OPTIMIZATION AND SORPTION ISOTHERMS ANALYSIS OF ANIONIC DYE EOSIN YELLOW DECONTAMINATION BY GOETHITE ADSORBENTS

Abstract

In this work, removal of Eosin Yellow (EY) using Natural Goethite (NGT) and Synthetic Goethite (SGT) particles was studied using batch equilibrium technique. Different parameters such as initial dye concentration, particle size (NGT only), pH, and adsorbent dose were optimized to investigate the sorbents efficiency for the dye. The experimental data were tested for fitness into five common adsorption isotherm models. The various equilibrium parameters studied were found to have remarkable influence on the adsorption processes, showing optimum removal at dye concentration (150 mg/L for EY-NGT and 200 mg/L for EY-SGT), NGT particle size (0.112mm), pH (2), and dosage (0.05g), with SGT exhibiting relatively higher adsorption efficiency. The sorption data fitted well the various isotherm models in the order; Freundlich (R2 = 0.9032) > Temkin (0.8294) > Langmuir (0.8268) > DKR (0.6431) > Flory Huggins (0.616) for EY-NGT, and Langmuir (0.9831) > Flory Huggins (0.9639) > Freundlich (0.9597) > Temkin (0.8944) > DKR (0.5993) for EY-SGT. The monolayer adsorption capacity (qm) was calculated as 1.17 and 20.80 mgg-1 for NGT and SGT respectively. Additionally, combined information obtained from the isotherm study revealed that the processes were favourable, spontaneous and proceeded by a multilayer physical adsorption on already chemisorbed layer. Conclusively, the results of this study have provided useful information on the optimum working condition and mechanism of EY uptake onto goethite surfaces.