BRANQUEAMENTO COM OZÔNIO EM PH NEUTRO - UM NOVO CONCEITO

Carvalho, Fernando de; Asbahr, Denis; Godoy, Antonio A. R.; Colodette, Jorge Luiz

doi:10.5902/198050981889

RESUMO

Foram avaliados o efeito do pH da ozonólise, a média consistência, em amostras industriais (fibra curta de eucalipto) de polpa marrom e pré-deslignificada com oxigênio (pré-O2) obtidas na VCP - Unidade Luiz Antônio, tratadas ou não com um estágio de hidrólise ácida (A). O objetivo principal do estudo foi determinar a viabilidade de se elevar o pH da etapa da ozonólise, visando a reduzir o custo variável de fabricação. O estágio da ozonólise foi estudado numa ampla faixa de pH (2,5-9,0), considerando-se alguns fatores importantes: (1) número kappa da polpa que entra na ozonólise, (2) tratamento da polpa previamente à ozonólise (hidrólise ácida), (3) tratamento da polpa após a ozonólise (extração, dioxidação) e (4) relação lignina/HexA´s que compõe o número kappa. Assim, o pH da ozonólise foi investigado em processos de branqueamento tais como Z/DEopD e AZ/DEopD, Z/E e AZ/E, Z/DEop e AZ/DEop. Os resultados foram interpretados com base na eficiência, seletividade da ozonólise e na performance global do branqueamento, medida pelo consumo de reagentes químicos, qualidade da polpa e impacto ambiental. Concluiu-se que o aumento do pH da ozonólise de 2,5 para 7,0 tem impacto ligeiramente negativo na eficiência e na seletividade do processo, medidas após Z/DEop, mas esse efeito desaparece ao final do branqueamento pela seqüência Z/DEopD. A elevação do pH de 2,5 para 7,0 é justificável em nível industrial, visto que representa redução apreciável dos consumos de ácido sulfúrico e soda caústica para controle de pH na planta de branqueamento. O aumento do pH da ozonólise de 2,5 para 7,0 tem impacto muito negativo na eficiência e na seletividade dos processos Z/E e AZ/E.

Palavras-chave:
polpa ligno-celulósica; ozônio; ácidos hexenurônicos; hidrólise ácida

ABSTRACT

The effect of medium consistency ozone stage pH was evaluated for brown and oxygen delignified eucalyptus kraft pulp samples obtained from VCP - Luiz Antônio pulp mill. These samples were used as such or previously treated with the hot acid stage (A). The main objective of this study was to determine the viability of increasing the ozone stage pH aiming at decreasing bleaching variable costs. The ozone stage was studied in the pH range of 2.5-9.0, taking into account some important variables which affect ozone bleaching: (1) pulp kappa number entering the ozone stage, (2) reactivity of ozone towards lignin versus hexenuronic acids (HexA´s), (3) pulp treatments prior to ozone stage (acid hydrolysis), and (4) pulp treatments after the ozone stage (extraction or a chlorine dioxide stage). Therefore, the impact of ozone stage pH was investigated in bleaching process such as Z/DEop vs AZ/DEop, Z/DEopD vs AZ/DEopD, Z/E vs AZ/E. The results were interpreted based on ozone stage efficiency and selectivity, and overall bleaching performance measured by the total bleaching chemical consumption required to achieve full brightness, pulp quality and environmental impact. It was concluded that the increase of ozone stage pH from 2.5 to 7.0 has a slightly negative impact on the efficiency and selectivity, measured after Z/DEop sequence, but this effect is not expressive in the end of Z/DEopD bleaching sequence. The increase of ozone stage pH from 2.5 to 7.0 in the sequence Z/DEopD is cost-effective at industrial level because it represents expressive reduction of sulphuric acid and caustic soda demand for pH control in the bleaching plant. These gain areas achieved without any significant changes in pulp quality and effluent load discharge. Nevertheless, the increase of ozone stage pH from 2.5 to 7.0 has a very high negative impact on the efficiency and selectivity for the Z/E and AZ/E processes and it is not recommended in such cases.

