Preformed Particle Gel: Effects of Calcium Chloride and pH on Equilibrium Swelling Ratio by Using Response Surface Methodology

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 mathematical models, central composite design (CCD), the most popular form of Response Surface Methodology (RSM), was applied. Therefore, the main purpose was to establish functional relationship between the two factors and the equilibrium swelling ratio by using a statistical technique. 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 the equilibrium swelling ratios depended more on CaCl2 concentration than pH and also there was an interaction between these two factors.