crowding

in solvent extraction
https://doi.org/10.1351/goldbook.C01420
The displacement of an impurity from an extract phase by contact with a solution containing the main extractable solute. The main solute need not be present in a pure solution but should have a higher distribution ratio than the impurities present.
See also:
scrubbing
,
exchange extraction
Source:
PAC, 1993, 65, 2373. (Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)) on page 2386 [Terms] [Paper]