Nitrile-calixarene grafted magnetic graphene oxide for removal of arsenic from aqueous media: Isotherm, kinetic and thermodynamic studies.

A novel adsorbent was developed based on nitrile functionalized calix [4]arene grafted onto magnetic graphene oxide (N-Calix-MGO) for remediation of arsenic (III) ions from aqueous media. The nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The effective parameters on adsorption efficiency such as pH, adsorbent dosage, contact time, initial concentration, and temperature were studied. The adsorption process was provided with a high removal efficiency up to (90%) at pH 6 which followed by IUPAC Type II pattern. The mathematical models of kinetics and isotherm validated the experimental process. The adsorption kinetic is followed pseudo-first-order model with R > 0.9. The adsorption equilibrium was well fitted on the Freundlich model (R ∼ 0.96) as compared Langmuir model (R ∼ 0.75). Hence, the Freundlich model suggested a multilayer sorption pattern with a physisorption mechanism for arsenic (III) uptake ono developed nanocomposite with a sorption capacity of 67 mg/g for arsenic. The Gibbs free energy (ΔG° < -20 kJ/mol) showed As(III) uptake ono N-Calix-MGO nanocomposite was the physical adsorption mechanism.