No description available.

The work described in this thesis was aimed at obtaining a better understanding of the neutral sulphite semichemical pulping process employed by Mondi Kraft's Piet Retief mill, and to investigate ways to improve this process. The unique feature of the process in this mill is that hardwood and softwood species are pulped simultaneously in a continuous digester. The pulping trials described were carried out in a laboratory batch digester which was build as a part of this project. Pulps were evaluated for yield, Hypo number as an indication of the residual lignin content and strength properties. The first part of the experimental work focused on the effect that different pulping variables have on the process and the resulting pulp. Variables investigated were the chemical charge, pulping temperature, chip composition and anthraquinone dosage. The second part of the work was to investigate ways in which the process can be improved. In particular it was investigated whether it would be advantageous to pulp hardwood and softwood separately and mix the two pulps together after pulping. The effect of changing to an alkaline sulphite process was also briefly investigated. It was found that the current process is optimized as far as the chemical charge and pulping temperature is concerned. Increasing the softwood percentage used to 50 % (from current value of 41 %) increases the tear strength, whilst decreasing it to 30 % increases the tensile strength of the resulting pulp. It was also determined that increasing the AQ dosage from 0.1 % to 0.5 % might bring savings in chemical costs. It is suggested that this is investigated in a mill trial. It was further found that pulping the two species separately improves the tear strength of the pulp by about 20 % compared with that which was pulped simultaneously. The results indicate that no benefits concerning the chemical costs, pulping temperature, pulp yield, burst strength or tensile strength are to be gained from separate pulping. Preliminary results indicated that significant strength increases and possible chemical cost savings are to be gained by changing from a neutral sulphite to an alkaline sulphite process. Further work to determine the reproducibility of these results, as well as the effect of different chemical charge and ratios is suggested. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2000.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Description based on print version record. Includes bibliographical references (leaves 399-401).

SAPPI SAICCOR is a pulp and paper mill situated in Umkomaas, 50 kms south of the port of Durban in South Africa. It was the first company to produce high grade dissolving pulp from the Eucalyptus tree and is currently the world's largest manufacturer of chemical cellulose. SAICCOR is one of the few pulp and paper mills that produces its dissolving pulp by the acid sulphite process using both calcium and magnesium as bases in the form of calcium bisulphite and magnesium bisulphite. Four streams of effluent are produced during their process, namely, the calcium spent liquor, the magnesium pulp condensate and two streams from the bleaching stages. An acid hydrolysis of the effluent streams yielded a range of organic compounds such as lignans and lignin - type precursors as well as a triterpenoid. Column chromatography and thin layer chromatography, using various ratios of hexane, dichloromethane, ethyl acetate and methanol, were carried out in isolating and purifying the compounds. The structures of these compounds were determined using NMR spectroscopic and mass spectrometric techniques. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

The chemistry of the batch cooking process at Sappi Saiccor, relating to both the pulp and liquor, was investigated with the aim of using kinetic expressions to develop an improved process control model. The mill produces dissolving pulps using the acid sulphite method. Three process reactions were identified as important: cellulose hydrolysis, delignification and hemicellulose dissolution. Of these, cellulose hydrolysis is the most important since the primary aim is to achieve a targeted cellulose degree of polymerisation (DP) or viscosity (DP is commonly expressed in terms of this measurement). This is directly determined by the rate of this reaction during the cook, and the acidity of the cooking liquor was found to be the key factor. As existing equipment was not suitable for obtaining the data required to perform a kinetic analysis, a pilot plant was constructed. A commercially available probe was used for the first time to measure pH directly. The measured acidity is not directly equivalent to hydrogen ion activity at these temperatures and pressures; however, since the conditions of each cook are similar the errors incurred were found to be constant from cook to cook. The probe was found to be prone to drift due to ageing and this was accounted for by using an 'on line' calibration based on a liquor analysis. The kinetics of the cellulose hydrolysis reaction were determined using the on-line measurement of acidity and the concept of degradation increase (DI) which relates the reduction in DP value to the rate at which the polymeric chains are split. Delignification and hemicellulose dissolution were examined, since it is beneficial to maximise these reactions to reduce the quantities of chemicals consumed during the bleaching process. A model for controlling cooks to a set target cellulose DP value within a set time was developed based on the reaction kinetics. This was capable of predicting cooking conditions required with sufficient accuracy to control the cellulose DP value to within ±6 cp SNIA on the viscosity scale. / Thesis (M.Sc.Eng.)-University of Natal, 1992.

