Removal of Cadmium By Natural and Surfactant-Modified Mexican Zeolitic Rocks in Fixed Bed Columns

The dynamic removal of cadmium from aqueous solutions by natural and surfactant-modified Mexican zeolitic rocks (clinoptilolite–heulandite type) in fixed bed column systems was investigated. The performances of fixed bed columns were described through the breakthrough curves obtained from column experiments and the values of column parameters predicted as a function of bed height. The column adsorption data were evaluated in terms of the bed adsorption capacity and the efficiency of the process. The experimental results fitted well the bed depth service time model (BDST) for both adsorbents, and the empty bed residence time model (EBRT) was used to optimize column operating conditions. The surface modification of the zeolitic rock with surfactant affected the removal of cadmium in fixed bed systems. Moreover, a column experiment with surfactant modified zeolitic rock previously saturated with 4-chlorophenol was carried out and the results showed that this saturation had a negative effect on the performance of the column.