Keywords:
ligno-celullosic pulp; ozone; hexenuronic acids; acid hydrolysis

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REFERÊNCIAS BIBLIOGRÁFICAS

BOUCHARD, J.; NUGENT, H.M.; BERRY, R. The role of water and hydrogen ion concentration in ozone bleaching of kraft pulp at medium consistency. Tappi Journal, v. 78, n. 1, p. 74 -78, 1995.
BROW, D.G.; ABBOT, J. Effects of metal ions and stabilizers on peroxide decomposition during bleaching. Journal Wood Chemistry Technology, v. 15, n. 1, p. 85-11, 1995.
BRYANT, P. Metals management in the fiberline. In: MINIMUN EFFLUENT MILLS SYMPOSIUM, 1996, Atlanta. Anais..., Atlanta: TAPPI, 1996, p. 95- 100.
CANADIAN PULP AND PAPER ASSOCIATION. Technical section standard test methods. Montreal, 1986.
CHIRAT, C.; LACHENAL, D. Minimizing pulp degradation during totally chlorine free bleaching sequences including an ozone stage. Pulp and Paper Journal, v. 21, n. 9, p. 316-321, 1995.
CHIRAT, C.; LACHENAL, D. Others ways to use ozone in a bleaching sequence. In: PULPING CONFERENCE, 1995, Washington. Anais..., Washington, TAPPI, 1995, p. 415- 419.
COLODETTE, J.L.; GOMIDE, J.L.; SALLES, D.V.C.; BRITO, A.S.C.H. Factors affecting kraft pulp bleachability with oxygen derived chemicals. In INTERNATIONAL NON-CHLORINE BLEACHING CONFERENCE, Orlando, 1996. Anais..., Orlando: PULP & PAPER, 1996, 20p.
COLODETTE, J.L. et al. Ozone Bleaching Research Focuses on Reducing high cost and poor selectivity. Pulp and Paper Journal , v. 67, n. 6, p. 139-145, 1993.
VAN LIEROP, B.; SKOTHOS, A.; LIEBERGOTT, N. Ozone Delignification. In: DENCE, C.W.; REEVE, D. Pulp Bleaching: principles and practice. Tappi, 1996. p. 321-345.
DEVENYNS, J.; DESPREZ, F.; TROUGHTON, N. Metals control in TCF bleaching - implications for kraft bleaching sequence design. In: PULPING CONFERENCE, 1994, San Diego. Anais... San Diego: Tappi, 1994. v. 1, p. 233-247.
ERIKSSON, T.; RAGNAR, M.; REITBERGER, T. Studies on the radicals formation in ozone reactions with lignin and carbohidrate model compounds. In: INTERNATIONAL PULP BLEACHING CONFERENCE, 1998, Finlândia. Anais..., Finlândia : SPCI, 1998, p.119-126.
ERIKSSON, T.; REITBERGER, T. Formation of hydroxyl radicals from direct ozone reactions with pulps constituents. In: INTERNATIONAL SYMPOSIUM ON WOOD AND PULPING CHEMISTRY, 1995, Helsinki. Anais... Helsinki 1995, p.349-354.
GHOSH, A. K. The role of ozone in multistage TCF bleaching process. 1996. 96p. Tese (Doutorado em Wood and Paper Science) - North Caroline University State, Raleigh, 1996.
GIERER, J. The chemistry of delignification. A general concept. Part 2. Holzforschung, v. 36, n. 1, p. 43-51, 1982.
GIERER, J.; ZHANG, Y. The role of hydroxyl radicals in ozone bleaching process. In: INTERNATIONAL SYMPOSIUM ON WOOD AND PULPING CHEMISTRY, 1993, China. Anais..., China, 1993. p. 951-960.
GODSAY, M.P. Ozone-cellulose studies: Physic-chemical properties of ozone oxidized cellulosic and lignocellulosic materials. 1985. 239p. Tese (Doutorado em Ciência e Engenharia de Polímeros) - Polytechnic Institute of New York, New York, 1985.
