http://hdl.handle.net/2117/3167 Wed, 22 May 2013 23:16:29 GMT 2013-05-22T23:16:29Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/18887 Title: Cyclodextrin functionalization of several cellulosic substrates for prolonged release of antibacterial agents Authors: Cusola Aumedes, Oriol; Tabary, Nicolas; Naceur Belgacem, Mohamed; Bras, Julien Abstract: Several cellulosic substrates have been surface-functionalized with cyclomaltoheptaose (b-cyclodextrin, b-CD) using citric acid as a crosslinker agent to obtain new surface-modified materials able to release antiseptic molecules over a prolonged period, in view of their use in medical domain. Three different commercial cellulosic substrates were used, namely: (i) an uncoated paper, (ii) a crepe paper, and (iii) a medical bandage. They were successfully grafted by a crosslinked polymer consisting on b-CD molecules as assessed by scanning electron microscopy and Fourier transform infrared spectroscopy analysis. Several time–temperature kinetic cycles were performed to reach the optimum curing parameters. The grafted and nongrafted samples were loaded with chlorhexidine digluconate (digCHX), a widely used antiseptic agent. The drug-delivery kinetics of the encapsulated digCHX was carried out by immersing the sample under investigation into an aqueous medium, and the quantity of the released digCHX was measured, as a function of time, by UV spectroscopy. The optimal grafting conditions were established on the basis of the highest weight gain. These samples did not give the best release performance. Nevertheless, several grafted substrates were able to uptake an appreciable amount of active molecules and release them over a prolonged time of about 20 days Fri, 19 Apr 2013 11:04:05 GMT http://hdl.handle.net/2117/18887 2013-04-19T11:04:05Z Cusola Aumedes, Oriol; Tabary, Nicolas; Naceur Belgacem, Mohamed; Bras, Julien no Several cellulosic substrates have been surface-functionalized with cyclomaltoheptaose (b-cyclodextrin, b-CD) using citric acid as a crosslinker agent to obtain new surface-modified materials able to release antiseptic molecules over a prolonged period, in view of their use in medical domain. Three different commercial cellulosic substrates were used, namely: (i) an uncoated paper, (ii) a crepe paper, and (iii) a medical bandage. They were successfully grafted by a crosslinked polymer consisting on b-CD molecules as assessed by scanning electron microscopy and Fourier transform infrared spectroscopy analysis. Several time–temperature kinetic cycles were performed to reach the optimum curing parameters. The grafted and nongrafted samples were loaded with chlorhexidine digluconate (digCHX), a widely used antiseptic agent. The drug-delivery kinetics of the encapsulated digCHX was carried out by immersing the sample under investigation into an aqueous medium, and the quantity of the released digCHX was measured, as a function of time, by UV spectroscopy. The optimal grafting conditions were established on the basis of the highest weight gain. These samples did not give the best release performance. Nevertheless, several grafted substrates were able to uptake an appreciable amount of active molecules and release them over a prolonged time of about 20 days http://hdl.handle.net/2117/18297 Title: Application of surface enzyme treatments using laccase and a hydrophobic compound to paper-based media Authors: Cusola Aumedes, Oriol; Valls Vidal, Cristina; Vidal Lluciá, Teresa; Roncero Vivero, María Blanca Abstract: A new approach for the hydrophobization of finished cellulosic substrates based on a previously reported enzymatic technique is proposed. Commercial finished paper was hydrophobized by using laccase from Trametes villosa in combination with lauryl gallate (LG) as hydrophobic compound. The efficiency of the method was increased by the use of a lignosulfonate as a natural dispersant to improve the surface distribution of LG on the paper, raise its hydrophobicity and help preserve the enzyme activity. No similar threefold effect from a single compound for the improvement of enzymatic treatments was previously reported. The influence of processing