Sorption of Rhodamine B Dye onto Bentonite Clay-silane Composite Materials

The aim of this communication is to assess the sorption behavior of silanes grafted bentonite composite materials for Rhodamine B (RhB) from aqueous solution. The nanocomposites were synthesized by functionalization of the bentonite with 3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane under inert atmosphere. The batch experimental data indicated that the composite materials showed high percentage removal of RhB over a wide pH range, i.e., pH ~4.0 to 10.0. A high percentage removal of RhB was achieved within the concentrations studied from 1.0 to 25.0 mgL-1. Langmuir and Freundlich adsorption isotherm were obtained using equilibrium state sorption data. The equilibrium sorption was attained within 180 min of contact and the kinetic model best fitted the pseudo-second-order model. Further, the change in background electrolyte (NaCl) concentrations from 0.0001 to 0.1molL-1 NaCl and the presence of co-existing ions do not significantly affect the sorption of RhB by the composite sorbents except for EDTA.