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Open AccessArticle

Influence of Magnetic Nanoparticles on Modified Polypyrrole/m-Phenylediamine for Adsorption of Cr(VI) from Aqueous Solution

1
Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa
2
DST/CSIR Innovation Centre, National Centre for Nanostructured Materials, CSIR Material Science and Manufacturing, Pretoria 0001, South Africa
3
Chemistry Department, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho 2735, South Africa
4
Department of Environmental Sciences, College of Agriculture and Environmental Sciences, University of South Africa (UNISA), Florida Science Campus, Johannesburg 1710, South Africa
*
Authors to whom correspondence should be addressed.
Polymers 2020, 12(3), 679; https://doi.org/10.3390/polym12030679
Received: 21 January 2020 / Revised: 17 February 2020 / Accepted: 20 February 2020 / Published: 19 March 2020
(This article belongs to the Section Polymer Applications)
A novel, modified polypyrrole/m-phenylediamine (PPy–mPD) composite, decorated with magnetite (Fe3O4) nanoparticles, and prepared via an in-situ oxidative polymerisation, was investigated. The PPy–mPD/Fe3O4 nanocomposite was employed for the removal of highly toxic oxyanion hexavalent chromium Cr(VI) from an aqueous solution. The structure and successful formation of the PPy–mPD/Fe3O4 nanocomposite was confirmed and investigated using various techniques. The presence of Fe3O4 was confirmed by high resolution transmission electron microscopy, with an appearance of Fe lattice fringes. The estimation of the saturation magnetisation of the nanocomposite, using a vibrating sample magnetometer, was observed to be 6.6 emu/g. In batch adsorption experiments, PPy–mPD/Fe3O4 nanocomposite (25 mg) was able to remove 99.6% of 100 mg/L of Cr(VI) at pH 2 and 25 °C. Adsorption isotherms were investigated at different Cr(VI) concentration (100–600 mg/L) and temperature (15–45 °C). It was deduced that adsorption follows the Langmuir model, with a maximum adsorption capacity of 555.6 mg/g for Cr(VI) removal. Furthermore, isotherm data were used to calculate thermodynamic values for Gibbs free energy, enthalpy change and entropy change, which indicated that Cr(VI) adsorption was spontaneous and endothermic in nature. Adsorption–desorption experiments revealed that the nanocomposite was usable for two consecutive cycles with no significant loss of adsorption capacity. This research demonstrates the application potential for the fascinating properties of PPy–mPD/Fe3O4 nanocomposite as a highly efficient adsorbent for the removal of heavy metal ions from industrial wastewater. View Full-Text
Keywords: water pollution; m-phenylenediamine; magnetic polymer nanocomposite; kinetics; adsorption properties water pollution; m-phenylenediamine; magnetic polymer nanocomposite; kinetics; adsorption properties
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Maponya, T.C.; Ramohlola, K.E.; Kera, N.H.; Modibane, K.D.; Maity, A.; Katata-Seru, L.M.; Hato, M.J. Influence of Magnetic Nanoparticles on Modified Polypyrrole/m-Phenylediamine for Adsorption of Cr(VI) from Aqueous Solution. Polymers 2020, 12, 679.

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