Investigations of retention characteristics of persistence contaminant into eco-friendly multi-layers barrier under dynamic conditions

Cs retention characteristics onto novel eco-friendly multi-barrier were investigated under dynamic conditions that simulate different environmental conditions. In this respect, nano-clay and quartz samples were tested to optimize the design of the multi-barrier based on the hydraulic and retention performances. The morphology, particle size distribution, mineralogical structure, zeta potential, chemical structure and function groups were investigated. Nano clay is composed of a mixture of Mica, Chlorite, and quartz with minor amounts of Palygorskiteand Sepiolite. The material exhibited superior cesium retention performances via exchange with the intercalated cations in minerals structure. The dynamic retention characteristics of cesium into the barrier were studied under different scenarios that accounts for different contamination levels. The active sites did not reach its saturation capacity and that the equilibrium retention reaction time is much less than the smallest residence time in the barrier. The scenario of saline water or ground water did not affect the performance of the barrier in retaining cesium. The retention reaction is following Freundlich isotherm whereas the reaction kinetics is a first order reaction independent on the studied scenario. Cesium transport through the barrier is subjected to hydrodynamic dispersion, where the retarded hydrodynamic dispersion coefficients are insensitive to the studied scenario.