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

Hybrid nanocomposites based on UiO-66-NH 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-NH in the CNTs@UiO-66-NH composite than physically mixing CNTs/UiO-66-NH and chemically bonded CNTs-CONH-UiO-66. Coordination between carboxyl groups of CNTs and zirconium ions resulted in the interfacial growth of UiO-66-NH on CNTs. Adsorption experiments showed that CNTs@UiO-66-NH exhibited the highest adsorption efficiency towards methyl orange (MO). The adsorption capacity of CNTs@UiO-66-NH was up to 392 mg g, which was 77.45% and 201.5% higher than those of CNTs-CONH-UiO-66 and CNTs/UiO-66-NH respectively. Moreover, CNTs@UiO-66-NH could selectively adsorb MO from the MO/MB mixture.