KINETICS OF Na⁺-H−ION EXCHANGE IN CONCENTRATED BUFFER SOLUTIONS OF SODIUM TETRABORATE AND BORIC ACID

Abstract

Na⁺-H⁺ ion exchange between a fixed bed of Lewatite S 100 cationic ion exchange resin in R-H form and concentrated NaCl solutions at room temperature (298 K) and sodium tetraborate solutions at elevated temperature (338 K) was studied both experimentally and theoretically.

In the prediction of the break-through curves intraparticle and film diffusion resistances were considered. The variation of diffusion coefficient with the composition of the solid and liquid phases was accounted for by application of a Nernst-Planck model.

The shape of the break-through curves is very different in the two systems studied. A very favourable shape in the case of Na⁺-H⁺ ion exchange from sodium tetraborate solutions is due to the influence of borate buffer properties on equilibrium. The results of the computer simulation are in good agreement with the experimental data.

KEYWORDS:

• Kinetics
• Ion-exchange
• Concentrated buffer.