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.
The synthesis and biological evaluation as antiviral agents of a series of racemic 4-aryl-1,2,3-triazolo-2',3'-dideoxy-2'-iodocarbanucleosides and 4-aryl-1,2,3-triazolo-2',3'-dideoxy-2',3'-didehydrocarbanucleosides is presented. These compounds were produced using a click chemistry approach, with the iodoazide 13a as the key intermediary.
We have developed a useful modification of the classical preparation of phenanthrenes by UV irradiation of stilbenes in the presence of an oxidant. This modification involves the irradiation, in the presence of base, of stilbenes possessing a sulfonyl group linked to the central double bond. We have proved that this protocol can be successfully applied for the synthesis of diverse phenanthrenes and phenanthrenoids.
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