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 2mlmin(-1). Manganese was removed from column with 5.0ml of H(2)SO(4) 4moll(-1) and determined by flame atomic absorption spectrometric at 279.5nm. In this case, 0.lmug of manganese can be concentrated from 800ml of aqueous sample (where concentration is as low as 0.125mugl(-1)). Detection limit is 4.3mugl(-1) (3delta(bl)m(-1)) and analytical curve is linear in the 0.02-10mgl(-1) in final solution with correlation coefficient 0.9997 and relative standard deviation for eight replicate determination of 5mug of manganese in 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.