A dynamic chitosan-based self-healing hydrogel with tunable morphology and its application as an isolating agent. Issue 84 (26th August 2016)

• Record Type: Journal Article
• Authors: Maity, Santu; Datta, Arpita; Lahiri, Susanta; Ganguly, Jhuma
• Is Part Of: RSC advances. Volume 6:Issue 84(2016)
• Page Start: 81060
• Page End: 81068
• Publication Date: 2016-08-26
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra15138h
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : A biopolymer chitosan based hydrogel with good transparency and rapid self-healing activity has been synthesized and utilized to get high purity separation of 152 Eu ( T 1/2 = 13.33 a) and 137 Cs ( T 1/2 = 30.17 a) employing SLX technique. Abstract : A biopolymer chitosan based 3D hydrogel framework (ChF) with good transparency and rapid self-healing activity has been successfully synthesized and utilized to get high purity separation of long-lived fission products 152 Eu ( T 1/2 = 13.33 a) and 137 Cs ( T 1/2 = 30.17 a) employing solid liquid extraction (SLX) technique. The unique properties of covalently cross-linked polymeric ChF have been analyzed through FT-IR, solid-state 13 CP/MAS NMR, rheological measurement, SEM, AFM, TG-DTG, DSC, XRD and swelling study. Rheological analysis reveals that the maximum mechanical strength of a hydrogel is achieved upon synthesis using 1 : 0.43 chitosan to formaldehyde stoichiometry (ChF3). A plateau of storage modulus ( G ′), over a wide range of angular frequency of ChF reveals its visco elastic nature. On varying the cross linking of the hydrogel network, we found a precise tuning of morphology and properties of ChF. This ChF was utilized to separate 152 Eu from a mixture of 152 Eu and 137 Cs in aqueous HCl medium (pH 5) using SLX technique and it was observed that ChF specifically adsorbs 152 Eu without any contamination from 137 Cs. 152 Eu was back extracted easily using 1 M aqueous HCl from 152 Eu-adsorped-ChF. The adsorption of 152 Eu on ChF is influenced by pH, amount of hydrogel, time of contact, temperature, cross-linking density and dosage of γ-radiation. To establish the self-healing property of the gels, rheological analysis through step-strain measurements (strain = 0.1 to 100%) at 25 °C was monitored. The polymeric hydrogel network displays a reversible sol–gel transition for several cycles due to the dynamic equilibrium between the Schiff base linkage and the aldehyde and amine functional groups.