General Characteristics of Impregnated Resins

In a previous review [4] the preparation methods for producing efficient solvent-impregnated resins (SIRs) were classified as  

Dry impregnation method, in which the extractant is adsorbed directly to the macroporous support after contacting a solution of the extractant with the polymer and subsequent evaporation of the organic solvent, always a water-immiscible solvent. Then the obtained SIR is a two-component system polymer-extractant. 

Wet impregnation method, in which a solution of the extractant is absorbed by the polymer and the obtained impregnated resin is a three-component system polymer-extractant-organic solvent. 

Modifier addition method, in which a mixture of the extractant with a modifier agent which promotes water penetration into the polymer 

The last two impregnation methods were proposed as alternatives to the dry impregnation method, because of the high hydrophobic balance showed by impregnated resins obtained by this method. In both cases it is necessary to add a third (solvent in the wet method or the modifier agent in the modifier addition method) or more components in the system. 

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