Swelling behavior observation of gel resin in heavy metal adsorption process: gel resin containing sodium carboxylate

In previous researches, the adsorption process of gel resin has been described as ion exchange process. The strong hydrophilic and quick ionization property of -COONa group in solution have not been considered. Thus, this article aimed to elucidate the swelling behavior of gel resin in heavy metal solution, in which the active adsorption site was -COONa group. The experimental conditions included initial copper concentration, adding dose, reaction time, continuous adsorption, and regeneration experiment. Three indexes, including adsorption capacity, released sodium ion amounts, and water absorbency, were measured simultaneously. The results exhibited that the dried resin particles swelled quickly once immersing in heavy metal solution. When the adsorption saturation condition was not reached, gel resin absorbed water molecules and existed as the swelled particles. Significant negative correlation was found between adsorption capacity and water absorbency. The heavy metal adsorption process occurred in tandem with the initial water absorption and subsequent water loss processes. Up until the saturation point of heavy metal adsorption, the slow release of sodium ions and water molecules from the inflated gel was seen. The study findings offer a thorough grasp of gel resin adsorbing heavy metals and absorbing water molecules tendencies.