TY - JOUR
T1 - Synthesis of a novel poly-thiolated magnetic nano-platform for heavy metal adsorption. Role of thiol and carboxyl functions
AU - Odio, Oscar F.
AU - Lartundo-Rojas, Luis
AU - Palacios, Elia Guadalupe
AU - Martínez, Ricardo
AU - Reguera, Edilso
N1 - Publisher Copyright:
© 2016 Elsevier B.V. All rights reserved.
PY - 2016/11/15
Y1 - 2016/11/15
N2 - We report a novel strategy for the synthesis of magnetic nano-platforms containing free thiol groups. It first involves the synthesis of a poly(acrylic acid) copolymer containing disulfide bridges between the linear chains through di-ester linkages, followed by the anchoring of this new ligand to magnetite nanoparticles using a ligand exchange reaction. Finally, free -SH groups are obtained by treating the resulting disulfide-functionalized magnetic nano-system with tributyl phosphine as reducing agent. The characterization of the resulting 17 nm nanoparticles (Fe 3 O 4 @PAA-HEDred) by FTIR and TGA confirms the attachment of the copolymer through iron carboxylates. XRD, TEM and magnetic measurements indicate an increase in the inorganic core diameter and the occurrence of strong magnetic inter-particle interactions during the exchange reaction, although coercitivity and remanence drop to near zero at room temperature. Afterwards, Fe 3 O 4 @PAA-HEDred nanoparticles were tested as sorbent for Pb 2+ and Cd 2+ cations in aqueous media. XPS measurements were performed in order to unravel the role of both carboxyl and thiol functions in the adsorption process. For the sake of comparison, the same study was performed using bare Fe 3 O 4 nanoparticles and a nanosystem with disulfide groups (Fe 3 O 4 @DMSA). The joint analysis of the Pb 4f, Cd 3d, Fe 2p and S 2p high resolution spectra for the nanostructured materials indicates that metal-sulfur interactions are dominant if free -SH groups are present, but if not, the main adsorption route entails metal-carboxyl interactions. Even in presence of unbound thiol moieties, carboxyl groups participate due to favoured steric availability.
AB - We report a novel strategy for the synthesis of magnetic nano-platforms containing free thiol groups. It first involves the synthesis of a poly(acrylic acid) copolymer containing disulfide bridges between the linear chains through di-ester linkages, followed by the anchoring of this new ligand to magnetite nanoparticles using a ligand exchange reaction. Finally, free -SH groups are obtained by treating the resulting disulfide-functionalized magnetic nano-system with tributyl phosphine as reducing agent. The characterization of the resulting 17 nm nanoparticles (Fe 3 O 4 @PAA-HEDred) by FTIR and TGA confirms the attachment of the copolymer through iron carboxylates. XRD, TEM and magnetic measurements indicate an increase in the inorganic core diameter and the occurrence of strong magnetic inter-particle interactions during the exchange reaction, although coercitivity and remanence drop to near zero at room temperature. Afterwards, Fe 3 O 4 @PAA-HEDred nanoparticles were tested as sorbent for Pb 2+ and Cd 2+ cations in aqueous media. XPS measurements were performed in order to unravel the role of both carboxyl and thiol functions in the adsorption process. For the sake of comparison, the same study was performed using bare Fe 3 O 4 nanoparticles and a nanosystem with disulfide groups (Fe 3 O 4 @DMSA). The joint analysis of the Pb 4f, Cd 3d, Fe 2p and S 2p high resolution spectra for the nanostructured materials indicates that metal-sulfur interactions are dominant if free -SH groups are present, but if not, the main adsorption route entails metal-carboxyl interactions. Even in presence of unbound thiol moieties, carboxyl groups participate due to favoured steric availability.
KW - Disulfide
KW - Magnetite nanoparticles
KW - Metal carboxylate
KW - Metal thiolate
KW - Poly(acrylic acid)
KW - XPS
UR - http://www.scopus.com/inward/record.url?scp=84973920689&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2016.05.176
DO - 10.1016/j.apsusc.2016.05.176
M3 - Artículo
SN - 0169-4332
VL - 386
SP - 160
EP - 177
JO - Applied Surface Science
JF - Applied Surface Science
ER -