Polypyrrole Coating via Lemieux-von Rudloff Oxidation on Magnetite Nanoparticles for Highly Efficient Removal of Chromium(VI) from Wastewater

Md Kawsar Hossain; Md Mehadi Hasan; Md Shahidul Islam; O Thompson Mefford; Hasan Ahmad; Md Mahbubor Rahman

doi:10.1021/acsomega.3c09864

Polypyrrole Coating via Lemieux-von Rudloff Oxidation on Magnetite Nanoparticles for Highly Efficient Removal of Chromium(VI) from Wastewater

ACS Omega. 2024 Apr 22;9(17):19077-19088. doi: 10.1021/acsomega.3c09864. eCollection 2024 Apr 30.

Authors

Md Kawsar Hossain¹, Md Mehadi Hasan², Md Shahidul Islam², O Thompson Mefford³, Hasan Ahmad², Md Mahbubor Rahman^{2

3}

Affiliations

¹ Department of Chemistry, Pabna University of Science and Technology, Pabna 6600, Bangladesh.
² Polymer Colloids & Nanomaterials Group, Department of Chemistry, Faculty of Science, University of Rajshahi, Rajshahi 6205, Bangladesh.
³ Department of Materials Science & Engineering, Clemson University, Clemson, South Carolina 29634-0971, United States.

Abstract

An alternative way for the coating of polypyrrole (PPy) polymer on hydrophobic magnetite (Fe₃O₄) nanoparticles is reported here to capture toxic chromium ions, Cr (VI), present in water. Iron oxide magnetic nanoparticles (Fe₃O₄) were synthesized by the conventional coprecipitation technique using FeCl₃·6H₂O and FeSO₄·7H₂O iron precursors and subsequently modified with oleic acid (OA). Then OA-Fe₃O₄ hydrophobic nanoparticles were oxidized using the Lemieux-von Rudloff reaction to transfer OA into hydrophilic azelaic acid (AA) (HOOC(CH₂)₇COOH-modified magnetic nanoparticles (AA-Fe₃O₄). Finally, a PPy polymer coating was formed by a seeded polymerization of pyrrole, using AA-Fe₃O₄ as seeds. The average size of PPy/Fe₃O₄ nanocomposites is 12.33 nm and is almost spherical in shape. The surface composition is confirmed by FTIR and thermogravimetry analyses. An X-ray diffraction study confirmed the formation of highly crystalline Fe₃O₄ nanoparticles, and the crystallinity was retained after the surface modification. The adsorption study suggested that the Cr(VI) ion adsorption is highly pH-dependent and the maximum amount of adsorption is obtained at pH 2.0. The adsorption results revealed that the Langmuir model provided the best fit for the isotherm, with a maximum adsorption capacity reaching approximately 173.22 mg g^-1 at 323 K. Spontaneous and endothermic adsorption processes were confirmed by evaluating the thermodynamic parameters obtained in this investigation. The kinetics study showed that the interaction between Cr(VI) ions and magnetic nanocomposites was directed by a pseudo-second-order rate process indicating chemisorption. The prepared PPy/Fe₃O₄ nanocomposites would be promising adsorbents to purify water by eliminating Cr(VI) metal ions from wastewater.