JACOBSON, B.; LINDBLAD, P.; NILVEBRANT, N. Lignin reactions affect the attack of ozone on carbohydrates. In: INTERNATIONAL PULP BLEACHING CONFERENCE, Estocolmo, 1991. Anais..., Estocolmo: SPCI, 1991, p.46-58.
KANG, G.; NI, Y.; VAN HEININGEN, A.R.P. Influence of transition metal ions on high consistency O3 bleaching. In: PULPING CONFERENCE, Atlanta, 1996. Anais..., Atlanta: Tappi, 1996, p. 93-97.
KANG, G.; ZHANG, Y.; NI, Y.; HEININGEN, A. Influence of lignins on the degradation of cellulose during ozone treatment. Journal of Wood Chemistry and Technology, v. 15, n. 4, p. 413-430, 1995.
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LAPIERRE, L.; BOUCHARD, J.; BERRY, R.M. Chelation prior to hydrogen peroxide bleaching of kraft pulps: An overview. Journal of Pulp and Paper Science 21(8):J268-J273. 1995.
LIEBERGOTT, N.; VAN LIEROP, B.; SKOTHOS, A. A survey of the use of ozone in bleaching pulps : Part 1. Tappi Journal , v. 75, n. 1, p. 145-152, 1992.
MAGARA, K.; IDEDA, T.; TOMIMURA, Y. Accelerated degradation of cellulose in the presence of lignin during ozone bleaching. Pulp and Paper Journal , v. 24, n. 8, p. 264-268, 1998.
MUGUET, M.; SUNDAR, M. Ozone bleaching of secondary fibers. 1996. 23p. Internal Report.
PAN, G.Y.; CHEN, C.L.; CHANG, H.M. Studies on ozone bleaching. I. The effect of pH, temperature, buffer system and heavy metal-ions on stability of ozone in aqueous solution. Journal of Wood Chemistry and Technology , v. 4, n. 3, p. 367-387, 1984.
PARTHASARTHY, V.R.; PETERSON, R.C. The decomposition of ozone in aqueous solution- Influence of pH, temperature and transition metals on the rate kinetics of ozone decomposition. In: OXYGEN DELIGNIFICATION SYMPOSIUM, Toronto, 1990. Anais..., Toronto: Tappi, 1990, p. 23-52.
RAGNAR, M. On the importance of radical formation in ozone bleaching. 2000. 94p. Thesis (Ph.D.) - Kungliga Tekniska Högskolan, Stockholm, 2000.
SHACKFORD, L.D.; MILLER, W.J.; MINAMI, S. T.C.F. Bleaching in the modern pulp mill. In: ABTCP International Workshop, 1993, São Paulo. Anais... São Paulo: ABTCP, 1995. não paginado.
SMITH, P.K.; McDONOUGH, T. J. Transition metal ions catalysis of the reaction of a residual lignin-related compound with alkaline hydrogen peroxide. Svensk Papperstindning, n. 1, p. 106-112, 1985.
SONNENBERG, L.B.; POOL, K.M. Studies of high consistency ozone delignification of oxygen bleached pulps. In: INTERNATIONAL PULP BLEACHING CONFERENCE, Vancouver, 1994. Anais... Vancouver : Tappi, 1994. p. 101-108.
TECHNICAL ASSOCIATION OF THE PULP AND PAPER INDUSTRY. Test methods. Atlanta, 1998-1999. paginação irregular.
SHACKFORD, L.D.; MILLER, W.J.; MINAMI, S. T.C.F. Bleaching in the modern pulp mill. In: ABTCP International Workshop, 1993, São Paulo. Anais... São Paulo: ABTCP , 1995. não paginado.
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Datas de Publicação

