Application of mesoporous CaO@g-C3N4 nanosorbent materials for high-efficiency removal of Pb (II) from aqueous solution

[Display omitted] •Eco-friendly CaO@g-C3N4 nanocomposite were produced via ultrasonication and used for the removal of aqueous lead (II).•DFT-D4 calculations, Kinetics, isotherm and reusability study were used to investigate the removal of lead ions from water.•Maximum adsorption percentage and quantity of 99.88% and 525.5 mg/g, respectively were reached after 4 min at pH 3.•Removal of Pb(II) ions via their complexation with CaO@g-C3N4 is mainly a chemisorption process. Removing heavy metals from aqueous solutions is an environmental challenge of rising concern. Discovering new materials based on nanostructures with enhanced adsorption towards heavy metals can be experimentally difficult and expensive. As an alternative strategy, designing efficient nanostructures acting as adsorbents through computational studies is a viable solution in the adsorption research area. In the current study, density functional theory (DFT) calculations were performed prior to experimental investigation to predict the potential use of CaO@g-C3N4 nanostructure as an adsorbent for lead ions. The analysis of the interaction energies pointed out the effect of incorporating CaO into the g-C3N4 framework to improve the adsorption properties. The eco-friendly CaO/g-C3N4 composite was experimentally tested as an absorbent medium for the removal of lead ions in aqueous solution. The results show that lead (II) ions adsorption onto CaO@g-C3N4 equilibrated in 4 min, with an adsorption percent and quantity of 99.88% and 525.5 mg/g, respectively, at pH 3. Additionally, CaO@g-C3N4 nanostructures may be easily recovered from the solution for reuse after five successive cycles. The mathematical models Langmuir and PSO were shown to be the most appropriate for modeling the adsorption data in equilibrium and nonequilibrium states, respectively. The CaO@g-C3N4 nanostructures, therefore, can be used as a suitable adsorbent for aqueous lead (II) ions due to their ease of manufacture, high adsorption efficacy, recovery ability, and reusability.