fraction extracted, \(E\)
The fraction of the total quantity of a substance extracted (usually by the solvent) under specified conditions, i.e. \(E_{\text{A}} = \frac{Q_{\text{A}}}{Q_{\text{A}}^{'}}\) where \(Q_{\text{A}}\) is the mass of A extracted and \(Q_{\text{A}}^{'}\) is the total mass of A present at the start.
  1. \(E\) may be expressed as a percentage, \(\% \, E\).
  2. The term extractability is qualitative and should not be used as a synonym for fraction extracted.
  3. If the aqueous phase is extracted with \(n\) successive portions of solvent, the phase volume ratio (solvent/feed) being \(r\) each time, the fraction extracted is given by: \[E_{n} = 1 - \left ( rD + 1 \right )^{-n}\] If \(n = r = 1\) and \(E_{1} = \frac{D}{1+D}\) this expression is a concept of value in @C01075@ theory.
  4. The fraction extracted is also known as the @R05206@ factor, especially for a multistage process.
PAC, 1993, 65, 2373. (Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)) on page 2384 [Terms] [Paper]