Application of Mathematical Model of Three Parameters in Prediction of Sorption Isotherms for Four New Water Absorbent

Equilibrium Moisture Contents (EMC) of 4 new water absorbents were determined at 4 C by equilibrating about 1.6g samples at relative humidities in range of 0-100%, obtained using saturated salt solutions. The isotherms of new water absorbent were of BET type II. The results showed that the new water absorbent have an important capacity for water absorbed. The new water absorbent 3 has the biggest capacity for water absorbed at high water activity (aw>0.9). The amount of water absorbed by their product always reached 145 g H2O / 100 g dry basis. The GAB equation was evaluated for his ability to fit the experimental data for the 4 types of new water absorbent. A non-linear least square regression program was used to evaluate the model constants. The GAB equation gave the best fit to the experimental data of water absorbent 3. The predicted safe storage moisture contents of new water absorbent 1, 2, 3 and 4 were 20.113, 149.356, 28.359, 21.582% (d.b.), respectively.