Fabrication of Seashell-Incorporated Polyurethane for Sustainable Remediation of Fe(II)-Contaminated Acidic Wastewater

In this study, seashell-incorporated polyurethane (SPU) was synthesized for sustainable remediation of Fe(II)-contaminated acidic wastewater. Several batch and column experiments were conducted to find optimal seashell/PU ratio, particle size, bed volume and retention time. Seashell/PU ratio of 20 wt%, with high chemical stability, was found to be the optimum proportion with maximum Fe(II) removal capacity of 277.1 mg-Fe(II)/g-seashell. The primary removal mechanisms were adsorption and precipitation as ferric hydroxide and ferric carbonate. Crushed seashell with the particle diameter of 0.13 mm ≤ Ø < 0.15 mm posed the highest Fe(II) removal capacity. SPU, with the enhanced hydro-conductivity of the crushed seashell, showed consistent Fe(II) removal capacity (237.5 mg-Fe(II)/g-seashell) in both batch and column experiments. Large bed volumes increased Fe(II) removal efficiency, but the increment was not directly proportional to the removal efficiency. The breakthrough curve was also found to fit well to Yoon–Nelson Kinetic model and Thomas kinetic model with the determination coefficient of 0.867–0.987. In overall, SPU can be considered as a sustainable alternative for a low-cost absorbent for heavy metal contaminated acidic wastewater.