Parkia speciosa (Petai) pod as a potential low-cost adsorbent for the removal of toxic crystal violet dye

Abstract

This study focused on the use of Parkia speciosa (Petai) pod as a potential adsorbent for the removal of crystal violet (CV) dye. Batch adsorption isotherm experiments carried out under optimized conditions were fitted to six isotherm models, namely Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Redlich-Peterson and Sips. Of these, the Sips model best described the adsorption isotherm of Petai pod for the removal of CV dye, giving a desirable adsorption capacity (q_max) of 163.2 mg g^-1. Adsorption kinetics was found to follow the pseudo-second order, and further, intra-particle diffusion played a significant role. This study also revealed that the adsorption of CV by Petai pod is influenced by the ionic strength of the medium. However, Petai pod showed resilience towards changes in medium pH.