Preparation of Graphene Oxide/Chitosan Pellets and Their Adsorption Properties for Congo Red

A facile and easily separated adsorbent, graphene oxide (GO) pellets wrapped by chitosan (GOP) were prepared. Batch adsorption studies were carried out to study the adsorption properties of congo red onto GOP by varying the experimental parameters such as the contact time, the initial concentration of congo red, the solution pH, the adsorbent dose, and the temperature. The kinetic studies showed that the adsorption data fitted a pseudo-second-order model well. The isotherm analysis showed that the adsorption data fitted the Freundlich model well. The adsorption mechanism was mainly attributed to electrostatic interactions, pi-pi stacking interaction, hydrogen bond, and van der Waals force. Thermodynamic studies indicated that the adsorption process was endothermic and spontaneous.