conditions including the LG dose, treatment time and temperature was also examined, resulting in further increased hydrophobicity. Efficient fiber bonding and chemical functionalization were confirmed by thorough washing and Soxhlet extraction of the paper. As shown here for the first time, enzyme treatments have the potential to improve the surface hydrophobicity of paper-based media Thu, 14 Mar 2013 11:44:20 GMT http://hdl.handle.net/2117/18297 2013-03-14T11:44:20Z Cusola Aumedes, Oriol; Valls Vidal, Cristina; Vidal Lluciá, Teresa; Roncero Vivero, María Blanca no A new approach for the hydrophobization of finished cellulosic substrates based on a previously reported enzymatic technique is proposed. Commercial finished paper was hydrophobized by using laccase from Trametes villosa in combination with lauryl gallate (LG) as hydrophobic compound. The efficiency of the method was increased by the use of a lignosulfonate as a natural dispersant to improve the surface distribution of LG on the paper, raise its hydrophobicity and help preserve the enzyme activity. No similar threefold effect from a single compound for the improvement of enzymatic treatments was previously reported. The influence of processing conditions including the LG dose, treatment time and temperature was also examined, resulting in further increased hydrophobicity. Efficient fiber bonding and chemical functionalization were confirmed by thorough washing and Soxhlet extraction of the paper. As shown here for the first time, enzyme treatments have the potential to improve the surface hydrophobicity of paper-based media http://hdl.handle.net/2117/18230 Title: Laccase from Pycnoporus cinnabarinus and phenolic compounds: can the efficiency of an enzyme mediator for delignifying kenaf pulp be predicted? Authors: Andreu Terrén, Glòria; Vidal Lluciá, Teresa Abstract: In this work, kenaf pulp was delignified by using laccase in combination with various redox mediators and the efficiency of the different laccase–mediator systems assessed in terms of the changes in pulp properties after bleaching. The oxidative ability of the individual mediators used (acetosyringone, syringaldehyde, p-coumaric acid, vanillin and actovanillone) and the laccase–mediator systems was determined by monitoring the oxidation–reduction potential (ORP) during process. The results confirmed the production of phenoxy radicals of variable reactivity and stressed the significant role of lignin structure in the enzymatic process. Although changes in ORP were correlated with the oxidative ability of the mediators, pulp properties as determined after the bleaching stage were also influenced by condensation and grafting reactions. As shown here, ORP measurements provide a first estimation of the delignification efficiency of a laccase–mediator system. Tue, 12 Mar 2013 16:04:36 GMT http://hdl.handle.net/2117/18230 2013-03-12T16:04:36Z Andreu Terrén, Glòria; Vidal Lluciá, Teresa no Kenaf, Laccase, Phenolic mediators, Oxidation–reduction potential In this work, kenaf pulp was delignified by using laccase in combination with various redox mediators and the efficiency of the different laccase–mediator systems assessed in terms of the changes in pulp properties after bleaching. The oxidative ability of the individual mediators used (acetosyringone, syringaldehyde, p-coumaric acid, vanillin and actovanillone) and the laccase–mediator systems was determined by monitoring the oxidation–reduction potential (ORP) during process. The results confirmed the production of phenoxy radicals of variable reactivity and stressed the significant role of lignin structure in the enzymatic process. Although changes in ORP were correlated with the oxidative ability of the mediators, pulp properties as determined after the bleaching stage were also influenced by condensation and grafting reactions. As shown here, ORP measurements provide a first estimation of the delignification efficiency of a laccase–mediator system. http://hdl.handle.net/2117/18145 Title: Enzymatic grafting of natural phenols to flax fibres: development of antimicrobial properties Authors: Fillat Latorre, Amanda; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca Abstract: Unbleached flax fibres for paper production were treated with laccase from Pycnoporus cinnabarinus and low molecular weight phenols (syringaldehyde – SA, acetosyringone – AS and p-coumaric acid – PCA) to evaluate the potential of this treatment to biomodify high cellulose content fibres. After the enzymatic treatment with the phenols, an increase in kappa number was found, probably due to a covalent binding of the phenoxy radicals on fibres. Grafting was more evident in pulps treated with PCA (an increase of 4 kappa number points with respect to the laccase control was achieved). Paper handsheets from treated pulps showed antimicrobial activity against the bacteria tested: Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. An important reduction on microbial count was obtained after incubation of liquid cultures of the bacteria with grafted handsheets. AS and PCA grafted fibres showed a high antibacterial activity on K. pneumoniae, getting a nearly total growth inhibition. AS fibres also caused a high reduction in bacterial population of P. aeruginosa (97% reduction). Optical properties of handsheets from treated pulps were also determined, showing a brightness decrease and increase in coloration, evaluated by CIE L*a*b* system, caused by the laccase induced grafting of the phenols. The results suggest that these low molecular weight phenols, covalently bound to the flax fibres by the laccase treatment, can act as antimicrobial agents and produce handsheets with antimicrobial activity Fri, 08 Mar 2013 11:09:37 GMT http://hdl.handle.net/2117/18145 2013-03-08T11:09:37Z Fillat Latorre, Amanda; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca no Unbleached flax fibres for paper production were treated with laccase from Pycnoporus cinnabarinus and low molecular weight phenols (syringaldehyde – SA, acetosyringone – AS and p-coumaric acid – PCA) to evaluate the potential of this treatment to biomodify high cellulose content fibres. After the enzymatic treatment with the phenols, an increase in kappa number was found, probably due to a covalent binding of the phenoxy radicals on fibres. Grafting was more evident in pulps treated with PCA (an increase of 4 kappa number points with respect to the laccase control was achieved). Paper handsheets from treated pulps showed antimicrobial activity against the bacteria tested: Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. An important reduction on microbial count was obtained after incubation of liquid cultures of the bacteria with grafted handsheets. AS and PCA grafted fibres showed a high antibacterial activity on K. pneumoniae, getting a nearly total growth inhibition. AS fibres also caused a high reduction in bacterial population of P. aeruginosa (97% reduction). Optical properties of handsheets from treated pulps were also determined, showing a brightness decrease and increase in coloration, evaluated by CIE L*a*b* system, caused by the laccase induced grafting of the phenols. The results suggest that these low molecular weight phenols, covalently bound to the flax fibres by the laccase treatment, can act as antimicrobial agents and produce handsheets with antimicrobial activity http://hdl.handle.net/2117/17932 Title: Use of cyclic voltammetry as an effective tool for selecting effcient enhancers for oxidative bioprocesses: importance of pH Authors: Aracri, Elisabetta; Tzanov, Tzanko; Vidal Lluciá, Teresa Abstract: Seven natural phenols and two synthetic compounds were evaluated by means of cyclic voltammetry as enhancers for the oxidation of the lignin model compound veratryl alcohol (VAl) and a sulfonated lignin (SL). Their electrochemical behaviors and catalytic efficiencies (CEs) against both substrates were assessed as a function of pH. A general increase in CE of the phenols was for the first time observed in the oxidation of VAl at pH 7 and 8. Methyl syringate (MS), syringic acid (SRC), and syringaldehyde (SRD) exhibited the highest CEs against VAl among the studied phenolic compounds despite the reduced stabilities of their phenoxy radicals. This was a result of favorable stability−reactivity balances, which