Synthesis and characterization of a starch–AlOOH–FeS2 nanocomposite for the adsorption of congo red dye from aqueous solution

Abstract

This work described the synthesis and characterization of a starch–AlOOH–FeS₂ nanocomposite for the adsorption of congo red (CR) dye from aqueous solution. The morphology of the starch–AlOOH–FeS₂ was characterized by using scanning and transmission electron microscopy, N₂ adsorption–desorption isotherms, X-ray photoelectron spectroscopy, and fourier transform-infrared spectroscopy. The adsorption of CR onto starch–AlOOH–FeS₂ was evaluated as a function of contact time, solution pH, concentration and temperature. The adsorption results demonstrate that the maximum removal of CR was found to be at pH 5. The adsorption kinetics data fitted well to the pseudo first-order equation whereas the Freundlich equation exhibits better correlation to the experimental data. Thermodynamic parameters, such as the standard free energy change (ΔG°), the standard entropy change (ΔS°) and the standard enthalpy change (ΔH°), were also evaluated. The results suggested that starch–AlOOH–FeS₂ is a potential adsorbent for CR dye removal from aqueous solution.