MIRANDA Maria Victoria
capítulos de libros
Eco-friendly approach for Direct Blue 273 removal from an aqueous medium
PAMELA GONZALEZ CLAR; GUSTAVO LEVIN; MIRANDA MARÍA VICTORIA; VIVIANA CAMPOS DALL ORTO
Advanced Oxidation Technologies ? Sustainable solutions for environmental treatments
This was the first attempt of DB273 decolorization reported in literature up to now. The crude extract of SBP turned out to be a powerful biotechnological tool for the ecofriendly dye degradation, using hydrogen peroxide as oxidant. Up to now, this enzyme had only been tested on a few dyes, such as the Cu(II)-phthalocyanine Remazol Turquoise Blue G133 (Marchis et al 2011), the azo dye Direct Yellow 11 and the methine dye Basazol 46L (Knutson et al 2005). The decolorization efficiency of SBP on DB273 was strongly dependent on the amount of crude extract employed. An activity of 3.0 U mL was necessary to remove the 73% of the dye in 60 minutes, using 0.2 mM H2O2 for a 87 µM initial concentration of dye. A similar efficiency could be reached in 30 minutes with an activity of 9.0 U mL-1. Results were comparable to those obtained with peroxidases from other sources on different azo dyes, but the cost of the process with SBP would be significantly lower. The polyampholyte was also an effective adsorbent for the anionic dye at near-neutral pH. The rate of sorption was controlled by the diffusion through a boundary layer. The Temkin and Langmuir models fitted well the results from the equilibrium of physisorption, predicting that adsorption energies of the active sites were equivalent on the polyampholyte surface. The loading capacity was higher compared with inorganic sorbents, and somewhat lower compared with commercially available ion-exchange resins. On the other hand, the equilibrium constant of dissociation (KL, expressed in M units) was found to be lower, and the dissolved salts from the sample matrix would not affect significantly the efficiency of uptake. Decolorization of the dye-loaded polyampholyte was successfully achieved with 0.10M NaClO as oxidizing agent, preserving the adsorbent?s chemical structure. The preconcentration of the dye on the adsorbent surface allows to reduce the amount of oxidant necessary to achieve degradation.