Removal of congo red dye from aqueous solution by using limonia acidissima shell as adsorbent

Abstract

This research paper highlights the removal of a congo red from aqueous medium by using Limonia acidissima shell. Various factors such as initial dye concentration, dosage of adsorbent, time contact, effects of temperature and pH were studied. The characterizations of adsorbent were done by XRD and FTIR analysis. The equilibrium data analyzed using Freundlich, Langmuir, Temkin and Dubinin Radushkavich isotherm models. Out of four adsorption isotherm, the R2 value of Langmuir isotherm model was the highest. The maximum monolayer exposure from Langmuir isotherm model was determined to be 84.48mg/g, the separation factor (RL) indicating favorable sorption is 0.76. The kinetic results inveterate that pseudo-first-order kinetic model explained the removal of Congo red dye by Limonia acidissima shells in a better way. The rate constant of 2.8 mg/g min.-0.5. was shown by intra-particle diffusion model. Thermodynamic parameters like Gibb's free energy (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) illustrated that Congo red dye adsorption onto Limonia acidissima shells was realistic, spontaneous and endothermic.