Enhanced removal performance for methylene blue by kaolin with graphene oxide modification

In this study, graphene oxide modified kaolin (GO kaolin) composites (named 2% GK, 5% GK, and 10% GK) were synthesized by a facile method. Characterization results indicated the successful modification of GO on kaolin surface. To understand the dye removal performance of kaolin with GO modification, batch adsorption experiments were carried out using methylene blue (MB) as a model dye pollutant in various experimental conditions The adsorption results showed that the increase of GO content in modified kaolin composite could effectively enhance the removal of MB from aqueous solution in each experiment condition, which was attributed to the increase of special surface area and active adsorption sites. Kinetic analysis of MB adsorption by GO-kaolin samples was shown a better fitting to pseudo-second-order kinetic models. The adsorption isotherm data were better fitted to Langmuir isotherm models. The values of thermodynamics constants suggested that the adsorption reaction was endothermic in nature. Furthermore, adsorption process of MB on kaolin was changed after the introduction of GO. An excellent regeneration performance of 10% GK was observed via the regeneration experiment. The results show that kaolin modified with suitable GO content is a high-efficiency and reusable adsorbent in the removal of MB from wastewater. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.