Carbon nanotubes, graphene, and their derivatives for heavy metal removal

Carbon nanoadsorbents have attracted tremendous interest for metal ion removal from wastewater due to their extraordinary aspect ratios, surface areas, porosities, and reactivities. However, challenges still exist as they suffer from subpar dispersion and recovery, tending to aggregate, and so on. Thus, significant research efforts focus on modification of these carbon nanomaterials to increase the dispersions and recoveries, while maintaining or even enhancing the desirable properties. This review aims to give an in-depth look at recent and impactful advances in metal ion adsorption applications involving these modified carbon nanostructures. Here, the advanced design and testing of modified carbon nanostructures for metal ion removal are emphasized with comprehensive examples, and various adsorption behaviors and mechanisms are discussed, which are hoped to help the development of more effective adsorbents for water treatment.