XPS studies on the Cu (I,II)-polyampholyte heterogeneous catalyst: an insight into its structure and mechanism.

JUAN MANUEL LÁZARO MARTÍNEZ; ENRIQUE RODRÍQUEZ-CASTELLÓN; ROSA MARÍA TORRES SÁNCHEZ; LISANDRO ROBERTO DENADAY; GRACIELA Y. BULDAIN; VIVIANA CAMPO DALL' ORTO

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL

ELSEVIER SCIENCE BV

Lugar: Bristol; Año: 2011 vol. 339 p. 43 - 51

1381-1169

A complex between Cu(II) and a polyampholyte synthesized from methacrylic acid, imidazole andethyleneglycol diglycidyl ether was used as a heterogeneous catalyst for hydrogen peroxide activationand degradation of chlorophenols. The material was characterized by XPS and by measurements of thezeta potential. The isoelectric point determined experimentally was 8.0, differing from that obtained bytitration (6.4), which indicated the presence of fixed positive charges in disubstituted imidazole units.The XPS N 1s signal for pyridinic nitrogen in the imidazole units, and the O 1s signals from the carbonyl,hydroxyl and carboxylate groups shifted to higher binding energies after copper uptake, proving thechemical nature of Cu(II) adsorption on the polyampholyte. The XPS spectrum of the complex showed aCu 2p3/2 peak at 934.7 eV and the characteristic shake-up satellite of Cu(II). When the complex was usedas a heterogeneous catalyst for H2O2 activation, Cu(I) was proved to be a probable intermediate speciesand contributed to elucidate the mechanism. The Auger CuLMM spectrum supports the presence of Cu(I)with a kinetic energy value of 914.8 eV. The complex was applied in the oxidation of chlorinated phenolsin aqueous solution at room temperature without any loss in efficiency.© 2011 Elsevier B.V. All rights reserved.