Adsorption of fluoride from water by surface-functionalized polyurethane foam

Abstract

Surface-functionalized polyurethane foam (SPUF) showed an exceptionally high adsorption potential for defluoridation of drinking water. Kinetic experiments of fluoride adsorption on SPUF demonstrated quick adsorption in first 60 min and then achieved maximum adsorption (7.8 mg g−1). The adsorption isotherm was described using Bradley equation. The adsorption capacity of SPUF was significantly influenced by the pH of the solution. The highest adsorption capacity was attained at pH 6.7 and no drastic reduction noticed in the adsorption capacity of SPUF at normal pH range (5.8–8.2). The fluoride adsorption capacity of SPUF was compared with other adsorbents like activated carbon, soil, alumina and carbon nanotubes. The added advantage of SPUF adsorbent is, it can be easily recharged by altering the pH of the solution using NaOH or Ca(OH)2. The high adsorption capacity and easy-to-use nature of SPUF in batch mode and continuous system makes the new adsorbent a promising material for defluoridation of drinking water.