Removal of Pb²⁺, Ni²⁺ and Cd²⁺ ions in aqueous media using functionalized MWCNT wrapped polypyrrole nanocomposite

Abstract

Functionalized multi-walled carbon nanotubes, a wrapped polypyrrole (PPy/o-MWCNT) nanocomposite, were prepared by in situ chemical oxidative polymerization. Characterization of the PPy/o-MWCNT nanocomposite was carried out using attenuated total reflectance infrared spectroscopy, Raman analysis, diffuse reflective ultraviolet–visible spectroscopy, powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), transmission electron microscope (TEM) and selective area electron diffraction pattern (SAED). The obtained results confirmed successful synthesis of PPy/o-MWCNT nanocomposite. TEM provided the information about the wrapped tubular carbon nanotubes present in the polymer matrix and SAED pattern additionally confirms the crystalline pattern of the metal-loaded adsorbent. SEM images showed the o-MWCNT even dispersion of polymer matrix beyond the magnification of 200–500. EDAX data revealed the loading of metal ions onto polymer surface which was confirmed due to the presence of corresponding. The PPy/o-MWCNT nanocomposite was used as an efficient adsorbent for the removal of Pb²⁺, Ni²⁺and Cd²⁺ions in aqueous media. Batch experiments show maximum adsorption capacity of PPy/o-MWCNT nanocomposite on Pb²⁺(408 mg/g), Ni²⁺(409 mg/g) and Cd²⁺(392 mg/g). The heavy metal ions adsorption on PPy/o-MWCNT nanocomposite shows fast process and the kinetics followed a pseudo-second-order rate equation (R² ≈ 0.99).

Keywords:

• MWCNT
• Polypyrrole nanocomposite
• Adsorption
• Pb²⁺, Ni²⁺ and Cd²⁺
• Kinetic and thermodynamic studies

Acknowledgements

The research upon which this paper is based was supported by a grant from DST-FIST, UGC New Delhi, Govt. of India is acknowledged for their assistance with experimental design and analysis. The authors would also like to acknowledge financial support from the Anna Centenary Research Fellowship, Anna University, Chennai, Government of Tamil Nadu, India.