Application of Coconut Shell Activated Carbon for the Adsorption of Toxic Heavy Metals from Wastewater

Copper and lead are poisonous, non-biodegradable heavy metals that persist in the environment and can cause severe health challenges in the human body. This study investigates the effectiveness of coconut shell activated carbon (CSAC) as an adsorbent for the removal of copper and lead ions from wastewater in a batch mode. The effects of varying operating parameters in the adsorption process namely, initial concentration (10–200 mg/L), pH (2–12), adsorbent dosage (1–5 g) and particle size (75–300 µm) using the central composite design (CCD). The adsorbent was characterised prior to and after adsorption to determine the functional groups, morphological structure and the elemental composition with the aid of Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analytical instruments respectively. The analysis of variance (ANOVA) indicated a strong coefficient of determination (R2) for Cu2+ and Pb2+, measuring 0.9761 and 0.9689, respectively. Adsorption of Pb2+ showed higher capacity and stronger affinity than Cu2⁺. Isotherm studies showed that the Langmuir, Temkin, and Dubinin–Radushkevich (D–R) models provided a strong fit for Pb2+ but were significantly less suitable for describing the Cu2+ adsorption data. while kinetics followed pseudo-second order, confirming chemisorption. This research aids in the application of commercial activated carbon derived from coconut shell for treating water contaminated with copper and lead metal ions.