Separation and preconcentration of some heavy-metal ions using new chelating polymeric hydrogels

• Published in: Journal of applied polymer science Vol. 113; no. 2; pp. 1335 - 1344
• Main Authors: Sharaf, Mohamed A, Arida, Hassan A, Sayed, S.A, Younis, Ahmed A, Farag, A.B
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.07.2009; Wiley
• Subjects: addition polymerization; Applied sciences; copolymerization; Crosslinking; Entropy; Exact sciences and technology; functionalization of polymers; graft copolymers; Hydrogels; Isotherms; Organic polymers; Physicochemistry of polymers; Polyacrylamides; Properties and characterization; Solution and gel properties; Sorption; Zinc; copolymerization; Organic dithiocarbamate; Adsorption isotherm; graft copolymers; Metal ion; Acrylamide derivative copolymer; pH effect; Experimental study; Sulfur copolymer; Functional polymer; Colloidal gel; Chemical modification; Binding capacity; Ionic selectivity; Preparation; addition polymerization; functionalization of polymers; Complexing ion exchanger; Hydrogel; crosslinking
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.30137

Two new chelating polymeric hydrogels, crosslinked polyacrylamide/triethylenetetraamine/CS₂Na (hydrogel I) and crosslinked polyacrylamide/diethylenetriamine/CS₂Na (hydrogel II), were prepared by the transamidation and dithiocarbamylation of crosslinked polyacrylamide. The products were characterized with elemental analysis and IR spectroscopy. In both polymeric hydrogels, the optimum pH for the removal of Cd(II), Pb(II), and Zn(II) ions ranged from 7 to 8, from 6 to 7, and from 7 to 8, respectively. The sorption isotherms of the investigated metal ions on the prepared hydrogels were developed, and the equilibrium data fitted the Langmuir and Freundlich isotherm models well. At the optimum pH for each metal ion, the maximum sorption capacities of hydrogel I toward Cd(II), Pb(II), and Zn(II) ions, estimated from the Langmuir model, were 5.3, 0.63, and 1.27 mmol/g, respectively, and those of hydrogel II were 4.1, 0.59, and 0.89 mmol/g, respectively. The experimental sorption capacities of hydrogel I toward Cd(II), Pb(II), and Zn(II) ions were 4.5, 0.6, and 1.2 mmol/g, respectively. In the case of hydrogel II, the capacities were 3.7, 0.52, and 0.88 mmol/g in the same prescribed order. The thermodynamic parameters (the free energy of sorption, enthalpy change, and entropy change) for cadmium, lead, and zinc sorption on the prepared polymers were also determined from the temperature dependence.