Swelling properties and basic dye adsorption studies of polyacrylamide hydrogel

This study regrouped the swelling of polyacrylamide (PAAM) hydrogel and the use of this hydro gel in the removal of Safranine (SF) basic dye from an aqueous solution. The swelling experiments results show that the swell ratio of this hydrogel depends on several parameters: the presence of salts, the temperature, and the pH of the medium. Indeed, in the presence of distilled water only the polymer is capable of retaining its macromolecular chains more than 100 times its weight in water. On the other hand, the adsorption process of SF dye by PAAM polymer was investigated using independent variables namely initial pH, dye ion concentration, temperature, and adsorbent dosage. SF adsorption capacity of PAAM hydrogel is found to be 620 mg/g and the equilibrium is obtained after 3 h. The adsorption process could be well described by the Langmuir isotherm and pseudo-first order model in both linear and non-linear regressions. The adsorption was analyzed thermodynamically and the results revealed that the adsorption process was spontaneous and endothermic.