Synthesis, characterization of low density polyhydroxy polyurethane foam and its application for separation and determination of gold in water and ores samples

In this work, a new type of sorbent (low density polyhydroxy polyurethane Foam, LPPF) was synthesis by using water hydrolysis of polyurethanediazonium chloride salt. LPPF was characterized using different tools e. g. elemental analysis, UV-vis and IR spectra, TGA, SEM, density and pHZPC. It was tested for separation, preconcentration and determination of gold in environmental samples using batch and dynamic techniques. The sorption experimental data was fitted by the pseudo-first kinetic mathematical equation (R-2 = 0.991). The sorption rate of the Au (III) ions is very fast, the half-life (t(1/2)) approximate to 34 s. The equilibrium process is well described by the Freundlich isotherm model, the R-2 value is 0.967, which attributed to the heterogeneous surface structure of the LPPF. The breakthrough capacity of LPPF and the recovery of gold ions were 0.36 mmol g(-1) (70.5 mg g(-1)) and 99-100%, respectively. The lower detection limit of gold by using spectrophotometric method is 3.3 ng L-1 with preconcentration factors approximate to 450 (RSD similar to 1.66%, n = 4). The values of Delta G and Delta H for the sorption of gold onto LPPF were -12.5 and -103.5 kJ mol(-1), respectively, which indicate that the sorption of Au (III) onto LPPF is spontaneous and exothermic reaction. The obtained results indicate that the ion chelation and ion association might be the most probable mechanism of gold sorption onto LPPF. The study shows LPPF has the potential of application as an efficient sorbent for the extraction and determination of gold in water, gold alloys pharmaceutical and granite samples. (C) 2013 The Authors. Published by Elsevier B. V. All rights reserved.