Synthesis of some anion exchange resins for selective separation of 99Mo and 131I: A comparative study

Abstract

ABSTRACT Amination of styrene-divinylbenzene (SDVB) copolymers is a traditional process for preparing strong anion exchange resins that can greatly improve their performance and applications. In the present investigation, poly(styrene-co-divinyl benzene) copolymers functionalized by various amino groups were synthesized by the amination route. The performance of synthesized exchange resins for the separation and recovery of active Mo(VI) and I(I) isotopes from their aqueous solutions was compared to that of three commercial ion exchange resins, used in the actual production of these radioisotopes in the Radioisotopes Production Facility. The morphology and structural properties of the synthesized copolymers as well as the commercial reference resins were characterized using FT−IR, SEM, TG, and XPS. The results demonstrate that the copolymer was successfully functionalized with amino groups, where trimethylamine produced amination greater than triethylamine. Furthermore, the thermal stability of synthesized anion exchanges was significantly higher than that of commercial beads. The synthesized polymer networks presented excellent radiation stability under applied experimental conditions. Compared to the reference resins, the synthesized co-polymeric beads showed enhanced adsorption capability for MoO4 2− and I− ions from an aqueous solution. Further, the uptake affinity of the networks aminated with trimethylamine for both radioisotopes, in optimal conditions, was greater than that of triethylamine aminated beads. The sorption mechanism was inferred through FT−IR and XPS analysis, and the results clarified that the separation of both radioisotopes was substantially related to the amine functional groups on the resin framework. The spectroscopic analysis illustrated that one molybdenum ion (in the form of MoO4 2−) was subjected to an ion-exchange interaction and two Cl− ions in the amine resin. A similar exchange mechanism was predicted for I− with Cl− ions. Further, the enhanced sorption of Mo(VI) could be additionally attained through coordination interactions with N atoms in the amine groups that have good chelating capability toward metal ions. The reusability performance of the synthesized exchange resins is better than that of the commercial reference resins, where they could be effectively regenerated for up to five cycles. Finally, this study presents a new technique for the separation and recovery of Mo(VI) and I(I) from irradiated low-enriched U-targets by employing highly promising amino-modified polystyrene-divinyl benzene microspheres.