Gamma radiation synthesis of hydroxyethyl cellulose/acrylic acid/CYANEX 471X hydrogel for silver ions capture from acidic nitrate medium

AbstractThe current novelty in this study is to recover silver ion with selective extractant such as cyanex 471X (triisobutylphosphine sulfide) through a clean and green method with high efficiency. Herein, a sustainable hydrogel (HEC/AAc/CX3) was fabricated from triisobutylphosphine sulfide, hydroxyethyl cellulose (HEC), and acrylic acid (AAc) using gamma irradiation polymerization and implanted for the sorption of silver Ag (I) ions from a nitrate acidic medium. Different techniques were employed for characterization of HEC/AAc/CX3 hydrogel such as FT-IR, SEM, XRD, and EDX, before and after the sorption process of Ag(I) ions. Gel content and swelling kinetics ratio of hydrogels at different irradiation doses (10, 20, 30, 40, and 50 kGy) were studied. The Fickian diffusion model results indicate that HEC/AAc/CX3 hydrogel is non-Fickian diffusion, which confirmed that the diffusion and relaxation rates are compatible and were selected for further sorption of Ag(I). The irradiated HEC/AAc/CX3 hydrogels, which contain 0.1 g of cyanex 471X, were employed for batch sorption of 100 mg/L Ag(I) from an acidic solution, and the suggested conditions were pH = 1, time = 60, and v/m = 0.05 L/g, which gives a sorption percentage of 75%. The values of thermodynamic parameters ΔH, ΔG, and ΔS were evaluated as—62.80 kJ/mol, 5 kJ/mol, and -227 J/mol, which indicate that the sorption system was exothermic and nonspontaneous in nature. The maximum adsorption capacity of irradiated HEC/AAc/CX3 for Ag(I) was found to be 12 mg. g−1 at 298 K. Furthermore, the maximum desorption percent of Ag ions from HEC/AAc/CX3 was found to be 70% and achieved with 0.5 M NH4SCN after one desorption cycle. The prepared hydrogel proved its selectivity towards silver ions with facile desorption steps and reusability cycles. Graphical Abstract