Sustainable Removal of Cadmium and Chromium from Petroleum Wastewater Using Coconut Husk-Derived Activated Carbon

• Abraham T. OTAYOKHA

  Author

• Elizabeth J. ETERIGHO

  Author

• Moses T. LANGKUK

  Author

• Gift OKHIAI

  Author

• Francis EZEBOR

  Author

Toxic heavy metals in petroleum wastewater pose serious environmental and health risks due to their persistence and bioaccumulation. This study examined the adsorption of cadmium (Cd) and chromium (Cr) using coconut husk-derived activated carbon. Batch experiments assessed the effects of pH, contact time, adsorbent dosage, initial concentration, and temperature on removal efficiency. Equilibrium data were analyzed using the Langmuir and Freundlich models, while adsorption kinetics were evaluated using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models. Thermodynamic parameters were determined via Van’t Hoff analysis. Results showed near-complete removal of Cd (≈99.8–100%) and Cr (≈98.6–99.0%) under optimal conditions. The Langmuir model provided the best fit (R² = 0.99999), confirming monolayer adsorption with maximum capacities of 100.80 mg/g for Cd and 10.05 mg/g for Cr. Kinetic analysis identified pseudo-second-order chemisorption as the dominant mechanism, with intraparticle diffusion contributing due to microporosity. Thermodynamic evaluation revealed endothermic Cr adsorption and negative Gibbs free-energy values for both metals, confirming spontaneity. Generally, coconut husk activated carbon demonstrates high efficiency and sustainability, with adsorption behavior strongly supported by physicochemical characterization, and shows strong potential for industrial-scale petroleum wastewater treatment.

• 68_Otayokha et al. (2026)

Copyright (c) 2026 Abraham T. OTAYOKHA, Elizabeth J. ETERIGHO, Moses T. LANGKUK, Gift OKHIAI, Francis EZEBOR (Author)

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.