Lead (II) ion selective poly(aniline) solid contact electrode based on Tetramethylthiuram monosulfide ionophore as a sulfur containing sensing material is successfully developed. The electrode exhibits good linear response of 25.6 mV / decade (at 20±0.2℃, r2=0.995) within the concentration range of 1.0×10-1~4.0×10-7 M Pb (II). The composition of this electrode was Ionophore : PVC : dioctylphthalate : potassiumtetrakis(4-chlorophenyl)borate : Oleic acid = 5.0 : 20.0 : 25.0 : 4.0 : 5.0. When we consider the results of using different composition electrodes based on only one potassiumtetrakis(4-chlorophenyl)borate or Oleic acid liphophlic additive, poly(aniline) solid contact electrode based on Tetramethylthiuram monosulfide ionophore with potassiumtetrakis(4-chlorophenyl)borate and Oleic acid liphophlic additive had the best result in response characteristics. The electrode shows good selectivity for lead (II) ion in comparison with alkali, alkaline earth, transition and heavy metal ions. This electrode is suitable for use with aqueous solutions of pH 3.0 ~ 7.0 and their standard deviation in the measured emf differences was ±2.94 mV at Tris buffered lead sample solution of 1.0×10-2 M and ±2.82 mV at Tris buffered lead sample solution of 1.0×10-3 M. Their stabilization time was less than 710 s. and response time was less than 16 s.

The variation of the stable region of lead ion in aqueous environment has been studied according to the temperature change based on its stable region at standard state by constructing Pourbaix diagrams at different temperatures. The temperature range considered was between 278 ~ 338 K and the stable region of Pb2+ (aq) was observed to decrease as temperature rises, which was due to the decrease of the stable region of water and the increase of the stable region of solid lead hydroxide. The solid lead compounds considered were PbO(s), Pb3O4(s), and PbO2(s), and the pH at the boundary between the stable regions of PbO(s) and Pb2+ (aq) was observed to be lowered with temperature. For Pb3O4(s) and PbO2(s), their stable regions were estimated to be enlarged as temperature is raised. Considering the change of the stable region of lead ion with temperature, in the application of the precipitating method for the treatment of lead ion in water it was considered to be more desirable to treat lead ion as its hydroxide form rather than its elemental form at higher temperature.

The adsorption performance of lead ion was studied using five zeolites (Na-P1, sodalite (SOD), analcime (ANA), nepheline hydrate (JBW), cancrinite (CAN)) synthesized from Jeju scoria. The adsorption performances of lead ion decreased in the order of Na-P1 > SOD > ANA > JBW > CAN. These results showed that the synthetic zeolite with a higher cationic exchange capacity showed a higher adsorption performance. The uptake of lead ion by synthetic zeolites were described by Freundlich model better than Langmuir model. The adsorption kinetics of lead ion by synthetic zeolites fitted the pseudo 2nd order kinetics better than pseudo 1st order kinetics. The effective diffusion coefficients of lead ion by synthetic zeolites were ten times higher than the zeolite A synthesized from coal fly ash.

Several effects on Pb2+ removal by crab shell from aqueous solution were investigated. As the increase of initial Pb2+ concentration and decrease of initial crab shell concentration, the time required to reach an equilibrium state and the residual Pb2+ concentration increased. In our experimental ranges, the optimum initial Pb2+ concentration and crab shell concentration were below 103 mg/l and over 0.5 mg/l, respectively. Also, in order to investigate the mechanism of Pb2+ removal by crab shell in aqueous solution, the crab shell was compared with chitosan and chitin on aspects of Pb2+ removal capacity and Pb2+ removal rate. The Pb2+ removal by crab shell was greater than that by chitin and chitosan. The role of chitin was not so great in Pb2+ removal by crab shell. The Pb2+ removal by chitosan was not exactly correlated to the molecular weight of chitosan.