부산대학교 도서관

The extraction systems water-lanthanoid or actinide nitrate-tri-n butylphosphate are among those most studied. It was originally suggested that disolvates are formed when uranyl or thorium nitrates are extracted, whereas trisolvates are formed in the extraction of the lanthanoid nitrates. However, taking the formation of only these compounds into account does not enable the extraction equilibrium to be represented in some of the systems studied. The electrolytic dissociation of salts in the tri-n-butylphosphate phase is small. Their distribution is accompanied by the displacement of water from the organic phase. Therefore the extraction reaction can be written in the form: M/sup n+/ + nNO/sup -//sub 3/ + qS ..-->..reverse arrow M(NO/sub 3/)/sub n/S/sub q/ with the constant: K/sub q/ = m/(am/sup q//sub S/), where S is the extractant, q is the solvate number, a is the activity of a salt in a binary aqueous solution, and m is the molar concentration of the sale in the organic phase.