Influência do branqueamento com ozônio e peróxido de hidrogênio no rendimento e qualidade de fibras secundárias.

In this study, Total Chlorine Free (TCF) bleaching processes were evaluated for bleaching a secondary fiber of different origens. The samples were bleached to a target brightness of 78 % ISO. The results were interpreted on the basis of chemical cost to reach the target brightness, bleaching yield and bleached pulp quality as measured by viscosity, fluorescence and b* color coordinate. The ozone stage was responsible for improve TCF bleaching performance. The pulp bleached by sequences contained a ozone stage followed by chelation, without interstage washing (ZQ), and a final hydrogen peroxide stage unpressurized (P) or pressurized with oxygen (PO), designed as (ZQ)(PO) showed good results. These sequences decreased pulp b* coordinate significantly and fluorescence slightly. For  all three bleaching processes, it was determined that process yield is negatively affected by hot alkaline stages such as oxygen, O, peroxide, P, and peroxide pressurized with oxygen, (PO) and also for the origin of the pulps of secondary fibers.Nesse estudo, foram avaliadas seqüências "Total Chlorine Free" (TCF) para o branqueamento de fibras secundárias provenientes de três fontes diferentes. As polpas foram branqueadas a um nível mínimo de alvura de 78% ISO, sendo que a quantidade necessária de reagentes e as suas principais propriedades foram avaliadas. A utilização do ozônio mostrou-se eficiente no branqueamento TCF, pois permitiu alcançar a alvura objetivo nos três tipos de polpas, por meio das seqüências (ZQ)P e (ZQ)(PO). As letras apresentadas nas seqüências de branqueamento possuem os seguintes significados: os estágios de ozônio, Z, seguido de uma quelação, Q, e um simples estágio de peróxido, P, ou um estágio de peróxido pressurizado com oxigênio (PO). E também reduziu significativamente a coordenada de cor b* e ligeiramente a fluorescência das polpas. Os resultados de rendimento para os processos avaliados nesse estudo foram afetados negativamente por estágios alcalinos, como oxigênio, O, P e (PO), em altas temperaturas e também pela origem das polpas de fibras secundárias

MOLYBDENUM CATALYZED ACID PEROXIDE BLEACHING OF EUCALYPTUS KRAFT PULP

Molybdenum catalyzed peroxide bleaching (PMo Stage) consists of pulp treatment with hydrogen peroxide under acidic conditions in the presence of a molybdenum catalyst. Molybdenum is applied in catalytic doses (50-200 mg/kg pulp) and may originate from various sources, including (NH4)6Mo7O24.4H2O, Na2MoO4.2H2O, siliconmolybdate, etc. This work is aimed at optimizing the PMo stage and evaluating its industrial application in the OAZDP sequence. Optimum PMo stage conditions for bleaching eucalyptus pulp were 90 ºC, pH 3.5, 2 h, 0.1 kg/adt Mo and 5 kg/adt H2O2. The PMo stage was more efficient to remove pulp hexenuronic acids than lignin. Its efficiency decreased with increasing pH in the range of 1.5-5.5, while it increased with increasing temperature and peroxide and molybdenum doses. The application of the PMo stage as replacement for the A-stage of the AZDP sequence significantly decreased chlorine dioxide demand. The PMo stage caused a decrease of 20-30% in the generation of organically bound chlorine. The quality parameters of the pulp produced during the PMo stage mill trial were comparable to those obtained with the reference A-stage

COMPARISON BETWEEN ANALYTICAL PYROLYSIS AND NITROBENZENE OXIDATION FOR DETERMINATION OF SYRINGYL/GUAIACYL RATIO IN Eucalyptus spp. LIGNIN

Pyrolysis-gas chromatography/mass spectrometry (Py-GC-MS) was applied to measure the lignin syringyl/guaiacyl (S/G) ratio in E. dunni, E. grandis, E. nitens, E. urograndis, and E. urophylla woods. A total of 41 compounds were identified, of which 11 were derived from carbo-hydrates and 30 from lignins. The S/G ratio was calculated on the basis of the areas of peaks recorded in the pyrograms and compared with the results obtained by alkaline nitrobenzene oxidation. The values of S/G found by pyrolysis were similar for all the species using the compounds guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, 4-ethylsyringol, 4-vinylsyringol, homosyringaldehyde, acetosyringone, and syringylacetone, as lignin markers. The selected markers were efficient for the deter-mination of S/G ratio in eucalyptus wood by Py-GC-MS. The Py-GC-MS technique produced results that are comparable to the nitrobenzene oxidation method, with the advantage of requiring small wood samples and a short analysis time

Branqueamento ECF e TCF de celulose de fibras secundárias.

