Author(s): HA Awala, MM El Jamal
Adsorption of three dyes methylene blue, methyl red, and fluoresceine onto feldspar have been investigated in this study. To assess the use of feldspar to remove dyes from aqueous solution, the effect of dye concentrations, pH, mass of adsorbent, temperature, and shaking speed have been evaluated. Methyl red and fluoresceine did not show any adsorp-tion at any pH, however methylene blue showed low adsorption. Pseudo-first and pseudo-second order kinetic models were applied to the adsorption data. Pseudo second order model was well in line with the experimental data. Langmuir, Temkin and Freundlich isotherm models were also investigated. According to Langmuir isotherm, the maximum adsorp-tion capacity was estimated as 0.66 mg/g at 40oC. The positive enthalpy indicated that the adsorption was endothermic. The negative values of Gibbs free energy revealed that adsorption was spontaneous.