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Estudos sôbre a neutralização do caldo de cana nas usinas de açúcar: I - determinação do CaO e MgO totais e CaO disponível da Cal

Resumos

Neste trabalho, que faz parte de uma série de pesquisas relacionadas com a neutralização do caldo de cana nas usinas de açúcar, é descrita a técnica de determinação quelatométrica do CaO e MgO totais e CaO disponível da cal. Os resultados fornecidos pela técnica preconizada foram comparados com aqueles obtidos através do emprêgo de métodos usuais. São também apresentados os primeiros estudos efetuados a respeito da capacidade neutralizadora da cal, em função do seu teor em oxido de calcio total e disponível, quando empregada na forma solida, na neutralização do caldo de cana.


This paper is the first of several papers about the studies of neutralization of sugar cane juice, after treatment with SO2 in the cane sugar fabrication. The present work reports a study about the chelatometric method for the determination of total calcium oxide and magnesium oxide of lime and the available lime. The proposed method (by EDTA titration) for determining available lime was compared with the method based on sulfuric acid titration, with good agreement. The results showed that the chelatometric method is rapid and affords good precision. For the study about the neutralization of sugar cane juice, after treatment with SO2, were employed samples of lime containing several per cent of available lime. The quantities of lime to be added, to one liter of treated juice, was calculated based in the total calcium oxide of the lime. The solid samples of lime were added to the juice slowly and the material shaken intermittently during the period of fifteen minutes after the addition of lime. The pH was determined both 15 minutes and 2 1/2 hours after the addition of lime. Them it was brought to ebullition, cooled at room temperature and the pH was again determined. The results permit to conclude that the samples containing small amounts of available lime showed the poorest neutralization. Even with samples containing high percentage of available lime it was not possible to obtain a juice with pH 7,0 after the treatment, probably due to the presence of carbonates in the samples of lime. This study showed that the principal characteristic of lime to be employed in the juice neutralization is the available lime.


IDepartamento de Química da ESALQ

IIDepartamento de Tecnologia Rural da ESALQ

RESUMO

Neste trabalho, que faz parte de uma série de pesquisas relacionadas com a neutralização do caldo de cana nas usinas de açúcar, é descrita a técnica de determinação quelatométrica do CaO e MgO totais e CaO disponível da cal. Os resultados fornecidos pela técnica preconizada foram comparados com aqueles obtidos através do emprêgo de métodos usuais. São também apresentados os primeiros estudos efetuados a respeito da capacidade neutralizadora da cal, em função do seu teor em oxido de calcio total e disponível, quando empregada na forma solida, na neutralização do caldo de cana.

SUMMARY

This paper is the first of several papers about the studies of neutralization of sugar cane juice, after treatment with SO2 in the cane sugar fabrication. The present work reports a study about the chelatometric method for the determination of total calcium oxide and magnesium oxide of lime and the available lime.

The proposed method (by EDTA titration) for determining available lime was compared with the method based on sulfuric acid titration, with good agreement. The results showed that the chelatometric method is rapid and affords good precision.

For the study about the neutralization of sugar cane juice, after treatment with SO2, were employed samples of lime containing several per cent of available lime. The quantities of lime to be added, to one liter of treated juice, was calculated based in the total calcium oxide of the lime. The solid samples of lime were added to the juice slowly and the material shaken intermittently during the period of fifteen minutes after the addition of lime. The pH was determined both 15 minutes and 2 1/2 hours after the addition of lime. Them it was brought to ebullition, cooled at room temperature and the pH was again determined.

The results permit to conclude that the samples containing small amounts of available lime showed the poorest neutralization. Even with samples containing high percentage of available lime it was not possible to obtain a juice with pH 7,0 after the treatment, probably due to the presence of carbonates in the samples of lime. This study showed that the principal characteristic of lime to be employed in the juice neutralization is the available lime.

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LITERATURA CITADA

Entregue para publicação em 23/3/70.

  • BUTLER, J.N., 1964 - Solubility and pH calculations. Addison-Wesley Publishing Company, Inc. Reading, Massachussets. 104 pp.
  • FREISER, H. & 0. FERNANDO, 1963 - Ionic Equilibria in Analytical Chemistry. John Wiley & Sons, Inc. New York. 334 pp.
  • GLÓRIA, N.A., R.A. CATANI & T. MATUO, 1967 - A determinação de calcio e magnesio em rochas carbonatadas pelo método do EDTA. Revista da Agricultura, 42: 65-74.
  • HONING, P., 1953 - Principles of Sugar Technology. Vol. 1. Elsevier Publishing Co., Amsterdan. 767 pp.
  • MEAD, G.P., 1967 - Manual del Azúcar de Caña. Traduzido por Mário G. Menocal. Montaner y Simon, Barcelona. 940 pp.
  • MOELLER, T., 1958 - Qualitative Analysis. 1st ed. McGraw-Hill Book Company, Inc., New York. 550 pp.
  • PUERTAS, R.P., 1952 - Manual para el laboratorio azucarero. Editorial Técnico Azucarero, Havana. 371 pp.
  • SCOTT, W.W., 1955 - Standards Methods of Chemical Analysis. 5th ed. Vol. I, D. Van Nostrand Company, Inc., New York. 1234 pp.
  • STANLEY, G.S., 1937 - The iodimetric determination of alkali. Analyst, 62: 590-596.
  • STOHMANN, F. & K. BRUNO (ed.), 1930 - Gran Enciclopedia de Química Industrial. Tomo V. Francisco Seix-Editor, Barcelona. 872 pp.
  • Estudos sôbre a neutralização do caldo de cana nas usinas de açúcar: I - determinação do CaO e MgO totais e CaO disponível da Cal

    N.A. da GlóriaI; A.A. DelgadoII
  • Datas de Publicação

    • Publicação nesta coleção
      11 Jun 2012
    • Data do Fascículo
      1970
    Universidade de São Paulo, Escola Superior de Agricultura Av.Páduas Dias, 11, C.P 9 / Piracicaba - São Paulo, Brasil, tel. (019)3429-4486, (019)3429-4401 - Piracicaba - SP - Brazil
    E-mail: scientia@esalq.usp.br