Removal of iron and copper from aqueous solutions using Jordanian kaolin and zeolitic tuff

The goal of this paper is to investigate the removal of iron and copper from aqueous solutions using adsorption. Zeolitic tuff and kaolin were used as adsorbents and were collected from different areas in Jordan. Batch adsorption experiments using synthetic Fe3+ and Cu2+ solutions were employed to study the effects of adsorbent dose, initial concentration, particle size, pH, and temperature on metal uptake. Zeolitic tuff had higher Fe3+ and Cu2+ adsorption capacities (20.70 and 20.83mg/g, respectively) compared with kaolin (14.68 and 9.81mg/g, respectively). The optimum pH values for Fe3+ and Cu2+ removal on kaolin were found to be 4 and 6, respectively. For the initial metal concentration of 100ppm, 100% of Fe3+ and 62% of Cu2+ were adsorbed. As the temperature increased from 25 to 55 degrees C, the adsorption capacity of Fe3+ on kaolin increased, thereby indicating the endothermic nature of the process. At the highest investigated temperature of 55 degrees C, the Fe3+ removal using kaolin was 95.5%. The kinetic data obtained for Cu2+ removal confirmed the pseudo-second-order model. Fe3+ removal using zeolitic tuff was not affected by the particle size, while Cu2+ removal increased as the particle size decreased. This study suggests that zeolitic tuff and kaolin can be used as low-cost adsorbents for Fe3+ and Cu2+ removal with high efficiency. Kaolin was modified by pillaring with Al-13 polyoxycation and acid activation. The mineralogy of the kaolin, analyzed using X-ray diffraction, confirmed that its structure was not changed significantly due to Al-pillared activation. Both pillaring and acid activation decreased the adsorption capacity.