Comparative Biosorption of Cu(II) and Pb(II) Ions from Aqueous Solutions using Soursop (Annona muricata L) Leaf Powder: Characterisation, Isotherm and Kinetic Studies

Abstract

Heavy metals are a major contaminant as they originate from natural and anthropogenic activities. High concentrations of Cu(II) and Pb(II) ions in drinking water cause serious harm to aqueous systems and human health. This work assessed the adsorption potential of Annona muricata L. leaf (AML) powder for Cu(II) and Pb(II) ions. The Fourier-transform infrared (FTIR) spectrophotometer, pH of point-zero-charge (pH_PZC), and pH_slurry analyses were carried out to characterise the functional groups in AML. Experimental conditions such as contact time, AML dosage, pH, and initial Cu(II) ion concentrations, all of which could affect Cu(II) and Pb(II) ions adsorption, were investigated. AML showed good selectivity and adsorption capacity towards Pb(II) ions compared to Cu(II) ions. The adsorption kinetic and isotherm were successfully described by the pseudo-second-order and Langmuir models. The maximum monolayer adsorption capacities for Cu(II) ions and Pb(II) ions were 0.460 mmol/g (29.23 mg/g) and 0.911 mmol/g (187.76 mg/g), respectively. This work indicated that AML is a promising alternative adsorbent for removing Cu(II) and Pb(II) ions from aqueous solutions