from the extraction isotherms , absorption spectra of the organic phases and dependence of the extraction coefficients on extractant concentration , it was found that the singly-charged anions hl ( - ) are extracted preferentially , but acidic groups other than sulphonate can also form ion-pairs with alkylammonium cations at higher ph values of the aqueous phase , and at high acidity these dyes can be extracted other than by an anion-exchange reaction .
C0022023
ion
C0003075
anion