Neodymium embedded ordered mesoporous carbon (OMC) for enhanced adsorption of sunset yellow: Characterizations, adsorption study and adsorption mechanism

Discharging coloring products in the natural streams has degraded water quality irreversibly over the past several decades. Order mesoporous carbon (OMC) was modified by embedding neodymium(III) chloride for the first time onto the surface of OMC to enhance the adsorption capacity for these contaminants. The modified OMCs were characterized using Nitrogen Adsorption-Desorption Isotherm, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FT-IR) spectra, and X-ray Photoelectron Spectroscopy (XPS). TEM images of neodymium modified OMCs revealed ordered structure. Analysis of FT-IR and XPS spectra revealed the formation of hydroxides coordinated with neodymium(III). In the lower pH region, the modified OMCs have increased positively charged sites for adsorption of anionic sunset yellow. Adsorption kinetics revealed that the adsorption of sunset yellow was better fitted with the Pseudo-Second-Order Kinetic model than the Pseudo-First-Order Kinetic Model. The adsorption isotherms were well fitted with Langmuir Model depicting the formation of monolayer adsorbates onto the surface of OMC-Nd. The maximum monolayer adsorption capacity of 285.7 mg g(-1) was observed for OMC-2Nd. The overall adsorption capacity was increased by 40% compared to the virgin OMC. The interaction mechanism involved ligand exchange between Nd-modified OMC and sunset yellow.