Potential of Exhausted Kahwa Coffee as Activated Carbon to Remove Cd2+ and Zn2+

Abstract

This study has examined the potential of exhausted kahwa coffee (EKC) as a precursor of activated carbon (AC) to remove the heavy metal ions, Cd2+ and Zn2+ from aqueous solution. The AC was activated by different activation methods using KOH, ZnCl2, H3PO4 and without activation agent. The EKC sample was impregnated with the chemical agents with the ratio of 1:1. Afterward, the carbonization was conducted at temperature of 400°C for 60 minutes. The removal efficiency (RE) and adsorption capacity (qt) of the ACs on Cd2+ and Zn2 were evaluated. In addition, ACs were characterized with fourier transforms infrared spectroscopy (FTIR) for the surface functional groups and scanning electron microscopy (SEM) for surface porosity morphology. The experimental results showed that highest RE and qt were obtained by EKC activated with KOH (EKC-KOH). The highest REs achieved were 96.96% for Cd2+ and 99.52 % for Zn2+, while the highests qt were 4.37 g/mg for Cd2+ and 3.79 g/mg for Zn2+. The results indicate that exhausted kahwa coffee has a potential as a low-cost activated carbon for removal of Cd2+ and Zn2+ ions from aqueous solution.