Thermal modified Kaolinite as useful material for separation and preconcentration of trace amounts of manganese ions

This work assesses for the first time the potential of natural Kaolinite as adsorptive material for preconcentration of metal traces. Manganese is quantitatively retained by 2-(5-bromo)-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) on thermal modified Kaolinite by column method in pH range of 8.5-10.0 at flow rate of 2 ml min(-1). Manganese was removed from column with 5.0 ml of H2SO4 4 mol(-1) and determined by flame atomic absorption spectrometric at 279.5 nm. In this case. 0.1 mug of manganese can be concentrated froin 800 ml of aqueous sample (where concentration is as low as 0.125 mug 1(-1). Detection limit is 4.3 mug 1(-1) (3 delta(bl) m(-1)) and analytical curve is linear in the 0.02-10 mg 1(-1) in final solution with correlation coefficient 0.9997 and relative standard deviation for eight replicate determination of 5 mug of manganese in C final solution is 0.71%. The interference of a large number of anions and cations has been studied in detail to optimize the conditions and method was successfully applied for determination of manganese in complex materials. (C) 2004 Elsevier B.V. All rights reserved.