Adsorption of Cu(II) in aqueous solution using microwave-assisted titanate nanotubes

Abstract

This study aims to investigate the adsorption behavior and mechanism of Cu(II) over microwave-assisted titanate nanotubes (MTNTs, NaxH2−xTi3O7). The effect of power level of microwave irradiation during MTNT synthesis on the adsorption mechanism is also examined. Regarding the adsorption potential of Cu(II) over MTNTs, more than 80% of Cu(II) is removed within the first minute, and the adsorption equilibrium is reached by half an hour. The adsorption capacities of MTNTs obtained from Langmuir model fall in the range of 1.86–2.46 mmol g−1. According to the characterizations including ICP–AES, XRD, FT–IR/DRIFT, XPS, and H2-TPR, the amount and binding intensity of intercalated Na+ within MTNTs, which are greatly dependent upon the power level of microwave irradiation during MTNT synthesis, dominate the adsorption kinetics, the adsorption capability, the adsorption stabilization, and the extent of copper complexation. An adsorption mechanism is also proposed such that ion exchange process and complexation reaction are both involved in the Cu(II) adsorption over MTNTs.