Waste plastic filter modified with polyaniline and polypyrrole nanoparticles for hexavalent chromium removal

Mehran Janmohammadi; Majid Baghdadi; Tanveer M Adyel; Naser Mehrdadi

doi:10.1016/j.scitotenv.2020.141850

Waste plastic filter modified with polyaniline and polypyrrole nanoparticles for hexavalent chromium removal

Sci Total Environ. 2021 Jan 15:752:141850. doi: 10.1016/j.scitotenv.2020.141850. Epub 2020 Aug 21.

Authors

Mehran Janmohammadi¹, Majid Baghdadi², Tanveer M Adyel³, Naser Mehrdadi¹

Affiliations

¹ School of Environment, College of Engineering, University of Tehran, Tehran, Iran.
² School of Environment, College of Engineering, University of Tehran, Tehran, Iran. Electronic address: m.baghdadi@ut.ac.ir.
³ Department of Civil Engineering, Monash University, 23 College Walk, Clayton, VIC 3800, Australia.

PMID: 32889277
DOI: 10.1016/j.scitotenv.2020.141850

Abstract

Chromium (Cr) is a toxic heavy metal for environmental compartments and human health. In this study, waste polypropylene hollow filters (PPF) with an optimal pore size of 5 μm were amino-functionalized with an optimized amount of polyaniline (PANI) and polypyrrole (PPy) as an adsorbent for removing Cr (VI). The adsorbent was characterized by scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and the Brunauer-Emmett-Teller method, showing the successful polymerization of co-polymer on the surface of PPF and increasing the surface area up to 15.08 m² g^-1. A Box-Behnken design was applied by a quadratic model with 99.15% accuracy, revealing a significant impact of the initial concentration of Cr (VI) on the removal efficiency. Dynamic adsorption was conducted in a continuous and semi-continuous system with over 99% removal efficiency for various initial concentrations of Cr(VI). The fitted data showed that the adsorption process followed the pseudo-second-order kinetics and Langmuir isotherm models at the optimum pH of 2 with the predicted maximum adsorption capacity of 510.9 mg g^-1 of PANI+PPy, which was significantly higher than some reported adsorbents. The effect of coexisting cations (Cu²⁺, Ni²⁺, and Zn²⁺) and anions (SO₄^2-, Cl^- and NO₃^-) on the removal efficiency revealed selective adsorption of Cr(VI) by the adsorbent. The produced adsorbent was capable of removing 76.6% of Cr(VI) from real electroplating wastewater. Regeneration of the adsorbent was performed by NaOH 1 mol L^-1 up to three cycles with a 20% reduction in adsorption performance. All data showed that PPF@PANI+PPy was a promising adsorbent for Cr(VI) removal from aqueous solutions and real-world wastewater.

Keywords: Hexavalent chromium; Polyaniline; Polypropylene; Polypyrrole; Waste plastic.