β-Cyclodextrin-based polyurethane (β-CDPU) polymers as solid media for adsorption and determination of Pb(II) ions in dust and water samples

In this work, beta-CD-based polyurethane copolymers (beta-CDPU) have been prepared by reacting beta-CD with hexamethylene diisocyanate as cross-linked agent in dry DMF. This polymer showed high selectivity for preconcentration of Pb(II) at trace level prior to its flame atomic absorption spectrometric determination. The effect of several parameters such as pH, flow rate of sample, eluent kind and volume was investigated. The adsorption behaviors and mechanisms of Pb(II) on the samples were also studied. The maximum adsorption amount of Pb(II) was 8 mg g(-1) with the preconcentration factor of 250 for Pb(II). The Langmuir isotherm was proved to describe the adsorption data better than the Freundlich isotherm and a pseudo-first-order kinetic model fits the adsorption kinetic processes well. The calibration curve was linear in the range of (3-200 ng mL(-1)) with a correlation coefficient of 0.9996. The limit of detection based on three times the standard deviation of the blank was 1.15 ng mL(-1). The relative standard deviations for the determination of 10 and 100 ng mL(-1) of Pb(II) were 3.60 and 0.43 % (n = 10), respectively. The method was successfully applied to the determination of lead in some environmental samples such as Tehran and Bushehr drinking water, river water and dust samples.