In this study, ECF and TCF bleaching processes were evaluated for the bleaching of a deinked mixed office waste (MOW) pulp sample produced in a pilot plant. The sample was bleached by all processes to a target brightness of 78 % ISO minimum. The results were interpreted on the basis of chemical cost to reach the target brightness, bleaching yield and bleached pulp quality as measured by viscosity, fluorescence and b* color coordinate. Among the ECF sequences, the mosattractive was the DEDD which showed the lowest chemical cost and produced bleached pulp of high quality as measured by viscosity, fluorescence and b* coordinate. The best TCF sequence with ozone was the Q(PO)(ZQ)(PO) which resulted in very high brightness ceiling. This sequence decreased moderately the pulp b* coordinate and viscosity and slightly its fluorescence. Among the TCF sequences without ozone the Q(PO)Q(PO) was the most effective but showed poor flexibility with regard to brightness ceiling. This sequence had little effect on pulp viscosity, fluorescence and b* coordinate. For all three  bleaching processes, it was determined that process yield is negatively affected by hot alkaline stages such as O, P and (PO).secundárias destintadas provenientes de uma mistura de composição conhecida de lixo de escritório (MOW) e produzidas em planta piloto. A polpa foi branqueada a um nível mínimo de alvura de 78% ISO, sendo que o requerimento de reagentes e as principais propriedades da polpa foram avaliadas. Dentre as seqüência ECF, a mais atrativa foi a DEDD que apresentou o mais baixo custo e ainda eliminou toda a fluorescência e grande parte da coordenada de cor b* da polpa. As seqüências ECF resultaram em polpas de alta viscosidade em relação às convencionais. A seqüência TCF com ozônio mais atrativa foi a Q(PO)(ZQ)(PO) que se mostrou flexível quanto ao teto de alvura, além de reduzir significativamente a coordenada de cor b* e ligeiramente a fluorescência da polpa. A melhor seqüência TCF sem-ozônio Q(PO)Q(PO) apresentou-se pouco flexível quanto ao teto de alvura e teve pouco efeito na fluorescência e coordenada de cor b* da polpa. As viscosidades finais das polpas, branqueadas pelos processos TCF, foram aceitáveis. Os resultados de rendimento, para os  processos avaliados nesse estudo, foram afetados negativamente por estágios alcalinos, como O, P e (PO), em alta temperatura

Influência do conteúdo de xilanas na branqueabilidade, propriedades higroscópicas, fisico-mecânicas e óptica de polpas branqueadas de eucalipto

Bleached eucalypt kraft pulps are widely used in print and writing (P&W) and tissue paper manufacture. Among the quality requirements of pulp for these papers, xylan content has been controversial. The objective of this study was to evaluate the influence of xylan content on bleachability, hygroscopic, physic-mechanical and optical properties of the pulp. In this study industrial unbleached eucalyptus kraft pulp (15.6% xylans) treated with different NaOH loads to change its xylan content was used. Subsequently, pulps were bleached by the ODHT(EP)D sequence to achieve 90% ISO of brightness, then refined and submitted to hygroscopic, physicomechanical and optical tests. NaOH treatments decreased the xylan content to 14.5-5.9% using NaOH loads of 10-70 g L-1. Pulp bleachability was not significantly affected by xylan content decrease. The decrease in xylan content negatively affected the water retention value and Klemm capillarity of the pulp, while water absorption capacity was positively affected. Tensile and tear index were negatively influenced by the reduction in xylan content, whereas bulk and light scattering coefficient increased

Análise comparativa entre vários métodos de quantificação de hemiceluloses da madeira de eucalipto

Pulp hemicelluloses can be extracted with NaOH and quantified by colorimetric and gravimetric techniques. However the most usual methods to measure eucalyptus pulp hemicelluloses have been through the pentosan method or through xylan analyses by GC or HPLC techniques. In this study a comparison was made between the more traditional methods and indirect method of NaOH 5% extraction followed by colorimetric analyses. It was observed that the content of NaOH 5% extract correlates very well with pulp xylan content and reasonably well with the pentosan content. It is concluded that the 5% NaOH solubility method can be used in replacement of the other two, since it is faster, simpler and less costly to carry out than the others

Relative importance of wood density and carbohydrate content on pulping yield and product quality

