Thiourea modified polyacrylnitrile fibers as efficient Pd(II) scavengers
A series of thiourea modified fibers were prepared and characterized. The N-(2-aminoethyl)thiourea functionalized polyacrylonitrile fiber (AETU-PANF) was then evaluated for palladium absorption. The absorption process follows a pseudo-second-order model and the equilibrium data fit well to the Langmuir isotherm model. The maximum absorption capacity according to the Langmuir model was 169.2 mg g−1 with an absorption limit of 0.03 ppm. Wetted AETU-PANFs exhibited excellent absorption properties in organic solutions and the sorption rates were higher in organic solvents than in aqueous solutions. This is due to a special microenvironment that is formed inside the AETU-PANFs. The AETU-PANFs were also used to remove palladium from an organic solution containing active pharmaceutical ingredients. The Pd content was reduced from 310 ppm to 0.07 ppm.