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Mechanism of heavy metal uptake by a hybrid MCM-41 material: Surface complexation and EPR spectroscopic study

Stathi, P and Dimos, K and Karakassides, MA and Deligiannakis, Y (2010) Mechanism of heavy metal uptake by a hybrid MCM-41 material: Surface complexation and EPR spectroscopic study. Journal of Colloid and Interface Science, 343. pp. 374-380. ISSN 0021-9797

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Abstract

A novel hybrid MCM-41-based material was synthesized by incorporation of AEDTC [N-(2-aminoethyl)dithiocarbamate] in the MCM-41 pores. The derived MCM-41 ⊗ AEDTC material possesses high AEDTC loading 35% [w:w], and a well-defined array of regular mesopores with a specific surface area of 632 m /g. Heavy metal, Cd, Pb, Cu, and Zn, uptake was studied in detail at physiological pH values 6-8, by a combination of analytical and electron paramagnetic resonance (EPR) spectroscopic techniques. The analytical data show a significant improvement, i.e., 200-500%, for Pb, Cu, and Zn uptake by the MCM-41 ⊗ AEDTC hybrid vs the unmodified MCM-41. In contrast, Cd shows an exceptional behavior: (a) Cd uptake by MCM-41 ⊗ AEDTC is very low. (b) Competitive metal uptake experiments reveal that Cd ions cause a characteristic inhibition of Cu or Pb uptake by the MCM-41 ⊗ AEDTC while Cd binding itself always remained low. The present findings are analyzed by a combination of surface complexation modeling and EPR spectroscopy. Accordingly, in the MCM-41 ⊗ AEDTC the sulfur atoms of AEDTC provide strong binding sites for metal binding, with a stoichiometry [S ]:[Metal] = 1:1. Cd inhibits accessibility of Cu or Pb ions in the AEDTC sites. © 2009 Elsevier Inc. All rights reserved. 2 AEDTC

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 12 Jun 2018 01:34
Last Modified: 15 Apr 2021 05:06
DOI: 10.1016/j.jcis.2009.11.029