed that (1) among the ions Pb(II), Ni(II), or Sr(II), which one is much easier to react with graphene oxides; (2) which group, -OH, -COOH or –COO, is mainly responsible for the adsorption of metal ions; (3) how do the adsorption and desorption reactions carry out; and (4) Pb(II) can easily abstract the OH groups from graphene oxides (GOs) to form much more stable Pb(OH)-GO complex. For the first time, we proposed the OH-abstracting mechanism for the excellent adsorption property of graphene oxide, and to understand the interaction of different heavy metal ions with graphene oxides from experiments and