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

Abstract

A novel, modified polypyrrole/m-phenylediamine (PPy-mPD) composite, decorated with magnetite (Fe 3 O 4 ) nanoparticles, and prepared via an in-situ oxidative polymerisation, was investigated. The PPy-mPD/Fe 3 O 4 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/Fe 3 O 4 nanocomposite was confirmed and investigated using various techniques. The presence of Fe 3 O 4 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/Fe 3 O 4 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/Fe 3 O 4 nanocomposite as a highly efficient adsorbent for the removal of heavy metal ions from industrial wastewater.

Inorganic nanoparticles for reduction of hexavalent chromium: Physicochemical aspects

“…It is urgent to develop various methodologies for elimination of Cr(VI) from water bodies. Various methodologies such as adsorption ( Ali and Gupta, 2006 ; Maponya et al, 2020 ), membrane filtration ( Kaya et al, 2016 ), solvent extraction ( Venkateswaran and Palanivelu, 2004 ), electrochemical precipitation ( Sun et al, 2015 ), coagulation ( Golbaz et al, 2014 ), bioremediation ( Beller et al, 2013 ; Benazir et al, 2010 ), ion exchange ( Xiao et al, 2016 ) and catalytic reduction ( Saikia et al, 2017 ) in addition to some traditional strategies ( Barrera-Díaz et al, 2012 ; Malaviya and Singh, 2011 ) based on reduction followed by precipitation have been employed for removal of Cr(VI) from aqueous medium. Although adsorption technology is an in-expensive and green methodology and does not involve formation of any side products.…”

Preparation of a Novel Polystyrene-Poly(hydroxamic Acid) Copolymer and Its Adsorption Properties for Rare Earth Metal Ions

“…The negative ∆ G values indicated that the adsorption was spontaneous. The positive ∆ S indicated there was a high affinity between rare earth ions and the resin [ 41 ]. The adsorption was an endothermic chemical adsorption.…”

Application of Nanotechnology in Analysis and Removal of Heavy Metals in Food and Water Resources

“…PPy-mPD/Fe 3 O 4 nanocomposite is a potential adsorbent for Cr(VI) removal due to its high adsorption capacity and selectivity. It is also a very low-cost super-adsorption material for heavy metal ions [ 167 ].…”