Experimental and theoretical calculation investigation on efficient Pb(ii) adsorption on etched Ti₃AlC₂ nanofibers and nanosheets

Layered 2D etched Ti₃AlC₂ nanofibers and nanosheets with different morphologies (named as e-TACFs and e-TACSs) were successfully synthesized by a simple hydrothermal treatment. The adsorption of Pb(ii) on e-TACFs and e-TACSs under various conditions was found to be strongly dependent on pH and ionic strength. Thermodynamic parameters calculated from temperature-dependent isotherms showed that the adsorption of Pb(ii) on both samples was spontaneous and endothermic. Specifically, due to their enhanced specific surface area and complexation affinity with Pb(ii), the maximum adsorption capacity of Pb(ii) on e-TACFs at pH 5.0 was 285.9 mg g^-1, which was higher than that of Pb(ii) on e-TACSs (218.3 mg g^-1). The interaction mechanisms of Pb(ii) with e-TACFs and e-TACSs were mainly attributed to cation exchange and outer-sphere surface complexation, which synergistically promoted the adsorption kinetics and enhanced the adsorption capacity. The DFT computational results were in good agreement with the batch experimental observations. Such a fluoride-free hydrothermal synthesis method and excellent heavy metal removal capacity demonstrate that 2D etched Ti₃AlC₂ nanomaterials are promising materials for the efficient removal of Pb(ii) in environmental pollution remediation.