EN
A simple and sensitive spectrophotometric method for the determination
of azine (neutral red) and triphenyl methane (rosaniline) dye has been
developed using tannic acid-polyurethane foam (TPF). TPF was prepared
by coupling a polyhydroxypolyurethane foam matrix with tannic acid. TPF
was characterized using a combination of analytical methods including
IR and NMR spectroscopy, elemental analysis, density and pHZPC. The
qualitative and quantitative determination of dyes is based on its sorption
on the surface of the TPF. The sorption behavior of dye onto the TPF was
investigated by batch and dynamic processes. The maximum sorption
of neutral red and rosaniline was in the pH range of 7-9. The kinetics of
sorption of the dye by the TPF was found to be fast with average values of
half-life of sorption of 1.2 min. The equilibrium process was well described
by the Freundlich isotherm model. The visual detection limit of dye in
aqueous solution is 0.1 μg mL-1. The Sandell’s sensitivity is 0.26 ng cm-2 with molar absorptivity 1.3 × 106 L mol-1 cm-1. The average sorption
capacity of TPF and the recovery of dyes were 0.47 mmol g-1 and 96.4 %
(RSD ~ 1.5%, n=7). The method has been applied to various wastewater
samples.