Optimisation, kinetic and thermodynamic studies on the removal of copper and lead ions from aqueous solution using functionalised Persea Americana activated carbon biosorbent

Abstract

Background

Adsorption is currently one of the promising technologies widely used in the clean-up of heavy metal ions in the aquatic environment due to its affordability, ease of use, and efficiency. The study investigated the efficacy of activated and functionalised carbon prepared from the stem bark of Persea Americana (C-PA) using ethylenediaminetetraacetic acid (EDTA), to obtain M-PA.

Methods

Both biosorbents were characterized using Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The suitability of biosorbents for the clean-up of Cu²⁺ and Pb²⁺ contaminated aqueous solutions was investigated under various experimental conditions.

Results

The maximal percentage uptake by C-PA was 98.56% for Cu²⁺ and 67.78% for Pb²⁺, observed at optimal conditions of duration of 30 min contact time, pH of 5, temperature of 70 °C, dosage of 0.6 g, and initial metal concentrations of 30 mg/L (Cu²⁺) and 40 mg/L (Pb²⁺). Biosorption kinetic model for Cu²⁺ followed both pseudo-first order and intra-particle diffusion, while Pb²⁺ followed the pseudo-second order. Experimental data for both metal ions best fitted the Langmuir isotherm model. Studies conducted using M-PA under the above set optimal conditions enhanced the percentage uptake of Cu²⁺ (99.08%) and Pb²⁺ (99.60%).

Conclusion

Overall, both C-PA and M-PA showed remarkable potential as biosorbents for Cu²⁺ and Pb²⁺ clean-up in aqueous solutions.