Decolorization of chlorolignin with hydrogen peroxide in the presence of silica [bis(dibenzoylmethido) copper ii] as catalyst
1 Alexandru Ioan Cuza University, Faculty of Chemistry, Carol I - 11, 700506 Iasi, Rom nia
2 Petru Poni Institute of Macromolecular Chemistry, Centre of Advanced Research in Nanobioconjugates and Biopolymers, Gr. Ghica Vod 41 A, 700487 Iasi, Rom nia
3 Gheorghe Asachi Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, 73 Prof.dr.docent Dimitrie Mangeron Street, 700050 Iasi, Rom nia
2 Petru Poni Institute of Macromolecular Chemistry, Centre of Advanced Research in Nanobioconjugates and Biopolymers, Gr. Ghica Vod 41 A, 700487 Iasi, Rom nia
3 Gheorghe Asachi Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, 73 Prof.dr.docent Dimitrie Mangeron Street, 700050 Iasi, Rom nia
Abstract
This paper reports an improved chlorolignin (CL) oxidative decolorization in alkaline media by the use of a heterogeneous system consisting of hydrogen peroxide and a silica [bis(dibenzoylmethido) copper II] (S1) catalyst. The catalytic functions of S1 in the presence of H2O2 were evaluated by comparing the chlorolignin decolorization in media with and without addition of catalyst. Since decolorization is associated with CL degradation, the pH variation and chloride release assays were carried out to monitor both processes. The influence of several factors such as H2O2 and chlorolignin concentration, initial pH, reaction time, temperature, and catalyst dose were assessed to improve the catalytic reactions. Also, the stability and potential reusability of the catalyst were studied. It was found that the oxidative reaction follows pseudo-first order kinetics with respect to chlorolignin concentration. Activation energy, as well as activation enthalpy and entropy, were calculated using the Arrhenius and Eyring equations, respectively.
Keywords
chlorolignin; Cu (II) catalyst; decolorization; hydrogen peroxide; oxidative degradation