Enhanced Sorption of Naphthalene onto a Modified Clay Adsorbent: Effect of Acid, Base and Salt Modifications of Clay on Sorption Kinetics

摘要

This paper examined the influence of acid, base and salt modifications of clay on its rates of naphthalene adsorption. The modifiers used include hydrochloric acid (HCl), citric acid, sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), sodium chloride (NaCl) and zinc chloride (ZnCl2). The results obtained showed that equilibrium adsorption of naphthalene from the bulk solution was attained at a faster rate using modified clay when compared with the unmodified clay. HCl-modified clay had the highest rate of adsorption with a surface area and porosity of 49.05 mm2 and 53.4%. This was closely followed by NaOH-modified clay while down the order was the ZnCl2-modified clay which had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4%. The implication of the retention time obtained from the equilibrium study is significant as it provides the bench mark for interplay between sorption and degradation for transport and transformation of contaminant solutes within the soil matrix.