DETERMINATION AND PRECONCENTRATION OF NICKEL IN WATER WITH FLAME ATOMIC ABSORPTION SPECTROMETRY BY THIOUREA-FORMALDEHYDE AS CHELATING RESIN

Thiourea-formaldehyde chelating resin is synthesized simply and rapidly from thiourea and formaldehyde by condensation polymerization and characterized by IR spectra and studied for the preconcentration and determination of trace Ni (II) ion from solution samples. The optimum pH value for sorption of the metal ion was 6.5. The sorption capacity of resin for Ni (II) was determined. The chelating resin can be reused for 20 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 96% was obtained for the metal ion with 0.5 M HNO3 as eluting agent. The equilibrium adsorption data of Ni (II) on modified resin were analyzed by Langmuir, Freundlich, and Temkin models. Based on equilibrium adsorption data, the Langmuir, Freundlich, and Temkin constants were determined to be 0.045, 0.022, and 0.133 at pH 6.5 and 20 degrees C. The method was applied for nickel ion determination from a river water sample.