Removal of lead from aqueous solution using superparamagnetic palygorskite nanocomposite: Material characterization and regeneration studies

Rusmin R 1 , Sarkar B 2 , Tsuzuki T 3 , Kawashima N 4 , Naidu R 5

Affiliations 

  • 1 Future Industries Institute, University of South Australia, Building X, Mawson Lakes, SA 5095, Australia; Faculty of Applied Sciences, Universiti Teknologi MARA, 40450, Shah Alam, Selangor, Malaysia. Electronic address: ruhaida.rusmin@mymail.unisa.edu.au
  • 2 Future Industries Institute, University of South Australia, Building X, Mawson Lakes, SA 5095, Australia. Electronic address: Binoy.Sarkar@unisa.edu.au
  • 3 Research School of Engineering, College of Engineering and Computer Science, Australian National University, Acton, ACT 2601, Australia
  • 4 Future Industries Institute, University of South Australia, Building X, Mawson Lakes, SA 5095, Australia
  • 5 Global Centre for Environmental Remediation (GCER), The University of Newcastle, ATC Building, Callaghan, NSW 2308, Australia; CRC CARE - Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, P.O. Box 486, Salisbury, SA 5106, Australia. Electronic address: Ravi.Naidu@newcastle.edu.au
Chemosphere, 2017 Nov;186:1006-1015.
PMID: 28838038 DOI: 10.1016/j.chemosphere.2017.08.036

Abstract

A palygorskite-iron oxide nanocomposite (Pal-IO) was synthesized in situ by embedding magnetite into the palygorskite structure through co-precipitation method. The physico-chemical characteristics of Pal-IO and their pristine components were examined through various spectroscopic and micro-analytical techniques. Batch adsorption experiments were conducted to evaluate the performance of Pal-IO in removing Pb(II) from aqueous solution. The surface morphology, magnetic recyclability and adsorption efficiency of regenerated Pal-IO using desorbing agents HCl (Pal-IO-HCl) and ethylenediaminetetraacetic acid disodium salt (EDTA-Na2) (Pal-IO-EDTA) were compared. The nanocomposite showed a superparamagnetic property (magnetic susceptibility: 20.2 emu g-1) with higher specific surface area (99.8 m2 g-1) than the pristine palygorskite (49.4 m2 g-1) and iron oxide (72.6 m2 g-1). Pal-IO showed a maximum Pb(II) adsorption capacity of 26.6 mg g-1 (experimental condition: 5 g L-1 adsorbent loading, 150 agitations min-1, initial Pb(II) concentration from 20 to 500 mg L-1, at 25 °C) with easy separation of the spent adsorbent. The adsorption data best fitted to the Langmuir isotherm model (R2 = 0.9995) and pseudo-second order kinetic model (R2 = 0.9945). Pb(II) desorption using EDTA as the complexing agent produced no disaggregation of Pal-IO crystal bundles, and was able to preserve the composite's magnetic recyclability. Pal-IO-EDTA exhibited almost 64% removal capacity after three cycles of regeneration and preserved the nanocomposite's structural integrity and magnetic properties (15.6 emu g-1). The nanocomposite holds advantages as a sustainable material (easily separable and recyclable) for potential application in purifying heavy metal contaminated wastewaters.

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