Removal of lead from aqueous solution using superparamagnetic palygorskite nanocomposite: Material characterization and regeneration studies
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2017
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Rusmin, R.
Sarkar, B.
Tsuzuki, T.
Kawashima, N.
Naidu, R.
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Chemosphere, 2017; 186:1006-1015
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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-Na 2 ) (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 m 2 g −1 ) than the pristine palygorskite (49.4 m 2 g −1 ) and iron oxide (72.6 m 2 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 (R 2 = 0.9995) and pseudo-second order kinetic model (R 2 = 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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Copyright 2017 Elsevier
Access Condition Notes: Post print will be available after 1 October 2019