Synthesis of flower-shaped ZrO2–C composites for adsorptive removal of trichlorophenol from aqueous solution

Abstract

In the current study, examples of a novel kind of nanoflake zirconia–carbon (ZrO₂–C) composite were synthesized through a simple method by using gallic acid and ZrCl₄ as precursors. The as-synthesized ZrO₂–C composites were observed to have high specific surface areas and a chrysanthemum-like structure. High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, X-ray diffraction, and Raman analyses revealed that the ZrO₂–C composites were composed of graphitized carbon and numerous ZrO₂ nanoparticles (3–4 nm in diameter). The ZrO₂–C composites were successfully used as adsorption materials to remove 2,4,6-trichlorophenol (TCP) from simulated water samples. The results showed that ZrO₂–C exhibited a much higher adsorption capacity for TCP than did some reported carbon materials. The hydrophobic interaction and/or π–π stacking interaction between TCP and the carbon phase, hydrogen bonding with functional groups of ZrO₂–C, and metal–anion binding with ZrO₂ nanoparticles contributed to the high adsorption ability. Generally, TCP uptake was favorable in an acidic environment and increased as the initial TCP concentration and temperature were increased. The adsorption process obeyed pseudo-second-order kinetics, and the adsorption isotherms could be well described by the Freundlich equation.