Adsorption of naphthalene onto activated carbons derived from milk bush kernel shell and flamboyant pod

Abstract

The suitability and the performance of activated carbon produced from flamboyant pod (FB) and milk bush kernel shell (MB) for the effective removal of naphthalene from simulated wastewater was conducted to determine the influence of increasing initial concentrations (50 – 150 mg/L) on adsorption. The activated carbon obtained from milk bush kernel shell (25 – 40%, w/w) decreased with increased carbonization temperature (300 - 600°C) while those obtained from flamboyant pod was 15 - 20%, w/w. The removal efficiencies of FB produced at 300°C (FB300) increased from 51.49 - 53.28%, while removal efficiencies of FB produced at 500°C (FB500) and 600°C (FB600) decreased from 55.51 - 54.42% and 59.71 - 58.56%, respectively, as the initial concentrations of naphthalene increased. The removal efficiencies of MB were relatively lower than those obtained from FB and decreased from 48.18 - 43.65%, 53.55 - 50.37% and 56.41 - 52.53% for adsorbent produced at 300°C (MB300), 500°C (MB500) and 600°C (MB600), respectively, as the initial concentrations of naphthalene increased. The Freundlich exponent ‘n’ for the adsorption of naphthalene onto FB300, FB500, FB600, MB300, MB500 and MB600 were 0.94, 1.04, 1.05, 1.19, 1.13 and 1.16, respectively, and were within the range (1<n<10), except FB300. Similarly, the separation factor (RL) for the adsorption of naphthalene unto FB300, FB500, FB600, MB300, MB500 and MB600 were 1.27, 0.97, 0.85, 0.64, 0.70 and 0.65, respectively and satisfied the condition (0< RL <1), except FB300. This study suggests that effective adsorbent from the selected agricultural materials can be achieved at selected carbonization temperatures except 300°C for FB. Furthermore, the results indicate that these adsorbents may be more adsorptive at lower concentrations of naphthalene.