SOLID-PHASE EXTRACTION OF HEAVY-METAL IONS ON A HIGH-SURFACE-AREA TITANIUM-DIOXIDE (ANATASE)

The adsorption of heavy metal cations on two TiO2 (anatase) samples wa s investigated. The first sample (T1) was synthesized by hydrolysis of TiCl4, whereas the second (T2) was a commercial product. The adsorpti on kinetics, pH curves, adsorption isotherms and adsorption capacities were studied. Sample T1 possesses a significant capacity towards sorp tion of heavy metal cations (approximately 5000 mu g g(-1)), which is much higher than the adsorption capacity of the commercial sample T2 a nd, in most instances, higher than the capacity of silica. Quantitativ e and fast sorption of various heavy metal ions in trace concentration s on T1 occurs, but in different pH ranges for each element. At pH 8 q uantitative sorption was detected for Bi, Cd, Co, Cr, Cu, Fe, Ge, In, Mn, Ni, Pb, Sb, Sn, Te, T1, V and Zn. All of the elements can be elute d with HNO3 and EDTA and this procedure does not adversely affect the titania for subsequent sorptions. On the basis of the results obtained , optimum conditions for the joint and quantitative solid-phase extrac tion of the most common heavy metal ions are proposed. A column system for preconcentration was developed. The conditions for the quantitati ve and reproducible elution and of subsequent AAS were established. A method for the determination of trace elements in different waters is proposed. It is characterized by high precision, reproducibility and c oncentration factor.