Adsorption characteristics of pomelo skin toward toxic Brilliant Green dye

Abstract

Pomelo skin was investigated for its adsorption ability toward Brilliant Green dye. An hour of shaking time was sufficient for the adsorbate-adsorbent system to reach equilibrium. Of the three isotherm models (Langmuir, Freundlich and Sips) used to fit the experimental data, the adsorption was best described by the Freundlich model, indicating multi-layer adsorption onto a heterogeneous surface, followed by the Sips and the Langmuir models. Adsorption was exothermic in nature and kinetics was best described by the pseudo second order and pore diffusion was found to be not the rate determining step. No adjustment of medium pH was required throughout the study and pomelo skin was able to maintain good adsorption capability under various ionic strength. Successful regeneration and reusability of spent pomelo skin, coupled with high maximum adsorption capacity (q_max) of 325 mg/g (Langmuir) and 400 mg/g (Sips) compared with many reported adsorbents, make pomelo skin a potential candidate to be considered in real life application of wastewater remediation.