Competitive Adsorption of Pb^II, Ni^II, and Sr^II Ions on Graphene Oxides: A Combined Experimental and Theoretical Study

Abstract

Abstract The individual and competitive adsorption of Pb II , Ni II , and Sr II on graphene oxides (GOs) was investigated by experimental and density functional theory (DFT) studies. Experimental results indicate that 1) in all the single, binary, and ternary metal‐ion adsorption systems, the sequence of maximum adsorption capacities is Pb II >Ni II >Sr II on GOs; 2) the desorption hysteresis of metal ions from GOs shows the adsorption affinity in the same sequence: Pb II >Ni II >Sr II . For the first time, DFT calculations indicate that 1) Pb II and Ni II prefer to interact with the COH group, whereas Sr II interacts with COH and COC comparably, and 2) Pb II can easily abstract the OH group from the GOs to form the much more stable Pb(OH)–GO complex. These findings are very important and useful for understanding the mechanisms of heavy‐metal‐ion adsorption on GOs and assessing the adsorption of coexisting heavy‐metal ions on GOs.