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Zeolite was used as a low-cost adsorbent to evaluate its ability to remove color from textile effluents. The zeolite (clinoptilolite) used in this study is a natural clay mineral from the Gördes 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.

The ability of zeolite (clinoptilolite) to remove textile dyes from aqueous solutions was investigated. Adsorption tests conducted on natural zeolite indicated that adsorption density decreases with increasing solids concentration, and the curve slows down at 50 mg/mL. The conditioning (mixing) time of 4 h was found to be sufficient for reaching equilibrium. The data obtained show that Everzol Yellow 3RS H/C, Everzol Black B and Everzol Red 3BS are adsorbed into zeolite with a recovery of 35%, 35% and 25%, respectively. Natural zeolite is not a suitable adsorbent for the uptake of reactive azo dyes and exhibits even negative adsorption, but zeolite modified with a typical quaternary amine surfactant (HTAB) was made amenable for the adsorption of anionic dyes. The adsorption isotherms with modified adsorbents indicate three regions of interest, each corresponding to a different adsorption mechanism. Precipitation was observed in Region II above Cr = 10 mg/L dye concentration. A comparison of natural and modified zeolites at 5% solids concentration indicated that modification of zeolite with HTAB yields adsorption densities of 2.9, 3.7 and 7.6 mg/g for Everzol Black B, Everzol Red 3BS and Everzol Yellow 3RS H/C dyes, respectively. Studies are in progress to explore the possibility of using zeolite as a soil conditioner by ion exchanging zeolite with ammonia and also to find possible means of disposing of only the dye.