Bioadsorption of 2,6-Dichlorophenol from Aqueous Solution onto Plantain and Pineapple Peels Mixture Used as Adsorbent: Optimization Studies Based on Taguchi Method, Batch Equilibrium, and Kinetic Modelling

Abstract

The feasibility of using pineapple/plantain peels mixture to remove 2, 6-dichlorophenol (2,6-DCP) from its aqueous solutions was investigated under batch mode. The effects of factors such as pH, initial 2, 6-DCP concentration, temperature and pineapple/plantain peels adsorbent ratio on the removal process were evaluated. Four factors and three levels according to Taguchi’s (L9) orthogonal array were used to assess and optimize the bioadsorption behaviour of pineapple/plantain peels mixture. Analysis of variance was applied to determine the significant factors that affect bioadsorption.  The levels of significant factors were optimized using Signal to Noise ratio. The results showed that bioadsorption of 2, 6-DCP was dependent on these factors. However, pH was the major factor that affects the percentage (%) removal of 2,6-DCP with its % contribution of 52.23. An optimum parameter combination for the maximum percentage removal of 2,6-DCP was obtained using the analysis of Signal to Noise (S/N) ratio. The best conditions for bioadsorption of 2,6-DCP were determined by the Taguchi method and desirability approach as pH = 7, initial 2,6-DCP concentration of 300 mg/l, temperature 50 °C, and pineapple/plantain adsorbent ratio of 2:1. The equilibrium bioadsorption data were analyzed by Langmuir and Freundlich isotherm models. The Freundlich isotherm model provided the best fit (R² = 0.9980) to the experimental data. The maximum monolayer bioadsorption capacity ( ) was found to be 76.92 mg/g. The bioadsorption kinetics data of 2, 6-DCP were analyzed by pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The pseudo-second order kinetic model gave the best fit. Therefore, pineapple/plantain peel adsorbent mixture has potential for application as an effective bioadsorbent for 2, 6-DCP removal from aqueous solution.

Keywords: Bioadsorption; Bioadsorption isotherms; Kinetics; Pineapple-Plantain peel mixture; 2, 6-Dichlorophenol; Taguchi method.