Multi-walled carbon nanotube/amino-functionalized MIL-53(Fe) composites: Remarkable adsorptive removal of antibiotics from aqueous solutions.

A novel adsorbent composite was synthesized by combining amino-functionalized MIL-53(Fe) with multi-walled carbon nanotubes (MWCNT), and used to adsorb tetracycline hydrochloride (TCN) and chlortetracycline hydrochloride (CTC). The maximum adsorption capacities of TCN and CTC over MWCNT/NH-MIL-53(Fe) at 25 °C were 368.49 and 254.04 mg g, which are, respectively, 1.79 and 8.37 times higher than that of chaff biochar. Interestingly, the mesoporosity of MWCNT/NH-MIL-53(Fe) significantly increased through introduction of MWCNT into NH-MIL-53(Fe), which proved to be favorable for the production of active adsorption sites. Besides, the remarkably increased adsorption capacity can be ascribed to the hydrogen bonding between amino functional groups on MWCNT/NH-MIL-53(Fe) and hydroxyl functional groups on TCN or CTC. Moreover, the π-π interaction between adsorbate and adsorbent was considered the main reason for the adsorption of TCN and CTC. The great adsorption capacity, as well as excellent reusability, demonstrated the potential application of MWCNT/NH-MIL-53(Fe) in the removal of TCN and CTC from aqueous solutions.