Enhanced copper-adsorption removal from water by easy-handling silica aerogel-polyurethane foam composites

Abstract

Safe water supply has become one of the main concerns of our society due to the intense industrial activities generating hazardous waste. Among the water pollutants, copper ions are known for potential diseases caused by accumulation of this metal. Therefore, different adsorbents have been produced for this purpose, highlighting aerogels for their effective adsorption owing to their high surface areas and porosity. Herein the synthesis of a novel silica aerogel-based composite for copper removal is described. It was produced by the sol–gel technique, synthesizing the silica aerogel into a reticulated-polyurethane foam that acted as a macrocellular skeleton, preventing a strong shrinkage of the aerogel during the ambient pressure drying. The produced aerogels and composites were characterized in terms of density, textural properties, hydrophobicity, and copper removal efficiency. Isotherm studies revealed a significantly improved adsorption capacity in comparison with the monolithic aerogel, reaching a maximum value of 46.13 mg g⁻¹. The predominant adsorption mechanism was Langmuir- Freundlich adsorption. The adsorption kinetics were also evaluated by different models, as well as the ability to function as filtration medium. Therefore, this work provides a promising strategy for copper uptake avoiding tedious filtration steps to separate the adsorbent, thus reducing time and costs.