Preconcentration of heavy metals on oxides of cerium and zirconium and their determination by FAAS

摘要

The use of commercial oxides of cerium and zirconium as potential sorbents in a column system was investigated. Efficacy of preconcentration of Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb ions on CeO2 and ZrO2, prior to their determination by flame atomic absorption spectrometry (FAAS) was described. The influences of experimental parameters including pH of the sample solution and sample volume from pure multielement aqueous solutions of known concentration of analytes on the preconcentration efficiency have been investigated, applying the column method. Under optimum conditions (pH; 8, preconcentration factor; 10) the recovery values for CeO2 were: 87 % (Cd), 96 % (Co), 89 % (Cr), 104 % (Cu), 102 % (Fe), 74 % (Mn), 102 % (Ni) and 99 % (Pb); while using ZrO2 the recoveries were: 89 % (Cd), 97 % (Co), 86 % (Cr), 103 % (Cu), 105 % (Fe), 87 % (Mn), 103 % (Ni) and 95 % (Pb). Limits of detection were between 3.2-26.3 μg/L by using CeO2 as sorbent, as well, between 2.5-24.1 μg/L by using ZrO2 as sorbent. The precision expressed as relative standard deviation (R.S.D.) obtained for 0.1 mg/L of Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb were 7 % for CeO2 and 5 % for ZrO2, calculated from eight measurements. Moreover, the sorption capacity of the CeO2 and ZrO2 were compared with other sorbents, and it was found that both sorbent offer good sorption capacity values and could be applicable to more analytes.