Adsorption; lead (II); coal;

Adsorption behavior of lead (II) ions on bituminous and subbituminous coals was investigated at temperatures 30 and 60°C. The shape of the adsorption isotherms indicated that the adsorption data could be tightly fitted by the Langmuir adsorption model. For both coal types, practically no change in adsorption capacity of the coals to Pb(II) ions was ascertained with increasing temperature. On the other hand, practically doublefold increase in the values of adsorption rate constant k was found when temperature rises from 30 to 60°C. The interaction of lead (II) ions with the coals was then confirmed to be slightly exothermic process.