10 research outputs found
Biological decolorization of xanthene dyes by anaerobic granular biomass
Biodegradation of a xanthene dyes was investigated for the first time using anaerobic granular sludge. On a first screening, biomass was able to decolorize, at different extents, six azo dye solutions: acid orange 7, direct black 19, direct blue 71, mordant yellow 10, reactive red 2 and reactive red 120 and two xanthene dyes—Erythrosine B and Eosin Y. Biomass concentration, type of electron donor, induction of biomass with dye and mediation with activated carbon (AC) were variables studied for Erythrosine B (Ery) as model dye. Maximum color removal efficiency was achieved with 4.71 g VSS L−1, while the process rates were independent of the biomass concentration above 1.89 g VSS L−1. No considerable effects were observed when different substrates were used as electron donors (VFA, glucose or lactose). Addition of Ery in the incubation period of biomass led to a fivefold increase of the decolorization rate. The rate of Ery decolorization almost duplicated in the presence of commercial AC (0.1 g L−1 AC0). Using different modified AC samples (from the treatment of AC0), a threefold higher rate was obtained with the most basic one, \textAC\textH2ACH2, as compared with non-mediated reaction. Higher rates were obtained at pH 6.0. Chemical reduction using Na2S confirmed the recalcitrant nature of this dye. The results attest that decolorization of Ery is essentially due to enzymatic and adsorption phenomena.This work was supported by the PTDC/AMB/69335/2006 project grants (Fundacao para a Ciencia e Technologia, FCT, Portugal), BRAIN project (ID 6681, European Social Found and Romanian Government and the grant of the Romanian National Authority for Scientific Research, CNCS-UEFISCDI, project number PN-II-ID-PCE-2011-3-0559, Contract 265/2011
Effect of acidic fluoride solution on the corrosion resistance of ZrTi alloys for dental implant application
The electrochemical behavior of Zr5Ti, Zr25Ti, and Zr45Ti, with and without surface modification were monitored in acidic artificial saliva (pH = 3) containing NaF concentrations 0.2, 0.5, and 1 wt.%, simulating the fluoride concentrations in dental rinses. A passive behaviour for thermally oxidized ZrTi alloys was found using EIS, and XPS data show that the protective oxide film contains both TiO2 and ZrO2, though titanium contents in the outer layer bigger than those in the base alloy result from thermal oxidation. High corrosion resistance to acidic fluoridated environments of ZrTi alloys treated using thermal oxidation in air at 500 ºC