Linear correlation between electronegativity and adsorption energy of hydrated metal ions by carboxyl-functionalized single-walled carbon nanotubes

Most metals dissolve in aqueous solution in ionic form that tasks of purifying contaminated environments are always challenging for us, and the accurate prediction in the adsorption process is essential to identify determinants in surface science. We propose the simple representations of parameters described by Conceptual Density Functional Theory for hydrated metal ions. Different calculation methods through density functional theory (DFT) are developed and corresponding performance is revealed that the high correlation occurs between the global electronegativity and inner-sphere adsorption energy of hydrated metal ions by carboxyl-functionalized single-walled carbon nanotubes, in particular, the calculation concept involving fractional occupation numbers that R-square is above 0.8. The hydration energy is not negligible when determining the adsorption energy and it promotes the stability of the complexes in aqueous phase. That metal ions with trivalent charge exhibit stronger hydration energy than those with divalent charge is found. Meanwhile, the efficient system simulated by the meaningful fractional occupation methods for the wastewater treatment and optimal materials designing could be rationalized and accelerated.