Application of Magnesium Oxide Nanoparticles for Sunset Yellow Removal in Aqueous Solutions: Adsorption Isotherm, Kinetic, and Thermodynamic Studies

In this research, the ability of magnesium oxide (MgO) nanoparticles to the adsorbent was studied for the removal of Sunset Yellow (SY) dye in an aqueous solution. Different techniques, including Fourier Transform InfraRed (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM) were employed to identify the adsorbed dye. Adsorption experiments were carried out in a batch mode with varying pHs, MgO concentrations, initial dye concentrations, contact times, and temperatures. To study SY adsorption's efficiency on the surface of MgO nanoparticles, pseudo-first-order, second-order, and intra-particle diffusion kinetic models were investigated. The pseudo-second-order kinetic model demonstrated a better fitting than other kinetic models (correlation coefficient: R2=0.99). The Freundlich model with an R2=0.93 value proved to fit with equilibrium data. In addition, thermodynamic parameters consisting of enthalpy, entropy, and activation energy were calculated too. It was noticed that the adsorption of SY on MgO was exothermic and spontaneous at low temperatures. The suggested adsorbent can be utilized for removing SY with an efficiency of more than 85%.