Adsorption of Brilliant Green dye from aqueous solution onto red clay

This study was aimed at the adsorption of Brilliant Green (BG) dye on naturally existing red clay (RC) through batch adsorption experiment. Adsorbent characterization showed Brunauer-Emmett-Teller surface area 100.28 m2/g, pore volume 0.88 cm3/g, and pore diameter 148.2 Å. Batch studies were carried out to investigate the effect of experimental factors such as pH (2-10), particle size (58-150 μm), adsorbent dose (0.3-1.5 g/L), contact time (5-1500 min), initial dye concentration (20-100 mg/L), and temperature (25-65 °C) on the adsorption of BG dye. Langmuir (R2 = 0.993), Freundlich (R2 = 0.997), Hansley (R2 = 0.997) and Redlich-Peterson (R2 = 0.999) isotherms were fitted to describe the equilibrium of BG adsorption process. Isothermal models showed that BG adsorption was a favorable process on RC. Adsorption kinetics were well fitted by Pseudo-second order kinetic model (R2 = 0.999). Thermodynamic study revealed that BG adsorption on RC was spontaneous, favorable and physiosorptive. The maximum adsorption capacity of RC was found to be 125 mg/g. These results showed that BG dye can be effectively removed from aqueous solution employing RC as a cheap adsorbent.