Development of sorption and diffusion data acquisition method in compacted bentonite, 1; Sorption and diffusion of Ni as functions of pH and salinity of porewater

Tachi, Yukio  ; Shimoda, Satoko*; Nakazawa, Toshiyuki*; Suyama, Tadahiro*; Yotsuji, Kenji

Sorption and diffusion behaviors of Ni in compacted montmorillonite were investigated under different pH and salinity conditions by batch sorption and diffusion experiments. The Ni sorption was measured under four conditions with different pH (6, 8) and salinities (0.05, 0.5 M NaCl), and as functions of Ni concentration and reaction time. The tracer-depletion curves and depth profiles obtained for compacted montmorillonite with dry density of 800 kg/m were interpreted by first-order kinetics sorption based on batch sorption results. The Kd increased with increasing pH and with decreasing salinity of porewater, which are consistent between batch and diffusion tests. Sorption and diffusion behaviors were interpreted by coupling the thermodynamic sorption model, and the diffusion model based on EDL theory in narrow pores.