were apparently influenced by both the chemical structures of the enhancers and the experimental conditions. Violuric acid (VAc) proved the most efficient compound in oxidizing lignin, followed by SRD and MS, which showed regeneration in the interval of pHs studied Fri, 22 Feb 2013 11:50:22 GMT http://hdl.handle.net/2117/17932 2013-02-22T11:50:22Z Aracri, Elisabetta; Tzanov, Tzanko; Vidal Lluciá, Teresa no Seven natural phenols and two synthetic compounds were evaluated by means of cyclic voltammetry as enhancers for the oxidation of the lignin model compound veratryl alcohol (VAl) and a sulfonated lignin (SL). Their electrochemical behaviors and catalytic efficiencies (CEs) against both substrates were assessed as a function of pH. A general increase in CE of the phenols was for the first time observed in the oxidation of VAl at pH 7 and 8. Methyl syringate (MS), syringic acid (SRC), and syringaldehyde (SRD) exhibited the highest CEs against VAl among the studied phenolic compounds despite the reduced stabilities of their phenoxy radicals. This was a result of favorable stability−reactivity balances, which were apparently influenced by both the chemical structures of the enhancers and the experimental conditions. Violuric acid (VAc) proved the most efficient compound in oxidizing lignin, followed by SRD and MS, which showed regeneration in the interval of pHs studied http://hdl.handle.net/2117/17435 Title: Performance of new and commercial xylanases for ECF and TCF bleaching of eucalyptus kraft pulp Authors: Valls Vidal, Cristina; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca Abstract: Since xylanases can differ widely in their bleaching efficiency, the performance of one new and two commercial xylanases was evaluated in an eucalyptus kraft pulp following XD (X: xylanase; D: chlorine dioxide) and XP (P: hydrogen peroxide) sequences. The new xylanase did not show a significant bleach boosting effect but increased the hexenuronic acid (HexA) removal by 10% after the D stage. The two commercial xylanases behaved in a different way, being one of them (XC) the most effective in increasing delignification (9%) and brightness (3%ISO). Its effectiveness was related to its greater action on releasing the xylan polymer, thus producing also a strong decrease in the HexA contents during the enzymatic stage (15%). All xylanases produced morphological changes in the fibre surfaces, but only with XC cracks and holes that improved the diffusion of reactives were observed. Finally, the best bleaching results were obtained with the XD sequence and therefore, a complete bleaching sequence XDEopD1 (Eop: alkaline extraction with oxygen and peroxide) was carried out with the best enzyme Mon, 21 Jan 2013 12:01:00 GMT http://hdl.handle.net/2117/17435 2013-01-21T12:01:00Z Valls Vidal, Cristina; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca no Since xylanases can differ widely in their bleaching efficiency, the performance of one new and two commercial xylanases was evaluated in an eucalyptus kraft pulp following XD (X: xylanase; D: chlorine dioxide) and XP (P: hydrogen peroxide) sequences. The new xylanase did not show a significant bleach boosting effect but increased the hexenuronic acid (HexA) removal by 10% after the D stage. The two commercial xylanases behaved in a different way, being one of them (XC) the most effective in increasing delignification (9%) and brightness (3%ISO). Its effectiveness was related to its greater action on releasing the xylan polymer, thus producing also a strong decrease in the HexA contents during the enzymatic stage (15%). All xylanases produced morphological changes in the fibre surfaces, but only with XC cracks and holes that improved the diffusion of reactives were observed. Finally, the best bleaching results were obtained with the XD sequence and therefore, a complete bleaching sequence XDEopD1 (Eop: alkaline extraction with oxygen and peroxide) was carried out with the best enzyme http://hdl.handle.net/2117/17384 Title: Simulation of bleaching of soda pulp from Hesperaloe funifera by polynomial and neural fuzzy models Authors: Rosal, Antonio; Valls Vidal, Cristina; Roncero