Adsorption Isotherm Equation for Coexistence of Two Kinds of Metal Ions in Acidic Solution on Chelating Resin

Abstract

Abstract Adsorption isotherms for the coexistence of two metal ions (combinations of Zn2+, Cd2+, and Pb2+) in acidic solutions on chelating resins were measured at 25 °C. They were analyzed in relation to the adsorption isotherm equation of a single metal ion, Q=Qmax⁄(1+ACM−αCHβ), as was reported in the preceding paper. It is found that the adsorption isotherms of two metal ions (i and j) in acidic solution on chelating resins can be generally expressed by the equation; Q i,j=Qmax⁄{1+AiCi−αiCHβi(1+Ki,jCjαjCH−βj)} over wide ranges of concentrations of the metal ion, C, and the hydrogen ion, CH (mol dm−3). Where Qi and Qi,j are the adsorption amounts (m mol/g-dry resin) of i metal ion in the absence and in the coexistence of j metal ion. Qmax is the maximum adsorption amount, α and β are parameters in the adsorption of single metal solution, A and K are correction factors, and subscripts i and j identifing i and j metal ions. The adsorption capacities of two metal ions in acidic solution can be obtained from the isotherms parameters Ai, αi, αj, βi and βj for an individual single metal ion and only one additional parameter Ki,j is needed.