Publicação nesta coleção
Jan-Mar 2006

Histórico

Recebido
01 Dez 2004
Aceito
10 Fev 2006

Este é um artigo publicado em acesso aberto sob uma licença Creative Commons

[1] BOUCHARD, J.; NUGENT, H.M.; BERRY, R. The role of water and hydrogen ion concentration in ozone bleaching of kraft pulp at medium consistency. Tappi Journal, v. 78, n. 1, p. 74 -78, 1995.

[2] BROW, D.G.; ABBOT, J. Effects of metal ions and stabilizers on peroxide decomposition during bleaching. Journal Wood Chemistry Technology, v. 15, n. 1, p. 85-11, 1995.

[3] BRYANT, P. Metals management in the fiberline. In: MINIMUN EFFLUENT MILLS SYMPOSIUM, 1996, Atlanta. Anais..., Atlanta: TAPPI, 1996, p. 95- 100.

[4] CANADIAN PULP AND PAPER ASSOCIATION. Technical section standard test methods. Montreal, 1986.

[5] CHIRAT, C.; LACHENAL, D. Minimizing pulp degradation during totally chlorine free bleaching sequences including an ozone stage. Pulp and Paper Journal, v. 21, n. 9, p. 316-321, 1995.

[6] CHIRAT, C.; LACHENAL, D. Others ways to use ozone in a bleaching sequence. In: PULPING CONFERENCE, 1995, Washington. Anais..., Washington, TAPPI, 1995, p. 415- 419.

[7] COLODETTE, J.L.; GOMIDE, J.L.; SALLES, D.V.C.; BRITO, A.S.C.H. Factors affecting kraft pulp bleachability with oxygen derived chemicals. In INTERNATIONAL NON-CHLORINE BLEACHING CONFERENCE, Orlando, 1996. Anais..., Orlando: PULP & PAPER, 1996, 20p.

[8] COLODETTE, J.L. et al. Ozone Bleaching Research Focuses on Reducing high cost and poor selectivity. Pulp and Paper Journal , v. 67, n. 6, p. 139-145, 1993.

[9] VAN LIEROP, B.; SKOTHOS, A.; LIEBERGOTT, N. Ozone Delignification. In: DENCE, C.W.; REEVE, D. Pulp Bleaching: principles and practice. Tappi, 1996. p. 321-345.

[10] DEVENYNS, J.; DESPREZ, F.; TROUGHTON, N. Metals control in TCF bleaching - implications for kraft bleaching sequence design. In: PULPING CONFERENCE, 1994, San Diego. Anais... San Diego: Tappi, 1994. v. 1, p. 233-247.

[11] ERIKSSON, T.; RAGNAR, M.; REITBERGER, T. Studies on the radicals formation in ozone reactions with lignin and carbohidrate model compounds. In: INTERNATIONAL PULP BLEACHING CONFERENCE, 1998, Finlândia. Anais..., Finlândia : SPCI, 1998, p.119-126.

[12] ERIKSSON, T.; REITBERGER, T. Formation of hydroxyl radicals from direct ozone reactions with pulps constituents. In: INTERNATIONAL SYMPOSIUM ON WOOD AND PULPING CHEMISTRY, 1995, Helsinki. Anais... Helsinki 1995, p.349-354.

[13] GHOSH, A. K. The role of ozone in multistage TCF bleaching process. 1996. 96p. Tese (Doutorado em Wood and Paper Science) - North Caroline University State, Raleigh, 1996.

[14] GIERER, J. The chemistry of delignification. A general concept. Part 2. Holzforschung, v. 36, n. 1, p. 43-51, 1982.

[15] GIERER, J.; ZHANG, Y. The role of hydroxyl radicals in ozone bleaching process. In: INTERNATIONAL SYMPOSIUM ON WOOD AND PULPING CHEMISTRY, 1993, China. Anais..., China, 1993. p. 951-960.

[16] GODSAY, M.P. Ozone-cellulose studies: Physic-chemical properties of ozone oxidized cellulosic and lignocellulosic materials. 1985. 239p. Tese (Doutorado em Ciência e Engenharia de Polímeros) - Polytechnic Institute of New York, New York, 1985.

[17] JACOBSON, B.; LINDBLAD, P.; NILVEBRANT, N. Lignin reactions affect the attack of ozone on carbohydrates. In: INTERNATIONAL PULP BLEACHING CONFERENCE, Estocolmo, 1991. Anais..., Estocolmo: SPCI, 1991, p.46-58.

[18] KANG, G.; NI, Y.; VAN HEININGEN, A.R.P. Influence of transition metal ions on high consistency O3 bleaching. In: PULPING CONFERENCE, Atlanta, 1996. Anais..., Atlanta: Tappi, 1996, p. 93-97.

