FAAS Determination of Lead in Water After Enrichment by Adsorption on PAN-Modified Organobentonite

Bentonite was denaturated by reacting with CTMAB solution,and after drying,it was modified with PAN ethanol solution.The structure and property of adsorptivity of the PAN-modified organobentonite (PAN-OBNTN) were studied.In an aqueous medium of pH 6,the PAN-OBNTN behaved to adsorb Pb2+-ion strongly and equilibrium of adsorption was achieved by shaking with PAN-OBNTN for 45 min,and the adsorptive capacity of Pb2+-ion at equilibrium was 5.7 mg·g-1.The Pb2+-ion adsorbed on the surface of PAN-OBNTN was completed desorbed by shaking with EDTA solution for 5 min,in which the lead content was determined by FAAS.Detection limit (3S/N) of the method found was 8.3 μg·L-1,with the enrichment multiple of 10,and value of RSD (n=6) found by this method with the initial Pb2+-ion concentration of 0.2 mg·L-1,was 4.3%.Recovery was tested on samples of tap-water and river water by standard addition method,giving results of recovery in the range of 93.8% to 101.0%.