Equilibrium and Kinetics Investigations on Sorption of C.I. Basic Red 14 onto Low-cost Feldspar

Feldspar as a low-cost mineral adsorbent based on silica was used to removal a cationic dye, C.I. Basic red 14 (Brilliant red 4G), from aqueous solution. The adsorbent was characterized using scanning electron microscopy (SEM), X-ray Fluorescence (XRF) and Fourier Transform Infra-Red spectroscopy (FTIR). The effect of some parameters such as the amount of adsorbent, contact time, the initial concentration of dye, initial pH and electrolyte on dye removal was investigated. Results showed that dye removal increased by increasing pH; contact time and adsorbent dosage, whereas decreased by increasing the dye concentration. Also, the addition of electrolyte caused a negligible decreasing in dye removal. It took about 1 hour to equilibrium the feldspar with C.I. Basic red 14 and dye removal efficiency was 96%. So, feldspar is a suitable and powerful absorbent for removal of cationic dye from aqueous solutions. Equilibrium isotherms were analyzed by Langmuir, Freundlich, Temkin, Redlich-Peterson, and Dubinin–Radushkevich adsorption models and found that the experimental data were correlated reasonably well with Freundlich isotherm. The adsorption kinetics was studied by using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models and realized the adsorption of C.I. Basic red 14 on feldspar followed the pseudo-second-order equation which indicates to chemical sorption.