Removal of Toxic Pb (II) Ion from Aqueous Solution Using ZnO/K₂SO₄ Nanocomposites: Kinetics, Isotherms and Error Function Analyses

Heavy metals are considered one of the most serious toxic substances since they are non-biodegradable and can cause several health implications. The removal of heavy metals enhances the quality of the water and makes it suitable for drinking as well as other domestic uses. Therefore, the goal of the current work was to synthesize and utilize ZnO/K2SO4 nanocomposites as an adsorbent for the efficient removal of Pb (II) ions from the aqueous solution. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Fourier Transform Infrared (FTIR) Spectroscopy were employed to characterize the synthesized nanocomposites. The FTIR and EDX data confirmed the successful incorporation of K2SO4 in the ZnO structure. The XRD result revealed that the average particle size of ZnO/K2SO4 was similar to 34 nm. Batch adsorption studies showed that the maximum percentage of Pb (II) ions was eliminated at pH 5, contact time of 60 min, adsorbate concentration of 60 mg/L, and adsorbent dosage of 0.04 g. The analysis of Langmuir and Freundlich's isotherms implied that the Freundlich model provided the maximum fit for the adsorption of Pb (II) ions. From a kinetic perspective, the pseudo-second-order kinetics was most suitable to explain the adsorption process rather than pseudo-first-order kinetics, which was also confirmed by the error function analyses. Overall, the present study concluded that the newly synthesized ZnO/K2SO4 nanosorbents could be used as a promising material for the sequestration of Pb (II) ions.