APPLIED CLAY SCIENCE, cilt.109, ss.22-32, 2015 (SCI-Expanded)
The adsorption characteristics of toxic Basic Red 9 (BR9) onto expanded vermiculite were determined. The effect of contact time, initial dye concentration, pH and temperature on the adsorption process was investigated. The adsorption amount of BR9 onto expanded vermiculite increased with increasing initial dye concentration and pH, but it displayed a decrease with increasing temperature. The adsorption kinetics of BR9 followed the pseudo second-order model. Freundlich model provided the best fitting with the experimental adsorption isotherm data obtained at 25,35 and 45 degrees C. Thermodynamic parameters indicated that the adsorption process was exothermic, occurred spontaneously and led to an increase in the randomness at the solid/solution interface. The desorption of dye from spent adsorbent was investigated in water, ethyl alcohol and benzyl alcohol. The sign of the zeta potential value of clay changed from negative to positive due to the adsorption of BR9 onto expanded vermiculite. The adsorption of BR9 led to some changes in the FTIR spectrum of adsorbent material. The maximum adsorption capacity of expanded vermiculite for BR9 adsorption is comparable with other adsorbents reported in the literature. Therefore, expanded vermiculite as an efficient and economical adsorbent may be used for the removal of dyes from wastewaters. (C) 2015 Elsevier B.V. All rights reserved.