Removal of Copper and Lead using Banana Biochar in Batch Adsorption Systems: Isotherms and Kinetic Studies

Abstract

This study involved investigating the adsorption potential of biochar prepared from banana peel for the removal of copper ( $$\hbox {Cu}^{2+})$$ and lead ( $$\hbox {Pb}^{2+})$$ . Process parameters for batch adsorption including contact time, pH, adsorbent dose, and initial metal concentrations were optimized. The time at which the equilibrium adsorption was attained was recoded as 30 min with a higher removal efficiency of $$\hbox {Pb}^{2+}$$ when compared to $$\hbox {Cu}^{2+}$$ . Optimum removal was observed at a pH of approximately 5.5 and 9 for $$\hbox {Cu}^{2+}$$ and $$\hbox {Pb}^{2+}$$ , respectively. A linear increase in metal removal efficiency was achieved with increases in the adsorbent dose from 0.2 to 1.4 g. The latter was estimated as the optimum adsorbent dose. A 50–70% decrease in removal efficiency was observed when the initial $$\hbox {Cu}^{2+}$$ and $$\hbox {Pb}^{2+}$$ concentrations were increased from 50 to 300 mg $$\hbox {L}^{-1}$$ and from 200 to 1000 mg $$\hbox {L}^{-1}$$ , respectively. Among the isotherm models, the Freundlich model agreed best with the experimental data for $$\hbox {Pb}^{2+}$$ while the Langmuir model exhibited a better ability to describe the adsorption of $$\hbox {Cu}^{2+}$$ with each model providing the highest respective coefficient of determination. A pseudo-second-order kinetic model better described the kinetic behavior of both metal ions on the investigated adsorbent, namely banana biochar.