O objetivo deste estudo foi avaliar a densidade b\ue1sica, a composi\ue7\ue3o qu\uedmica e as dimens\uf5es de fibras de dez amostras de madeira de Eucalyptus spp. e, verificar o impacto desse conjunto de par\ue2metros e sua combina\ue7\ue3o no rendimento do processo de polpa\ue7\ue3o kraft e na qualidade da polpa branqueada. A madeira de dez esp\ue9cies de eucalipto, com densidade b\ue1sica variando entre 365 a 544 kg/m3 e teores de carboidratos totais variando entre 70,0 a 74,5% foi transformada em polpa Kraft, com n\ufamero kappa 15,5- 16,7 e branqueada a 90% ISO por uma seq\ufc\ueancia de quatro est\ue1gios (OD(PO)D) composta de deslignifica\ue7\ue3o com oxig\ueanio (O), deslignifica\ue7\ue3o com di\uf3xido de cloro (D), extra\ue7\ue3o alcalina com per\uf3xido pressurizado (PO) e branqueamento com di\uf3xido de cloro (D). A densidade b\ue1sica da madeira mostrou melhor correla\ue7\ue3o com as dimens\uf5es da fibra e qualidade da polpa que a sua composi\ue7\ue3o qu\uedmica. Por\ue9m o rendimento depurado foi mais influenciado pela composi\ue7\ue3o qu\uedmica da madeira do que pela densidade b\ue1sica. Madeiras de menor densidade apresentaram maiores rendimentos de polpa\ue7\ue3o, mas o consumo espec\uedfico de madeira foi mais baixo para as madeiras mais densas. Os resultados de qualidade de polpa sugerem que madeiras com densidade mais baixa devam ser direcionadas \ue0 fabrica\ue7\ue3o de papel refinado (impress\ue3o e de escrita), enquanto que as mais densas sejam destinadas ao segmento de pap\ue9is sanit\ue1rios (tissue).The purpose of this study was to evaluate basic density, chemical composition and fiber dimensions of ten Eucalyptus sp wood samples and to verify the impact of this set of parameters and their combination on the Kraft pulping process yield and on bleached pulp quality. Ten eucalypt woods of different species, with basic densities varying from 365 to 544 kg/m\ub3 and total wood carbohydrate contents varying from 70.0 to 74.5%, were transformed into kraft pulp of kappa number 15,5-16,7 and bleached to 90% ISO brightness by the sequence OD(PO)D. Wood basic density showed stronger correlations with fiber dimensions and pulp quality than did chemical composition. However, pulping yield was strongly affected by chemical composition. Lighter woods resulted in higher pulping yields. However, wood specific consumption was lower for denser woods, even though these demanded more drastic pulping conditions to achieve a given kappa number. The pulp quality results suggest that lower density woods should be directed towards fabrication of refined paper (printing and writing grades) while the denser woods should be directed to the sanitary papers segment (tissue grades)