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-12T17:09:21Z No. of bitstreams: 1 ThaisPaiva.pdf: 594078 bytes, checksum: dab90ce2d1146580c6639f13c540e873 (MD5) / Made available in DSpace on 2017-06-12T17:09:21Z (GMT). No. of bitstreams: 1 ThaisPaiva.pdf: 594078 bytes, checksum: dab90ce2d1146580c6639f13c540e873 (MD5) Previous issue date: 2016-07-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Contaminated waters not only directly affect human health but also cause serious damage to the aquatic biota, causing deterioration in fish quality. The objective was to evaluate the hygienic-sanitary conditions of the water and the fresh fish from the Mearim river in BacabalMa during the rainy season, through the identification of the potentially pathogenic bacteria. A total of 54 samples of water and 54 samples of fresh fish that were colected between October 2015 and March 2016, which were submitted to the quantification of total and thermo tolerant coliformes by the thechnique of Most Probable Number (MPN/g) and Clostridium sulphite reducing research. After that, the biochemical identification of isolated bacteria coming from the Enterobacteriaceae family was performed using commercial biochemical tests. The results showed that the microbiological quality of the water and the fish is unsatisfactory due to the high contamination rates of thermotolerant coliforms, being below the microbiological quality standards, as well as the the presence of total coliforms and Clostridium sulphite reducers in considerable concentrations both in water and in fish. The water’s contamination by coliforms was significantly higher than in the fishes, in the dry season as well as in the rainy season. Escherichia coli was the bacterium with the highest frequency of isolation in water samples, both in the dry season and in the rainy season. Citrobacter diversus and Serratia odorífera also had important isolation frequency in the water samples of the two seasons. In the fish samples, the highest frequency of identification was also from Escherichia coli. Serratia odorífera and Citrobacter diversus also had relevant frequencies in the dry season. In the rainy season Escherichia coli kept the highest frequency of isolation, followed by Serratia odorífera and Citrobacter freundii. / Águas contaminadas não só afetam diretamente a saúde humana como também causam sérios danos à biota aquática, provocado deterioração na qualidade dos peixes. Objetivou-se avaliar as condições higiênico-sanitárias da água e dos peixes frescos oriundos do rio Mearim, Bacabal/MA, no período seco e chuvoso, através da identificação de bactérias potencialmente patogênicas. Foram analisadas 54 amostras de água e 54 amostras de peixes frescos coletadas no período de outubro de 2015 a março de 2016, as quais foram submetidas à quantificação de coliformes totais e termotolerantes pela técnica do Número Mais Provável (NMP/g) e pesquisa de Clostridium sulfito redutor. Em seguida a identificação bioquímica das bactérias isoladas da família Enterobacteriaceae foi realizada utilizando testes bioquímicos comerciais. Os resultados mostraram que a qualidade microbiológica da água e dos peixes estava insatisfatória, devido aos elevados índices de contaminação por coliformes termotolerantes, estando fora dos padrões de qualidade microbiológica exigidos pelas legislações vigentes, e pela presença de coliformes totais e Clostridium sulfito redutores. A contaminação da água por coliformes foi significativamente maior que nos peixes, tanto no período seco quanto no chuvoso. Escherichia coli foi a bactéria com maior frequência de isolamento nas amostras de água, tanto no período seco quanto no chuvoso. Citrobacter diversus e Serratia odorífera também tiveram importante frequência de isolamento nas amostras de água dos dois períodos. Nas amostras de peixes a maior frequência de identificação também foi de Escherichia coli. Serratia odorífera e Citrobacter diversus também tiveram frequências relevantes no período seco. No período chuvoso Escherichia coli manteve-se com maior frequência de isolamento, seguida de Serratia odorífera e Citrobacter freundii.

