asefe Mousavi Moghadam - Chemical Engineering Department, Tarbiat Modares University, P.O. Box: ۱۴۱۱۵-۱۱۴, Tehran, Iran.
Mahsa Baghban Salehi - Chemical Engineering Department, Tarbiat Modares University, P.O. Box: ۱۴۱۱۵-۱۱۴, Tehran, Iran.
Mohsen Vafaie Seftie - Chemical Engineering Department, Tarbiat Modares University, P.O. Box: ۱۴۱۱۵-۱۱۴, Tehran, Iran.
Ahmad Dadvand Koohi - Chemical Engineering Department, Guilan University, P.O. Box ۱۸۴۱, Rasht, Iran

In this study, preformed particle gel was prepared from a hydrogel crosslinking of an aqueous solution containing chromium acetate (III) and the co-polymer of 2-acrylamido-2methylpropanesulfonic- acid sodium salt (AMPS) and acrylamide (PAMPS). The effects of CaCl2 concentration and pH were investigated on swelling behavior. In order to determine the significant factors that affect the equilibrium swelling ratio and also to develop the quadratic mathematicalmodels, central composite design (CCD), the most popular form of Response Surface Methodology (RSM), was applied. Therefore, the main purpose was to establish functionalrelationship between the two factors and the equilibrium swelling ratio by using a statisticaltechnique. The results of analysis of variance (ANOVA) of the developed model illustrated that the fitted model was significant in 99% confidence limit. The results were also shown that theequilibrium swelling ratios depended more on CaCl2 concentration than pH and also there was an interaction between these two factors.

preformed particle gel, equilibrium swelling ratio, central composite design