Pectin-[(3-acrylamidopropyl) trimethylammonium chloride-co-acrylic acid] hydrogel prepared by gamma radiation and selectively silver (Ag) metal adsorption

Pectin-[(3-acrylamidopropyl) trimethylammonium chloride-co-acrylic acid] hydrogel has been prepared from the aqueous blend solution of pectin, (3-acrylamidopropyl) trimethylammonium chloride (APTAC), and acrylic acid (AAc) by applying gamma radiation of different doses (1–25 kGy) from ⁶⁰Co gamma source. The hydrogels were characterized by equilibrium swelling, Fourier transform infrared, differential scanning calorimetry, and scanning electron microscopy. The hydrogels were used in multielement adsorption and it was found that pectin-(APTAC-co-AAc) gel is highly selective toward silver (I) ion among 27 metal ions. The data obtained from equilibrium adsorption studies were fitted in Langmuir and Freundlich adsorption isotherm models and model parameters evaluated. The maximum adsorption capacity of pectin-(APTAC-co-AAc) gel was found to be 67.6413 mg/g of dry gel at sample volume of 25 mL. The kinetic data were tested using pseudo-first order and pseudo-second order kinetic models and different adsorption diffusion models such as film diffusion and intra-particle diffusivity model. Thiourea solution was used for desorption of adsorbed metal ions from the hydrogel.