The AD(EO)D process - a new concept

In this study, cooking of the wood had been investigated until kappa numbers 17 and 14 for a process kinetically modified, elimination of oxygen delignification from the fiber line, and application of AD(EO)D and AD(PO)D techniques for pulp of kappa 17 and AD(EO)D and DHT(EPO)DP for pulp of kappa 14 for the bleaching at 90% ISO. As references, cookings had been carried out until kappa number 17 and 14, oxygen delignification in simple stage and conventional bleaching with sequences A/D(EO)D, A/D(EPO)D, A/D(EO)DP and A/D(EPO)DP for the kappa number 17 pulp and oxygen delignification in simple stage and conventional bleaching sequence DHT(EPO)DP for pulp of kappa 14. For the pulp of kappa 17, one concluded that processes AD(EO)D and AD(PO)D produced pulp of brightness 90% ISO with good viscosity and brightness stability, using TAC\ub4s (totally active chloro) relatively low, and it\u2019s not necessary the oxygen delignification. Amongst these two processes, the first one revealed to be more attractive to reach the level of 90% ISO brightness. However, comparatively to the reference processes, with oxygen delignification, for example O-A/D(EPO)DP, process AD(EO)D results in increase of the operational cost of the order of US$7-8/odt, including wood and reagents. For the kappa number 14 pulp, process AD(EO)D also revealed to be attractive, but the sequence DHT(EPO)DP was the one that used lower TAC`s; however, when compared with the reference (O-DHT(EPO)DP), it resulted in an increase of operational cost of the order of US$5/odt. Therefore, it can be concluded that the alternative process, without the deslignification with oxygen, is viable only for pulps of lower kappa number.Nesse estudo, investigaram-se cozimentos da madeira at\ue9 n\ufameros kappa 17 e 14 por um processo cineticamente modificado, elimina\ue7\ue3o da deslignifica\ue7\ue3o com oxig\ueanio da linha de fibras, e aplica\ue7\ue3o das t\ue9cnicas AD(EO)D e AD(PO)D para polpa de kappa 17 e AD(EO)D e DHT(EPO)DP para polpa de kappa 14 para o branqueamento at\ue9 90% ISO. Como refer\ueancias, foram realizados cozimentos at\ue9 n\ufameros kappa 17 e 14, deslignifica\ue7\ue3o com oxig\ueanio em simples est\ue1gio e branqueamento convencional pelas seq\ufc\ueancias A/D(EO)D, A/D(EPO)D, A/D(EO)DP e A/D(EPO)DP para a polpa de kappa 17 e deslignifica\ue7\ue3o com oxig\ueanio em simples est\ue1gio e branqueamento convencional pela seq\ufc\ueancia DHT(EPO)DP para polpa de kappa 14. Para a polpa de kappa 17, concluiu-se que os processos AD(EO)D e AD(PO)D produzem polpa de alvura 90% ISO com boa viscosidade e estabilidade de alvura, utilizando TAC\ub4s (Cloro Ativo Total) relativamente baixos, e dispensam completamente a deslignifica\ue7\ue3o com oxig\ueanio. Dentre esses dois processos, o primeiro se mostrou mais atrativo para atingir o n\uedvel de alvura de 90% ISO. Por\ue9m, comparativamente aos processos de refer\ueancia, contendo a deslignifica\ue7\ue3o com oxig\ueanio, ex. OA/ D(EPO)DP, o processo AD(EO)D resulta em aumento do custo operacional da ordem de US7-8/tas, inclusos madeira e reagentes. Para a polpa de n\ufamero kappa 14, o processo AD(EO)D tamb\ue9m se mostrou atrativo, sendo que a seq\ufc\ueancia DHT(EPO)DP foi a que utilizou o menor TAC`s, por\ue9m quando comparada com a refer\ueancia (O-DHT(EPO)DP) resultou num aumento de custo operacional da ordem de US4/tas. Portanto, pode se concluir que o processo alternativo, sem a deslignifica\ue7\ue3o com oxig\ueanio, \ue9 vi\ue1vel somente para polpas de n\ufameros kappa mais baixos

Technological characterization of Eucalyptus benthamii wood for kraft pulp production

O objetivo deste trabalho foi avaliar a qualidade tecnol\uf3gica da madeira de Eucalyptus benthamii para produ\ue7\ue3o de celulose kraft. Suas caracter\uedsticas foram comparadas com as de um h\uedbrido de Eucalyptus grandis x Eucalyptus urophylla que \ue9, provavelmente, o clone mais plantado no Brasil e, portanto, de grande import\ue2ncia no setor nacional de celulose e papel. Determinaram-se a densidade b\ue1sica, composi\ue7\ue3o qu\uedmica e caracter\uedsticas dimensionais das fibras das duas esp\ue9cies. A madeira do Eucalyptus benthamii apresentou estrutura anat\uf4mica bastante semelhante \ue0s outras esp\ue9cies do g\ueanero e, ainda, densidade b\ue1sica e dimens\uf5es das fibras dentro dos par\ue2metros dos clones de Eucalyptus utilizados atualmente pela ind\ufastria nacional de celulose e papel. Do ponto de vista de constitui\ue7\ue3o qu\uedmica, o Eucalyptus benthamii demonstrou possuir qualidade tecnol\uf3gica inferior \ue0 do h\uedbrido urograndis, pois apresentou maiores teores de extrativos e de lignina, menor teor de glucanas, maior teor de galactanas e menor rela\ue7\ue3o S/G (Siringila/Guaiacila), caracter\uedsticas que contribuem para um menor rendimento em polpa. Estudos dever\ue3o ser realizados para avaliar o desempenho da esp\ue9cie na polpa\ue7\ue3o kraft, no branqueamento e as propriedades de resist\ueancias da polpa celul\uf3sica.The purpose of this study was to evaluate the quality of Eucalyptus benthamii wood for kraft pulp production. A hybrid of Eucalyptus urophylla x Eucalyptus grandis , probably the most planted Eucalyptus clone in Brazil, was also analyzed for comparison purposes. Basic density, chemical composition and fiber dimensions were determined for the two species. The Eucalyptus benthamii wood presented an anatomical structure, basic density and fiber dimensions quite similar to those of other species planted by the Brazilian pulp industry. However, it presented poorer wood quality characteristics when compared to the hybrid urograndis species, with higher amounts of extractives and lignin, lower amount of glucans, more galactans and lower S/G ratio, characteristics leading to lower pulping yield. Additional studies should be carried out to establish its pulping, bleaching and paper strength properties

