Graphene Oxide Decorated with Nickel Cobaltite Nanoparticles as an Adsorbent for Cationic Methyl Green Dye: Kinetic, Isotherm, and Thermodynamic Studies

In this study, graphene oxide (GO) flakes were embellished with NiCo2O4 2 O 4 (NC) nanoparticles by in situ deposition, and the produced composite (NC: GO) was utilized as an adsorbent to remove methyl green dye (MG) from aqueous solutions. The successful coating of graphene oxide with nickel cobaltite nanoparticles (NC) was verified using FT-IR, SEM and X-ray diffraction (XRD) studies. The crystalline particle sizes of NC nanoparticles and NC nanoparticles decorated GO were 10.53 nm and 9.30 nm respectively. The impact of several experimental factors, including time of contact, the dosage of adsorbent, and temperature were investigated. The optimal contact time and adsorbent dosage were 120 minutes and 3 mg/L, respectively. The adsorption data fitted better to Freundlich isotherm. Four kinetic models were used to track the adsorption process: a pseudo first-order equation, a pseudo second-order equation, an intraparticle diffusion equation, and the Boyd equation. Modeling of the experimental data revealed that the adsorption kinetics was well represented by the pseudo-second order model(R2=0.9945) 2 =0.9945) with a rate constant of 3.2 x10-3-3 (g/mg. min). MG dye is gradually absorbed by the NC nanoparticles through intraparticle diffusion and is afterward held in smaller pores. The values of the thermodynamic analysis showed that the MG dye adsorption was an endothermic in nature, spontaneous and phyisorption process.