A tailored magnetic composite synthesized by graphene oxide, chitosan and aminopolycarboxylic acid for diminishing dye contaminant

Abstract

This research study aims to remove methyl violet from aqueous solutions with a novel composite. The composite was synthesized by magnetite nanoparticles decorated with amino-silane, graphene oxide, and grafted chitosan-diethylenetriaminepentaacetic acid. The adsorbent was characterized by FT-IR, XRD, FESEM, TEM, EDX, elemental mapping, TGA, VSM, and BET. The Central Composite Design was used for planning the adsorption experiments. The maximum dye removal was equal to 94.87% for an initial dye concentration of 10.0 mg L−1. The coulombic attraction, H-bonding, and pi stacking interactions were proposed as the key factors for dye removal. The initial pH and temperature were fixed at 9.8 and 52.3 °C and the adsorbent dosage was 2.0 g L−1 in the kinetics and equilibrium studies. The adsorption process was almost completed within five min. The modified pseudo-n-order model was the best equation to fit the kinetics data. It was demonstrated that film diffusion was the rate-limiting step at the initial stages of dye removal after which the dye adsorption was the rate-determining step. The equilibrium data was fitted by modified Langmuir–Freundlich isotherm and the maximum equilibrium adsorption was 243.8 mg g−1. Besides, the composite recovery was done by a low amount of acidic eluent. The adsorption efficiency did not change even after five desorption-adsorption cycles.