In this study, removal of dyestuff from aqueous solutions by adsorption was investigated. Sepiolite, sepiolite activated by HCl, sepiolite activated by HNO3, slag, and powdered activated carbon were used as adsorbents. Black B solution (30 mg L-1) was used in batch adsorption experiments. Different parameters (contact time, pH, adsorbent dosage, initial dye concentration, and temperature) effects on removal of Black B were examined. The equilibrium time was found to be 1320, 150, 120, 360 and 45 min. for sepiolite, sepiolite activated by HCl, sepiolite activated by HNO3, slag, and powdered activated carbon, respectively. The most effective pH for Black B removal was 2 for sepiolite, sepiolite activated by HCl, and slag, and pH did not affect Black B removal significantly for the other adsorbents. Adsorbent dosages were varied from 0.1-2 g per 50 mL solution. An increase in adsorbent dosage increased the percent re-moval of Black B. A series of isotherm studies were undertaken, and the data evaluated for compliance with the Langmuir and Freundlich isotherm models. To investigate the adsorption mechanisms, three simplified kinetic models, i.e., pseudo first-order, pseudo second-order, and intraparticle diffusion, were tested. Adsorption followed pseudo second-order rate kinetics. The correlation coefficients for pseudo-second order kinetic model are greater than 0.9926. Experimental data show that slag and powdered activated carbon were effective for Black B removal. © by PSP 2006.