Oxidative Degradation of Azo Dyes by Manganese Peroxidase under Optimized Conditions

Abstract

The application of enzyme-based systems in waste treatment is unusual, given that many drawbacks are derived from their use, including low efficiency, high costs and easy deactivation of the enzyme. The goal of this study is the development of a degradation system based on the use of the ligninolytic enzyme manganese peroxidase (MnP) for the degradation of azo dyes. The experimental work also includes the optimization of the process, with the objective of determining the influence of specific physicochemical factors, such as organic acids, H(2)O(2) addition, Mn(2+) concentration, pH, temperature, enzyme activity and dye concentration. A nearly total decolorization was possible at very low reaction times (10 min) and at high dye concentration (up to 1500 mg L(-)(1)). A specific oxidation capacity as high as 10 mg dye degraded per unit of MnP consumed was attained for a decolorization higher than 90%. Among all, the main factor affecting process efficiency was the strategy of H(2)O(2) addition. The continuous addition at a controlled flow permitted the progressive participation of H(2)O(2) in the catalytic cycle through a suitable regeneration of the oxidized form of the enzyme, which enhanced both the extent and the rate of decolorization. It was also found that, in this particular case, the presence of a chelating organic acid (e.g., malonic) was not required for an effective operation. Probably, Mn(3+) was chelated by the dye itself. The simplicity and high efficiency of the process open an interesting possibility of using of MnP for solving other environmental problems.

Enzyme Initiated Radical Polymerizations

“…Likewise halophenols [178][179][180][181][182] bisphenol A, [183][184][185] various hormones and so-called endocrine disrupting compounds [186][187][188] or even TNT [189,190] have been reported. Non-phenolic compounds may be ‗inactivated' using the LMS or PMS strategy [36,[191][192][193][194][195][196][197][198].…”

Recent Advances in Azo Dye Degrading Enzyme Research

“…Previous studies have demonstrated that MnP, with its cofactors in adequate concentration, can degrade azo dye Orange II, reaching 90% decolorization in a relatively short period of time [109]. Phanerochaete chrysosporium, Phanerochaete ostreatus, Trametes versicolor, and Aureobasidium pullulans were screened for degradation of sulfonic azo dyes.…”

Wood production, wood technology, and biotechnological impacts

“…see Young & Yu 1997, Gunther et al 1998, Kim et al 1998, Ferreira et al 2000, Verma & Madamwar 2002, Mielgo et al 2003, Mohorcic et al 2006, Ferreira-Leitoa et al 2007, Tinoco et al 2007). Whilst application of enzyme solutions to such compounds have shown their effectiveness, living fungal cultures are better applied for bioremediation of contaminated soils and other materials and for purification of aqueous solutions since they produce the necessary enzymes together with H2O2 due to the action of the auxiallary enzyme machinery of lignocellulose degradation (Pointing 2001, Gianfreda & Rao 2004, Tortella et al 2005, Śušla & Svobodová 2006.…”