No description available.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Made available in DSpace on 2016-01-13T13:27:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-07-28. Added 1 bitstream(s) on 2016-01-13T13:33:18Z : No. of bitstreams: 1 000855548.pdf: 1685828 bytes, checksum: e3301ca45c4c1e600e9478296606f770 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A indústria de polpa de celulose kraft de eucalipto no Brasil possui grande importância para a economia do setor de celulose e papel. Os parâmetros de carga alcalina e de temperatura devem ser controlados durante o processo de polpação e otimizados para que se obtenha polpa de alta qualidade e alto rendimento. A etapa de refino é uma das que mais consome energia nas indústrias e deve ser bem controlada para a economia de custos, podendo-se atrelar as variáveis de cozimento com a necessidade de refino da polpa. Deste modo, o objetivo deste estudo é avaliar a influência da carga alcalina e da temperatura da polpação kraft de eucalipto na branqueabilidade e refino. O material utilizado foi uma amostra de cavacos de Eucalyptus grandis x E. urophylla. Os cavacos foram caracterizados e submetidos a cozimentos com as temperaturas de 155 °C, 160 °C e 165 °C, e para cada um deles, foi aplicada a carga alcalina para que se obtivesse polpas com número kappa de 13, 15 e 17. Posteriormente, parte das amostras foi branqueada pela sequência OAHTD(Ep)D. Ambas polpas, branqueada e nãobranqueada, foram refinadas em moinho PFI para diferentes níveis de refino e realizados testes físico-mecânicos. Este trabalho está dividido em quatro Capítulos, a saber: (1) avaliação do efeito da temperatura e da carga alcalina na classificação de fibras, refino e testes físicomecânicos da polpa marrom; (2) impacto da polpação na branqueabilidade e no refino da polpa celulósica branqueada de eucalipto; (3) potencial da sequência curta de branqueamento AHTDP de polpa kraft de eucalipto para a obtenção de 90% ISO de alvura; (4) composição química da lignina residual de polpas kraft de eucalipto, provenientes de cozimentos realizados em 155, 160 e 165 °C por métodos da oxidação por nitrobenzeno e ressonância magnética nuclear (RMN)... (Resumo completo, clicar acesso eletrônico abaixo) / The eucalyptus kraft industry in Brazil has great importance for the sectors economy. The alkali charge and temperature parameters must be controlled during the kraft pulping and optimized in order to obtain high quality and high yield pulp. The refining is the process that consumes most energy in the mill and should be well controlled to the capital reduction. Thus, the aim of this study is to evaluate the influence of alkali load and final temperature of eucalyptus kraft pulping on refining and bleachability. Eucalyptus grandis x E. urophylla chips were characterized and cooked to different temperatures of 155 °C, 160° and 165 °C, and for each of them, the alkali charge that was applied to obtain pulps with a kappa number of 13, 15 and 17. Subsequently, part of the samples was bleached by the sequence OAHTD(Ep)D. Both bleached and unbleached pulps were refined in PFI mill and physical and mechanical tests were performed. This work is divided into four chapters, namely: (1) evaluation of temperature, alkali charge and its influence on fiber fractionation, refining and physical-mechanical testing; (2) the impact of the pulping parameters on its bleachability and refining; (3) the potential of a short sequence bleaching, AHTDP, of kraft eucalyptus pulp to 90% ISO brightness; (4) analysis of the chemical composition of the residual lignin in kraft eucalyptus pulp by nitrobenzene oxidation and nuclear magnetic resonance (NMR). The main conclusions of these chapters are: Chapter 1: lower cooking temperatures are beneficial to the cooking performance, selectivity, viscosity, and preservation of xylans. The use of low alkalinity in pulping increased the mechanical strength of the paper due to better preservation of carbohydrates; the final cooking temperature did not affect the refining with the same intensity as the alkali charge; Chapter 2: higher ... (Complete abstract click electronic access below)

