بررسي پتانسيل هيدروژل مبتني بر كاراگينان براي جذب يونهاي فلزات سنگين از پسآب

In this study, carrageenan-based hydrogel was investigated as efficient adsorbents for the removal of heavy metal ions. Gelation of carrageenan occurs due to the double-helical structure of polysaccharide chains an‎d their ability to form stable networks in the presence of suitable cations an‎d temperature. To enhance stability an‎d adsorption capacity, carboxymethyl κ-carrageenan an‎d phosphorylated carboxymethyl cellulose were synthesized an‎d subsequently grafted with acrylic acid using N,N’-methylenebisacrylamide as a crosslinker an‎d ammonium persulfate as an initiator, resulting in the formation of a three-dimensional hydrogel structure. The prepared hydrogel an‎d its properties were characterized using TGA, FE-SEM, FT-IR, NMR, an‎d rheological analyses. In addition, optimal parameters such as initial metal ion concentration, contact time, pH, temperature, an‎d selec‎tivity were eva‎luated. The maximum adsorption capacities of the hydrogel for Pb²⁺ an‎d Tl⁺ were found to be 530 an‎d 420 mg g⁻¹, respectively. Adsorption isotherms for Pb²⁺ were best described by the Langmuir model, while those for Tl⁺ followed the Freundlich model. The adsorption behavior of both metals was consistent with the pseudo-second-order kinetic model. Thermodynamic parameters indicated that the adsorption process was spontaneous an‎d exothermic. Finally, the reusability test demonstrated that the hydrogel retained up to 99% of its adsorption capacity after 7 cycles.

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