Abstract
Two natural limestone samples, collected from the Campanian–Maastrichtian limestones, Tunisia, were used as adsorbents for the removal of toxic metals in aqueous systems. The results indicated that high removal efficiency could be achieved by the present natural limestones. Among the metal ions studied, Pb2+ was the most preferably removed cation because of its high affinity to calcite surface. In binary system, the presence of Cu2+ effectively depressed the sorption of Cd2+ and Zn2+. Similarly Cu2+ strongly competed with Pb2+ to limestone surface. In ternary system, the removal further decreased, but considerable amount of Pb2+ and Cu2+ still occurred regardless of the limestone sample. The same behavior was observed in quadruple system, where the selectivity sequence was Pb2+ > Cu2+ > Cd2+ > Zn2+. From these results, it was concluded that the studied limestones have the required technical specifications to be used for the removal of toxic metals from wastewaters.
Highlights
MethodsTwo limestone samples (S and Z) of the Campanian– Maastrichtian Abiod formation were collected from the outcroppings in the areas of Gafsa (southern Tunisia, Z samples) and Bizerte (northern Tunisia, S sample) where the geological particularities of the material allow its use in a wide range of industrial and environmental applications (Bouaziz et al 2007; Aloui and Chaabani 2007)
Numerous activities including metal plating, fertilizer industry, mining operations, metallurgy, battery manufacturing and textile dyeing generate a huge volume ofAppl Water Sci (2013) 3:29–39 and multi-element systems, (2) to determine the mechanisms involved in the removal processes, (3) to study the competitive sorption of Pb2?, Cd2?, Cu2? and Zn2? in single, binary, ternary and quadruple systems and (4) to discuss the feasibility of using natural limestones from Tunisia in wastewater cleanup
It showed that the limestone samples collected from the southern area (i.e., Z sample) was characterized by its high purity, while the northern S sample contained more than 16.856 % SiO2 and minor amounts of iron and aluminum oxides (Table 1)
Summary
Two limestone samples (S and Z) of the Campanian– Maastrichtian Abiod formation were collected from the outcroppings in the areas of Gafsa (southern Tunisia, Z samples) and Bizerte (northern Tunisia, S sample) where the geological particularities of the material allow its use in a wide range of industrial and environmental applications (Bouaziz et al 2007; Aloui and Chaabani 2007). The collected limestone blocks were crushed, sieved and a grain size of less than 210 lm was used for batch sorption. Working standards were prepared by the dilution of the stock solution (1,000 mg/L), prepared by dissolving proper amount of copper, cadmium, lead and zinc chloride in 100 mL of hydrochloric acid (0.1 mol/L). Solutions of 0.1 M HCl and 0.1 M NaOH were used for pH adjustment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
