Application of the graphene oxide/chitosan nanocomposite in the removal of methyl orange from aqueous solutions: a mechanism study

Graphene oxide (GO) and the functionalized graphene oxide with chitosan (GO-C) has been used for the removal of methyl orange from aqueous solutions. Batch experiments such as solution pH, amount of adsorbents, contact time, concentration of the methyl orange and temperature were carried out to study sorption process. Kinetic studies were well described by pseudo-second-order kinetic model for both adsorbents. Isotherm studies showed that the Langmuir isotherm for GO and GO-C were found to best represent the measured sorption data. Negative ∆G◦ values indicated the nature of spontaneous adsorption process. Physical sorption was suggested for the adsorption process. In addition, methyl orange molecules can be desorbed from GO-C up to 79.2% at pH =11 and that the consumed GO-C could be reutilized up to 5th cycle of regeneration