Resumo

MARTINEZ, Karina et al. Kinetics of ion-exchange in raw and commercial pasteurized milkCinética de intercambio iónico en leche cruda y pasteurizada comercial. Rev. Téc. Ing. Univ. Zulia [online]. 2006, vol.29, n.2, pp.182-193. ISSN 0254-0770.

In this work the ion-exchange kinetics of Ca⁺⁺-Na⁺ system in raw and pasteurized milk was determined by decreasing the sodium, and increasing the calcium levels in milky media. The kinetics data of the ionic systems were fitted by the Fick’s law with a variable diffusion coefficient expressed by the Gilliland model. The experimental methodology involved the use of batch tests under agitation, constant temperature, between sample milk and cationic resin type Ionac C-249, during a contact period of 6 hours. The ion-exchange reactions were followed by sampling the liquid phase every one hour. In the milky phase the concentrations of sodium and calcium were determined by spectrophotometry of atomic absorption. The results show that the exchange of Na⁺ ions into resin presents a distribution pattern S and the kinetics can be expressed by Gilliland model as , on the other hand, the exchange of Ca⁺⁺ ions presents a distribution pattern C and the kinetics given by .

Palavras-chave : Ion-exchange kinetics; Ca⁺⁺-Na⁺ system; ion exchange in milk.