PRE-CONCENTRATION OF Cd, Cu, Ni, Pb and Zn FROM FUEL ETHANOL AND NATURAL WATER SAMPLES BY SORPTION ON P-AMINOBENZOIC MODIFIED CELLULOSE AND SUBSEQUENT FLAME AAS DETERMINATION

This work describes the synthesis of p-aminobenzoic modified cellulose (Cell-PAB), and the results of a study on the sorption and pre-concentration (using batch and in flow-through column methods) of Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) in ethanol and aqueous medium. The sorption capacities for each metal ion were (in mmol.g-1); Ethanol medium: Cd(II) = 1.45, Cu(II) = 1.85, Ni(II) = 1.65, Pb(II)= 1.40 and Zn(II)= 1.50; Aqueous medium: Cd(II)= 1.30, Cu(II)= 1.80, Ni(II)= 1.50, Pb(II)= 1.20 and Zn(II)= 1.40. A recovery of almost 100% of the metal ions was obtained from ethanol as well as aqueous medium, the ions being sorbed in a column packed with 1 g of Cell-PAB, using 5 mL of 2.0 mol L-1 HCl solution as eluent. An enrichment factor of 45 (250 mL sample, 5 mL concentrate) was obtained by this preconcentration procedure. The sorption desorption procedure applied allowed the development of a preconcentration method for metal ions at trace level in fuel ethanol and natural water samples. After elution, the metal ions were determined by flame atomic absorption spectrometry.