Lead Ions Removal From Water Using Alkali-Modified Solanum marginatum Leaf/Graphene Oxide Composite

Abstract

Lead (Pb) ions, frequently found in industrial and agricultural wastewater, are highly concerning pollutants. Removal provides an effective and cost-efficient solution for removing Pb(II) ions from wastewater, even at low concentrations. In this study, alkali-modified Solanum marginatum leaves (AM-SML) and its composite with graphene oxide (AM-SML/GO) have been synthesized and tested as a potential biomaterial for the removal of Pb(II) ions from wastewater. The composite was characterized using Fourier transform infrared (FTIR) and x-ray diffractometer (XRD). The adsorption characteristics of SML, AM-SML, and AM-SML/GO for Pb(II) were thoroughly assessed through batch adsorption, isotherm models, kinetics, and thermodynamic studies. Key parameters, such as pH, adsorbent dosage, initial concentration, and contact time, were optimized to maximize adsorption capacity and removal efficiency. AM-SML/GO revealed a maximum adsorption capacity of 334.62 mg/g and a removal efficiency of 99.8%. The Langmuir isotherm model showed a better fit with the experimental data compared to the Freundlich model. Kinetic studies showed that the adsorption process primarily followed the pseudo-second-order model, with a high correlation coefficient (R2 = 0.999), surpassing the pseudo-first-order model. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) confirmed that Pb(II) adsorption was spontaneous and endothermic. AM-SML/GO composite adsorbent with low cost, high efficiency, and minimal secondary waste is a promising candidate for mitigating environmental pollution.