Removal of dyestuff from wastewater using zeolites as adsorbents

Removing the dye from the wastewater of the textile industry is a matter of importance due to environmental implications. Extensively used reactive dyes are toxic for some microorganisms and may cause severe harm to the natural habitat. Thus dye removal is crucial prior to the wastewater discharge. Adsorption is extensively used to remove the dyestuff from the wastewater for its processing ease, low cost and regeneration possibility, among other processes for dye removal.Natural clinoptilolite is a good adsorbent with a highly porous structure, uniform pore size distribution and low price due to its abundance. Its usage as an adsorbent ranges from aquatic solutions of cationic dyes to purification of natural gas. Although being used as an adsorbent for a wide range of dyes, due to its negative surface charge, clinoptilolite is not suitable to adsorb anionic reactive azo-dyes from aqueous solutions. Usage of clinoptilolite as an adsorbent for such dyes require a pretreatment of the clinoptilolite particles with a suitable surfactant to render its surface charge positive.In this work, dodecyl dimethyl ethyl benzyl ammonium chloride is used to modify the clinoptilolite surface. Modification and process conditions such as solid/liquid ratio, contact time, initial concentration, pH and temperature are studied and the results show that modified clinoptilolite is a good adsorbent for the reactive azo-dyes Chemazol Black B (C. I. Reactive Black 5), Chemazol Blue KNR (C. I. Reactive Blue 19), Chemazol Turquoise G (C. I. Reactive Turquoise Blue 21), Chemazol Yellow 4GL (C. I. Reactive Yellow 186).