Removal of lead and cadmium ions from aqueous solutions by adsorption process was investigated. Low cost and locally
available natural mineral of manganoxide mineral was used as an adsorbent. The kinetics of adsorption process data was examined
using the pseudo-first-order, pseudo-second-order kinetics and the intra-particle diffusion models. The rate constants of adsorption
for all these kinetics models were calculated and compared. The adsorption kinetics was best described by the pseudo second-order
model. The Langmuir and Freundlich adsorption isotherm models were applied to the experimental equilibrium data at different
temperatures. The experimental data well fitted to Langmuir isotherm model. The maximum adsorption capacities of manganoxide
mineral for lead and cadmium ions were calculated from the Langmuir isotherm and were 98 and 6.8 mg/g, respectively.
Thermodynamic parameters such as the change of Gibbs free energy, enthalpy and entropy of adsorption were also calculated and it
was found that the lead and cadmium uptake reactions by manganoxide mineral were endothermic and spontaneous in nature.
Therefore, manganoxide mineral can be used as adsorbents for lead and cadmium ions removal processes as an alternative natural
mineral among the others.