Influence of Na+, Ca2+, Mg2+and NH4+ on the sorption behavior of Cd2+ from aqueous solutions by a Mexican zeolitic material

The present study involves an investigation of a Mexican zeolitic material, for the removal of cadmium from aqueous solutions. The effects of pH and contact time on the adsorption process were examined. The adsorption was similar in the pH range from 4 to 6. Sorption equilibrium was reached in about 48 h and the rate of cadmium sorption by the zeolite was rapid in the first 5 h of the reaction time. Kinetic experiments were best described by the pseudo-second order model, batch adsorption experiments conducted at room temperature (25 °C) showed that the adsorption pattern followed the Langmuir–Freundlich isotherm model, these results indicated chemisorption of cadmium on a heterogeneous material. Sodium, calcium, magnesium and ammonium interfere in the sorption of cadmium by the zeolitic material but calcium interferes most in this process.