Physical-Mechanical Properties Evaluation Of Pulps Produced With Novel Bleaching Sequences

A efici\ueancia da deslignifica\ue7\ue3o com oxig\ueanio (pr\ue9-O2) \ue9 muito baixa para polpas de baixo n\ufamero kappa e que cont\ueam altas concentra\ue7\uf5es de \ue1cidos hexenur\uf4nicos, pois o oxig\ueanio n\ue3o reage com esses \ue1cidos, sendo m\uednima a elimina\ue7\ue3o destes durante a deslignifica\ue7\ue3o com oxig\ueanio em simples ou duplo est\ue1gio. Neste estudo, investigaram-se as propriedades f\uedsico-mec\ue2nicas de polpas produzidas por cozimentos cineticamente modificados at\ue9 n\ufamero kappa 17 e 14 e branqueadas pelas t\ue9cnicas AD(EO)D, para polpa de kappa 17 e DHT(EPO)DP, para polpa de kappa 14. O objetivo principal do estudo foi o de avaliar as propriedades f\uedsico-mec\ue2nicas das polpas submetidas a sequ\ueancias de branqueamento sem o oxig\ueanio, no in\uedcio da sequ\ueancia. Como refer\ueancias, foram produzidas polpas de n\ufamero kappa 17 e 14 as quais foram posteriormente deslignificadas com oxig\ueanio e branqueadas com sequ\ueancias convencionais: A/D(EO)D, para polpa de n\ufamero kappa 17 e DHT(EPO)DP, para polpa de kappa 14. O branqueamento alternativo, sem a pr\ue9-O2, resultou em polpas branqueadas de maior integridade que as da refer\ueancia, o que foi comprovado pelos valores significativamente mais altos de VEA (bulk), \uedndice de rasgo, opacidade e resist\ueancia \ue0 passagem de ar (RPA) da polpa fracamente refinada (polpa para produzir papel tissue). Por outro lado, a alta integridade das fibras oriundas das polpas branqueadas por processos alternativos diminuiu suas conformabilidades e colapsabilidades, com consequente diminui\ue7\ue3o do \uedndice de tra\ue7\ue3o da polpa fracamente refinada. Por\ue9m, mediante um refino mais intenso (polpa para produzir papel de imprimir e escrever \u2013 P&W) o \uedndice de tra\ue7\ue3o foi recuperado. A alta integridade das polpas branqueadas sem a pr\ue9-O2 dificulta o seu refino. Para alcan\ue7ar o grau de drenagem de 35oSR com as polpas provenientes dos processos alternativos de branqueamento, foi necess\ue1rio aplicar cerca de 30% a mais de energia em rela\ue7\ue3o \ue0 refer\ueancia.The efficiency of oxygen delignification is very low for pulps of low number kappa and with high concentrations of hexenuronic acids, therefore the oxygen does not react with these acids, so being minimum the elimination of these during the oxygen delignification (pre-O2) in simple or double stage. In this study, the physical-mechanical properties of pulp of kappa number 17 and 14, produced with modified cooks and with the application of AD(EO)D techniques for pulp of kappa 17 and DHT(EPO)DP for pulp of kappa 14 for the bleaching up to 90% ISO, had been investigated. The main objective of this study was to evaluate the physical-mechanical properties in pulps submitted to the bleaching sequences without oxygen in the beginning of the sequence. As references, cooks had been carried until numbers kappa 17 and 14, oxygen delignification and conventional bleaching for sequences A/D(EO)D for pulp of kappa 17 and DHT(EPO)DP for pulp of kappa 14. The alternative bleaching, without pre-O2, resulted in bleached pulps with bigger integrity that of the reference, what it was confirmed by the values significantly higher of bulk, tear index, opacity and air resistance of the pulp weakly refined (for tissue papers). However, the high integrity of the fibers from pulps bleached with alternative processes lowered their conformabilities and collapsibility, with consequent reduction of tensile index of the pulp weakly refined. Therefore, with more intensive beating (for printing and writing papers), the tensile index was recovered. The high integrity of the bleaching pulps without pre-O2 makes beating difficulty. To reach the draining degree of 35\ub0SR with the pulps proceeding from alternative processes of bleaching, it was necessary to apply 30% more energy than the reference