Synthesis and characterization of an ion-imprinted polymer for selective solid phase extraction of thorium(IV)

A new surface ion-imprinted composite polymer containing 3-methyl-1-phenyl -4-(cis-acylbutenoic acid)-2-pyrazolin-5-one as the functional reagent is presented that is capable of extracting and preconcentrating traces of Th(IV) ion prior to its photometric determination. Parameters affecting the recovery of Th(IV) such as acidity, shaking time, initial concentration of Th(IV), elution condition, sample flow rate, and influence of potentially interfering ions were investigated. The maximum uptake capacity of this material and that of the non-imprinted polymer at pH 4.5 are 56.8 and 26.3 mg g(-1), respectively. Recovery exceeds 95% and is complete within 5 min. A Langmuir isotherm fits the experimental data. The relative selectivity factor for Th(IV)/U(VI), Th(IV)/La(III), and Th(IV)/Ce(III) are 50.8, 78.3, and 82.6, respectively. The relative standard deviation is < 2.5%, the detection limit is 0.54 mu g L(-1) (3 sigma). The imprinted polymer was coupled to spectrophotometry to separate and determine trace levels of Th(IV) in a soil standard material with satisfactory results.