An empirical kinetic model for calcium removal from calcium impurity-containing saturated boric acid solution by ion exchange technology using Amberlite IR–120 resin

In this study, the use of Amberlite IR–120, a strong acidic cation exchange resin, was investigated to remove calcium impurity from saturated boric acid solutions. Calcium impurity arised from high calcium content of colemanite ore is a very important problem as it increases impurity on the boric acid crystals. Ion exchange experiments were carried out in batch mode as a function of solution pH, resin-to-solution ratio, temperature, and resin contact time. Optimum operation conditions were determined as pH 1.5, resin-to-solution ratio 6.174 g/250 mL, temperature 303 (K), contact time 20 min and, in those conditions maximum calcium removal was about 99%. Also, data calculated by a mass balance equation were employed with the pseudo-first-order and the pseudo-second-order equations. It was determined that the pseudo-second-order equation was the best fitting kinetic equation with a correlation range of 0.991–1. Furthermore, an empirical kinetic model was developed to predict operational conditions of the batch process in the following form; t/qt = 6.1452 × (S/L)0.8903 × [H+]−0.00094 × exp(−31.2181/T) × [C0]−0.7319 × t0.9567.