Int. J. Mol. Sci. 2013, 14(5), 9834-9847; doi:10.3390/ijms14059834
Article

Effective and Selective Recovery of Precious Metals by Thiourea Modified Magnetic Nanoparticles

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Received: 1 April 2013; in revised form: 26 April 2013 / Accepted: 3 May 2013 / Published: 8 May 2013
(This article belongs to the Special Issue Magnetic Nanoparticles 2013)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Adsorption of precious metals in acidic aqueous solutions using thiourea modified magnetic magnetite nanoparticle (MNP-Tu) was examined. The MNP-Tu was synthesized, characterized and examined as a reusable adsorbent for the recovery of precious metals. The adsorption kinetics were well fitted with pseudo second-order equation while the adsorption isotherms were fitted with both Langmuir and Freundlich equations. The maximum adsorption capacity of precious metals for MNP-Tu determined by Langmuir model was 43.34, 118.46 and 111.58 mg/g for Pt(IV), Au(III) and Pd(II), respectively at pH 2 and 25 °C. MNP-Tu has high adsorption selectivity towards precious metals even in the presence of competing ions (Cu(II)) at high concentrations. In addition, the MNP-Tu can be regenerated using an aqueous solution containing 0.7 M thiourea and 2% HCl where precious metals can be recovered in a concentrated form. It was found that the MNP-Tu undergoing seven consecutive adsorption-desorption cycles still retained the original adsorption capacity of precious metals. A reductive adsorption resulting in the formation of elemental gold and palladium at the surface of MNP-Tu was observed.
Keywords: magnetic nanoparticle; thiourea; precious metals; reuse; recycle; green material; adsorption; nanotechnology
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MDPI and ACS Style

Lin, T.-L.; Lien, H.-L. Effective and Selective Recovery of Precious Metals by Thiourea Modified Magnetic Nanoparticles. Int. J. Mol. Sci. 2013, 14, 9834-9847.

AMA Style

Lin T-L, Lien H-L. Effective and Selective Recovery of Precious Metals by Thiourea Modified Magnetic Nanoparticles. International Journal of Molecular Sciences. 2013; 14(5):9834-9847.

Chicago/Turabian Style

Lin, Tai-Lin; Lien, Hsing-Lung. 2013. "Effective and Selective Recovery of Precious Metals by Thiourea Modified Magnetic Nanoparticles." Int. J. Mol. Sci. 14, no. 5: 9834-9847.


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