Cerium phosphate polypyrrole flower like nanocomposite: A recyclable adsorbent for removal of Cr(VI) by adsorption combined with in-situ chemical reduction

The present investigation aims to remove Cr(VI) by flower like Cerium Phosphate Polypyrrole nanocomposite material (CePO4-PPY). The material was synthesized by in situ oxidative polymerization method and characterized by FTIR, Raman, XRD, XPS, Zeta potential, N-2 adsorption-desorption isotherms, and TGA-DTA analysis. Field emission scanning electron microscopy and transmission electron microscopy images revealed the flower-like morphology of the synthesized nanocomposite. Meanwhile, the fabrication of polypyrrole on cerium phosphate nanoparticles provided a plentiful of active adsorption sites to interact with hexavalent chromium ions. The Cr(VI) adsorption followed the pseudo-second-order kinetic and Langmuir isotherm model showing a high adsorption capacity of 117.78 mg g(-1) at room temperature at lower pH. The high tolerance capacity of CePO4-PPY in the presence of other co-anions makes it a highly efficient adsorbent. The adsorption dynamic study demonstrated that the rate-determining step was controlled by surface diffusion, pore diffusion, and film diffusion. XPS spectra confirmed the simultaneous adsorption of Cr(VI) and in situ chemical reduction to Cr(III). Regeneration studies illustrated the efficiency of more than 80%, even after five cycles. Therefore, CePO4-PPY nanocomposite could be a unique alternative to act as a promising adsorbent for the effective treatment of Cr(VI) containing wastewater. (C) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

The CePO4-PPY nanocomposite with flower-like morphology was synthesized and characterized, showing a high adsorption capacity for Cr(VI) ions at lower pH. The material demonstrated efficient adsorption performance controlled by various diffusion processes, and confirmed the simultaneous adsorption and reduction of Cr(VI) to Cr(III) through XPS analysis. Regeneration studies showed a high efficiency of more than 80% even after five cycles, making CePO4-PPY a promising adsorbent for Cr(VI) removal in wastewater treatment.