[19] KANG, G.; ZHANG, Y.; NI, Y.; HEININGEN, A. Influence of lignins on the degradation of cellulose during ozone treatment. Journal of Wood Chemistry and Technology, v. 15, n. 4, p. 413-430, 1995.

[20] LACHENAL, D.; SEVILLANO, R. M.; GEORGE, J. Understanding the structure of residual lignin. A key to process in pulping and bleaching. In: FORUM ASSOCIATE MEMBERS, 3., 1998, Grenoble. Anais..., Grenoble : CTP, 1998, 15 p.

[21] L’AIR LIQUIDE; SOCIETE ANONYME POUR I’ETUDE ET I’EXPLOITATION DES PROCEDES GEORGES CLAUDE. Jack Kogan, Michelle Steiner. Method of reducing fluorescence in deinked pulp by treating pulp with ozone and a bleaching agent. Int. CI6D21C 5/02. US Patent 5,529,660.15 April 1994; 25 june 1996.

[22] LAPIERRE, L.; BOUCHARD, J.; BERRY, R.M. Chelation prior to hydrogen peroxide bleaching of kraft pulps: An overview. Journal of Pulp and Paper Science 21(8):J268-J273. 1995.

[23] LIEBERGOTT, N.; VAN LIEROP, B.; SKOTHOS, A. A survey of the use of ozone in bleaching pulps : Part 1. Tappi Journal , v. 75, n. 1, p. 145-152, 1992.

[24] MAGARA, K.; IDEDA, T.; TOMIMURA, Y. Accelerated degradation of cellulose in the presence of lignin during ozone bleaching. Pulp and Paper Journal , v. 24, n. 8, p. 264-268, 1998.

[25] MUGUET, M.; SUNDAR, M. Ozone bleaching of secondary fibers. 1996. 23p. Internal Report.

[26] PAN, G.Y.; CHEN, C.L.; CHANG, H.M. Studies on ozone bleaching. I. The effect of pH, temperature, buffer system and heavy metal-ions on stability of ozone in aqueous solution. Journal of Wood Chemistry and Technology , v. 4, n. 3, p. 367-387, 1984.

[27] PARTHASARTHY, V.R.; PETERSON, R.C. The decomposition of ozone in aqueous solution- Influence of pH, temperature and transition metals on the rate kinetics of ozone decomposition. In: OXYGEN DELIGNIFICATION SYMPOSIUM, Toronto, 1990. Anais..., Toronto: Tappi, 1990, p. 23-52.

[28] RAGNAR, M. On the importance of radical formation in ozone bleaching. 2000. 94p. Thesis (Ph.D.) - Kungliga Tekniska Högskolan, Stockholm, 2000.

[29] SHACKFORD, L.D.; MILLER, W.J.; MINAMI, S. T.C.F. Bleaching in the modern pulp mill. In: ABTCP International Workshop, 1993, São Paulo. Anais... São Paulo: ABTCP, 1995. não paginado.

[30] SMITH, P.K.; McDONOUGH, T. J. Transition metal ions catalysis of the reaction of a residual lignin-related compound with alkaline hydrogen peroxide. Svensk Papperstindning, n. 1, p. 106-112, 1985.

[31] SONNENBERG, L.B.; POOL, K.M. Studies of high consistency ozone delignification of oxygen bleached pulps. In: INTERNATIONAL PULP BLEACHING CONFERENCE, Vancouver, 1994. Anais... Vancouver : Tappi, 1994. p. 101-108.

[32] TECHNICAL ASSOCIATION OF THE PULP AND PAPER INDUSTRY. Test methods. Atlanta, 1998-1999. paginação irregular.

[33] SHACKFORD, L.D.; MILLER, W.J.; MINAMI, S. T.C.F. Bleaching in the modern pulp mill. In: ABTCP International Workshop, 1993, São Paulo. Anais... São Paulo: ABTCP , 1995. não paginado.

[34] ZHANG, Y. et al. Degradation of wood polisaccharide model compounds during ozone treatment. Pulp and Paper Journal . v. 23, n. 1, p. 23-27, 1995.

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