Abstract

INFANTE, Miguel et al. Microwave assisted oxidative degradation of lignin with hydrogen peroxide and its tensoactive properties. Rev. Téc. Ing. Univ. Zulia [online]. 2007, vol.30, n.Especial, pp.108-117. ISSN 0254-0770.

In this work the fractions obtained by microwave-assisted oxidative degradation with hydrogen peroxide of two pine lignins (LAA y LKM) and its tensoactive properties were studied. The reactions were carried out using different quantities of the oxidant agent in a domestic microwave oven in closed reactors. The reaction was completed quickly with the generation of water as by-product. The oxidation products were characterized by UV and FTIR spectroscopy. When comparing them with the original lignin samples in UV analysis, the absorption decreased near the 280nmdue to the oxidation of the aromatic rings. In the analysis by FTIR the signals corresponding to the groups C=O increased among 1,700-1,720 cm^-1 and 1,650-1,700 cm^-1 attributed to the oxidation of the lateral chains and aromatic rings, respectively. This results were evidenced because of the aromatic signal C=C around the 1,600 cm^-1 decreased. It was proven the efficiency and versatility of the radiation microwaves to carry out this type of reactions. The surface tension of the oxidized lignin increased due the new hydrophilic groups.

Keywords : Hydrogen peroxide; lignin; microwave; oxidative degradation; surface tension.