Vivero, María Blanca; Rodríguez Pascual, Alejandro Abstract: Influence of variables [soda, (0.5 to 3.0%), hydrogen peroxide (1.0 to 10.0%) and time (1 to 5 h)] in the bleaching of soda pulp of Hesperaloe funifera, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models had reproduced the results of Kappa number, brightness and viscosity of the pulps with errors less than 10 and 15%, respectively. By simulating the bleaching process of pulp H. funifera, with the polynomial and neural fuzzy models, the optimal values of operating variables can be found, so that the properties of bleached pulps differ little from their best values and instead will save chemical reagents, energy and plant size, operating with lower values of operating variables. Thus, by application of polynomial models, it was found that operating with a soda concentration of 0.5%, a hydrogen peroxide concentration of 5.5% and for a processing time of 3 h, it was possible to get a pulp with a brightness of 65.9% and a viscosity of 587 ml/g. Wed, 16 Jan 2013 10:48:32 GMT http://hdl.handle.net/2117/17384 2013-01-16T10:48:32Z Rosal, Antonio; Valls Vidal, Cristina; Roncero Vivero, María Blanca; Rodríguez Pascual, Alejandro no Influence of variables [soda, (0.5 to 3.0%), hydrogen peroxide (1.0 to 10.0%) and time (1 to 5 h)] in the bleaching of soda pulp of Hesperaloe funifera, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models had reproduced the results of Kappa number, brightness and viscosity of the pulps with errors less than 10 and 15%, respectively. By simulating the bleaching process of pulp H. funifera, with the polynomial and neural fuzzy models, the optimal values of operating variables can be found, so that the properties of bleached pulps differ little from their best values and instead will save chemical reagents, energy and plant size, operating with lower values of operating variables. Thus, by application of polynomial models, it was found that operating with a soda concentration of 0.5%, a hydrogen peroxide concentration of 5.5% and for a processing time of 3 h, it was possible to get a pulp with a brightness of 65.9% and a viscosity of 587 ml/g. http://hdl.handle.net/2117/17382 Title: Influence of enzyme and chemical adsorption on the thermal degradation path for eucalyptus pulp Authors: Barneto, A. G.; Valls Vidal, Cristina; Ariza, José; Roncero Vivero, María Blanca Abstract: Changes in thermal degradation path of eucalyptus pulp support enzymes (laccase from Trametes villosa) and chemicals (Tris–HCl or tartrate–tartaric buffer) adsorption on cellulose during biobleaching, thereby increasing cellulose amount that degrades at low temperature and decreasing the apparent crystallinity (ApC) of cellulose crystallites. Changes in ApC, which can be assessed by thermogravimetric analysis—but not X-ray diffraction spectroscopy—affect cellulose volatilization; thus, the higher ApC is, the lower is char production and the higher the volatilization temperature. A linear relationship between ApC and the volatilization/charring ratio (V/C) was observed in this work Wed, 16 Jan 2013 10:24:33 GMT http://hdl.handle.net/2117/17382 2013-01-16T10:24:33Z Barneto, A. G.; Valls Vidal, Cristina; Ariza, José; Roncero Vivero, María Blanca no Changes in thermal degradation path of eucalyptus pulp support enzymes (laccase from Trametes villosa) and chemicals (Tris–HCl or tartrate–tartaric buffer) adsorption on cellulose during biobleaching, thereby increasing cellulose amount that degrades at low temperature and decreasing the apparent crystallinity (ApC) of cellulose crystallites. Changes in ApC, which can be assessed by thermogravimetric analysis—but not X-ray diffraction spectroscopy—affect cellulose volatilization; thus, the higher ApC is, the lower is char production and the higher the volatilization temperature. A linear relationship between ApC and the volatilization/charring ratio (V/C) was observed in this work http://hdl.handle.net/2117/17381 Title: Obtaining biobleached eucalyptus cellulose fibres by using various enzyme combinations Authors: Valls Vidal, Cristina; Cadena Chamorro, Edith Marleny; Roncero Vivero, María