In this diploma thesis, the adsorption equilibrium of copper and nickel ions as heavy metal ions from the corresponding binary solutions on zeolites 5Å and 13X was investigated. Adsorption was carried out in a batch reactor at different initial concentrations of binary solutions, at a constant temperature of 298 K, a stirring speed of 200 rpm for 96 h. The impact of heavy metals equilibrium concentrations on the equilibrium amount of heavy metals adsorbed was investigated and it was found to increase as the equilibrium concentrations of heavy metals in the binary solutions rises, except for the adsorption of nickel ions on zeolite 13X. The adsorption efficiency of heavy metal ions on the zeolites 5Å and 13X decreases with the initial concentration of binary solution. The experimental data obtained were tested on Langmuir, Freundlich, Toth, Redlich-Peterson and Sips isotherms, respectively. By estimating the agreement quality of adsorption models with experimental data, by comparing calculated maximum adsorption capacity values with experimentally obtained, and comparing statistical parameters for RMSE and r2, it can be concluded that the best agreement with the experimental data showed Freundlich and Sips model for the adsorption of copper ions on both zeolites. For the adsorption of nickel ions on the zeolite 5Å, the best agreement showed Freundlich and Redlich-Peterson model while for the adsorption of nickel ions on zeolite 13X, none of the models showed satisfactory agreement.