Adsorptive Removal of Erythrosin B Dye onto Terminalia Catappa Endocarp Prepared Activated Carbon: Kinetics, Isotherm and Thermodynamics Studies

Abstract

The effectiveness of activated carbon prepared from Terminalia catappa (almond) endocarp via thermal and chemical activation for the adsorption of Erythrosin B (EB) dye was investigated. The thermally activated sample was impregnated with 60% by weight phosphoric acid (H₃PO₄) in 1:2 weight basis of activating agent to Terminalia catappa (almond) endocarp. Physico-chemical analyses results revealed the potential suitability of the prepared acid activated almond endocarp (AAAE) as an adsorbent. Further results obtained show that particle size, adsorbent dosage, pH, time, ion concentration and temperature had significant effect on the percentage of EB dye adsorbed. Freundlich model best fitted the experimental data compared to the results obtained for Langmuir and Dubnin-Radushkevich isotherm models. The adsorption kinetic data was modelled using the pseudo first-order, pseudo second-order and Elovich kinetic models. The kinetics of the adsorption process best followed the Elovich model. Thermodynamic parameters: Gibb’s free energy (ΔG^∘), enthalpy change (ΔH^∘) and entropy change (ΔS^∘) were determined to evaluate the feasibility of the process and the effect of temperature on the system. The negative free energy obtained confirms the feasibility of the adsorption process. The adsorption of EB on the acid activated almond endocarp was found to be exothermic.

Keywords: Adsorption; Almond endocarp; Erythrosin B; Isotherm; Kinetics; Adsorption thermodynamics