Equilibrium studies on the adsorption of reactive azo dyes into zeolite

Zeolite was used as a low-cost adsorbent to evaluate its ability to remove color from textile effluents. The zeolit (clinoptilolite) used in this study is a natural clay mineral from the Göbrdes region of Turkey. The adsorption of reactive dyes into zeolite was investigated by a series of batch adsorption experiments. Three reactive dyes (Everzol Black, Everzol Red, Everzol Yellow) were used in laboratory studies. Adsorption test were carried out as a function of solids concentration, conditioning time and dye concentration. The degree of hydrophilicity was found to play an important role in the uptake of reactive dyes. The adsorption results indicated that natural zeolite has a limited adsorption capacity for reactive dyes but can be distinctly improved by modifying its surfaces with quaternary amines. A comparison of natural and modified zeolites at 5% solids concentration indicated that, while the adsorption densities of dyes with natural zeolite yielded negative or slightly positive values, those with modified zeolite gave adsorption densities in the range of 2.9 to 7.6 mg/g.