Graphene fiber and its silver functionalization for radioactive iodine adsorption

Abstract

The efficient capture of radioiodine produced from used nuclear fuel reprocessing is now a days growing priority in the field of research and development of nuclear waste management. The aqueous reprocessing of used nuclear fuel (UNF), which involves dissolving in nitric acid (PUREX process), is the major source of radioiodine $^{129}I$. $^{129}I$ is greatest environment concern because it has long half-life of 1.6$\times$$10^7$y and potential incorporation into the human body. For the efficient capture of $^{129}I$, solid sorbents gained more attraction than wet scrubbing method. This work proposed reduced graphene oxide fiber (rGO) as an effective solid sorbent. rGO fibers are fabricated by wet spinning process from GO dispersion and reduced by L-ascorbic acid. Silver functionalized rGO fibers (Ag/rGO) are produced by dipping GO fibers in silver nitrate ($AgNO_3$) solution. Iodine adsorption experiment is conducted in closed iodine saturated environment at $150^\circ C$ temperature and ambient pressure. Both rGO and Ag/rGO shows excellent adsorption efficiency where the presence of iodine is more than 50wt%. rGO fibers capture iodine through physisorption process whereas chemical adsorption happens beside physisorption in Ag/rGo fiber. Physisorption characteristics of rGO fibers allows it to be used for multiple times. Ag/rGO may provide better selectivity at real environment and low desorption of iodine at higher temperature due to the chemical adsorption