Comparative biosorption of cu(II) and pb(II) ions from aqueous solutions using soursop (Annona muricata L) leaf powder: characterisation, isotherm and kinetic studies

Heavy metals are a major contaminant as they originate from natural and anthropogenic activities. Extremely high levels of Cu(II) and Pb(II) ions in drinking water are harmful to the aquatic environment and human health. This work assessed the biosorption potential of Annona muricata L. leaf (AML) powder for Cu(II) and Pb(II) ions in the batch method. The Fourier-transform infrared (FTIR) spectrophotometer, pHslurry, and pH of point-zero-charge (pHPZC) analyses were carried out to characterise the functional groups in AML. The biosorption of the investigated heavy metal ions was examined as a function of biosorption time, AML dose, pH, and initial Cu(II) ion concentrations. AML showed good selectivity and biosorption capacity towards Pb(II) ions relative to Cu(II) ions. Biosorption kinetics and isotherms could be described by the pseudo-second-order and Langmuir models, respectively. The determined monolayer biosorption capabilities for Cu(II) and Pb(II) ions were 0.460 mmol/g (29.23 mg/g) and 0.911 mmol/g (188.76 mg/g), respectively. Based on these results, AML shows potential as a unique biosorbent for reducing Cu(II) and Pb(II) ions from aqueous solutions.