3D Sponge-Like Structures of Carbon Nanotubes for Heavy Metal Adsorption

Herein, we investigate the synthesis and properties of carbon-based 3D frameworks aimed at their application to Cd2+ and Pb2+ removal from the water environment. The production of 3D sponge-like structures of nonfunctionalized carbon nanotubes (CNTs) by chemical vapor deposition is described, with the morphological and functional properties. After only a mild treatment in ethanol, their adsorption capabilities toward heavy metals were studied using reference analytical methods to disclose insights into the correlation between the structure and the adsorption efficiency. Moreover, a 3D-printed portable and easy-to-use system was designed to apply the CNT sponges to heavy metal removal in water, obtaining adsorption percentages of 15–48% for Cd2+ and 45–82% for Pb2+ in tap water. Compared with other carbon-based adsorbents, our strategy is competitive in removal efficiency while avoiding complex treatments, demonstrating an inspiring strategy for promoting effective actions in water remediation.