Document Type : research article


1 Institute for Sanitary Engineering, Water Quality and Solid Waste Management, University of Stuttgart, Bandtäle 2, 70569, Stuttgart, Germany

2 Faculty of Natural Sciences and Environment, Department of Environmental Engineering, Tehran Science and Research Branch, Islamic Azad University, Tehran, Iran


Batch adsorbers were designed for the adsorption of the fabric dyes Basic Violet 16 (BV16) and Reactive Red 195 (RR195) on locally available low-cost natural adsorbents of Persian bentonite, vermicompost and Persian charred dolomite. The adsorption isotherm data were in agreement with the Langmuir isotherm model (R2 > 99%). Results showed that with increasing the adsorption capacity of bentonite for BV16 from 434.78 to 833.33 mg/g due to the presence of the anionic dye, the amount of the adsorbent decreases by 50%. The adsorption capacity of vermicompost for the cationic dye was obtained 16 mg/g in single dye solution and of charred dolomite for the anionic dye was almost 7 mg/g in both dye systems. Based on the extended Langmuir model, the maximum adsorption capacity of natural bentonite for BV16 and of charred dolomite for RR195 were concluded 821.63 mg/g and 7.03 mg/g, respectively, which the capacities are almost the same in single and binary systems. The adsorption capacity and removal efficiency of Persian bentonite from contaminated water are comparable with that of activated carbon. Compared to activated carbon bentonite and the other natural adsorbents used in this study are less expensive and do not require a separate activation or pre-treatment step. Cost for 90% removal of dye from 100 m3 groundwater using 1 kg the studied adsorbents of vermicompost, charred dolomite and bentonite was calculated 0.06, 0.05 and 0.04 euro, respectively, in both single and binary systems.