Adsorption of tetracycline antibiotics from aqueous solutions on nanocomposite multi-walled carbon nanotube functionalized MIL-53(Fe) as new adsorbent.

Adsorption of tetracycline antibiotics from aqueous solutions by a multi-walled carbon nanotube (MWCNT) loaded iron metal-organic framework (MIL-53(Fe)) composite was studied. The adsorbent was characterized by environmental scanning electron microscope, energy dispersive X-ray spectroscopy, brunauer-emmett-teller, thermogravimetric analysis, X-ray diffraction, fourier transform infrared spectrum, and X-ray photoelectron spectrum. The adsorption kinetics of tetracycline hydrochloride (TCN), oxytetracycline hydrochloride (OTC), and chlortetracycline hydrochloride (CTC) were all well fitted to the pseudo-second-order equation as well as the adsorption isotherms could be well delineated via Langmuir equations. The main influencing factors such as pH and ionic strength were studied in detail. At initial pH of 7.0, maximum adsorption capacity of TCN, OTC and CTC on MWCNT/MIL-53(Fe) was 364.37, 325.59, 180.68 mg·g-1 at 25 °C, which was 1.25, 8.28 and 3.34 times than that of single MWCNT, respectively. The adsorption capacity of TCS for this adsorbent was in the order: TCN > OTC > CTC, which was determined by the adsorbate molecule magnitude. In addition, π-π adsorbate-adsorbent interactions played an important role during the adsorption process. The excellent reusability and great water stability indicated the potential application of this novel composite in the removal of TCS from aqueous solutions.