Characterization of Powdered Pineapple (Ananas comosus) Crown Leaves as Adsorbent for Crystal Violet in Aqueous Solutions

Abstract

This study investigated the potential of powdered pineapple crown leaves (PCL) as an effective adsorbent for the removal of crystal violet (CV) from aqueous solution using batch and column studies. The PCL was simply washed, dried, and powdered prior to adsorption. FTIR analysis of PCL surface before and after adsorption revealed that hydroxyl and carboxyl functional groups are among the groups responsible for surface bonding with CV. SEM photographs of the adsorbent before and after revealed clumping on the surface of PCL, possibly indicating the sites where CV had been adsorbed. Elemental analyses through XRF revealed that K+ ion is a major part of PCL, and this could explain the affinity of CV for PCL through cation-π interactions. Batch adsorption studies were carried out as a function of biosorbent dose and initial dye concentration. The %removal of PC increased as biosorbent dose was increased, but the biosorbent capacity decreased. This was attributed to scattering of CV to more active sites in PCL. Biosorbent capacity increased as the initial dye concentration was increased, while %removal decreased. This was due to the faster saturation of the substrate. For equilibrium studies, Langmuir and Freundlich isotherm models were applied. The equilibrium data fitted well to Langmuir isotherm with a maximum monolayer adsorption capacity of 6.4935 mg/g. The relatively high maximum biosorption capacity coupled with the absence of chemical treatment needed before adsorption makes PCL an effective and sustainable biosorbent for the removal of CV.