Suitability of various materials for porous filters in diffusion experiments

Abstract

Abstract The suitability of different porous materials (stainless steel, VYCOR® glass, Al2O3 and PEEK) for use as confining filters in diffusion experiments was evaluated by measuring the effective diffusion coefficients (D e) of neutral (HTO) and ionic solutes (Na+, Cs+, Sr2+, Cl – , SeO4 2−) in the materials in through-diffusion experiments. For stainless steel filters, the D e values of the target solutes correlated satisfactorily with their bulk diffusion coefficient in water (D w); thus, the diffusion process in the stainless steel filters was primarily controlled by the diffusivity of the solvated ions. For the remaining materials, the D e and D w values were also correlated for the target solutes, and the geometric factors were in the sequence: VYCOR® glass < Al2O3 < PEEK. Stainless steel and VYCOR® glass were the most appropriate materials because of their high D e values, but a specific interaction of caesium with VYCOR® glass was hypothesised because the D e values obtained for this solute were slightly higher than expected.