Enhanced adsorption capacity of ultralong hydrogen titanate nanobelts for antibiotics

Abstract

Limited by the relatively low adsorption capacity of inorganic nanomaterials for antibiotics , ultralong hydrogen titanate nanobelts (UHTNs) with a hollow structure and high surface area (442.21 m² g⁻¹) were synthesized to evaluate the feasibility as a potential adsorbent material for antibiotic removal. A batch of adsorption experiments were conducted by using norfloxacin (NFO), tetracycline (TC) and ofloxacin (OFO) as the model antibiotic molecules. The results indicate that the adsorption of antibiotics on UHTNs is better fitted to the pseudo-second-order kinetic model, and the UHTNs' maximum adsorption capacities calculated from the Langmuir isotherm model were 151.51 mg g⁻¹ for TC, 111.73 mg g⁻¹ for NFO, and 148.14 mg g⁻¹ for OFO at pH = 7, which are far better than those of most reported inorganic adsorbent materials. In the adsorption process of tetracycline, the surface complexation between the adsorbent and TC contributed most to the adsorption; this has been elucidated by Fourier Transform Infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). In addition, because the UHTNs are up to tens of micrometers in length, they can be easily aggregated to form a network. Therefore, a novel paper-like, free-standing UHTN membrane was fabricated via a simple vacuum filtration method, which also exhibits good adsorption capacity.