Blanca Abstract: Various combinations of laccases, xylanase and cellulase were used to biobleach cellulose fibres from eucalyptus. The Trametes villosa and Myceliophthora thermophila laccases were used in combination with violuric acid (VATvL system) and methyl syringate (MeSMtL system), respectively, as mediator. A dissimilar mode of action of the two systems was found: the VATvL treatment released both hexenuronic acids and lignin, whereas the MeSMtL released lignin alone. Pulp properties were further improved by applying the mediator before the enzyme during treatment. Pulp properties comparable to those provided by industrial TCF sequences were obtained by inserting a xylanase pretreatment before VATvL, but no significant effect was observed after the cellulase pretreatment. As an added value, the resulting enzymatically bleached fibres possess a reduced hexenuronic acid content. The chemical oxygen demand of the effluents from each stage was also assessed Wed, 16 Jan 2013 08:53:18 GMT http://hdl.handle.net/2117/17381 2013-01-16T08:53:18Z Valls Vidal, Cristina; Cadena Chamorro, Edith Marleny; Roncero Vivero, María Blanca no Various combinations of laccases, xylanase and cellulase were used to biobleach cellulose fibres from eucalyptus. The Trametes villosa and Myceliophthora thermophila laccases were used in combination with violuric acid (VATvL system) and methyl syringate (MeSMtL system), respectively, as mediator. A dissimilar mode of action of the two systems was found: the VATvL treatment released both hexenuronic acids and lignin, whereas the MeSMtL released lignin alone. Pulp properties were further improved by applying the mediator before the enzyme during treatment. Pulp properties comparable to those provided by industrial TCF sequences were obtained by inserting a xylanase pretreatment before VATvL, but no significant effect was observed after the cellulase pretreatment. As an added value, the resulting enzymatically bleached fibres possess a reduced hexenuronic acid content. The chemical oxygen demand of the effluents from each stage was also assessed http://hdl.handle.net/2117/17380 Title: A neural fuzzy model applied to hydrogen peroxide bleaching of non-wood soda pulps Authors: Rosal, Antonio; Valls Vidal, Cristina; Ferrer, Ana; Rodríguez, Alejandro Abstract: A neural fuzzy model was used to examine the influence of pulp bleaching variables of empty fruit bunches from oil palm (EFB) and Hesperaloe funifera, such as soda concentration (0.5-3%), hydrogen peroxide concentration (1-10%) and processing time (1-3 h), on Kappa number, brightness and viscosity. The experimental results are reproduced with errors below 10% and 15% for EFB and H. funifera, respectively. Bleaching pulp simulation permits to obtain optimal values of the operating variables, so that the properties of bleached pulps will only slightly differ from their best values, while the lower values of the operating variables will save chemical reagents, energy and plant size. Thus, if applying 0.5% soda and 3% peroxide for 3 h, it is possible to get a pulp with a brightness of 74.9% and a viscosity of 716 mL/g, for EFB pulp, and of 63.3% and 584 mL/g, respectively, for H. funifera pulp Wed, 16 Jan 2013 08:29:38 GMT http://hdl.handle.net/2117/17380 2013-01-16T08:29:38Z Rosal, Antonio; Valls Vidal, Cristina; Ferrer, Ana; Rodríguez, Alejandro no A neural fuzzy model was used to examine the influence of pulp bleaching variables of empty fruit bunches from oil palm (EFB) and Hesperaloe funifera, such as soda concentration (0.5-3%), hydrogen peroxide concentration (1-10%) and processing time (1-3 h), on Kappa number, brightness and viscosity. The experimental results are reproduced with errors below 10% and 15% for EFB and H. funifera, respectively. Bleaching pulp simulation permits to obtain optimal values of the operating variables, so that the properties of bleached pulps will only slightly differ from their best values, while the lower values of the operating variables will save chemical reagents, energy and plant size. Thus, if applying 0.5% soda and 3% peroxide for 3 h, it is possible to get a pulp with a brightness of 74.9% and