Interfacial growth of metal–organic framework on carboxyl-functionalized carbon nanotubes for efficient dye adsorption and separation

Abstract

Hybrid nanocomposites based on UiO-66-NH₂ and carboxyl-functionalized carbon nanotubes were developed in this study via different synthetic pathways. Combining them through interfacial in situ growth was beneficial for the better dispersity of UiO-66-NH₂ in the CNTs@UiO-66-NH₂ composite than physically mixing CNTs/UiO-66-NH₂ and chemically bonded CNTs-CONH-UiO-66. Coordination between carboxyl groups of CNTs and zirconium ions resulted in the interfacial growth of UiO-66-NH₂ on CNTs. Adsorption experiments showed that CNTs@UiO-66-NH₂ exhibited the highest adsorption efficiency towards methyl orange (MO). The adsorption capacity of CNTs@UiO-66-NH₂ was up to 392 mg g^-1, which was 77.45% and 201.5% higher than those of CNTs-CONH-UiO-66 and CNTs/UiO-66-NH₂ respectively. Moreover, CNTs@UiO-66-NH₂ could selectively adsorb MO from the MO/MB mixture.