抄録
Adsorption/desorption tests of Zn and the constant pressure microfiltration were conducted using bentonite slurry in order to clarify the adsorption/desorption properties of heavy metal for clayey soil as well as the change in soil property due to cation-exchange reaction caused by the addition of ions. The average specific filtration resistance of bentonite cake calculated from the result of microfiltration experiment decreased with the increase of Zn2+ uptake. It was shown that Zn2+ adsorbed onto bentonite was efficiently desorbed by the addition of Na+, K+, NH+4 and Ca2+. The marked decrease in the average specific filtration resistance was observed in cases where Zn2+ was desorbed by the addition of ions, and the average specific filtration resistance became almost constant being independent of the amount of Zn2+ preadsorbed onto bentonite expect the case of Na+. Thus, it was shown that the permeability of bentonite cake is largely influenced by the cation-exchange reaction.
