Synthesis, electron microscopy properties and adsorption studies of Zinc (II) ions (Zn2+) onto as-prepared Carbon Nanotubes (CNTs) using Box-Behnken Design (BBD)

Abstract

The high levels of zinc (II) ions (Zn2+) have long been harmful to the environment and this study explored the feasibility of adsorption of Zn2+ on as-prepared carbon nanotubes (CNTs) from simulated aqueous solutions in batch-model process. The as-prepared CNT using chemical vapor deposition (CVD) technique was systematically characterized using electron microscopy techniques. Effects of adsorption parameters were modeled using Box-Behnken design (BBD) of experiment and 99.50% Zn2+ ions removal was achieved at adsorbent dosage, 50 mg; pH, 6.0; contact time, 60 min and contact speed, 125 rpm. The Langmuir, Freundlich and Temkim adsorption isotherms were used to verify the as-prepared CNTs adsorption performance. It was found that the adsorption data were well fitted to the Langmuir model. Moreover, the kinetic studies revealed that the adsorption kinetic data follows a pseudo-second-order model. The results indicate high prospect of the as-prepared CNTs for Zn2+ ion removal. Keywords: Carbon nanotubes, Characterization, Batch adsorption, Box-Behnken design, Adsorption isotherms, Kinetic study