Central Composite Design Based Adsorption Study of Malachite Green Dye Using Reduced Graphene Oxide Nano-Adsorbent

Abstract

  The adsorption of Malachite Green (MG) dye was well studied and elucidated from the liquid phase using reduced Graphene Oxide (rGO) nano-adsorbent. The desired levels of the factors were determined to be the amount of adsorbent of 0.2 g/L, pH of 8.5, the concentration of the dye as 100 mg/L and the sonication time of 50 min by Central Composite Design (CCD). The removal of the dye was found to be 95% at the optimum levels of the variables. Furthermore, the removal of the dye was higher at the higher values of the amount of adsorbent and pH. Langmuir and Temkin models were observed significant for rGO-MG dye system. The values of Gibb's free energy, the entropy and the enthalpy were found to be -10.502 KJ/mol, 34.314 KJ/mol and 0.147 KJ/mol.K, respectively. The kinetic data were also found well fitted to pseudo second order kinetics model for the said system. Afterwards, the cost of the process was found to be US$0.654/dm3. Therefore, the adsorption process effectively removed the dye from the simulated aqueous phase using rGO nano-adsorbent.