Abstract
In the present study, titanate nanotubes (denoted as TNTs) synthesized through a simple hydrothermal approach was applied for the decontamination of Zn(II) from aqueous solution. Batch experimental results showed that the removal kinetics process was fast and reached equilibrium after 60min. The sorption of Zn(II) on TNTs was strongly dependent on pH and ionic strength at pH<6.0, while independent of ionic strength at pH>6.0. Based on Langmuir model fit, the maximum sorption capacity of Zn(II) at pH5.5 and 293K was calculated to be 139.44mg/g, being higher than a series of currently reported adsorbents. TNTs also exhibited a favorable recycling performance for the removal of Zn(II). According to the desorption experiments, surface complexation modeling, X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) analysis, cation exchange and/or outer-sphere surface complexation were the predominant removal mechanisms of Zn(II) at lower pH, while inner-sphere surface complexation and/or precipitation were the main driving forces at higher pH. The experimental findings herein demonstrated the application potentiality of TNTs for the highly efficient treatment of Zn(II)-bearing wastewaters.
TNTs synthesized via a simple hydrothermal method can be used as a cost-effective and green adsorbent for the purification of Zn(II)-bearing effluents. [Display omitted]
•TNTs with unique tubular morphology was synthesized by hydrothermal method.•The sorption kinetics of Zn(II) on TNTs achieved equilibrium within 60min.•The maximum sorption capacity at 293K and pH5.5 was 139.44mg/g.•TNTs exhibited favorable recycling performance towards Zn(II) removal.•EXAFS analysis implied disparate removal mechanisms under different conditions.