a viscosity of 716 mL/g, for EFB pulp, and of 63.3% and 584 mL/g, respectively, for H. funifera pulp http://hdl.handle.net/2117/16445 Title: A new procedure for the hydrophobization of cellulose fibre using laccase and a hydrophobic phenolic compound Authors: García Ubasart, Jordi; Colom Pastor, José F.; Vila Babarro, Carlos; Hernández, Núria; Roncero Vivero, María Blanca; Vidal Lluciá, Teresa Abstract: A new biotechnological procedure using laccase in combination with a hydrophobic phenolic compound (lauryl gallate) for the hydrophobization of cellulose fibres and internal sizing of paper was developed. Cellulose fibres from hardwood kraft pulp were incubated with laccase (Lac), in combination with lauryl gallate (LG). The Lac-LG treatment resulted in the internal sizing of paper, and also in significantly reduced water penetration in the handsheets and wettability of the paper surface. Paper was found not to be effectively rendered hydrophobic by LG alone. SEM images of the fibre network revealed the presence of the sizing agent: a product of the reaction between laccase and lauryl gallate. Binding of lauryl gallate to cellulose fibres was suggested by the increase in kappa number of the pulp and further confirmed by IR spectroscopy Thu, 06 Sep 2012 09:27:26 GMT http://hdl.handle.net/2117/16445 2012-09-06T09:27:26Z García Ubasart, Jordi; Colom Pastor, José F.; Vila Babarro, Carlos; Hernández, Núria; Roncero Vivero, María Blanca; Vidal Lluciá, Teresa no Cellulose fiber, Hydrophobization, Internal sizing, Laccase, Lauryl gallate A new biotechnological procedure using laccase in combination with a hydrophobic phenolic compound (lauryl gallate) for the hydrophobization of cellulose fibres and internal sizing of paper was developed. Cellulose fibres from hardwood kraft pulp were incubated with laccase (Lac), in combination with lauryl gallate (LG). The Lac-LG treatment resulted in the internal sizing of paper, and also in significantly reduced water penetration in the handsheets and wettability of the paper surface. Paper was found not to be effectively rendered hydrophobic by LG alone. SEM images of the fibre network revealed the presence of the sizing agent: a product of the reaction between laccase and lauryl gallate. Binding of lauryl gallate to cellulose fibres was suggested by the increase in kappa number of the pulp and further confirmed by IR spectroscopy http://hdl.handle.net/2117/16433 Title: Integrating a xylanase treatment into an industrial-type sequence for eucalyptus kraft pulp bleaching Authors: Fillat Latorre, Úrsula; Roncero Vivero, María Blanca; Sacón, Vera Maria; Bassa, Alexandre Abstract: 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 Wed, 05 Sep 2012 10:13:41 GMT http://hdl.handle.net/2117/16433 2012-09-05T10:13:41Z Fillat Latorre, Úrsula; Roncero Vivero, María Blanca; Sacón, Vera Maria; Bassa, Alexandre no 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 http://hdl.handle.net/2117/16392 Title: Nanofibrillated cellulose (NFC) as a potential reinforcement for high performance cement mortar composites Authors: Ardanuy Raso, Mònica; Claramunt Blanes, Josep; Arévalo Peces, Raquel; Parés Sabatés, Ferran; Aracri, Elisabetta; Vidal Lluciá, Teresa Abstract: In this work, nanofibrillated cellulose (NFC) has been evaluated as a potential reinforcement for cement mortar composites. Two types of vegetable fibres with different composition and properties (cellulose content and microfibrillar angle), sisal, and cotton linters pulps, were initially characterized in order to assess their reinforcement capability. Sisal pulp was found to be most suitable as reinforcement for their brittle cementitious matrix. Nanofibrillated cellulose was produced by the application of a high intensity refining process of the sisal pulp. It was found that 6 hours of refining time was required to obtain the desired nanofibrillation of the fibers. Cement mortar composites reinforced with both the sisal fibers and the nanofibrillated cellulose were prepared, and the mechanical properties were determined under flexural test. The cement mortar composites reinforced with the nanofibrillated cellulose exhibited