Chemically modified rice husk as an effective adsorbent for removal of palladium ions.

Bio-matrix of rice husk and Mobil Composition of Matter No. 41 (MCM-41) was modified with alizarin red S for preconcentration of Pd prior flame atomic absorption spectrometric determination. The prepared bio-matrix (RH@MCM-41@ARS) was characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope, energy dispersive X-ray spectrometer (SEM/EDX) and surface area studies. The impact of different parameters (solution pH, amount of sorbent, contact time, sample volume, initial Pd concentration and diverse ions) on the uptake of Pd were evaluated. The maximum adsorption capacity of Pd onto RH@MCM-41@ARS was 198.2 mg g at optimum conditions. Applying the optimized procedure as a preconcentration step led to limit of detection of 0.13 μg L and dynamic analytical range up to 500 μg L. The sorbent was regenerated by 0.5 mol L thiourea for at least 10 cycles without significant reduction of adsorption capacity. The method was applied for preconcentration of Pd from real samples.