Abstract
A new adsorbent material from sewage sludge of relatively high surface area (2,230 m2/g) was prepared by carbonization and chemical activation using steam at controlled semi-static conditions. The pore size distributions of the sludge-based activated adsorbent (SW-A2) and commercial activated carbon were compared and found to be remarkably different with noticeable presence of larger micro-pores and small meso-pores for SW-A2. The newly developed activated adsorbent was then evaluated for the adsorption of a polycyclic aromatic hydrocarbon (PAH); benzo (a) anthracene. The adsorption isotherms of benzo (a) anthracene on the adsorbent materials were fitted to both Lang-muir and Freundlich isotherms. The Langmuir isotherm was found to be the best fit for the adsorption of the benzo (a) anthracene on AC with K and qmax of 0.43L/mg and 70.5 mg/g, respectively. On the other hand, the adsorption isotherm for SW-A2 was found to follow the Freundlich isotherm with Kf and n of 100.8 mg/g (L/mol) –0.763 and 1.31, respectively. The adsorption kinetics for both adsorbents were found to follow pseudo second order kinetics with rate constant of 1.55 × 10–4 g mg–1 min–1 for SW-A2 and 1.44 × 10–4 g mg–1 min–1 for AC. The results of this study indicate the high potential of the newly developed sludge-based adsorbent as an efficient and successful material for the removal of carcinogenic PAHs from water body.
