Incorporation of Zero-Valent Silver and Polyvinyl Acetate on the Surface Matrix of Carbon Nanotubes for the Adsorption of Mercury and Chromium from Industrial Wastewater

Abstract

Herein, zero-valent silver (Ag⁰) and polyvinyl acetate (PVAc) was ultrasonically incorporated into the surface matrix of MWCNTs to produce a multifunctional MWCNTs-Ag⁰/PVAc nanocomposite. The MWCNTs, MWCNTs-Ag⁰ and MWCNTs-Ag⁰/PVAc were characterized for the thermal stability, crystallographic structure and morphology using thermogravimetric analysis (TGA), X-ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). Industrial wastewater containing Hg(II) and Cr(VI) ions were treated using the fabricated MWCNTs-Ag⁰/PVAc at different adsorption parameters such as pH, adsorbent mass, adsorption time and temperature. The characterization result obtained indicated successful incorporation of the Ag⁰ and PVAc to the surface matrix of MWCNTs-Ag⁰/PVAc. The materials were thermally stable and the crystalline peaks/patterns of the incorporated materials were evident on the MWCNTs-Ag⁰/PVAc. The adsorption study revealed maximum adsorption capacity of 249 mg/g and 237 mg/g for the Hg(II) and Cr(VI) by MWCNTs-Ag⁰/PVAc at the pH (6 for Hg(II) and 3 for Cr(VI)), adsorbent mass (40 mg), adsorption time (60 min) and temperature (30 °C). The experimental data effectively fitted the Langmuir isotherm and pseudo-second order kinetic, respectively. Finally, MWCNTs-Ag⁰/PVAc showed remarkable performance as a suitable adsorbent for heavy metals removal from industrial wastewater.