Sorption of Pb(II), Cd(II), and Zn(II) ions from aqueous solution using Thaumatococcus danielli leaves: kinetic, isotherm, and thermodynamic studies

The toxicity of Pb2+, Cd2+, and Zn2+ ions in an aqueous solution cannot be over-emphasized. Therefore, it is essential to treat industrial wastewater containing these heavy metals before being discharged into the environment. In this study, we evaluated the sorption of Pb2+, Cd2+, and Zn2+ metal ions onto Thaumatococcus danielli. We studied the effects of different influential parameters such as contact time, pH, metal ion concentrations, and temperature. The batch sorption study revealed that the sorption process is pH dependent, with optimum pH obtained at 4.0 for Pb2+ and Cd2+ and 5.0 for Zn2+, respectively. The sorption equilibrium and kinetic rates studied revealed that the adsorption data best fit Freundlich isotherm and pseudo-second-order models, respectively. The qmax values obtained are 95.215, 77.482 and 84.090 mg/g for Pb2+, Zn2+ and Cd2+, respectively. Thermodynamics analyses indicate that the metal ions sorption on Thaumatococcus danielli is feasible, spontaneous, and endothermic. The enthalpy values are 61.42, 42.17, and 41.34 kJ/mol for Pb2+, Cd2+ and Zn2+, respectively. Fourier-transform infrared analysis showed ionizable functional groups such as –OH, C=C, C≡C, C=O, C–O, and C–H, which could involve the metal binding. The results indicated that Thaumatococcus danielli could be a prospective sorbent for the sorption of Pb2+, Cd2+, and Zn2+ from polluted aqueous solution.