Permeation Behavior of Organic Matter in the Compacted Bentonite under Saline Condition

Tobitsuka, Sachiko; Kikuchi, Hirohito*; Matsumoto, Kazuhiro*; Iijima, Kazuki  ; Sato, Haruo

The permeation behavior of organic matter through a compacted bentonite was evaluated in low and high ionic strength condition. The concentration of organic matters eluting from bentonite was analyzed. Polyacrylic acid solutions (average molecular weight:15,000 or 450,000) were permeated during maximum 140 days to the compacted bentonite (Kunigel V1, 100%) at dry density 1.2 g/cm. In low ionc strength condition, polyacrylic acid sodium (MWave: 15,000) was detected after 70 days in the permeated solution. In high ionic strength condition, it was found after 52 days. Polyacrylic acid (MWave: 450,000) didn't permeate in the both of system. It indicates that organic matters less than MWave: 450,000 aren't filtrated by bentonite. It is supposed that the organic compound which can change its conformation to a chain-like structure, are not likely to be filtrated, even if its molecular weight is more than 15,000. In low ionic strength condition, the concentration of eluting organic carbon from bentonite is 7.4-12.5 mg /l. In high ionic strength condition it is 4.2-6.5 mg /l.