Synthesis, characterization of carbon polyurethane powder and its application for separation and spectrophotometric determination of platinum in pharmaceutical and ore samples

A new chelating sorbent was synthesized by covalently linking carbon nano-fiber with ion exchange polyurethane foam (CNF-PUFIX). CNF-PUFIX was characterized using different tools e.g. elemental analysis, IR spectrum and SEM. The functional groups of PUF have disappeared. The phenolic, carboxylic, quaternary ammonium salt and tertiary amine groups are detected in the CNF-PUFIX. The sorption properties of platinum (IV) onto CNF-PUFIX were investigated, the maximum sorption of platinum ions (similar to 100%) was at the ranges 4-5, shaking for 18 min and sample flow rate 1.3 mL min(-1). The experimental data was fitted by kinetic models, the pseudo-second order is predominant (R-2=0.998), the values of h and k(2) are 4.4 mmol g(-1) min(-1) and 0.15 g mmol(-1) min(-1), respectively. The sorption capacity of CNF-PUFIX and the recovery percentage of Pt (IV) were 0.19 mmol g(-1) and 99-103%, respectively (RSD=1.72%, n=5). The CNF-PUFIX could be used many times without decreasing their capacities significantly. The equilibrium process is well described by the Langmuir isotherm model (R-2=0.857), which is attributed to the homogeneous surface structure of the CNF-PUFIX. The values of Delta G and Delta H were -3.5 and -26.1 kJ mol(-1), respectively, which indicate that the sorption of platinum onto CNF-PUFIX is spontaneous and exothermic. The lower detection limit of platinum using spectrophotometric method is 2.4 mu g L-1 (RSD similar to 3.8%, n=6). The accuracy of the procedure was verified by the analysis of standard reference materials of pharmaceutical and granite samples. (C) 2014 Elsevier B.V. All rights reserved.