Equilibrium and kinetic modelling of adsorption of methyl orange dye on palmyra palm nut

Abstract

The adsorption of methyl orange dye by an agro waste based activated carbon prepared from palmyra nuts was investigated in order to analyze the equilibrium and kinetic effects of the process, as well as assess its viability as an adsorbent. The activated carbon was prepared using chemical activation with phosphoric acid (H3PO4). The effect of various factors namely pH, initial adsorbate concentration, adsorbent dosage, contact time, and adsorbent particle size was studied to identify the adsorption capacity of palmyra nutshell. The percentage removal of dye increased with increasing adsorbent dosage and contact time, but decreased with increasing dye concentration and adsorbent particle size. The highest uptake of 97.5% was observed at a pH of 8.0.Adsorption data were modeled using Langmuir and Freundlich isotherms. The kinetic data were also applied to the pseudo-first-order and pseudo-second-order models. However, the adsorption process was well described by Langmuir isotherm and conformed well to pseudo-first-order and pseudo-second-order kinetic models. It was evident from the results that palmyra nutshell, a low-cost adsorbent can be used for the removal of dyes from aqueous solution.