Orientador: Gustavo Ventorim / Coorientador: José Cláudio Caraschi / Banca: Augusto Batagin Neto / Banca: Claudio Angeli Sansigolo / Banca: Dalton Longue Júnior / Banca: Danielle Goveia / Este trabalho contou com o depósito de Patente no instituto Nacional de Propriedade Industrial sob número de registro BR1020140166920 em 04/jul/2014, através da Agencia Unesp de Inovação / Resumo: A indústria de polpa de celulose kraft de eucalipto no Brasil possui grande importância para a economia do setor de celulose e papel. Os parâmetros de carga alcalina e de temperatura devem ser controlados durante o processo de polpação e otimizados para que se obtenha polpa de alta qualidade e alto rendimento. A etapa de refino é uma das que mais consome energia nas indústrias e deve ser bem controlada para a economia de custos, podendo-se atrelar as variáveis de cozimento com a necessidade de refino da polpa. Deste modo, o objetivo deste estudo é avaliar a influência da carga alcalina e da temperatura da polpação kraft de eucalipto na branqueabilidade e refino. O material utilizado foi uma amostra de cavacos de Eucalyptus grandis x E. urophylla. Os cavacos foram caracterizados e submetidos a cozimentos com as temperaturas de 155 °C, 160 °C e 165 °C, e para cada um deles, foi aplicada a carga alcalina para que se obtivesse polpas com número kappa de 13, 15 e 17. Posteriormente, parte das amostras foi branqueada pela sequência OAHTD(Ep)D. Ambas polpas, branqueada e nãobranqueada, foram refinadas em moinho PFI para diferentes níveis de refino e realizados testes físico-mecânicos. Este trabalho está dividido em quatro Capítulos, a saber: (1) avaliação do efeito da temperatura e da carga alcalina na classificação de fibras, refino e testes físicomecânicos da polpa marrom; (2) impacto da polpação na branqueabilidade e no refino da polpa celulósica branqueada de eucalipto; (3) potencial da sequência curta de branqueamento AHTDP de polpa kraft de eucalipto para a obtenção de 90% ISO de alvura; (4) composição química da lignina residual de polpas kraft de eucalipto, provenientes de cozimentos realizados em 155, 160 e 165 °C por métodos da oxidação por nitrobenzeno e ressonância magnética nuclear (RMN)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The eucalyptus kraft industry in Brazil has great importance for the sectors economy. The alkali charge and temperature parameters must be controlled during the kraft pulping and optimized in order to obtain high quality and high yield pulp. The refining is the process that consumes most energy in the mill and should be well controlled to the capital reduction. Thus, the aim of this study is to evaluate the influence of alkali load and final temperature of eucalyptus kraft pulping on refining and bleachability. Eucalyptus grandis x E. urophylla chips were characterized and cooked to different temperatures of 155 °C, 160° and 165 °C, and for each of them, the alkali charge that was applied to obtain pulps with a kappa number of 13, 15 and 17. Subsequently, part of the samples was bleached by the sequence OAHTD(Ep)D. Both bleached and unbleached pulps were refined in PFI mill and physical and mechanical tests were performed. This work is divided into four chapters, namely: (1) evaluation of temperature, alkali charge and its influence on fiber fractionation, refining and physical-mechanical testing; (2) the impact of the pulping parameters on its bleachability and refining; (3) the potential of a short sequence bleaching, AHTDP, of kraft eucalyptus pulp to 90% ISO brightness; (4) analysis of the chemical composition of the residual lignin in kraft eucalyptus pulp by nitrobenzene oxidation and nuclear magnetic resonance (NMR). The main conclusions of these chapters are: Chapter 1: lower cooking temperatures are beneficial to the cooking performance, selectivity, viscosity, and preservation of xylans. The use of low alkalinity in pulping increased the mechanical strength of the paper due to better preservation of carbohydrates; the final cooking temperature did not affect the refining with the same intensity as the alkali charge; Chapter 2: higher ... (Complete abstract click electronic access below) / Doutor