Effect of support properties on preparation process and adsorption performances of solvent impregnated resins

The effect of support properties on preparation process and adsorption performances of solvent impregnated resins (SIRs) has been studied. Five SIRs were prepared by impregnating di(2-ethylhexyl)phosphoric acid (D2EHPA) in five macroporous absorbent resins (MARs), respectively and used to extract V(IV) from aqueous solutions. The impregnation equilibrium can be fast achieved for the MARs with smaller pore size and bigger specific surface area, where D2EHPA is preferentially adsorbed in the micropores approximately as wall-spreading to form monolayer films, resulting in the relatively high utilization efficiency of extractant and stability of the SIRs. However, the extractant is more likely to accumulate in the macropores and/or mesopores than in the micropores, which leads to the higher mass ratio of extractant and pore-filling percentage in the SIRs with abundant macropores and/or mesopores. D2EHPA can be adsorbed on XAD-7HP fabricated with poly(methyl methacrylate) by virtue of relatively strong Hydrogen-bond, thus it can exist not only inside the pores but also on the surface of the resin, which causes the high mass ratio of extractant and extremely high pore-filling percentage although it contains the minimum pore volume. The relatively strong hydrogen-bond between XAD-7HP and D2EHPA is also believed to be responsible for its high adsorption capacity for V(IV) and utilization efficiency of the impregnated extractant.