Design of β-cyclodextrin modified TiO2 nanotubes for the adsorption of Cu(II): Isotherms and kinetics study

This paper builds on previous literature showing the interesting adsorptive properties of TiO2 nanotubes. It further explores the positive effect of beta-cyclodextrin on these properties. Hence, beta-cyclodextrin modified TiO2 nanotubes were successfully prepared and characterized by XRD, N-2 physisorption at 77 K, Raman, FTIR-ATR, H-1 NMR, TEM and EPR. The adsorptive interaction of Cu(II) with materials was investigated in aqueous solution at pH 9.25 (NH4+/NH3). The main conclusion is that copper(II)-ammonia complexation equilibria play an important role in the adsorption process. The beta-cyclodextrin was found to improve the Cu(NH3)(4)(2+)-adsorption mainly by retarding its precipitation to high concentrations values (>400 mg L-1). Adsorption experimental data showed good fit with the pseudo-second-order model and the Langmuir isotherm model. (C) 2017 Elsevier Inc. All rights reserved.