Dye removal using the solid residues from Glossogyne tenuifolia based on response surface methodology

Glossogyne tenuifolia is one of the most important commercial crops in Taiwan. Many beneficial biological effects from Glossogyne tenuifolia have been demonstrated. However, considerable quantities of solid residues are generated after processing this crop, which negatively impacts the environment. This study utilizes the solid residues generated as an adsorbent for the removal of the dyes. The potential adsorbent was characterized using scanning electron microscopy (SEM) and Fourier transform infrared analysis (FTIR). The adsorption performance the adsorbent was evaluated using Congo red and malachite green dyes, and the effects of the pH, temperature, and initial dye concentration were investigated using a three-level Box-Behnken design response surface methodology. The adsorption kinetics and isotherm data were well fitted to a pseudo-second-order kinetic model and the Freundlich isotherm model, respectively. A thermodynamic analysis was conducted and revealed that the dye adsorption was a spontaneous, endothermic and physical process. This study indicated that solid residues from Glossogyne tenuifolia can be considered as a potential adsorbent for waste water treatment. (C) 2017 Elsevier B.V. All rights reserved.