Separation and Preconcentration of Trace Amounts of Cadmium(ii) and Mercury(ii) Ions on Rosaniline-grafted Polyurethane Foam

Rosaniline-grafted polyurethane foam (Ros-PUF) has been synthesized, by coupling polyether polyol, rosaniline, and toluene diisocyanate, and characterized, by use of UV–visible and IR spectroscopy and thermogravimetric analysis. The Ros-PUF was used as a new sorbent for extraction of trace amounts of Cd(II) and Hg(II) from water by batch and column techniques. Cd(II) and Hg(II) were completely separated from 2–6 M HCl solution containing 1 M KSCN in 10–20 min. The kinetics and thermodynamics of sorption of the metal ions by Ros-PUF were studied. The average values of ∆H, ∆S, and ∆G for sorption of Cd(II) and Hg(II) by Ros-PUF were −54.38 kJ mol, 159 J K mol, and –4.87 kJ mol, respectively. The Dubinin–Radushkevich equation was used to explain the equilibrium isotherm. The sorption capacities of Ros-PUF were 0.12 and 0. 08 mmol g for Cd(II) and Hg(II), respectively. The method has been successfully used to preconcentrate and remove Cd(II) and Hg(II) from tap water. Preconcentration factors were ~100 and recoveries were between 86.6 and 100% (average RSD ≈ 5.74).