enhanced flexural properties, but lower values of fracture energy, than the ones reinforced with the conventional sisal fibres. Tue, 28 Aug 2012 08:27:11 GMT http://hdl.handle.net/2117/16392 2012-08-28T08:27:11Z Ardanuy Raso, Mònica; Claramunt Blanes, Josep; Arévalo Peces, Raquel; Parés Sabatés, Ferran; Aracri, Elisabetta; Vidal Lluciá, Teresa no In this work, nanofibrillated cellulose (NFC) has been evaluated as a potential reinforcement for cement mortar composites. Two types of vegetable fibres with different composition and properties (cellulose content and microfibrillar angle), sisal, and cotton linters pulps, were initially characterized in order to assess their reinforcement capability. Sisal pulp was found to be most suitable as reinforcement for their brittle cementitious matrix. Nanofibrillated cellulose was produced by the application of a high intensity refining process of the sisal pulp. It was found that 6 hours of refining time was required to obtain the desired nanofibrillation of the fibers. Cement mortar composites reinforced with both the sisal fibers and the nanofibrillated cellulose were prepared, and the mechanical properties were determined under flexural test. The cement mortar composites reinforced with the nanofibrillated cellulose exhibited enhanced flexural properties, but lower values of fracture energy, than the ones reinforced with the conventional sisal fibres. http://hdl.handle.net/2117/16099 Title: Wet strength development in sisal cellulose fibers by effect of a laccase-Tempo treatment Authors: Aracri, Elisabetta; Vidal Lluciá, Teresa; Ragauskas, A.J. Tue, 19 Jun 2012 08:27:41 GMT http://hdl.handle.net/2117/16099 2012-06-19T08:27:41Z Aracri, Elisabetta; Vidal Lluciá, Teresa; Ragauskas, A.J. no http://hdl.handle.net/2117/15844 Title: Assessing the environmental impact of biobleaching: effects of the operational conditions Authors: Valls Vidal, Cristina; Quintana, Elisabet; Roncero Vivero, María Blanca Abstract: The environmental impact of enzyme bleaching stages applied to oxygen-delignified eucalypt kraft pulp was assessed via the chemical oxygen demand (COD), color, absorbance spectrum, residual enzyme activity and Microtox toxicity of the effluents from a laccase–HBT (1-hydoxybenzotriazole) treatment. The influence of the laccase and HBT doses, and reaction time, on these effluent properties was also examined. The laccase dose was found to be the individual variable most strongly affecting COD, whereas the oxidized form of HBT was the main source of increased color and toxicity in the effluents. Moreover, it inactivated the enzyme. Oxidation of the mediator was very fast and essentially dependent on the laccase dose. Using the laccase–mediator treatment after a xylanase stage improved pulp properties without affecting effluent properties. This result holds great promise with a view to the industrial implementation of biobleaching sequences involving the two enzymes in the future. Mon, 14 May 2012 11:50:44 GMT http://hdl.handle.net/2117/15844 2012-05-14T11:50:44Z Valls Vidal, Cristina; Quintana, Elisabet; Roncero Vivero, María Blanca no Biobleaching, Effluent properties, Laccase, Toxicity, Xylanase The environmental impact of enzyme bleaching stages applied to oxygen-delignified eucalypt kraft pulp was assessed via the chemical oxygen demand (COD), color, absorbance spectrum, residual enzyme activity and Microtox toxicity of the effluents from a laccase–HBT (1-hydoxybenzotriazole) treatment. The influence of the laccase and HBT doses, and reaction time, on these effluent properties was also examined. The laccase dose was found to be the individual variable most strongly affecting COD, whereas the oxidized form of HBT was the main source of increased color and toxicity in the effluents. Moreover, it inactivated the enzyme. Oxidation of the mediator was very fast and essentially dependent on the laccase dose. Using the laccase–mediator treatment after a xylanase stage improved pulp properties without affecting effluent properties. This result holds great promise with a view to the industrial implementation of biobleaching sequences involving the two enzymes in the future.