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Jacareí, Brazil

Fillat U.,University of Barcelona | Roncero M.B.,University of Barcelona | Sacon V.M.,CDTC | Bassa A.,CDTC
Industrial and Engineering Chemistry Research | Year: 2012

The influence of a treatment with two commercial xylanases on pulp and effluents obtained after the bleaching stages in the OXAZDP (O, oxygen stage; X, xylanase treatment; A, acid stage; Z, ozone stage; D, chlorine dioxide stage; P, hydrogen peroxide stage) sequence was studied. Also, the potential saving in chlorine dioxide was assessed. The enzyme treatment was performed on pulp containing some black liquor since the operating conditions were close to the conditions used in the storage tower in Fibria, identified as the most suitable point for application. The greatest differences in kappa number and hexenuronic acid content were observed after the X stage. Whereas, in brightness were observed after the Z stage. The effluent properties from the X stage were higher with the enzyme treatments. Also, the enzymes allowed chlorine dioxide consumption in the bleaching stage to be reduced. The control pulp contained twice as much adsorbable organic halides (AOX) and exhibited twice more brightness reversion than did the enzyme-treated samples. However, the tensile index and drainability at an identical degree of refining were lower in the enzyme-treated samples. © 2012 American Chemical Society. Source

Fillat U.,Polytechnic University of Catalonia | Roncero M.B.,Polytechnic University of Catalonia | Bassa A.,CDTC | Sacan V.M.,CDTC
Industrial and Engineering Chemistry Research | Year: 2010

To obtain a more realistic appraisal of the potential efficiency of xylanases in the industrial bleaching, the influence of pH and the presence of black liquor (measured as COD) on the bleaching efficiency of two commercial xylanases was studied at high temperature. These pHs, CODs, and temperatures are close to those used in the storage tower of the B fiber line in Jacareí unit of Fibria (Brazil). The pulp samples obtained after each bleaching stage were analyzed for kappa number, brightness, viscosity, and hexenuronic acid content, and so were the effluents for COD, TOC, color, turbidity, and pH after the enzymatic stage. On the basis of the results, the xylanases were found to increase pulp brightness in the treatment involving the most unfavorable conditions (viz. high COD and pH). However, an initial COD above 9 kgO 2 t -1 and/or a pH higher than 9.5 detracted from their bleaching efficiency. The effect on the kappa number and hexenuronic acids content of the pulp was apparent immediately after the enzymatic stage, and the most marked increase in brightness was observed after the chlorine dioxide stage. © 2010 American Chemical Society. Source

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