Removal of Fe(II) from water using raw and calcinated weathered basalt: Influence of mineralogy and physical properties.

In this study, raw weathered basalt (RWB) and calcinated weathered basalt (CWB), both low-cost natural geological materials, were employed for the removal of Fe(II) from contaminated aqueous solutions and groundwater. CWB was prepared by calcining RWB at 900 °C for 3 h. Batch adsorption experiments were conducted, and the data fitted best with the Langmuir isotherm model. The adsorption kinetics followed the pseudo-second-order and intra-particle diffusion models. Although calcination improved the surface area and porosity, RWB exhibited higher Fe(II) removal efficiency, likely due to its richer mineralogical composition, particularly the clay content. The results suggest that modification by calcination does not necessarily enhance adsorption performance. The proposed mechanisms involve chemisorption, electrostatic attraction, cation exchange, surface complexation, and adsorption-oxidation. Additionally, RWB showed better performance than CWB in reducing Mn, Ca hardness, NH₃, NO₃-, NO₂-, and TDS during groundwater treatment. Therefore, RWB offers a more cost-effective and sustainable option for water purification without requiring energy-intensive modification.